Frequency modulation in NI-5641R

[Ganesh20]

Hi,

    I have an NI- 5641R IF receiver and i am using Labview 2009 SP1.

    I need to receive FM radio channels by using the above.

    Please help me how to do or send me any examples related to this....

[GovBob]

Have you looked in the example finder in LabVIEW? Do you have a downconverter to go with your 5641? If you do see here

Hope this helps.

[Ganesh20]

Thanks GovBob.....

Now i am not having any downconverter. I am having NI PXIe-5641r only.

With this is it possible to do FM demodulation......

[GovBob]

I don't have that particular card. You would need the carrier frequency to be within the specifications of the 5641 in order to demodulate the signal.

[Lars.B]

Hi,

in RF communication library is a FM demodulator included: -> http://decibel.ni.com/content/docs/DOC-4068

Works with me - but without downconverter you would not fall in usual range of terrestrial FM radio stations (87 - 108 MHz). IFRIO just goes upto 80 MHZ as far as I remember.

Greets,

Lars

[Ganesh20]

Hi,

     Thanks for your reply Lars.B. I am trying to use the FM demodulation in RF communication library but i am getting the demodulated output as zero.

     I am attaching my code below.

     Please have a look.

[Lars.B]

In your FPGA code "input valid" is a constant value and "ready for output" not used.

"Input valid" should be wired to the feeding FIFO (in the way NOT[timed out?]) and "ready for output" linked to the output of your code - in this case "stream fifo 16".

"Ready for input" should control data source (here reading the FIFO "local") - only not necessary when your timing of the feeding source is always slower than the processing part (e.g. when atan is set to 1 sample per tick).

Actual the data flow is uncontrolled, so that the demodulator is not processing the correct (valid) data.

Also, I don't think that there will be 65500 elements in one second timeout... try a lower value (like 2000).

Maybe take a look in the example in the library, there it is how it works..,

Greets,

Lars