F-Intermod User Manual - Telecom Engineering Inc.
Contents
1. 3 1 or 3 0 Ch Save channel database Ctri s a Save channel database as Txl Load Template Save Template Print preview Print Ctrl P Export channel database gt Export Intermod output gt Save Overflow output to file gt Exit between and File New Channel Database Clears the input and output tables Load Channel Database Opens a saved input file with cdb extension Note it will also load older version txt database files Use this option if you have an input file saved from a previous version of F Intermod starting from R3 3 Load Channel Database from R3 2 3 1 or 3 0 Opens a saved input file from R3 0 to R3 2 You must use this option if you have an input file from these versions Using the previous Open Program File option will not work Save Channel Database Saves the input table data and options to the current selected file name with extension cdb for future loading with Load Channel Database Note this is a change from earlier versions that saved the database as txt file Save Channel Database as Saves the input table data and options to a file name with extension cdb for future loading with Load Channel Database Itis saved with the a new filename selected by the user Load Template Opens a saved template just F Intermod configuration settings does not affect loaded channel data Has tpl extension Save Template Saves template file for futur2. 22500 0 02500 9 00000 0 20000 0 12500 0 02500 0 22500 0 20000 0 15000 0 25000 1 In BP PION FiO BIN I He oje Njejejo Computer Platform Requirements and Specifications General Required computer Windows 98 NT XP ME 2000 Vista Minimum RAM memory 128 Mbytes Hard Drive Space 10 MB Resolution 800x600 VGA Monitor or better Other peripherals one printer not necessary 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm Input Transmit frequency 0 00001 to 999 999 99999 for any units kHz MHz GHz THz Number of transmit freq 1 to 10000 Intermodulation order 2 to 31 Receive frequency 0 00001 to 999 999 99999 for any units kHz MHz GHz THz Number of receive freq 1 to 10000 Frequency bandwidth 0 00000 to 999 999 99999 for any units kHz MHz GHz THz Output Intermodulation frequency range 0 00000 to 999 999 99999 for any units kHz MHz GHz THz Maximum number of intermodulation output frequency listings unlimited Computing time dependent on intermodulation order number of transmit frequencies receiver bandwidth sorting time and number of listings 14 of 14 9 Sep 13 6 41 PM
3. at A B C A B C are carrier frequencies The following assumptions are used for all F Intermod calculations a All intermod frequencies are created at one location b Transmitter carrier frequencies are not modulated and have no bandwidth 1 of 14 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm c Nonlinear coefficient for each intermod order are determined by field measurements Required only if absolute intermod power level is required see below explanation on Intermod Power d Losses due to propagation and or transmission are not considered in Intermod frequency power calculations See below section Calibrating Intermod Power for more details Note accurate values of nonlinear coefficient need to be used in order to achieve accurate intermod power levels Do not use default nonlinear coefficients provided with this program to determine absolute intermod levels Why do I need to calculate intermodulation products Intermodulation products should be calculated before installing two or more radio transmitters at a site in order to determine what new frequencies may be created by intermodulation These new frequencies can cause serious interference with the site radio receivers and other nearby receivers It is also a requirement by many frequency spectrum regulating agencies to ensure interference is not created for other existing radio stations Optical Four Wave Mixing This
4. possible to calibrate using intermod frequencies as follows a Find an intermod frequency for each intermod order that can be measured It is important to ensure that there is only one intermod existing on the frequency also no other interference at this frequency To do this run F Intermod and sort by Intermod frequency to determine if more than intermod could occur on the frequency b Measure the power of each intermod frequency for each intermod order c Run F Intermod and identify the frequency for each order and the associated power level The power level shown will not be the same as the power you measured d Click the menu Options and Nonlinear Coefficients and adjust the nonlinear coefficient for the intermod order associated with the measured intermod frequency Run F intermod again to recalculate the power levels and check the new recalculated intermod frequency power Keep adjusting the nonlinear coefficient until the recalculated power level for the frequency is the same as the measured level Once it is the same the nonlinear coefficient is known for that intermod order and continue to do the same for the next intermod order and frequency This completes the nonlinear coefficient procedure Intermodulation Examples The following examples use the default nonlinear coefficients that load with the program Example 1 Five channels are inputted 2 duplex 2 half duplex and 1 simplex receive only If the nonlinear coefficient i
5. 000 156 80000 Duplex 0 30000 Existing 200 000 Vv ora 157 12500 157 10000 H Duplex 0 30000 Existing 300 000 157 50000 Simplex 0 30000 Existing 0 000 P List All Intermod Output frequency range 157 70000 156 55000 156 72500 156 97500 157 37500 157 37500 157 52500 157 52500 159 95000 160 05000 156 57500 156 80000 156 80000 156 87500 157 27500 157 27500 157 30000 157 30000 157 30000 0 20000 0 25000 0 07500 0 17500 0 07500 0 12500 0 22500 0 02500 0 15000 9 25000 0 22500 0 30000 9 00000 0 07500 0 02500 0 22500 0 20000 9 00000 0 20000 NOM RF oO F OM FP PO woh FP Oo Oo 1 He 3 s 5 5 5 s 5 s 5 s 7 7 7 7 7 7 7 7 7 or A OP WO WwW PF WY hy Or OF wo ww M w vv yP Piw w YD WD DD DD Dy w NNN FPP OF FM OF FP FO Oo oo 80 HW ww oOo To see the total interfering intermod power for each channel uncheck Show channel name in output run again and then click T Pwr The Channel R T column will be sorted and total power value for each channel will be shown 12 of 14 9 Sep 13 6 41 PM F Intermod User Manual 13 of 14 A 2 nu F Intermod Frequency Intermodulation Calculation File Edit Options Industry Help file C Users Owner Documents Software from IBM Imod Interm Dw a amp E C Documents and Settings Bob My Documents S oftware from IBM Imod T est files 500 Test files newversion1 c List Intermod Frequencies Intermod For all c
6. F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm F Intermod User Guide Telecom Engineering Inc 2012 r61 Please visit our website at http www telecomengineering com software download1 htm to check for any updates Introduction Frequency Intermodulation Frequency Intermodulation IM occurs when 2 or more frequencies create new and usually unwanted frequencies that can cause interference The general equation describing intermodulation frequencies is LM nAtmBtnCr where IM is the newly created intermodulation frequency N z3 are integer or transmitter coefficients A B C are the existing radio transmit frequencies If IM falls within the bandwidth of a receiver it may cause interference in that channel The intermod order is the sum of the absolute values of all the transmitter coefficients ILM order For example A 2B 2C will give an intermod order of 5 1 2 2 5 F Intermod calculates intermodulation products in a given bandwidth equal to or below a selected intermodulation order Intermod Frequency Power Power of each intermod frequency is calculated using the below equations i 2 i 3 i i r Vp 49 taytay tay tay E cOS2TAt E pcos 2mBt E cos2aCt sees where V is the output voltage v is the input voltage a is the nonlinear coefficient E Ep Ec are the voltages of the carrier frequencies
7. ansmitter s frequencies bandwidth transmitter intermod and receiver frequencies bandwidth The program assumes the transmitter bandwidth is the same as the receiver bandwidth If the is not selected only intermod frequencies that fall in the receiver bandwidths will be calculated For an intermod study that is only concerned about receiver intermod interference leave this box uncheck Display Channel Name in Results Select this check box if you want to see the channel name in the output table rather than its frequency Channel name size is maximum 12 characters List All Intermod Leave this box normally unchecked unless you want to display all intermod frequencies created from 0 Hz to 1000 GHz If this box is checked output intermod listings can still be filtered into a more narrow frequency range by selecting Specify Output Frequency Range Specify Output Frequency Range Leave this box normally unchecked unless you want to specify an output frequency range then enter the lower and upper frequency range limits into the two boxes Input Table Copy Paste Delete Editing Right click while the mouse is over a input table cell will produce an additional menu that will allow you to Copy Paste Select Column Select All and Delete You can copy one or more entries to and from Excel using this method To copy columns of data from an Excel spread sheet highlight the column of frequencies to be copied in Excel and select copy Then in F Interm
8. ay the intermod frequencies that the planned channels contribute to This is useful for calculating the intermod frequencies for new transmitters receivers being added to an existing site A channel can be designated as planned by double clicking on the channel s Status entry in the input table A planned channel row will be green If For existing channels is selected the program will only use the existing channels in the calculation Planned channels will not be included and will not be displayed in the output results Channels are labeled Existing by default To change the status to Planned double click on that cell in the input table Planned channels are highlighted in green 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm Intermod Order Enter the intermod order an integer from 3 to 31 inclusive Typically intermod orders of less than 7 are used For odd intermod order use the pull down selection For even intermod order type value into the selection box Single Intermod Order Select this check box if you want the output to display only intermod order products of order equal to the order selected in the Jntermod Order box If it is not checked the output will display intermod products up to and including the order entered in the Jntermod Order box Include Tx Frequencies Select this check box only if you want intermod frequencies to be calculated that fall in the tr
9. e use with tpl extension This template file stores all F Intermod configuration options that are currently set Does not save channel data info Print preview Display how the output will be printed Print Ctrl P Print the current input and output Export channel database MSExcel Exports the input table data to an MS Excel compatible CSV file Text file Exports the input table to a text file displaying records rather than a table 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm 10 of 14 Export Intermod output Text file Exports the output table to a text file MS Excel compatible CSV file Exports the output table to a CSV file which can be opened with any spreadsheet program including MS Excel Text file showing intermod equations Exports the output to a text file showing the Intermod Equations rather than a table Save overflow output to file Select one file format that will be used by the program to save the output when screen output table is too small to display all intermod listings Exit Ends the program Options View Channel Info Displays the extra channel information dialog box Units Set the frequency unit to kHz MHz GHz THz or nm The default unit is MHz This option can only be set when the input table is empty Auto Rx Freq If checked then receive frequency will be automatically calculated from the difference betwee
10. ex or Simplex Select whether this channel is Full Duplex Half Duplex or Simplex Note that if Simplex is chosen you must enter a transmit OR receive frequency not both For duplex setting the program assumes that the channel transmitter and receiver are on all the time For half duplex setting the program assumes that the channel transmitter or receiver are on but not at the same time So when the transmitter is on the receiver is off and vice versa Therefore intermod created by the channel s transmit frequency will never appear in that channel s receiver For simplex setting the program assumes that there is only one way communications That is for that channel only the transmitter is on always 100 or the receiver is on always 100 But not both at any time Power Enter the transmitter effective radiated power ERP power in Watts Run Click to run the calculations for the input data seen in the input table Clear All Clears and resets all the data input and output tables except for units Clear Out Clears only the output table Add Click Add to enter data Channel Tx Frequency Rx Frequency Half Bandwidth into the input table Delete Row To delete a channel click on the row in the input table to select it and then click Delete List Intermod Frequencies If For all channels is selected the program calculates all intermod frequencies normally If For planned channels is selected the program will only displ
11. hannels Order For planned channels For existing channels Single Intermod E Order Include Tx a Frequencies z Show channel name in output P List All Intermod Output frequency range between Freq MHz 161 90000 159 80000 158 10000 157 12500 lt lt Add Tx Frequency MHz Rx Frequency MHz Clear Delete s ms Rx Freg MHz 157 30000 Duplex 159 80000 H Duplex 156 80000 Duplex 157 10000 H Duplex 157 50000 Simplex Channel Name 5 Chan alf eee Duplex ieks Simplex H BW MHz 0 30000 9 30000 9 30000 0 30000 0 30000 Existing Existing Existing Existing Existing H Pwr W Owner 400 000 400 000 200 000 300 000 0 000 Half Bandwidth MHz Order I Mod Freq Pwr dBW 156 55000 156 72500 156 97500 156 57500 156 80000 156 87500 156 80000 157 30000 157 37500 157 52500 157 27500 157 30000 157 70000 157 37500 157 52500 157 27500 157 30000 159 95000 160 05000 uo MONSIN ONIWO NS NSN non aaaaann As can be seen above the worst intermod is on channel 157 5 MHz 156 80000R 156 80000R 156 80000R 156 80000R 156 80000R 15 80000R 157 10000R 157 10000R 187 30000R 157 30000R 157 30000R 2 187 80000R 157 50000R 157 50000R 157 50000R 157 50000R 157 50000R 159 80000R 159 80000R 0 25000 0 07500 0 17500 0 22500 0 00000 0 07500 0 30000 0 20000 0 07500 0
12. hat WordPad cannot open use other programs available from the Internet that can open large files such as Textpad available at www textpad com Copying Right click while the mouse is over the output table will produce an additional menu that will allow you to Copy Paste Select Column and Select All You can copy one or more entries to the clipboard However you cannot paste to the output table TP Total Power This button is only available if the Power feature is purchased It sums all intermod powers that fall onto the same frequency or same channel If List All Intermod is selected the result is the sum of all intermod powers that fall onto the same frequency If List All Intermod is not selected the result is the sum of all intermod powers that fall onto the same channel Note that this button is only shown if you have the Power Option license installed and after you get results by pressing the Run button If the number of intermod listings overflows into an overflow file then this feature will not be able to sum any of the overflow intermods It only sums intermods shown in Output Table Menu Options 8 of 14 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm 9 of 14 T nu F Intermod Frequency Intermodulation Calculation Options Industry Help New channel database Ctrl N Load channel database Ctri o Load chan database from version 3 2
13. intermod frequencies within each intermod order To calibrate and determine the nonlinear coefficients follow the below procedure If the nonlinear coefficient for each intermod order is known for the environment then select menu Option and click Nonlinear Coefficients Enter the nonlinear coefficient directly for each intermod order When a nonlinear coefficient value is entered it is immediately stored do not click Calculate 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm If the nonlinear coefficient is not know then a Find one of the fundamental carrier frequencies that is generating the intermod products and measure its power and the power of all of its harmonics to the highest order needed in your calculations For best accuracy use an unmodulated carrier For example if you need to determine intermod products up to and including Sth order then measure all harmonics of a carrier up to and including the 5th harmonic For best accuracy be sure that there are no other interfering carriers at the same frequency as the carrier fundamental or the harmonics which will skew measured results b Click the menu Options and then Nonlinear Coefficients and enter for each intermod order the carrier power and each harmonic power Click Calculate for each intermod order for the nonlinear coefficient to be calculated If a carrier frequency harmonic cannot be found or is not available it is
14. ktop Fig4example cdb List Intermod Frequencies Channel Name 3 Chan Intermod lt lt dd Remote B Duplex Order C For planned channels ate Tx Frequency MHz Rx Frequency MHz Half Bandwidth MHz B z For existing channels Clear Delete o 2 14000 2 22000 5 00000 Tx Freq MHz Rx Freq MHz ff Status Pwr W Owner E Order 3 51000 3 10000 Duplex 00000 Existing 700 000 Include Tx i 3 50000 3 00000 Duplex 5 00000 Existing 700 000 5 Frequencies B 2 14000 2 22000 Duplex 5 00000 Planned 700 000 u Show channel name in output F List All Intermod Half 3 Duplex Simplex r Output frequency range between 0 01000 0 01000 0 01000 1 36000 1 36000 1 36000 37000 37000 37000 28000 28000 4 28000 5 64000 5 64000 5 64000 g Ennn 3 10000R 3 09000 2 22000R 2 21000 3 00000R 2 99000 3 10000R 1 74000 2 22000R 0 86000 3 00000R 1 64000 2 22000R 0 85000 3 10000R 1 73000 3 00000R 1 63000 3 10000R 1 18000 3 00000R 1 28000 2 22000R 2 06000 3 00000R 2 64000 2 22000R 3 42000 3 10000R 2 54000 2 annnnD ssnann I I 1 I 1 NM HM MM NM NM NR RD i He He oO oO 1 oO PP PP RP PP PP BP PoP RP RB VN NM HM HM HM HM MH MH HM MH FN NM RD OD I 9Y NM HM MM MH MH MH MH MR RD RD RD OD 9 NM NN Oj O O C0 o SCo F Pir O o1o r ie RPi PLP IN INPUT First choose a frequency unit for F Inter
15. ly entered press RUN to execute the program Depending on factors such as the number of channels intermod order bandwidth and speed of your computer the run process can take a second or hours You may stop the calculations by pressing CANCEL at any time Output The output is displayed in chart form sorted by intermodulation order Order and intermodulation frequency I Mod Freq Sorting by other columns is possible by double clicking on the header of the column to be sorted Note sorting the I Mod Freq Power Channel and Difference columns will take much longer than other columns since a special sorting routine is used for these columns 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm 7 of 14 If no intermodulation IM listings are found then a red No IM Found label will be displayed in the Total Listings Found called Intermod Total in new versions box Total Listings Found fiz Between Frequencies 120 80650 and 996 44450 MHz 123 01450 123 89750 Locall 143 89050 Direct 994 90300 Cell2 995 73600 Cell2 994 46150 Cell2 996 22750 Cell2 224 71150 Aari 121 69000 Locall 222 34700 Airl 224 27000 Airl 121 24850 Locali ooroorrrer ooo Columns The first column Order contains the intermodulation order of calculated intermodulation frequencies The second column J Mod Freq contains the calculated intermodulation frequencies in units
16. mod to use The default unit is MHz To change it to another unit such as kHz or GHz click Options gt Base Frequency Unit and select the desired unit This must be done when the input table is empty Channel Name Enter the channel name or label to a maximum of 12 characters An entry in this field is not required Tx Frequency Enter a transmit frequency for the channel The maximum and minimum value that can be entered are 999 999 99999 and 0 00001 respectively Note that this software assumes that the Tx frequency is not modulated and has no bandwidth If Tx bandwidth results are required user may want to run F Intermod multiple times and change the Tx frequency to the end points of the Tx bandwidth in order to capture intermod frequencies that may be produced across the Tx bandwidth Rx Frequency Enter a receive frequency for the channel The maximum and minimum value that can be entered is 999 999 99999 and 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm 4 of 14 0 00001 respectively Half Bandwidth Enter the receiver half bandwidth for the communications channel For example if the bandwidth is 30 MHz then enter 15 MHz Maximum value is 500 000 00000 and minimum value is 0 00000 If zero bandwidth is entered only intermod frequencies that fall exactly on the Rx frequency will be displayed All output and display bandwidths are half bandwidth values Duplex Half Dupl
17. n the last transmit and receive frequency pair Default difference on startup is zero Nonlinear Coefficients Enter proper nonlinear coefficients for each intermod order to obtain accurate power output levels for that order Industry Selecting the appropriate industry will hide non appropriate options for that industry Selecting Radio industry will show all options Help Guide Opens this document in your default internet browser About Displays program version and a link to our website www telecomengineering com Check for Updates Checks for a newer version of F Intermod at www telecomengineering com If a newer version exists you will be prompted to download the new installation file Note If you have any type of software firewall running on your computer be sure to allow F Intermod to access the internet for this option to work Calibrating Intermod Power In order to achieve any accuracy in the calculated intermod output powers each intermod order s nonlinear coefficient needs to be calibrated and adjusted to your project s specific environment Note the default nonlinear coefficients loaded when the program starts will not provide any degree of accuracy of intermod power outputs and should not be used as absolute values However the default non linear coefficients can be used to generate intermod frequency powers that can be viewed as relative values These relative values will provide worst and least offending
18. od input table click on the first frequency cell that has been copied right click and select paste Individual input table cells can be edited directly by double left clicking on the cell Any input or output table column can be sorted ascending or descending by double right clicking on the header of the column to be sorted Channel Database click on lt lt button 5 of 14 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm 6 of 14 HE Channel Data Channel Name Status Local A Existing Planned Tx Freq MHz Rs Freq MHz 3 51000 3 10000 Half Bandwidth MHz Type Duplex Ea Tx Power vv 700 000 Location m Contact Name Phone Number EE Channel Description lt lt Previous Channel Next Channel gt gt Delete Channel Add New Channel Exit Save Data Click on the lt lt button to access the Channel Data form This is another method to view edit and add information to the Channel Database To edit a channel make changes on the form and then click Save Data To add a new channel click Add New Channel enter the information then click Save Data It is possible to export the Channel Database Input Table to an MS Excel compatible CSV file or to a text file as records Click on File then Export Channel Database The text file will display each channel data as separate records When all your channels have been correct
19. program also calculates fiber optic system four wave mixing FWM products that can occur in DWDM links Four wave mixing is the fiber optic equivalent to radio frequency intermodulation interference and can cause interference over DWDM channels This software calculates the possible interference frequencies that may occur in DWDM system Enter the DWDM channels in THz Additional Intermod information can be found at these sites Wikipedia Intermodulation www tpg com Good explanation ARRL explanation Installation Download the FIntermodSetup exe file onto a temporary directory in your computer then run FIntermodSetup exe You may also run it directly from a CD Follow on screen instructions as the program loads FIntermodSetup exe can be deleted after installation is complete This restricted version of F Intermod will only calculate the Intermod frequencies for up to 3 channels and will expire after 20 days After the trial period expires you will be prompted to purchase a license key If you have purchased a license enter the unlock code when prompted The registered version will calculate intermods for up to 10000 channels Program Operation 2 of 14 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm 3 of 14 eI s Fy F intermod Frequency Intermodulation Calculation File Edit Options Industry Help L amp E C Documents and Settings Bob Des
20. roducts that are printed Note printer font size is set to Courier 8 Increasing font size will result in misaligned rows in printout and unreadable The output can also be to exported to a text file MS Excel compatible CSV file or text file which displays the intermod equations rather than the output grid For example if the intermod frequency is 138 365 MHz the file will display the equation for this frequency as 138 36500 1 154 01000 1 149 71000 1 142 66500 where 1 1 and 1 are the intermod coefficients and 154 01 149 71 and 142 665 are sample transmit frequencies 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm The CSV file can be opened with any spreadsheet program It will show both the input and output tables along with the channel database data Output Too Large for Grid If there is a large amount of data to display the display table may have insufficient size to show all results Before the limit is reached F Intermod will prompt the user to save the calculated intemod listings to a file The data is then saved to one of 3 file formats txt csv and txt displaying intermod equations that is selectable by the user in the File Save output to Overflow file menu Note Some programs will be incapable of displaying large files The text files can be viewed with Microsoft WordPad or any standard text word processor For very large text files t
21. s measured and is accurate then the worst offending intermod is 3rd order on channel 5 the simplex channel Power of 6 9 dBW Channels and 2 contribute to this intermod If the nonlinear coefficient is not calibrated then we can say that there will be one 3rd order hit on channel 5 with unknown strength For 5th order intermod the worst offenders strongest intermod will be on channels 1 3 and 5 Intermod power levels are unknown For 7th order intermod the worst offenders strongest intermod will be on channel 3 Intermod power levels are unknown 11 of 14 9 Sep 13 6 41 PM F Intermod User Manual file C Users Owner Documents Software from IBM Imod Interm gt EN F Intermod Frequency Intermodulation Calculation IE E x File Edit Options Industry Help D gH hAg m B EADocuments and Settings Bob My Documents Software from IBM Imod Test files 500 Test files newversion1 c List Intermod Frequencies Channel Name 5 Chan Half i Intermod For all channels lt Add Channel 5 C Duplex C Duplex Simplex Order For planned channels Tx Frequency MHz Rx Frequency MHz Half Bandwidth MHz z g For existing channels Cear _ Delete 157 50000 0 30000 r Single Intermod Tx Freq MHz Rx Freq MHz H BW MHz Status Pwr W Owner Order 161 90000 157 30000 Duplex 0 30000 Existing 400 000 po Include Tx 159 80000 159 80000 H Duplex 0 30000 Existing 400 000 Frequencies 158 10
22. selected The third column Channel R T contains the channel frequency or name if Display Channel Name selected that is being interfered The R or 7 designates if the intermod is receiver or transmitter intermod The fourth column contains the difference between the calculated Intermod frequency J Mod Freq and the channel frequency being interfered Note if List All Intermod option is selected then values in this column have no meaning The remaining columns identifying header is Tx frequency channel name or COxx in printout contain transmit frequency coefficients n n n ze that produced the listed intermodulation frequency Mod Freq Note that the speed of the program depends on the number of Tx and Rx frequencies intermod level and bandwidth entered To speed up the calculations use a lower intermod level do not select Include Tx Freq option or use a faster computer Also select Single IM Order to reduce output Printing and Exporting Output To print the output click File gt Print or press Ctrl P To view the print preview click File gt Print Preview Note If there are more than 9 transmit frequencies not all of the transmit frequency output columns will show in the printout due to paper width limitation Transmit columns after the 9th frequency will be truncated To print more columns try changing paper orientation to Landscape This does not effect the number of Intermod Frequency rows intermod p
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