record a wave file

[madd]

Hello

Is it possible to record a wave file(of a spectrum) using ni RFSA 5660. can i record a wave file (of a spectrum) for a minute or so. i have tried to save a wave file out of IQ data repesentation of  ni RFSA Demo and watch it on Matlab my spectrums are not same.

Ok another one  when i mention center frequency as 100Mhz  and span as 20Mhz it means lower frequency is maaped at 90Mhz and upper at 110Mhz to make bandwidth 20Mhz. after passing through downconverter situation becomes like this  center frequency at 15Mhz

 lower freq at 5Mhz and upper freq at 25Mhz.now i want to make a wave file for this spectrum i have acquired how to do it so that when i paly the wave file in matlab/labview i can see the spectrum as i have acquired.

Regards

Madd

[dansch]

Hi madd,

You should be able to record the spectrum data in the same way that you recorded the IQ data. You just need to acquire the spectrum such as with an example program, and then write this data to file. I am not really sure how you are viewing this data and comparing it to Matlab, or what method you are using in Matlab, so it is hard to tell why the data is not matching. The main thing to keep in mind is that the spectrum data is the same as the IQ data, but it has been transformed and is in the frequency domain. Also, regarding your question about the 15 MHz downconversion, this is done by the 5600 to get the RF signal to IF so that the 5620 can digitize it, but this IF data is further downconverted in software to be at baseband. The spectrum should still be the same, only you will now just have the message signal of interest without the carrier frequency. Hope this helps,

[madd]

Tnx 4 ur response

 what if i have 5661(5600+5142)  and same question . in this case also ther will be no carrier e.t.c

Regards

madd

[Ana P]

Hi madd,

The 5661 have similar behavior to the explained by Daniel. The 5600 is the downconverter and also translates the frequency to be centered around 15 MHz. The 5142 digitizes the data. With this device you should also be able to save the spectrum information to a file. Can you give more information on what is different in the spectrum that you watch from what you expect? Also how are you acquiring the spectrum in the 5661? With more information we might be able to help you better. Have a nice day,