Noise Leakage in transmission

GNU Radio
1

HI,
I havedesignedan server client Gnuradio companion programs to transmit
pmr446 received channel. It then transmits it to server via TCP. Then
the USRp transmit it over the air tochannel7 in PMr446 radio. But when
theprogramruns a leakage noise adds up in the system. Can any one help
out in this. The grc files are attached.

Best Regards,
SAJJAD SAFDAR

2

Hi Sajjad,

From a quick first glance without testing the flowgraphs on any
hardware i’ve noticed the following issues:

Corrections for both:

  1. Your Tau and Max D.iation values are not the same.
  2. you are sending data over TCP at 250e3 samp_rate to the server
    which is expecting 50e3
  3. lower the refresh rate on the Wx FFT to cut down on CPU usage

Tranceiver_Client Corrections:

  1. 50e3 * 2.83447 is not 250e3. make the resample rate = 5 in your
    polyphase arbritrary resampler.
  2. Your low pass filter is decimating by 2 and should be 1

Tranceiver Server correcitons:

  1. in your polyphase arbritrary resampler, you should make the number
    of phases = 32 and then multiply the samp rate in the taps by 32 also.

Cheers,

Mike

–
Mike J. M0MIK BSc
Radio Communications Technology Specialist
Email: [email protected]
Web: http://www.scanoo.com