JEA247ESAC
Contents
1. necessary to lower this value to 1 msec Open the System control panel gt System gt Hardware gt Ports Com amp LPT and select the port number corresponding to the one used right click go to Properties Port Setting Advanced anche Ulteriori informazioni online Centro operativo Windows Update Prestazioni del sistema The latency time is now set to 1 msec In the case of transmission from a PC to the device the protocol is already structured to transmit packets employing a time of 1 msec or greater Setting Parameters Once you have entered the correct number of the communication port enter the number of units for ex 12 in the box Geophones Number Before you acquire channels must be enabled and their identification number defined Select from the menu CHANNELS JEA247ESAC 1 0 As you can see the 12 channels have been labelled if you exit this setup will be remembered All 12 channels are enabled check below channels not enabled will not be shown in the graph The circle dot in the top of each unit represents the choice of the place to connect the trigger but now we do not care In this example has been set a sampling frequency of 4000Hz for a number of samples per channel equal to 256 open the Parameters window As is shown the acquisition takes 64 msec In fact 256 samples 4000Hz 64 msec It is possible to see in real time while the system acquires al2. NA DOLAN Geophysical JEA247ESAC SEISMOGRAPH user manual Installing the Software Refer to the folder directory of the installation file whose name is Installation Disk JEA24TESAC There is a file with the name Installing USB Drivers FTDI pdf Open it and follow the prompts to install the USB drivers needed to operate the equipment After installation of the driver run the installation file JEA247ESACSetup exe Will be created in C drive default JEA247ESAC folder inside there will be the application file with the name JEA247ESAC exe Since the application also makes use of a software for geoseismic interpretation SmartRefract wich makes use of acquired data you need to copy a folder in the following way Go to the installation file Setup Disk JEA24TESAC in which is contained in the folder SmartRefract Copy this folder to the folder created by the installation program on your computer which is usually c JEA247ESAC After you have installed the USB driver and application JEA247ESAC see file Install USB Driver FTDI pdf connect the device to your PC Each unit will epics In this the term unit channel denote the same thing as each ve numbering from 1 to 12 13 to 24 25 to 36 etc 240 bine composed of 12 units or 6 Only the portion from 1 to 12 can be connected to the PC as it has the USB socket It may also have lengths of 6 units with geophon
3. a smartRefract Upega 201306052037 TER File Edt Impostazioni Navigate View Tools Window Help Finestra di benvenuto File recenti Accedi all home page Licenza attiva TT start Be F Programmi VB6 E EJ JEA247ESAC Manual About this software is free for refraction postprocessing and also the customer have the right for internet assistance for any problems concerning postprocessing Special DOLANG Service Is available to make the processing upon payment of a small amount Sampling Rate To perform a correct acquisition should be thoroughly learned what it means signal what is its spectrum filtering reconstruction of signal from its samples sample rate etc otherwise you may set the parameters without understanding why and do not correctly interpret what happens The basic parameters of the process of acquisition is the sampling frequency Fs from sampling frequency and resolution see below The reciprocal value of Fs is the sampling interval Ts by sampling time In the application in the Parameters window it acts directly on Fs Hz and as a result of Ts milliseconds To find out how long is the acquisition process the formula is as follows Acquisition Time Number of samples Fs or Acquisition Time Number of samples x Ts For example if I want a long acquisition time at a high Fs I expect a large number of samples It is not simple to deal wi
4. es distances from 5 to 10 meters Once you launch the program JEA247ESAC EXE you will notice this screen JEA247ESAC V1 0 x mmm GEOPHONES oC 256 1 4000 n CHANNEL Number 1000 100 10 COM1 COM14 In the green box appear the RS232 ports available on PC which in this example are the number 1 14 and 16 Port numbers range from 1 to 16 To remove ambiguity about which port is correct for the equipment just disconnect the USB port and run the software again The correct number will be that disappeared The other parameters are the default ones Note It still possible that at the first plugging of the device the operating system decides to assign a different number over 16 to the port In this case the port would not appear in the green box and you have to change its number Go to Control Panel gt System Device Manager Ports COM amp LPT In this example port 20 can not be seen to change the number to go to USB Serial Port 20 right click Properties Port Settings Advanced Number of the COM port then set a number less than or equal to 16 Important It is necessary to vary the value of latency time which is measured in msec It is related to data transmitted from device to PC The equipment connected to the USB socket will wait for a time equal to the time lag between one packet of data and the next It is
5. ion i is determined by the of bits of the AD converter he see small signals t 7 sun geophone can give maximum range of AD theoretical minimum measurable signal is 2volt 12 24 lt 119 0 oo aes sae ie 18 factor to measure of an An acquisition at 16 bit at least theoretically is 256 times worse than at 24 bit Signal noise ratio This 18 5 sake can measure and tell us what is actually possible to Vi phone and short circuit the inputs of he unit only noise source is internal ta the quipment or from electromagnetic interference aud eventually due to the digital sion which gives rise to the quantization noise The quantization noise decreases with the of the bits of conversion This noise is reduced by the averages that are performed to get Fs from 32000Hz For example at 4000Hz there is a quantization noise slightly lower than 8000Hz This process of noise reduction is called Noise Shaping The equipment in question provides a value for this ratio better than 124dB for Fs 1 kHz or so which is a very good result If the noise was completely invalid and this was only the quanti relationship we have approximately 144dB which is a theoretical tion noise with 24 bits for the ideal value even remotely This va
6. l JEAZ4TESAC V1 0 FILE STACKING GEOMETRY CHANNELS PARAMETERS DISPLAY SPECTRUM SMARTREFRACT EXIT om Pome LK E a 57 8 black JEA24TESAC 1 0 3 FILE STACKING GEOMETRY CHANNELS PARAMETERS DISPLAY SPECTRUM SWARTREFRACT EXIT GEOPHONES amplin amplin a el LE i 1 A 10 Blue Red JEA2ATESAC V1 0 FILE STACKING GEOMETRY CHANNELS PARAMETERS DISPLAY SPECTRUM SMARTREFRACT EXIT Samplin Samplin CHANNEL 1000 LS 12 2000 256 10 Menu File From the File menu you can reload the acquisitions done in the Trigger mode Go to the folder where you saved the files relating to previous acquisitions and upload the file with the extension Txt iles data txt e data_trigger Files data txt and data_trigger txt The application creates for each acquisition with trigger a file data_trigger txt and another file sgy the latter with the user defined name File data_trigger txt is updated every acquisition and located in Data directory The file data txt is created for each acquisition without the tri er option and is located in the directory JEA247ESAC updated at each acquisition In running operation is not saved any files Files data txt and data trigger txt are for internal use SMARTREFRACT is free See www vs30 it_ BGEDPHANES ro
7. l the channels set but first remember to Set all Channels By default the amplification screen is autoranging then you will see even the slightest signal Press now GO running If there are not connected geophones what you will see is the background noise of the apparatus All graphs will be updated the faster the lower the number of samples set now 256 as the sampling and receiving process will lasts less with less data To end press STOP units will flash in a different way and after about 2 seconds the system will be ready for a new command The command GO running is usefull to verify connection between units and geophones Acquisition with Triggers For operation with the trigger must be set a sampling frequency equal to 1000Hz 2000Hz 4000Hz 8000Hz 16000Hz 32000Hz In the Parameters defines whether the trigger signal will work in opening eg Explosion or closing eg Hammered of the contact For example for a seismic refraction can be suitable for the value of 512 samples and the sampling frequency of 2000Hz TRIGGER and press the GO button Window will appear on the geometry co running Set the distance between geophones which in example is four meters and the position of trigger with respect to the first unit now 2 meters to the left By clicking OK the geometry disappears and a message WAITING FOR TRIGGER will begin to flash The system is waiting f
8. lue is often not very seriously stated on many devices along with other parameters more or less invented Technical Data of JEA247ESAC gt WATER PROOF lt PC connected by USB RS485 to sampling units 240 for more than 24 a repeater is needed Sampling Frequency Fs 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000Hz 16000Hz 32000Hz Number of samples Fs gt 500Hz max Number 16384 Number of samples Fs 500Hz 250Hz max number 5M samples if 24 channels 2 5M if 48ch if 120 ch Sampling duration Fs 500Hz about 2h 50m 24 ch Fs 250Hz about 5h 40m 24 ch Trigger Each unit can be connected to a trigger wire of desired length to work in opening or closing contact Power Rechargeable battery unit included in USB RS485 box more than 7h autonomy with 24 units in continuous work First 24 ch powered by USB PC Bandwidth Up to KHz 2 poles low pass filter DC component rejection Input impedence 1500 ohm Nyquist frequency 16000Hz at every Fs gt 124dB at Fs 1000Hz input shorted Units serially connected to PC by RS485 standard at MHz baudrate Application for Windows XP 7 and 8 allows easy setting of all acquisition parameters and produces a sgy seg2 file for further analisys Geophones Each Unit corresponding to a channel can be connected to a geophone with desired specifications
9. or a trigger event but if for some reason you want to leave this condition you just have to click on exit When you have finished the application will ask whether to save the acquired data If you decide to save two versions of the file will be saved one with extension Sg2 and the other with extension txt File txt will be useful in case you want to review recently file previously saved Below is an example of acquisition JEA247ESAC V1 0 FILE Moving the mouse over a track in the CHANNEL Number will be displayed the number of the track channel Always moving the mouse over a point in a track in a window will be visible relative time Acquisition without triggering If the sampling frequency is equal to 500Hz or 250Hz the trigger function is disabled but the acquisition is possible for a long time that for 24 channels at maximum can be Sampling frequency of 500Hz 2 hours 51 Sampling frequency of 250Hz 5 hours 42 To start Acquisitions without trigger select the Continuous sampling In the following example has been set a sampling frequency of 500Hz for a time of acquisition of 20m and 5 sec JEAZATESAC V1 0 CHANNEL Number Clicking on START acquisition begins and a progress bar will indicate the progress of the process At the end you have to save the file in SGY format STACKING In the goal of reducing the Gaussian noise it is theo
10. retically sufficient to mediate The STACKING do this as it lets you add together the traces acquired through trigger at successive times The resulting signal should be more clean as long trigger is always carried out in the same exact condition and nothing has changed in the geo acquire with method Stacking go to menu and select stacking The graph will become blue At every triggering tracks will be added together After each triggering will be shown Keep on staking Answer no it ends the process of stacking and the file acquisition can be saved SPECTRUM In the menu you can select Spectrum to carry out the spectral analysis of a track In following example has been selected track 1 Moving the mouse over the graph we can determine the value of the frequency accurately JEA247ESAC 1 0 x 05 lg E 512 GEOPHONES 1 CHANNEL Number Number Autorange oa 1000 1 KHE mm mm i gg FEER Frequency Numbi 4 om pois Being 2000Hz the acquisition frequency the maximum frequency of 1000Hz is displayed in the graph in accordance with the sampling theorem DISPLAY This menu is only active in the acquisition triggered Going to the menu Display you can choose the type of visualization of the acquired traces For example the following shows three different views norma
11. th a large number of samples for cases where it is required a long period of acquisition a low Fs is used A basic rule of sampling is that Fs must be at least twice the highest frequency contained in the signal to be acquired Nyquist theorem If the rule is broken the acquired signal contains errors aliasing By the nature of the signals to be acquired which are coming from a geophone the spectrum barely reaches a few hundred Hz starting from a minimum of a few Hz depending on the geophone used thus not requiring a high Fs So in the case of a geophone that when triggered it is expected to provide signals until 300 400Hz the sampling frequency must be at least twice or 800Hz This consideration is only theoretical because in reality to acquire a ai that has any practical value you must acquire a much higher frequency Otherwise the available s few to easily reconstruct the original signal The application JEA247ESAC acquires always at Fs 32000Hz The lower rates are cy of 4000 H from the actual oe use ful to diminish a any Y higher r f case in the enone over the 125Hz A hardware filter on this unit provides to eliminate mitigate frequencies not useful coming from geophone In sampling without trigger even if you can acquire at 250Hz it is better to opt for the higher frequency of 500Hz to avoid the danger of aliasing error Resolution The resolut
Download Pdf Manuals
Related Search
JEA247ESAC