[Discuss-gnuradio] Transmit and Receive hopping Sequence in FHSS (using gr-spread module) mismtach

[Ajinkya D Kadam]

HI All, 

I am using gr-spread module to transmit a signal using FHSS. When I receive the FHSS signal, the received signal has a completely different hopping sequence as from the transmitted one. I am using USRP N210 for transmission and reception. I am not sure why this is happening. The transmitted sequence is (frequencies in Khz)

    187.5

   -12.5

   162.5

   -62.5

    62.5

   137.5

   -112.5

   -37.5

   112.5

   -162.5

   -137.5

   -87.5

   12.5

   37.5

   87.5

 and the received sequence is 

      37.5

      62.5

      112.5

      -187.5

      12.5

      187.5

     -37.5

      87.5

      162.5

     -87.5

      0

      137.5

     -137.5

     -112.5

      -62.5

      37.5

      62.5

I have created a movie out of the images which plots the IQ, FFT and WaterFall plot for the transmitted signal and the received signal using the "plot_psd_base.py" file in gr-utils. Please have a look at both of them here and here. 

Please see the attached files for the flowgraphs, I am using as the transmitter and receiver.

I have stored the received and transmitted signal to a file. Since these are large files I have uploaded them to google drive here. 

Could someone please help me understand the behavior I am observing ? 

Is this some sort of synchronization issue ? What am I missing ?

Thanks in advance. 

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fhss_tx.py
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fhss_rx.py
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