LabView

[sine_help]

hi Kyle S

 i have problem with Power&Freq Est vi  ie it is not working for IQ data. i have attached a file which is recorded by 5142. i want to fiind the center frequency of that signal which is 0 in that case but vi showing  someting 600k+ frequency. how to make this vi to find frequency of complex signal. 

[Smootastic]

Hi sine help,

Can you go ahead and attach your VI so far?  That way we can see how you are calling the VI. 

[sine_help]

i have attached the VI . please edit it and explain what is problem.

[Smootastic]

Hi sine help,

If you make a plot of the Power Spectrum entering the Estimation VI, is the spectrum correct?  I have attached a listing of how to use the Power & Frequency Estimation VI (http://zone.ni.com/reference/en-XX/help/371361D-01/lvanls/power_frequency_estimate/).  This should give you a good idea of how to use the VI for your application.

[sine_help]

please check the Vi that i have send . power spectrum is ok ie. it is -FS/2  0  Fs/2 . ie center at zero as in case of complex waveform. but it is not showing or detected any frequeny at 0. do you know any other vi which can detect that frequency . please edit my VI so that it can work.

[Smootastic]

Hi sine help,

I couldn't see some of the VIs that you were using, but it seemed you were doing everything correctly.  I made a small example to further test the VI and I attached screenshots below.  I would check to verify that the signal you are acquiring is correct. 

[sine_help]

HI

i have a question specially from R&D  and repair department, what are the main or most common causes of damage of downconverter PXI 5600. specially mixer ic and other components that are contected directly to RFinput pin.  Is there any affect on working of downconverter PXI 5600 if system is not grounded specially when we are using it in  portable vehicle where proper ground is not avaliable. switching power supply used in almost all computers and PXI , puts approx. half voltage on chasis through bypass capacitor. if system is not grounded , we can see a sine of 50Hz of 112V(if input volt is 230V @50Hz) every where in circuit and chasis with respect to ground. can it damage converter RF input stage.all other computers and devices  works fine even if they are not grounded but i want to specially know about PXI 5600. also tell me how can i use PXI 5600 where ground is not avaliable specially in vehicles which are contantly moving.also please tell me is there any reported case of damage of RF input stage of PXI5600 or any other downconverter, if any what was the causes and how it was corrected by repacing which component. i am using VHF antenna . my first damaged downconverter is showing 20dbm loss in every signal and other dont show any signal .in both cases PXI  and antenna was properly grounded. please reply as soon as possible.

regards.

[chris_amadasun]

Hello, I have to talk this over with our hardware developers but we do have some recommended DC power converter.

Can you give use some more information on your system, what PXI chassis, controller and modules are you seeing. Also what is the power supply you are using?

Thanks

[sine_help]

thanks for reply . it is 18 slot chesis having downconverter and digitizer 5142. supply voltage is 230V@50Hz. i dont think that it is a power management or it need DC to DC converter . because RF input mixer IC is damaging .i use   passive  VHF antenna. whole setup was working fine for last 18 months. waiting for  ur reply.

regard 

[chris_amadasun]

Hello

Its likely that there is some ESD damage to the mixer of your device. You will have to send in both devices for repair.

Normally on a grounded system you need to make sure you ground yourself to the chassis ground before touching the antenna.

A google search for "ESD Prevention measures" for floating systems should come up with some useful information.

Let me know if you have any follow up questions.