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ADVANCED CODAS USER`S MANUAL

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1. 1 1 or 1 1 missing sqrt 1 sqrt 1 missing digit 1 _ 1 2 too many constants illegal constant 4 1 Specified channel number must not exceed the total number in the file 2 Phase shift argument must not exceed 20 3 Total number of constants appearing in the formula must not exceed 21 4 Constants specified in the formula must fall within the range of 1 79E7308 to 1 79 308 5 Each underlined character indicates where WAO error detection code places the cursor to indicate the location of the problem Immediately upon detecting an error in the formula WAO software enters an editor mode that allows a convenient method for correcting the formula The gt and lt cursor control keys may be used to move the cursor across the characters of the formula HOME and END keys move to the beginning and end of the formula line the INS key may be used to toggle between the insert and overwrite typing modes pressing the DEL key deletes the character at the cursor and pressing ESC clears the entire formula line MENU LEVEL CALCULATED ERROR DETECTION If while generating the calculated channel an arithmetic error occurs the software will display Arithmetic error at TBF X at the bottom of the menu screen Quantity X indicates the elapsed time in seconds from the beginning of the file TBF stands for Time from Beginning of File where the error occurred When you return to the playback program
2. 1988 2009 Dataq Instruments Inc ADVANCED CODAS Increasing the threshold percentage will mask these minor inflections leaving only true cyclic peaks and valleys detected PVC result when threshold is too high FIGURE 6A 8 This figure demonstrates what can happen when the threshold level of the PVC function is too large The algorithm fails to detect cyclic changes in waveforms that are smaller in amplitude than others in the waveform stream Decreasing the threshold percentage will increase the sensitivity of the algorithm to allow detection of smaller amplitude albeit valid waveform cycles PEAK CAPTURING IN THE PRESENCE OF WAVEFORM ARTIFACT Another consideration when using PVC is to ensure that the waveform data being peak captured is free of artifact see FIGURE 6A 9 such as that caused by gain changes loose signal connections and large step changes caused by stopping then starting disk storage during data acquisition Should the waveform you need to peak capture contain such artificial components there are two approaches that may be used to avoid confusing the PVC algorithm 1 Try peak capturing the waveform as is using the default threshold level of 30 If your result indicates that more sensitivity is needed which will probably be the case if step changes are present try decreasing the threshold level until the waveform is properly peak captured In the presence of very large step changes it may not be possible to properly
3. Report Generator Features The Advanced CODAS Report Generator is used to generate a report of peak and valley detected waveforms The Report Generator may be configured to report the value of an input waveform coincident with a peak and or valley tag the period of the waveform or its mean value on a cycle by cycle or 2 32 767 cycle average Supported Report generator file formats are a spreadsheet ASCII compatible format and ASY ST ASY STANT format Waveform Copy Feature With this feature you can copy a selected channel or portion of a channel from a source file to a selected channel or portion of a channel in a destination file You can transfer the calibration screen scaling and event markers of the copied channel while leaving the sample rate of the destination file alone 6A 2 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS GETTING READY TO USE ADVANCED CODAS INSTALLING ADVANCED CODAS ROUTINES Before installing Advanced CODAS verify the following e Your computer contains at least 640K of memory e You are using PC DOS or MS DOS version 3 0 or greater e You are using AT CODAS or WINDAQ Waveform Browser playback and analysis software You will find the Advanced CODAS software on the same The WinDaq Resource CD that you installed your WinDaq software from When you insert the CD a welcome window will appear Select Install Software and then select Advanced CODAS You will need the passw
4. This moves the window in a negative time direction to the last enabled event marker positioning the data cursor directly on top of the event marker 3 Edit the file AT CODAS User s To delete a marker press the DEL key on your computer keyboard s key pad while the the waveform playback program cursor is directly over a peak or valley marker To insert a peak or valley marker position the waveform playback program s cursor at the point on a waveform where you d like a marker to be placed Pressing the INS key the first time will place a peak marker positive going at the point of waveform cursor intersection Pressing the INS key a second time will place a valley marker negative going at the point of waveform cursor intersection Alternate pressing of the INS key will toggle between peak and valley marker placement WINDAQO User s To delete a marker choose Delete Mark from the Edit menu This deletes an event marker that is coincident with the waveform cursor To insert a peak or valley marker choose Insert Mark from the Edit menu This inserts a peak marker positive going at the point of waveform cursor intersection Repeating the Edit Insert Mark action toggles the peak marker to a valley marker negative going PEAK CAPTURING CHANNEL ONE s WAVEFORM As with all Advanced CODAS functions channel one s analog waveform is considered sacred by PVC meaning that operating on this channel is not directly possible However chann
5. Advanced CODAS s integrator is its ability to allow you to define whether integration will be applied to positive and negative positive only negative only or the absolute value of input signal transitions relative to zero reference Refer to FIGURE 6A 4 for a graphic demonstration of how waveform rectification can assist in waveform analysis of integrated waveforms 3 An Optional HOLD Function For every integration mode of operation a hold feature can be enabled that forces CALC to hold the peak integral value that was calculated before a reset In applications where only the peak integral value is of interest use of the hold feature yields an uncluttered histogram like waveform For applications that require a determination of the integral value at discrete steps before reset the hold option may be disabled Refer to FIGURE 6A 4 for a graphic example of the integrator s output with the hold feature enabled 4 Adjustable RESET INTEGRATION PERIOD Advanced CODAS s integration program does not force the integral to reset only on zero crossings By supplying a sample number period between 2 and 32 767 samples the integral will reset upon reaching the specified sample count For example given a waveform sampled at 1 000 samples per second specifying an integration period of 1000 will force the integral to reset every one second 1 1 000 seconds sample 1 000 samples 1 second A running integral one that never resets of a waveform may be ge
6. RG Whenever it is enabled to report on a peak captured waveform RG will report six values per cycle or group of c J ycles if a cyclic average is selected These in order of appearance in the output file are Waveform value at valley marker If valley markers are present on the input waveform the value at waveform valley marker intersection will be reported in the waveform s unit of measure If valley markers are not present in the waveform a value of zero 0 will be reported 2 Waveform value at peak marker If peak markers are present on the input waveform the value at waveform peak marker intersection will be reported in the waveform s unit of measure If peak markers are not present in the waveform a value of zero 0 will be reported Waveform mean value The cyclic mean value of the waveform will be reported where a cycle is defined by you to be one of the following From peak marker to peak marker From valley marker to valley marker e From valley marker to peak marker e From peak marker to valley marker For example in the case of an arterial blood pressure waveform a cycle could be defined as valley to valley The mean value of the waveform would be reported as that calculated between these markers Mean values are calculated by RG as the summation of all data points between the indicated markers divided by elapsed time 4 Cycle timing Using the cycle definition defined in item 3 above RG
7. channel number Output channel number Smoothing factor Example d path filename ext specifies the file name containing the waveform to be moving averaged The disk drive specifier path and file name extension are optional A basic file name must be supplied DOS Command Line X is the channel number of the waveform to be moving averaged where 1 lt X lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 1 lt X lt 144 for WINDAQ EXP multiplexer users Y is the channel number within the file to contain the moving averaged result where 2 lt Y lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 2 lt Y lt 144 for WINDAQ EXP multiplexer users If Y lt the total number of channels contained in the file before the moving average operation then the result is placed in waveform channel Y and the original contents of channel Y are overwritten and destroyed If Y gt the total number of channels contained in the file before the CALC operation then the result is appended to the input file with the channel number equal to the original total number of channels 1 Z specifies the moving average span to be applied to the input waveform where 2 lt Z lt 10 000 samples for low pass filter simulation or 9 999 lt Z lt 2 samples for high pass filter simulation Higher values of IZI apply greater smoothing constraints on the resulting waveform If Z 1 then no smoothing is applied and the specified input channel
8. is found in ASYST ANT data files only The last comment This file MUST BE TRANSPOSED is found in ASYST ANT data files only and serves as a reminder to transpose the data file before operating on it The transpose command TRANS inverts the sense of the two dimensional array generated when an RG file is imported to ASYST or ASYSTANT For example assume data for 500 cycles is imported by ASYSTANT The two dimensional array initially created and stored in an array variable assume array variable R is used has a dimension of 500 x 6 Placing array variable R on the stack then typing TRANS changes the sense of the array to 6 x 500 After restoring the transposed array to R analysis may begin 6A 33 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS RG DOS COMMAND LINE AND CALC MENU SYNTAX REPORT argument argument d path filename ext X Y Z R A where CALC Menu Prompt Channel to report Select cycle definition Select file output format Select cycle units Select cycle average Example d path filename ext specifies the file name containing the waveform to be reported The disk drive specifier path and file name extension are optional A basic file name must be supplied DOS Command Line X is the channel number of the peak captured waveform to be reported where 1 lt X lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 1 lt X lt 144 for
9. last valid entry 2 Upon detecting any keyboard entry other than ENTER the invalid response will be erased and your new entry will appear at the cursor Upon pressing ENTER this new entry will be either accepted or rejected as described ACTIVATING MENU SELECTIONS Following your entry of specific menu items action is taken at any menu level by pressing the ESC key on your keyboard The last entry on any menu level determines whether the software will C ontinue or E xit If this selection was C then the appropriate analysis action will be activated Following completion of the selected analysis procedure control will be returned to the activating menu with the cursor positioned at the top menu item Note that at this point the Continue Exit selection has been changed to E xit thus allowing you to simply press ESC to exit and return to the first level menu Note also that upon changing the input file name or entering a blank line assuming you want to operate again on the same file the state of the Continue Exit selection changes to C ontinue Should E xit be enabled from the first level menu at the time the ESC key is pressed control will be returned either to the waveform playback program or DOS depending upon which was active at the time CALC was enabled 6A 6 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM ARITHMETIC OPERATIONS USING ADVANCED CODAS GENERAL The Waveform Arithmetic Operati
10. of two packages provided by ASYST Software Technologies ASYST or ASYSTANT The name of the RG created file is fixed and carries the same basic name as the waveform file used as the input but with a AX extension X will be a number ranging from 2 to 29 for AT CODAS and WINDAQ non EXP multiplexer users or from 2 to 144 for WINDAQ EXP multiplexer users and will be equal to the channel number of the input waveform file being reported For example if channel number 16 in file RUN1 DAT is reported the ASYST ANT compatible file created on disk will carry a file name of RUN1 A16 Imported data is handled by ASYST or ASYSTANT as a two dimensional array where one dimension is the number of cycle sets imported and the second dimension is always 6 The second dimension handled as rows by ASYSTANT and ASYST are each of the six data categories described in the parameters section above Both file formats contain the following comments which describe various parameters of the data file 1 Name of the parent data file from which the peak captured data was derived 2 The channel number of the peak captured waveform being reported 3 The engineering units of the reported waveform 4 The sample rate at which the peak captured waveform was acquired 5 The cycle definition used by RG may be V V P P P V or V P 6 The number of cycles over which point values are averaged 1 32 767 7 This file MUST BE TRANSPOSED This comment
11. peak capture the waveform using this approach 2 Isolate clean waveform data from artifact through use of the waveform playback program s COPY PASTE FUNCTION Separate data files may be created each containing clean waveform data that may be peak captured individually Waveform data containing artifacts al Na FIGURE 6A 9 This figure is an example of a waveform containing artifacts which may interfere with PVC s ability to extract proper peak and or valley information Approach such situations with caution and try using the techniques described above to extract useful information 6A 25 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS GOOD DATA ACQUISITION PRACTICE LEADS TO GOOD PVC PERFORMANCE The time to start thinking about peak and valley capture of waveform data is during data acquisition The PVC algorithm is a very forgiving utility that can adjust to many variations in waveform quality However it can have difficulty if poor data acquisition procedures are used Listed below are some suggestions related to data acquisition practice that will help you maximize your productive use of PVC 1 Ensure that the dynamic range of the A D converter is maximized by closely matching the full scale voltage of your input signal to that of the A D converter A D cards with programmable gain can be used to great advantage in this area by selecting gain factors on a channel by channel basis to compensate for varyin
12. point in the source file that you would like to begin copying 6A 36 Copyright 1988 2009 Dataq Instruments Inc
13. 3 Using TEST DAT located on drive C subdirectory RUNI as the input waveform data file multiply channel times the natural log of the difference of channel 3 from channel 2 Store the result as waveform channel 15 6A 11 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM DERIVATIVES USING ADVANCED CODAS GENERAL The waveform derivative program provided with Advanced CODAS allows any waveform within a CODAS or WINDAQ acquired data file to be differentiated with respect to time The differentiated waveform is placed within the same file by either inserting the waveform as an additional channel assuming less than 29 original channels or by overwriting an existing channel If the latter approach is selected care should be taken to ensure that the original content of the overwritten channel is not pertinent since it will be destroyed AUTOMATIC ENGINEERING UNIT CALIBRATION When a waveform is differentiated by Advanced CODAS the calibration information associated with the data is automatically adjusted so that when the differentiated waveform is reviewed through the waveform playback program a display of its value at any given point is in appropriate engineering units The engineering unit tag associated with the calculated waveform and displayed on the waveform playback program screen will always be s where is the channel number of the waveform used as an input to create the derivative and s denote
14. D ERROR DETECTION If an arithmetic error occurs while generating the calculated channel the screen will echo the formula starting with the operator or operand involved with the error along with an error message describing the nature of the error For example should you attempt ARITH DATA DAT 5 1 2 and channel 2 at one point equals zero the following messages will be echoed to the screen 2 fp divide by 0 at TBF x As with menu level operations the value equated to TBF defines the location of the offending operation relative to the beginning of the data file in seconds When you run the playback program the cursor will automatically be positioned at the exact point where the error exists WAO AND DYNAMIC RANGE ERRORS The WAO program performs all calculations using double precision floating point operations At the end of a calculation operation the floating point numbers are converted to 14 bit signed integers written to the CODAS or WINDAQ file and the channel s m and b scaling constants are adjusted accordingly During the conversion process to 14 bit precision the highest value floating point numbers are scaled to display at the top of the window and the lowest at the bottom The presence of transient information in the resulting waveform may damage lower value accuracy since a one count change in the 14 bit number represents a comparatively huge step change in the floating point output WAO DOS COMMAND LINE and CALC MENU SYNTA
15. If Y gt the total number of channels contained in the file before the CALC operation then the result is appended to the input file with the channel number equal to the original total number of channels 1 A specifies the type of integration to be performed as follows If A B ipolar then channel X will be integrated over both positive and negative transitions relative to zero reference If A then only the positive going transitions of channel X relative to zero reference will be displayed and integrated If A then only the negative going transitions of channel X relative to zero reference will be displayed and integrated 6A 16 Copyright 1988 2009 Dataq Instruments Inc Integral reset period Level reset units External reset Hold integrated waveform Example ADVANCED CODAS If A A bsolute then the integral will be applied to the absolute value of channel X relative to zero reference Z specifies the reset period of the integral where 0 lt Z lt 32767 If Z 0 then the integral will reset upon every zero crossing of the input waveform IF Z 1 then the specified waveform is integrated from beginning to end without recognizing zero crossing as a valid reset condition Reset may still occur upon a specified level or external event if these features are enabled If 2 lt Z lt 32767 then the integral will reset after every Zth sample to a maximum of 32 767 samples L evel r
16. Inc ADVANCED CODAS Selectable LEVEL RESET Resetting on an EXTERNAL WAVEFORM EVENT Waveform Integral DOS Command Line and CALC Menu Syntax WAVEFORM MOVING AVERAGE USING ADVANCED CODAS General Automatic Engineering Unit Calibration Applying Advanced CODAS s Moving Average Program Waveform Moving Average DOS Command Line and CALC Menu Syntax WAVEFORM PEAK AND VALLEY CAPTURE USING ADVANCED CODAS General Peak and Valley Capture PVC Operation Peak Capturing in the Presence of Waveform Artifact Good Data Acquisition Practice Leads to Good PVC Performance Editing PVC selected Event Markers Peak Capturing Channel Ones s Waveform PVC DOS Command Line and CALC Menu Syntax WAVEFORM RECTIFICATION USING ADVANCED CODAS General Automatic Engineering Unit Calibration Advanced CODAS s Waveform Rectification Features Positive only Half wave Rectification Negative only Half wave Rectification Absolute Value Waveform Rectification DOS Command Line and CALC Menu Syntax REPORT GENERATION OF PEAK VALLEY EVENTS USING ADVANCED CODAS General Defining the Parameters Reported by RG RG Data File Creation and Storage Formats RG DOS Command Line and CALC Menu Syntax WAVEFORM COPY FEATURE USING ADVANCED CODAS General Waveform Copy DOS Command Line and CALC Menu Syntax Copyright 1988 2009 Dataq Instruments Inc 6A 20 6A 23 6A 29 6A 32 6A 35 ADVANCED CODAS AN INTRODUCTION TO ADVANCED CODAS The Advanced CODAS package from D
17. S Invoking CALC from COPY AND PASTE The COPY AND PASTE FUNCTION of playback software allows any range of waveform information to be extracted from a waveform data file The extracted waveform information can then be converted into a data storage format as specified through the COPY PASTE menu of AT CODAS or through the Save As dialog box of WINDAQ Waveform Browser When the CALC option is selected using either method the following events take place 1 A new data file is created on disk carrying the file name you supplied when COPY PASTE was first invoked using AT CODAS or when the Save As dialog box was opened using WINDAQ Waveform Browser 2 The specified range of waveform information is extracted copied from the currently active waveform data file then pasted into the newly created file using the CODAS with data file header format Note that CALC will not produce accurate results if the data is pasted in a compressed format 3 CALC is run and initialized with the default file name of that containing the pasted waveforms At this point the CALC first level menu will be displayed and you may execute your required CALC function s on the data file containing the pasted waveforms or even change the default file name to operate on another file When CALC is exited control returns to the playback software in the state that existed just before COPY PASTE was selected using AT CODAS or just before Save As was selected using WINDAQ Wavef
18. S s integration routine allows control over reset conditions and signal polarity Waveforms may be integrated over bipolar positive only negative only or absolute value transitions relative to zero reference Reset may be programmed to occur upon zero crossing of the input waveform after n samples where 2 lt n lt 32 767 at a specified level or as triggered by a different channel such as an ECG waveform Another option allows 0 integrated values to be displayed in a sample hold fashion where the previous integrated value is held until a new value is available When this sample hold feature is enabled reset transitions of the integrated waveform are not displayed Waveform Arithmetic Functions This operation allows any number of waveforms contained in the data file to be combined mathematically according to a user defined arbitrary formula Supported operations are exp log log sqrt and abs Another operation supports phase shifting of the input waveform in precise increments 6A 1 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS Waveform Moving Average Features Advanced CODAS s waveform moving average program allows waveform filtering independent of Advanced CODAS s waveform derivative program It can be used to achieve waveform smoothing in the presence of noise or with the proper filter factor the mean value of a given periodic waveform may be extracted or subtracted from the input wav
19. WINDAQ EXP multiplexer users Y defines waveform cycle end points used for calculating mean values and reporting the cycle interval in seconds rate in terms of cycles per second Hertz or rate in terms of cycles per minute Valid Y entries are Y PP for cycles defined from peak to peak Y VV for cycles defined from valley to valley Y PV for cycles defined from peak to valley Y VP for cycles defined from valley to peak Variable Z defines the format of the output file to be either spreadsheet or ASYST and ASYSTANT compatible Z A fora ASYST and ASYSTANT compatible file format Z L for a spreadsheet compatible file format Optional variable R defines whether a cycle is reported as an interval in seconds or as a rate in Hertz cycles per second or cycles per minute The default state of R is interval R T reports cycle time in seconds default R H reports cycle rate in Hertz cycles per second R M reports cycle rate in cycles per minute Optional variable A defines the number of consecutive cycles to average before reporting where 1 lt A lt 32 767 The default value of A is 1 each cycle value is reported without averaging REPORT DATA1 DAT 4 VP A Generates file DATA1 A4 containing cycle by cycle point values of waveform channel 4 of file DATAI DAT Output format is ASYST and ASYSTANT compatible with a cycle definition of valley to peak Cycle timi
20. X ARITH argument argument d path filename ext Y expression where d path filename ext specifies the file name containing the waveforms to be manipulated The disk drive specifier path and file name extension are optional A basic file name must be supplied CALC Menu Prompt DOS Command Line Output channel number Y is the channel number within the file to contain the calculated waveform where 2 lt Y lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 2 lt Y lt 144 for WINDAQ EXP multiplexer users If Y lt the total number of channels contained in the file before the operation then the result is placed in waveform channel Y and the original contents of channel Y are overwritten and destroyed If Y gt the total number of channels contained in the file before the operation then the result is appended to the input file with the channel number equal to the original total number of channels 1 6A 10 Copyright 1988 2009 Dataq Instruments Inc Enter expression Examples ADVANCED CODAS This is the formula containing input channel numbers constants and functions combined mathematically and according to the rules established earlier in this section to generate the desired output channel Y ARITH DATA DAT 4 14 2 3 Using DATA DAT as the input waveform data file subtract channel 3 from the sum of channels 1 and 2 and store the result as waveform channel 4 ARITH C RUN1 TEST DAT 15 1 LOG 2
21. ach case 6A 8 Copyright 1988 2009 Dataq Instruments Inc MENU LEVEL ERROR DETECTION ADVANCED CODAS When operating the WAO program from the menu level two lines are reserved within the menu area for error reporting One at the bottom of the screen and one directly underneath the user formula line The type of message appearing in each area depends upon whether the error was calculated or the result of an improperly formatted formula MENU LEVEL FORMULA ERROR DETECTION Whenever an improperly formatted expression is entered at the formula prompt of the menu the message Fix expression ESC clears it appears at the bottom of the menu screen immediately after attempting to evaluate the operation This message indicates that the formula provided does not adhere to certain rules governing the syntax of WAO program formula expressions At the same time the above message is displayed a companion message located directly beneath the erroneous formula provides more detail about the nature of the syntax error One of the following 13 possible error messages may be displayed Error Message Erroneous Example Corrected Example illegal digit A 1 141 illegal channel number 3041 241 illegal delay value 1 25 1 20 illegal function in 1 log 1 illegal operator HLSH2 1 2 missing operator 1 1 2 2 1 1 2 2 missing operand 1 _ 1 2 missing 14 1_ 1 1 or 141 extra 1 1
22. ained in one typical signal cycle A good first order approximation for the frequency response of the mean signal is as follows Frequency mean 1 6 x Sample Rate n Where n The number of points contained in the moving average filter Sample Rate The per channel sample rate at which the input signal was originally acquired in Hertz Frequency mean The bandwidth of the mean signal in Hertz This formula may be algebraically rearranged as follows to solve for n n 1 6 x Sample Rate Frequency mean The use of this formula can best be described by example Assume that an arterial blood pressure waveform was sampled at 250Hz and that a mean ABP signal with a frequency response of 1Hz needs to be generated Plugging these numbers into the above equation solves for the moving average span n n 1 6 x 250 1 400 samples Using 400 as the moving average smoothing constant is a good first order approximation for the desired result The waveform moving average utility may also be used to simulate a high pass filter by specifying smoothing factors less than zero When a moving average factor less than zero is specified the resulting output is the input signal minus the moving averaged result 6A 21 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM MOVING AVERAGE DOS COMMAND LINE and CALC MENU SYNTAX AVERAGE argument argument d path filename ext X Y Z where CALC Menu Prompt Input
23. amples from the original 4 14 samples ENGINEERING NOTATION WITH THE WAO PROGRAM As with other Advanced CODAS utilities the WAO program supports automatic engineering notation of its output or calculated channels However since it is not possible to predict how the output relates to time due to the diverse range of possible calculations the output units name is a concatenation of up to 4 unique input channel numbers in the order of first appearance in the WAO formula Channel numbers above 9 are represented alphabetically with A for channel 10 through T for channel 29 If you are using an EXP channel multiplexer you have access to as many as 144 channels In this case the standard ASCII character set is used to represent channels beyond channel 35 For example the result of the operation 1 4 9 12 would carry engineering units annotation of 149C You can change this annotation whenever desired from playback software by enabling the window containing the waveform pressing F9 then entering a space followed by up to 4 characters of annotation for AT CODAS or by enabling the window containing the waveform choosing Low Calibration from the Edit menu then entering up to four characters of annotation for WINDAQ Waveform Browser FORMULA AND CALCULATED ERROR DETECTION Error detection and reporting is supported by the WAO program both from the CALC menu and DOS command line levels However error handling is different in e
24. ataq Instruments is a waveform integration differentiation moving average peak and valley capture and rectification utility that operates on an existing waveform data file created by AT CODAS WINDAQ Pro or WINDAQ Pro data acquisition software Common Features Except for the peak and valley capture function Advanced CODAS is a waveform oriented analysis package meaning that the package accepts waveforms as an input and generates waveforms as an output The output waveform may be the integral derivative mathematical combination moving average or a rectified result of the input waveform Advanced CODAS permits output waveforms to be inserted directly into the original file that contained the input waveform Two formats are supported 1 The resulting waveform may be overwritten into an existing waveform channel thereby destroying the original contents of that channel or 2 The resulting waveform may be appended to the file containing the input waveform provided the number of channels contained in the file before appending is less than 29 for AT CODAS and WINDAQ Waveform Browser without the EXP channel multiplexer option or less than 144 for WINDAQ Waveform Browser with the EXP channel multiplexer option Waveform Differentiation Features Advanced CODAS s waveform differentiation program allows any input waveform to be differentiated with respect to time Following insertion into the file the differentiated waveform will be scaled automatical
25. back program screen will always be s where is the channel number of the waveform used as an input to create the integral and s denotes times seconds In this manner the integrated channel s unit of measure is always the unit of measure of the input waveform multiplied by seconds Note that the engineering units tag of any enabled channel may be changed at any time from the waveform playback program by pressing either the F9 or F10 key then entering up to a 4 character the first character must be an alpha descriptor for AT CODAS users or by choosing either Low Calibration or High Calibration from the Edit menu then entering up to a four character descriptor in the Engr Units text box for WINDAQ Waveform Browser users Input waveform characteristics volts second seconds Output integrated waveform characteristics j seconds FIGURE 6A 2 The integration program of Advanced CODAS generates the integral of an input waveform Just as the above ideal example illustrates the integrated waveform generated by Advanced CODAS is scaled to the appropriate unit of measure to allow a complete evaluation of the result Assuming that the input waveform was CODAS channel 4 the engineering unit tag on the output waveform would be displayed as 4 s on the waveform playback program screen to indicate that the unit of measure is channel four s unit of measure multiplied by seconds in this case volts 6A 14 Copyrig
26. by integration software the waveform being integrated will reset 6A 15 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS gt Q seconds ml sec reset ml Reset fadt seconds ml FIGURE 6A 3 Demonstrating the use of the level reset function the integrated waveform is set up to reset at a specific value When the value is reached integration is reset WAVEFORM INTEGRAL DOS COMMAND LINE and CALC MENU SYNTAX INTEGRAL argument argument d path filename ext X Y A Z L T_M H where CALC Menu Prompt Channel number to integrate Output channel number Integration mode d path filename ext specifies the file name containing the waveform to be integrated The disk drive specifier path and file name extension are optional A basic file name must be supplied DOS Command Line X is the channel number of the waveform to be integrated where lt X lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 1 lt X lt 144 for WINDAQ EXP multiplexer users Y is the channel number within the file to contain the integrated waveform where 2 lt Y lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 2 lt Y lt 144 for WINDAQ EXP multiplexer users If Y lt the total number of channels contained in the file before the integral operation then the result is placed in waveform channel Y and the original contents of channel Y are overwritten and destroyed
27. crossings to reset the integrator The result is stored in waveform channel 2 INTEGRAL C DATA LABWORK RUN2 DAT 4 8 B 32000 Using file RUN2 DAT located in subdirectory LABWORK which is a subdirectory of DATA take the integral of waveform channel 4 with no rectification bipolar and store the result in channel 8 This is a running integral resetting after 32000 data points INTEGRAL D DATA TEST 8 7 3 20 H Using waveform file TEST 8 located in subdirectory DATA on drive D integrate channel 7 using the positive only rectification mode and resetting every 20 samples The output waveform is channel 3 and each 20 point integration value will be held until the next is available Refer to FIGURE 6A 3 INTEGRAL DATA DAT 2 3 32000 134 Using Waveform file DATA DAT integrate waveform channel 2 storing the result as waveform channel 3 Rectify the input waveform so that only negative transitions relative to zero reset are integrated Reset every 32 000 samples or upon 134 integrated units which ever occurs first INTEGRAL DATA DAT 2 3 32000 134 14 6A 17 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS Using Waveform file DATA DAT integrate waveform channel 2 storing the result as waveform channel 3 Rectify the input waveform so that only negative transitions relative to zero reset are integrated Reset every 32 000 samples upon 134 integrated units or upon a positive going external event on channel 14 which
28. ction with but before Advanced CODAS s waveform derivative program thus prefiltering the signal before differentiating Such an approach may be used when it is necessary to isolate the derivative function from its built in smoothing capability In these cases a smoothing factor of 2 no filtering should be chosen from Advanced CODAS s derivative program AUTOMATIC ENGINEERING UNIT CALIBRATION When a waveform is averaged by Advanced CODAS the calibration information associated with the data is automatically adjusted so that when the moving averaged waveform is reviewed through the waveform playback program a display of its value at any given point is in appropriate engineering units The engineering unit tag associated with the moving averaged waveform and displayed on the waveform playback program screen will always be MA where is the channel number of the waveform used as an input to create the moving averaged waveform and MA implies M oving A verage The only exception to this rule is when a moving average factor of 1 is specified In this case the input channel is copied without modification to the output file including engineering units Note that the engineering units tag of any enabled channel may be changed at any time from the waveform playback program by pressing either the F9 or F10 key then entering up to a 4 character the first character must be an alpha descriptor for AT CODAS users or by choosing either Low Calibra
29. e channel The default source file is the same as the destination and the default source channel is 1 The default start point in the source is 0 which copies from the start of the file and other values of this parameter specify the number of data values to skip in the source channel If some of the source data would be copied past the end of the destination file it would be discarded Although the Advanced CODAS menus disallow channel 1 as a destination channel to protect acquisition starts and event marks COPYCHAN itself when invoked from a command line allows this if both starting points are zero However the feature will copy the event mark information from the trailer of the source file to the destination or part of it if the destination file is shorter along with the acquisition start and end times from the source file header It is also recommended but not required that the source channel be 1 so the Option Event Marks will show corresponding event marks in its channel data To see the format of a COPYCHAN command line type COPYCHAN with no parameters from an MS DOS prompt Some warning messages Source sample rate differs from that of destination file and will be ignored Copy Channel never changes the sample rate per channel in the destination file so the time scale of the data just copied from the source is incorrect Part of destination not written had calibration changed to that of source This means that some o
30. e to rectify a waveform as an interim step before integrating Although Advanced CODAS s integration utility supports rectification directly the rectified waveform is not available as an intermediate result From the perspective of presentation you can use Advanced CODAS s rectification utility to generate the rectified waveform to one channel then generate the integral of the rectified waveform to another channel A hard copy can be generated of all three waveforms input rectified integrated to fully document analysis flow On a more practical side the full wave rectification capability of Advanced CODAS can be applied to accurately establish a zero reference in the presence of base line noise FIGURE 6A 10 illustrates a raw EMG signal acquired in the presence of a high degree of base line noise and with zero reference established at the midpoint of the bipolar signal 0 volts Passing this waveform through Advanced CODAS s full wave absolute value rectifier yields the second waveform EMG Using the waveform playback program s ENGINEERING UNITS FUNCTION for AT CODAS users or WAVEFORM CALIBRATION FIXED METHOD for WINDAQ users zero reference may be reestablished at a point above the previous zero reference to eliminate the entire band of base line noise The signal of FIGURE 6A 10 labeled as EMGl is the waveform that will be integrated if a rectify mode of positive only is selected as an integration option Note that signal EMG is
31. eform The moving average program may be applied over 2 to 10 000 samples Waveform Peak and Valley Capture PVC Features This Advanced CODAS mode allows the cycle by cycle extraction of peak valley or peak and valley data points from a periodic waveform PVC may be applied to a variety of waveforms whenever it is necessary to reduce a large number of continuous waveform data values to one or two values per waveform cycle representing the maximum minimum or maximum and minimum signal excursion within the cycle For example an arterial pressure waveform may be peak captured for systolic diastolic or systolic and diastolic pressures on a beat by beat basis Unlike other Advanced CODAS functions PVC does not generate a waveform as a result Instead the input waveform or any other channel in the file is tagged by PVC with positive and negative going event markers to indicate cyclic peak and valley points respectively The Advanced CODAS Report Generator included is then used to extract waveform values coincident with the event markers and to generate a report of these values in one of two data storage formats Waveform Rectification Features Another mode of Advanced CODAS allows input waveforms to be converted into positive only negative only or absolute value transitions relative to zero reference without integration The application of waveform rectification is useful for verifying a stable zero reference baseline before integration
32. el one as well as any other channel may be duplicated by using Advanced CODAS s moving average utility and specifying a moving average factor of 1 Specify the input channel number as that to be duplicated PVC DOS COMMAND LINE AND CALC MENU SYNTAX PEAK argument argument 6A 27 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS d path filename ext X C Y Z S where CALC Menu Prompt Channel to peak capture Enter channel number to mark Select capture mode Select threshold level not displayed Example d path filename ext specifies the file name containing the waveform to be peak captured The disk drive specifier path and file name extension are optional A basic file name must be supplied DOS Command Line X is the channel number of the waveform to be peak valley captured where 2 lt X lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 2 lt X lt 144 for WINDAQ EXP multiplexer users Note that channel 1 may be specified only if peak and or valley markers are to be written to another channel C is an optional channel number within the file to contain the peak captured waveform where 2 lt X lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 2 lt X lt 144 for WINDAQ EXP multiplexer users The default value of C is equal to variable X providing X 1 Y is the capture mode which defines whether the peak valley capture utility will flag peaks vall
33. eset when included specifies the maximum number of units relative to the output waveform that will be accumulated before a reset will occur For example given an input waveform calibrated in milliliters per second a value of 100 ml could be entered for level which would cause the integrator to reset every 100 ml Values supplied for level reset may range from 1 79x103 8 to 1 79x10308 units An external Trigger may be enabled to force reset of the integral as a function of a peak and or valley event occurring on another channel within the same file The variable T defines the channel number containing the reset trigger event where 2 lt T lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 2 lt T lt 144 for WINDAQ EXP multiplexer users and variable M may assume one of three states or B M specifies whether reset will occur on a positive going peak event a negative going valley event or both Note that variables T and M must be separated by a space when implementing this feature from a DOS command line Hold when included specifies that the last integrated value will be held until the next is calculated When H is not specified reset transitions will be displayed INTEGRAL D DATA TEST 1 3 2 A 0 Using TEST 1 located in subdirectory DATA on drive D as the input waveform data file take the integral of channel 3 using the absolute value full wave rectification mode and using zero
34. ever occurs first Respiratory Flow Q Q Zero reference Inspiratory Zero Volume crossing J Q dt reset J Qdt Expiratory Volume J Q dt J IQ dt Inspiratory with hold and Expiratory Volume J Qdt Inspiratory and Expiratory Volume 6A 18 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS FIGURE 6A 4 Waveform rectification and reset upon zero crossing of the input signal allows great flexibility in the presentation of integrated waveforms Note how the hold option yields an uncluttered trace when only the peak value of the integral on a cycle by cycle basis is required 6A 19 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM MOVING AVERAGE USING ADVANCED CODAS GENERAL In cases where a given waveform is cluttered with noise where a mean needs to be extracted from a periodic signal or where a slowly drifting baseline needs to be removed from a higher frequency signal Advanced CODAS s moving average filter may be applied to achieve the desired result Its wide span of smoothing factors 2 10 000 allow a great deal of flexibility in waveform moving average applications Typically a smaller smoothing factor is applied when in noise reduction applications while larger factors are applied to generate the mean value of an input waveform or to remove the affects of a slowly drifting baseline The moving average filter may also be used in conjun
35. eys or peaks and valleys Valid entries are Y P for peaks only Y V for valleys only Y PV or VP for peaks and valleys Z specifies the peak valley capture utility threshold level where 1 lt Z lt 99 The default value for Z is 30 If Peak is given a negative threshold 99 lt Z lt 1 its operatoin is limited to the data between the cursor and the time marker This is helpful for use on files in which the amplitude changes too much for a single value to work on the whole file Refer to the PEAK AND VALLEY CAPTURE OPERATION section for details on proper threshold adjustment S optionally specifies the smoothing factor applied by the peak detection algorithm The default value of S is 11 which is adequate for most applications Lower values should be specified when the waveform to be peak captured has been under sampled Higher values should be specified in the presence of noise The range of S is 2 lt S lt 64 PEAK DATA DAT 2 VP Peak capture channel 2 of file DATA DAT for peaks and valleys using the default threshold value of 30 PEAK D LABDATA TEST1 DAT 5 4 P 25 Peak capture channel 5 of file TEST1 DAT located on drive D and subdirectory LABDATA for peaks only using a threshold value of 25 The peak markers are written to channel 4 6A 28 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM RECTIFICATION USING ADVANCED CODAS GENERAL You may find it desirabl
36. f the original data remains calibrated inappropriately There is no message when adding a channel in which case points outside the copied data have the value of the calibration intercept baseline after WWB Scaling Show Dynamic Range Source and dest ranges overlap and updated dest may be used as source The source and destination channels are the same channel in the same file Since the start point in the source is to the left of the start point in the destination data copied from the source phase shifted into the destination may have been reread and reshifted later in the process This causes corruption to the channel data instead of just phase shifting it This can be avoided by making a copy of the channel to be shifted first CALC Menu Prompt DOS Command Line Destination file name d path filename ext This specifies the destination file to which you are copying a selected channel or portion of a channel Destination channel number Specifies the channel that will display the copied data 6A 35 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS Start point in destination channel Specifies at what point on the channel the data will begin to be displayed Source filename d path filename ext This specifies the source filename of the data you want to copy Source channel number Specifies the channel in the source file that contains the data you want to copy Start point in source channel Specifies the
37. from the Edit menu then entering up to a four character descriptor in the Engr Units text box for WINDAQ Waveform Browser users Advanced CODAS s WAVEFORM RECTIFICATION FEATURES The Advanced CODAS waveform rectification program provides three rectification modes 1 Positive only half wave rectification Applying this rectification mode to a waveform will yield only positive waveform transitions relative to zero reference 2 Negative only half wave rectification Applying this rectification mode to a waveform will yield only negative waveform transitions relative to zero reference 3 Absolute value full wave rectification Applying this rectification mode to a waveform will force negative portions of the input waveform to be folded above zero reference to join the positive transitions thus forming the absolute value 6A 29 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM RECTIFICATION DOS COMMAND LINE and CALC MENU SYNTAX RECTIFY argument argument d path filename ext X Y Z where CALC Menu Prompt Input channel number Output channel number Rectification mode d path filename ext specifies the file name containing the waveform to be rectified The disk drive specifier path and file name extension are optional A basic file name must be supplied DOS Command Line X is the channel number of the waveform to be rectified where 1 lt X lt 29 for AT CODAS a
38. g full scale channel voltages 2 Minimize noise present on signals to be acquired Be sure to use quality shielded signal cable at all points in the signal path 3 Avoid poor signal connections that could cause intermittent signal drop outs 4 Do not make a habit of starting and stopping data acquisition to disk indiscriminately When acquisition to disk is halted and then started again an event marker is automatically inserted in channel 1 s data stream so that when the waveforms are played back through the waveform playback program it will be obvious when a discontinuity could exist This practice will help you avoid peak capturing across data acquisition session boundaries EDITING PVC SELECTED EVENT MARKERS The points selected by PVC may be reviewed through use of the waveform playback program For AT CODAS user s run the waveform playback program and select the SEARCH FOR EVENT FUNCTION F8 followed by an E keystroke to enable the display of positive and negative event markers For WINDAQ user s run the waveform playback program and choose Event Markers from the View menu In either case refer to the SEARCH FOR EVENT FUNCTION in the Post Acquisition using POST or WINDAQ chapter of the AT CODAS Users Manual or in the WINDAQ Waveform Browser Users Manual for complete details Your review of a peak captured waveform will yield one of three possible results 1 PVC selected minimum and or maximum events will be grossly in er
39. ht 1988 2009 Dataq Instruments Inc ADVANCED CODAS EXTENDED FEATURES OF ADVANCED CODAS s INTEGRATOR Besides integration Advanced CODAS s integrator program supports many features not available on any other commercially available software product 1 SUM and PULSE Modes of Integration The sum mode of integration reflects that which is commonly available in software integration products The input waveform is continually integrated without providing the ability to reset the integral The pulse mode of signal integration forces the integrator to reset whenever the input signal crosses or equals zero It is important to note that zero is defined as zero reference which does not need to be and in most cases is not equal to zero volts Rather zero is defined by the value of the input waveform that was calibrated through the waveform playback program to be equal to zero regardless of the actual voltage applied to the A D converter Remember that through use of the waveform playback program s ENGINEERING UNITS FUNCTION for AT CODAS users or WAVEFORM CALIBRATION FUNCTION for WINDAQ Waveform Browser users you have the ability to set zero reference at any place on an input signal s waveform This ability combined with signal integration relative to zero reference allows the integrator to reset as a function of actual signal value rather than as a function of signal voltage 2 Signal RECTIFICATION Before Integration Another unique feature of
40. ji DATAQ INSTRUMENTS ADVANCED CODAS USER S MANUAL Software Release Level 3 Manual Revision I Copyright Notice Copyright 1988 2009 by Dataq Instruments Inc ALL RIGHTS RESERVED The documentation contained herein is the exclusive property of Dataq Instruments Inc except as otherwise indicated and shall not be reproduced transmitted transcribed stored in a retrieval system or translated into any human or computer language in any form or by any means electronic mechanical magnetic optical chemical manual or otherwise without expressed written authorization from Dataq Instruments Inc The distribution of this material outside the company may occur only as authorized by Dataq Instruments Inc in writing Dataq Instruments hardware and software products are not designed to be used in the diagnosis and treatment of humans nor are they to be used as critical components in any life support systems whose failure to perform can reasonably be expected to cause significant injury to humans REPRODUCTION OF ANY PART OF CALC SOFTWARE BEYOND THAT PERMITTED BY SECTION 117 OF THE 1976 UNITED STATES COPYRIGHT ACT WITHOUT PERMISSION OF DATAQ INSTRUMENTS INC IS UNLAWFUL D DATAQ INSTRUMENTS 241 Springside Dr Akron Ohio 44333 USA www dataq com Telephone 330 668 1444 FAX 330 666 5434 Designed and manufactured in the United States of America ADVANCED CODAS TABLE OF CONTENTS AN INTRODUCTION TO ADVANCED CODAS C
41. k to the top menu item after pressing the ENTER key If you attempt to enter an invalid argument for any menu item the cursor will fail to move to the next menu item Blank entries those where only the ENTER key was pressed with no arguments are ignored and force the cursor to the next menu item ENTERING MENU ITEM ARGUMENTS For each individual menu parameter a pair of brackets is provided lt gt between which only valid arguments are displayed In many cases a menu item will be provided with a default parameter such as a default input channel number or default output channel number These of course may be changed but they do provide a convenient starting point for analysis The initial cursor position is immediately following the valid entry brackets lt gt An argument is entered into a menu item by typing it at the cursor position then pressing the ENTER key If your argument is valid the entry will appear within the brackets your typed response following the bracket will be erased and the cursor will move to the next menu item If your entry is invalid the cursor will simply reinitialize to its starting position and fail to move to the next menu item Your invalid response remains displayed until either of two inputs is provided 1 Pressing the ENTER key alone will cause the cursor to move to the next menu item The previous invalid response is erased and the argument accepted for that menu item is either the default or the
42. ly to the engineering units of the input waveform divided by seconds For example an input waveform with millivolts as units becomes mV sec when differentiated When reviewed through the waveform playback program the differentiated waveform will carry all attributes of an acquired channel Timing measurements can be made from the differentiated channel and when cursors and channel annotation are enabled the value of the differentiated channel may be read directly from the screen in the appropriate units Filtering of the differentiated waveform is accomplished by allowing the selection of the number of points over which the derivative is calculated Step sizes from 2 no filtering to 64 may be chosen Waveform Integration Features Similar to differentiation Advanced CODAS s waveform integration program allows any input waveform to be integrated with respect to time Following insertion into the file the integrated waveform will be scaled into the engineering units of the input waveform multiplied by seconds i e millivolts becomes mVesec When reviewed through the waveform playback program the integrated waveform will carry all attributes of an acquired channel Timing measurements can be made from the integrated channel and when cursors and channel annotation are enabled the value of the integrated channel may be read directly from the screen in the appropriate units Unlike all other commercially available integration utilities Advanced CODA
43. may be configured to calculate and report the cycle interval in seconds cycle rate in Hertz cycles per second or cycle rate in cycles per minute 5 Sample number at valley If valley markers are present on the input waveform the sample number at waveform valley marker intersection will be reported relative to the beginning of the data file Should the first data point in the waveform contain a valley marker its sample number would be reported as zero 0 Likewise should the 1 000th point in the waveform contain a valley marker its sample number would be reported as 999 If valley markers are not present in the waveform a value of 1 will be reported The sample number may be used to plot valley values versus time since multiplying the sample number by the reciprocal of the waveform s sample rate per channel yields the location of the value in time 6 Sample number at peak If peak markers are present on the input waveform the sample number at waveform peak marker intersection will be reported relative to the beginning of the data file Should the first data point in the waveform contain a peak marker its sample number would be reported as zero 0 Likewise should the 1 000th point in the waveform contain a peak marker its sample number would be reported as 999 If peak markers are not present in the waveform a value of 1 will be reported The sample number may be 6A 32 Copyright 1988 2009 Da
44. may be copied without modification to the specified output channel This feature may be used to peak capture waveform channel 1 which may not be done on channel 1 directly AVERAGE DATA DAT 2 5 350 Using DATA DAT as the input waveform data file take the moving average of waveform channel 2 and store the result as waveform channel 5 using a 350 point moving average 6A 22 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM PEAK AND VALLEY CAPTURE USING ADVANCED CODAS GENERAL Anyone with the most basic knowledge of physiological waveforms can glance at a blood pressure waveform determine where the heart cycle begins and ends then measure the minimum diastolic maximum systolic and mean pressures Another simple calculation yields the heart rate The problem is not one of procedure but time Consider a more typical application involving not one but several hundred heart cycles and the need to calculate with reasonable accuracy the four blood pressure parameters on a beat by beat basis The task becomes overwhelming Without question the process may be simplified by eyeballing large groups of waveforms for average maximum minimum mean and rate values But what happens to accuracy and all important repeatability The obvious solution is to computerize Everyone knows that computers excel in their ability to evaluate large quantities of numbers Although it is true that for any number of samples a comp
45. millivolts Zero p gt Une iy Nnenmenn cauired reference tt h TETI ali dee tea EMG l i signal millivolts 2 ie 2 E New zero reference millivolts EMG less noise FIGURE 6A 10 This figure demonstrates the application of Advanced CODAS s full wave rectifier to eliminate the effects of base line noise The input signal is full wave rectified to obtain its absolute value Next zero reference is reestablished at a level above the original zero reference When integrated using the positive only integration mode the last waveform EMG becomes the integrator s input thereby preventing base line noise from distorting the result 6A 31 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS REPORT GENERATION OF PEAK VALLEY EVENTS USING ADVANCED CODAS GENERAL The Report Generator RG allows peak and valley event markers contained on a waveform and placed there by the PVC or the peak valley marker editor to be extracted as point values These values may then be placed in a S preadsheet or ASYST and ASYSTANT compatible file along with additional information describing cycle intervals and sample numbers corresponding with the peak and valley points RG essentially finishes what was S tarted by PVC by allowing a convenient way to report critical cyclic waveform point values in a format suitable for further analysis and plotting DEFINING THE PARAMETERS REPORTED BY
46. nd WINDAQ non EXP multiplexer users or 1 lt X lt 144 for WINDAQ EXP multiplexer users Y is the channel number within the file to contain the rectified waveform where 2 lt Y lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 2 lt Y lt 144 for WINDAQ EXP multiplexer users If Y lt the total number of channels contained in the file before the rectification operation then the result is placed in waveform channel Y and the original contents of channel Y are overwritten and destroyed If Y gt the total number of channels contained in the file before the rectification operation then the result is appended to the input file with the channel number equal to the original total number of channels 1 Z specifies the rectification mode as follows Z passes signal transitions that are greater than or equal to zero reference positive half wave rectification Z passes signal transitions that are less than or equal to zero reference negative half wave rectification Z A applies an absolute value function so that all signal transitions less than zero reference are folded above zero reference by an equal amount full wave rectification Example RECTIFY DATA DAT 16 A Using waveform data file DATA DAT apply the absolute value full wave rectification function to waveform channel 1 storing the result in channel 6 Refer to FIGURE 6A 10 6A 30 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS
47. nerated by specifying an integration period of 1 5 Selectable LEVEL RESET Another method of achieving integration reset is by specifying a specific level in the output waveform s engineering unit of measure For example if the waveform used as the input to the integrator is calibrated in quarts per second specifying a level reset of 700 quarts will force reset when this quantity is reached in the integrated waveform Levels within the range of 1 79x10398 to 1 79x10308 units may be specified Refer to FIGURE 6A 3 for a graphic example of the level reset function When you need to integrate an entire waveform stream and reset only when the specified level is achieved you must set the reset integration period to 1 This forces integration software to reset only upon a valid level threshold 6 Resetting on an EXTERNAL WAVEFORM EVENT The final method for resetting the integral is upon an event occurring on a different waveform channel An event is defined as a peak marker valley marker or either occurring on another channel within the same file A typical application for the external reset function is resetting integration as a function of an ECG waveform Using this approach you would first peak capture the ECG waveform using Advanced CODAS s Peak and Valley Capture program then specify the external reset trigger option from either the CALC integral menu or DOS command line Each time a peak and or valley marker on the ECG waveform is encountered
48. never displayed but rather interpreted in the manner shown by the integrator AUTOMATIC ENGINEERING UNIT CALIBRATION When a waveform is rectified by Advanced CODAS the calibration information associated with the data file is automatically adjusted so that when the rectified waveform is reviewed through the waveform playback program a display of its value at any given point is in appropriate engineering units The engineering unit tag associated with the calculated waveform and displayed on the waveform playback program screen will always be OR where is the channel number of the waveform used as an input to create the rectified waveform and O describes the applied operation O may assume one of three possible values denotes positive only rectification denotes negative only rectification and A denotes absolute or full wave rectification For example assume that waveform channel 1 is full wave rectified and the result is stored to channel 3 Channel 3 s engineering unit tag would be ARI Likewise if the operation was positive only half wave channel 3 s engineering units tag would be R1 Note that the engineering units tag of any enabled channel may be changed at any time from the waveform playback program by pressing either the F9 or F10 key then entering up to a 4 character the first character must be an alpha descriptor for AT CODAS users or by choosing either Low Calibration or High Calibration
49. ng in mind that a smoothing factor of 2 should be used under only the most ideal circumstances Advanced CODAS supports smoothing factors ranging from 2 to 64 WAVEFORM DERIVATIVE DOS COMMAND LINE and CALC MENU SYNTAX DERIV argument argument d path filename ext D X Y Z where d path filename ext specifies the file name containing the waveform to be differentiated The disk drive specifier path and file name extension are optional A basic file name must be supplied CALC Menu Prompt DOS Command Line Input channel number X is the channel number of the waveform to be differentiated where 1 lt X lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 1 lt X lt 144 for WINDAQ EXP multiplexer users Output channel number Y is the channel number within the file to contain the differentiated waveform where 2 lt Y lt 29 for AT CODAS and WINDAQ non EXP multiplexer users or 2 lt Y lt 144 for WINDAQ EXP multiplexer users If Y lt the total number of channels contained in the file before the derivative operation then the result is placed in waveform channel Y and the original contents of channel Y are overwritten and destroyed If Y gt the total number of channels contained in the file before the derivative operation then the result is appended to the input file with the channel number equal to the original total number of channels 1 Smoothing factor Z specifies the smoothing factor to be applied to the differentia
50. ng the number or letter of the display window containing the waveform to 6A 26 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS be modified For example say window two is displaying the peak and valley captured result of channel five You would press the 2 key to enable the channel displayed in window 2 in this case channel 5 for marker editing When pressed the 2 5 annotation near the bottom of the screen in AT CODAS or in the right or left annotation margin in WINDAQ will be highlighted indicating channel 5 is enabled for marker editing operations 2 Move to the desired point in the waveform To move to the next displayed peak or valley marker in the enabled channel proceed as follows AT CODAS User s CTRL moves to the next peak or valley marker by scrolling the waveform in a left or right direction depending upon the state of the waveform movement preference switch specified from the CODAS configuration or installation program CTRL lt moves to the next peak or valley marker by scrolling the waveform in a right or left direction depending upon the state of the waveform movement preference switch specified from the CODAS installation program WINDAQ User s Choose Next Mark from the Search menu This moves the window in a positive time direction to the next enabled event marker positioning the data cursor directly on top of the event marker Choose Previous Mark from the Search menu
51. ng will be reported in seconds REPORT D TESTS SET 1 12 PP LM 8 Generates file SET L12 in subdirectory TESTS containing 8 cycle average point values of waveform channel 12 of file SET 1 Output format is spreadsheet compatible with a cycle definition of peak to peak Cycle timing will be reported as a rate in cycles per minute units 6A 34 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM COPY FEATURE USING ADVANCED CODAS GENERAL The Waveform Copy Feature allows you to copy to a destination file starting at a specified destination point from a source channel in the same file or another file The copied information includes calibration units scaling and user annotation but excludes acquisition channel method input type gain and input level range In WinDaq Waveform Browser set Options Select Marker Display to Samples from Marker and set Options Time Marker at the start of the file to view the point numbers required by the Copy Channel program when copying part of a destination or source channel The default destination channel is the number of channels plus 1 which adds a new channel to the file The default start point in the destination channel is 0 which copies to the start of the file and other values of this parameter leave the specified number of data values in the destination channel or baseline when adding a channel untouched to the left of the first data copied from the sourc
52. ommon Features Waveform Differentiation Features Waveform Integration Features Waveform Arithmetic Functions Waveform Moving Average Features Waveform Peak and Valley Capture PVC Features Waveform Rectification Features Report Generator Features Waveform Copy Feature GETTING READY TO USE ADVANCED CODAS Installing Advanced CODAS Routines Accessing Advanced CODAS Routines Invoking CALC from COPY AND PASTE Invoking CALC Using the CALC HOT KEY FUNCTION Invoking Advanced CODAS from DOS WORKING WITH CALC MENUS General Movement Through CALC Menu Items Entering Item Arguments Activating Menu Selections WAVEFORM ARITHMETIC OPERATIONS USING ADVANCED CODAS General WAO Operators and Built in Functions Combining Functions and Operators Into WAO Program Formulas Engineering Notation With the WAO Program Formula and Calculated Error Detection WAO and Dynamic Range Errors WAO DOS Command Line and CALC Menu Syntax WAVEFORM DERIVATIVES USING ADVANCED CODAS General Automatic Engineering Unit Calibration Selecting a Smoothing Factor Waveform Derivative DOS Command Line and CALC Menu Syntax WAVEFORM INTEGRATION USING ADVANCED CODAS General Automatic Engineering Unit Calibration Extended Features of Advanced CODAS s Integrator SUM and PULSE Modes of Integration Signal RECTIFICATION Before Integration Optional HOLD Feature Adjustable RESET INTEGRATION PERIOD 6A 3 6A 6 6A 7 6A 12 6A 14 Copyright 1988 2009 Dataq Instruments
53. on WAO program of Advanced CODAS may be used to generate calculated channels as a function of user supplied formulas The program supports a host of operations including phase shifting and fully automatic calibration of the output waveform Since all processing by the arithmetic operations program is performed using floating point math use of a math coprocessor will enhance the speed with which these operations are carried out WAO OPERATORS AND BUILT IN FUNCTIONS WAO supports 8 operators and 7 functions Each of the 8 operators is described as follows according to its syntax precedence in relation to other operators and full description Operator Syntax Precedence Description 1 Arithmetic addition 1 Arithmetic subtraction 2 Arithmetic multiplication 2 Arithmetic division Negation 3 Arithmetic negation e g 2 12 123 7 4 Exponentiation e g 2 7 2 2 2 7 5 Parentheses to change the order that arithmetic operations are performed Number following the character specifies data of an absolute channel number The WAO program also supports 7 functions as follows Function Syntax Description ABS x Absolute value of argument x SQRT x Square root of argument x EXP x e raised to the power of argument x LOG x Natural logarithm of argument x LOG10 x Common logarithm of argument x Y X Phase shift waveform channel Y x samples 1 to 20 samples maximum x Phase shift
54. ord you acquired when you purchased Advanced CODAS to complete the installation One subdirectory containing both Advanced CODAS files and AT CODAS or WINDAQ files allows the waveform playback programs of either to access the integration differentiation moving average peak and valley capture rectification and report generation routines provided by Advanced CODAS A summary of each Advanced CODAS file is as follows ARITH EXE ARITH EXE is the arithmetic functions program This program is automatically accessed by the menu oriented program CALC EXE or may be run directly from DOS AVERAGE EXE AVERAGE EXE is the waveform moving average program This program is automatically accessed by the menu oriented program CALC EXE or may be run directly from DOS CALC EXE CALC EXE is a menu oriented user interface that is accessed by the waveform playback program whenever CALC is invoked CALC EXE may also be accessed from the DOS level by typing CALC When CALC is in use it automatically accesses all waveform analysis programs as required DERIV EXE DERIV EXE is the waveform differentiation program This program is automatically accessed by the menu oriented program CALC EXE or may be run directly from DOS INTEGRAL EXE INTEGRAL EXE is the waveform integration program This program is automatically accessed by the menu oriented program CALC EXE or may be run directly from DOS PEAK EXE PEAK EXE is the waveform peak and valley capture p
55. orm Browser The waveform data file from which waveforms were copied remains as the active waveform playback file You may change this file to the one containing the pasted waveforms by invoking the SWITCH FILES FUNCTION Refer to the SWITCH FILES FUNCTION in the AT CODAS Users Manual or in the WINDAQ Waveform Browser Users Manual for complete details Invoking CALC Using the Playback Software s CALC HOT KEY Function AT CODAS User s Only Unlike the COPY PASTE method of invoking CALC which operates on a specified subset of the currently active waveform data file the CALC HOT KEY function ALT F6 operates on the entire currently active waveform data file The following sequence of events describes the operation of the CALC HOT KEY function 1 Invoke the CALC ADVANCED CODAS FUNCTION using ALT F6 keystrokes Refer to the CALC ADVANCED CODAS FUNCTION in the Post Acquisition using POST or WINDAQ chapter of the AT CODAS Users Manual for complete details 6A 4 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS 2 The CALC first level menu is displayed CALC s default file name is the same as that in effect prior to the time HOT KEY was enabled 3 You may now operate on the file using CALC functions When CALC is exited control is returned to the waveform playback software with the active file being the one that was open when the HOT KEY was enabled Assuming you did not change the file name from within CALC the wavef
56. orms contained in the file should now reflect the operations performed by CALC Invoking Advanced CODAS Routines From DOS Assuming a CODAS acquired waveform data file exists each Advanced CODAS routine may be invoked directly from DOS using the following methods 1 CALC Typing this syntax from the DOS command prompt invokes the first level menu of CALC No default conditions are established 2 CALC filename Typing this syntax from the DOS command prompt invokes the first level menu of CALC filename is used as the default file name 3 CALC filename CALC filename CALC filename CALC filename CALC filename CALC filename CALC filename Typing any of these commands from the DOS prompt invokes CALC from its A rithmetic functions D erivative Report G enerator I ntegral M oving Average P eak and valley capture or R ectify menu respectively In all three cases filename is used as the default file name AuvusHOQUP 4 CALC Displays a help screen describing the syntax required to enter CALC at the menu level pertaining to any Advanced CODAS function 5 FUNCTION argument Where argument forms a complete command line for the specified Advanced CODAS FUNCTION It is possible to invoke any Advanced CODAS analysis routine with a complete command argument that allows you to bypass CALC s menus entirely Such an approach is most useful for repetitive Advanced CODAS operations where the analysis procedure is always the same or whe
57. output channel x samples e 2 71828 COMBINING FUNCTIONS AND OPERATORS INTO WAO PROGRAM FORMULAS WAO formulas are generated much like any other computer language with two exceptions Unique to the WAO program are two symbols that perform specific operations they are the pound symbol and the colon Data for a channel is denoted by followed by the channel number This approach allows channel numbers to be differentiated from constants The channel number may be followed by an optional colon and positive delay number of sample intervals ranging from 1 to 20 to allow phase shifting of the channel data Proper formula generation can best be described by way of example 6A 7 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS Desired Operation Resulting WAO Formula Channel 1 plus Channel 2 1 2 The quantity Channel 1 plus Channel 2 divided by the quantity Channel 1 times Channel 8 1 2 1 8 Common log of Channel 14 log10 14 The quantity Channel 1 plus 573 2 divided by 02881 1 573 2 02881 The quantity of the absolute value of channel 3 plus the natural log of channel 15 divided by the quantity of Channel 3 raised to the power of Channel 7 abs 3 log 15 3 7 Channel 4 right phase shifted 14 samplest 4 141 Note that WAO functions are not case sensitive e g LOG log and that spaces must not appear in the formula tResult of a waveform phase shifted 14 s
58. rates positive and negative going event marker tags on the input waveform corresponding to cycle by cycle maximum and minimum waveform values PVC may also be configured to detect peaks only or valleys only Note that event markers must be enabled from the waveform playback utility before peak and or valley markers will be displayed The procedure used by PVC software to determine cyclic peak and valley waveform values involves the use of a threshold detector Through command arguments from either the DOS or menu levels you control the threshold setting as a percentage within the range of 1 to 99 The default value of the threshold detector is 30 The default threshold level is an extremely good starting point for most waveforms encountered in physiology Even so you may have the need to adjust the default threshold level to accurately respond to some waveforms depending upon how they were acquired FIGURE 6A 6 shows the result of a properly peak captured waveform FIGURE 6A 7 shows the same waveform that was peak captured using a threshold level that was too low In contrast FIGURE 6A 8 shows the same waveform that was peak captured using a threshold level that was too high PVC result when threshold is too low FIGURE 6A 7 This figure demonstrates what can happen when the threshold level of the PVC function is too small The algorithm interprets minor changes in waveform inflections as valid peaks and valleys 6A 24 Copyright
59. re you need to process a file or a number of different files in a defined manner This approach also requires less memory since the CALC menu is not loaded A DOS batch file may be written that allows the flexibility of enabling many complex operations with a single command Refer to your computer s DOS manual for further information related to batch file processing Refer to the appropriate section of this chapter for a complete treatment of DOS command line syntax for waveform arithmetic functions derivative integration moving average peak and valley capture rectification and report generation Advanced CODAS operations 6A 5 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WORKING WITH CALC MENUS GENERAL Assuming CALC is accessed from the DOS level or from waveform playback software a user interface consisting of several menus that allow you to specify any Advanced CODAS parameter in a straight forward manner will be displayed The menus used in CALC are designed to allow you to modify all menu parameters any number of times before executing the specific Advanced CODAS operation The specific action configured by you at any menu level is activated only after pressing the escape key ESC on your keyboard MOVEMENT THROUGH CALC MENU ITEMS Generally the cursor moves from the top of the menu item through the last or bottom menu item each time the ENTER key is pressed When at the bottom menu item the cursor moves bac
60. rogram This program is automatically accessed by the menu oriented program CALC EXE or may be run directly from DOS 6A 3 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS RECTIFY EXE RECTIFY EXE is the waveform rectification program This program is automatically accessed by the menu oriented program CALC EXE or may be run directly from DOS REPORT EXE REPORT EXE is the peak and valley report generator This program is automatically accessed by the menu oriented program CALC EXE or may be run directly from DOS ACCESSING ADVANCED CODAS ROUTINES CALC is a menu driven post recording analysis program that allows the integration differentiation mathematical combination moving average peak and valley capture rectification and report generation of specified waveforms CALC and its supporting waveform analysis routines may be accessed three ways 1 The CALC menu may be accessed as an option from the COPY PASTE menu refer to the COPY AND PASTE FUNCTION in the Post Acquisition using POST or WINDAQ chapter of the AT CODAS Users Manual or in the WINDAQ Users Manual 2 For AT CODAS users the CALC menu may be accessed through the playback software s CALC HOT KEY function ALT F6 is the key sequence Refer to the CALC ADVANCED CODAS FUNCTION in the Post Acquisition using POST or WINDAQ chapter of the AT CODAS Users Manual for complete details 3 Individual Advanced CODAS routines may be accessed directly from DO
61. ror 2 The waveform will be properly peak captured cycle by cycle end to end 3 Except for a few minor instances the waveform will be properly peak captured In the event of item 1 you should return to PVC and attempt to properly peak capture the input waveform by selecting a different threshold value Increase or decrease the threshold value depending upon the results of your first attempt and by using the concepts described in the PEAK AND VALLEY CAPTURE OPERATION section above In the event of item 2 no further PVC operations need to be performed You may proceed with the report generator to produce a point value file You have two options in the event of item 3 You can rerun PVC with a slightly different threshold value in an attempt to correct the few peak capture errors or you can use the event marker editing facility of the waveform playback program to insert and or delete event peak and valley markers Assuming that peak and valley markers are enabled for display you are in the waveform playback program with a peak captured waveform displayed and the data cursor is displayed WINDAQ user s the markers may be edited as follows note that marker editing cannot be used when the waveform compression factor is greater than 1 the waveform must be uncompressed to edit markers 1 Enable the channel for peak and valley marker editing operations A channel is enabled for peak and valley marker editing operations by pressi
62. s per second In this manner the differentiated channel s unit of measure is always the unit of measure of the input waveform divided by seconds Note that the engineering units tag of any enabled channel may be changed at any time from the waveform playback program by pressing either the F9 or F10 key then entering up to a 4 character the first character must be an alpha descriptor for AT CODAS users or by choosing either Low Calibration or High Calibration from the Edit menu then entering up to a four character descriptor in the Engr Units text box for WINDAQ Waveform Browser users Input waveform characteristics me Cc fe O Oo n gt KA e gt seconds FIGURE 6A 1 The derivative program of Advanced CODAS generates the first derivative of an input waveform Just as this ideal example demonstrates the differential waveform generated by Advanced CODAS is scaled to the appropriate unit of measure to allow a complete evaluation of the result Assuming that the input waveform was CODAS or WINDAQ channel 4 the engineering unit tag on the output waveform would be displayed as 4 s on the waveform playback program screen to indicate that the unit of measure is channel four s unit of measure divided by seconds in this case volts per second 6A 12 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS SELECTING A SMOOTHING FACTOR A feature of Advanced CODAS s waveform derivative program i
63. s built in smoothing of the differentiated waveform As you may be aware noise present on an input waveform will be greatly magnified when the waveform is passed through a differentiating function This is true of not only digital differentiators such as Advanced CODAS but of analog differentiators as well A feature common to the later to help compensate for noise in the output signal is a low pass filter with selectable corner frequencies The smoothing factor parameter of Advanced CODAS s waveform differentiator accomplishes the same noise quieting result The value of the smoothing factor determines the number of samples evaluated from the input waveform for determining a slope It follows that the greater the smoothing factor the more heavily filtered the output signal becomes A smoothing factor of 2 no filtering yields an output signal that is much more sensitive to rates of change in the input waveform than a smoothing factor of 11 Clearly a balance must be achieved when selecting a smoothing factor so that the resulting waveform is not cluttered with so much noise as to make evaluation difficult while ensuring that true rates of change in the input waveform are not masked by a smoothing factor that is too great This digital filtering technique comes without the disadvantages of analog filtering which causes substantial phase shift of the output vs input signals Generally a smoothing factor between 3 and 7 yields the best performance keepi
64. taq Instruments Inc ADVANCED CODAS used to plot peak values versus time since multiplying the sample number by the reciprocal of the waveform s sample rate yields the location of the value in time Note that all values described above may be reported on a cycle by cycle or on a 2 32 767 cycle average basis RG DATA FILE CREATION AND STORAGE FORMATS RG can generate two data file storage formats each containing the same information spreadsheet compatible and ASYST ANT compatible When configured to create a data file in the spreadsheet storage format RG generates an ASCII file that may be imported directly to a spreadsheet using for example Lotus s IMPORT command The file may also be typed to the computer s screen or printed to a line printer using DOS s TYPE and PRINT commands The name of the RG created file is fixed and carries the same basic name as the waveform file used as the input but with a LX extension X will be a number ranging from 2 to 29 for AT CODAS and WINDAQ non EXP multiplexer users or from 2 to 144 for WINDAQ EXP multiplexer users and will be equal to the channel number of the input waveform file being reported For example if channel number 5 in file TEST DAT is reported the Lotus compatible file created on disk will carry a file name of TEST L5 When configured to create a data file in the ASYST ANT storage format RG generates a floating point binary file that may be imported directly to either
65. ted waveform where 2 lt Z lt 64 Higher values of Z apply greater smoothing constraints on the resulting waveform A factor of 2 chosen for Z produces no smoothing of the resultant waveform Example DERIV DATA DAT 1 4 3 Using DATA DAT as the input waveform data file take the derivative of waveform channel 1 and store the result as waveform channel 4 using a smoothing factor of 3 6A 13 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS WAVEFORM INTEGRATION USING ADVANCED CODAS GENERAL The waveform integration program provided with Advanced CODAS allows any waveform within a CODAS acquired data file to be integrated with respect to time The integrated waveform is placed within the same file by either inserting the waveform as an additional channel assuming less than 29 original channels or by overwriting an existing channel If the latter approach is selected care should be taken to ensure that the original content of the overwritten channel is not pertinent since it will be destroyed AUTOMATIC ENGINEERING UNIT CALIBRATION When a waveform is integrated by Advanced CODAS the calibration information associated with the data is automatically adjusted so that when the integrated waveform is reviewed through the waveform playback program a display of its value at any given point is in appropriate engineering units The engineering unit tag associated with the calculated waveform and displayed on the waveform play
66. the cursor will automatically be positioned at the exact point where the error exists At the same time the above message is displayed a companion message located directly beneath the formula provides more detail about the nature of the arithmetic error In addition the first character of the formula operator that was involved with the error is displayed with intensified video One of the following messages will be displayed in the formula area 6A 9 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS Error Message Expanded Description fp divide by 0 The quantity 0 appeared in the denominator fp overflow The operation exceeded the range of double precision floating point numbers fp func domain error An illegal arithmetic operation was attempted such as the log of a negative number fp func singular error An operation occurred that forced the result to infinity such as log 0 COMMAND LEVEL FORMULA ERROR DETECTION When the WAO program is invoked from the DOS command line formula error detection is still maintained The same formula error messages described above for menu level operations will be echoed to the screen when an invalid formula is attempted In addition the formula will be echoed starting with the offending character For example the following messages will be echoed to the screen upon attempting the operation ARITH DATA DAT 4 1 LN 2 12 5 LN 2 12 5 illegal function COMMAND LEVEL CALCULATE
67. tion or High Calibration from the Edit menu then entering up to a four character descriptor in the Engr Units text box for WINDAQ Waveform Browser users APPLYING Advanced CODAS s MOVING AVERAGE PROGRAM The application of Advanced CODAS s moving average program as with all other moving average functions is an exercise in trial and error and intuition When it is necessary to remove a noise component from an input waveform only you can judge the suitability of the result whether the number of averaged points selected was too high too low or just right Such subjective criterion exists since what may appear to one user to be a properly filtered waveform may appear to another to be too noisy As a general rule you should start with a low filter factor then increase it if necessary until the desired result is achieved Also realize that more than one iteration may be needed to converge on an acceptable result 6A 20 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS 130 mmHg Mean Arterial BP 60 mmHg FIGURE 6A 5 This figure demonstrates the ability of Advanced CODAS s moving average filter to generate a mean waveform from a periodic input waveform When using Advanced CODAS s moving average program to display the mean value of an input signal the smoothing factor should be selected so that the number of points contained in the moving average window is proportional to the number of sampled points cont
68. uter can be programmed to report the highest and lowest values it fails in its ability to duplicate the intuitive process applied by an experienced researcher when he or she identifies the beginning and end of a heart cycle for example Since the accurate determination of systolic diastolic mean and rate information depends on an equally accurate determination of heart cycle end points the computer based solution fails The development of Dataq Instruments Peak Capture Algorithm focused on solving the end point determination problem since this was the only barrier preventing the computer from automating the labor intensive process described above Through innovative software design and by making the researcher part of the evaluation process the Peak Capture Algorithm represents the first computer based solution to the automatic detection of peak valley mean and period information on either a cycle by cycle or a 2 to 32 767 cycle average basis PEAK AND VALLEY CAPTURE PVC OPERATION PVC does not generate waveforms Instead it uses any waveform channel except channel 1 as an input then places positive and or negative going event markers directly on the waveform to indicate cyclic peak and or valley waveform points 6A 23 Copyright 1988 2009 Dataq Instruments Inc ADVANCED CODAS Waveform before PVC Waveform after PVC peak lt 1 marker My valley marker FIGURE 6A 6 The Peak and Valley Capture PVC function gene

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