RE: [Discuss-gnuradio] Problem using benchmark_rx.py

[Tom Rondeau]

Tarun,


> From: Tarun Tiwari [mailto:address@hidden 
>
> Thank you Tom,
>
> I did change the bit rate for Rx and used -v mode, but its still not
working. Please see the output of program:
>
> Transmitter:
> address@hidden ~]# ./benchmark_tx.py -f 100e6 --tx-amplitude=500 -M 2 -r
100e3 -v 
> >>> gr_fir_fff: using SSE
> bits per symbol = 1
> Gaussian filter bt = 0.35
> Using TX d'board A: Basic Tx
> Tx amplitude     500.0
> modulation:      gmsk_mod
> bitrate:         100kb/s
> samples/symbol:    4 
> interp:          320
> Tx Frequency:    100M
>.......................................................
>........................................................
>.............................
>
>
> Receiver: 
> address@hidden ~]# ./benchmark_rx.py -f 100e6 -r 100e3 -v
> >>> gr_fir_fff: using SSE
> bits per symbol = 1
> M&M clock recovery omega = 4.000000
> M&M clock recovery gain mu = 0.050000
> M&M clock recovery mu = 0.500000
> M&M clock recovery omega rel. limit = 0.005000
> frequency error = 0.000000
> Using RX d'board A: Basic Rx
> Rx gain:         10
> modulation:      gmsk_demod
> bitrate:         100kb/s
> samples/symbol:    4 
> decim:           160
> Rx Frequency:    100M
>
>
>
> I am connecting the the two boards using cables using -32dB RF attenuator
on each port of daughterboards.
>
> I am using Basic Tx and Basic Rx Boards.

That's what I thought. You can't transmit at 100 MHz with the Basic boards
(DAC is 128 Msps; you can really only transmit up to 44 MHz). Cut it down to
something like 20 MHz.

> Please advise me, if I need to do some changes in benchmark_rx.py program.
And meanwhile, can you tell me do we need to call any function between 
>
>    fg.start()        # start flow graph
>    fg.wait()         # wait for it to finish 
>
> To debug the program, I tried printing something inside rx_callback
subroutine, but I think rx_callback is not being called anywhere in the
program, thats why I am > not able to see any printed output on screen. Am I
right? I tried this one: 
>
>    def rx_callback(ok, payload):
>        global n_rcvd, n_right
>        (pktno,) = struct.unpack('!H', payload[0:2])
>        n_rcvd += 1
>        if ok:
>            n_right += 1
>        print "Hello Tarun\n"
>        print "ok = %5s  pktno = %4d  n_rcvd = %4d  n_right = %4d" % (
>                ok, pktno, n_rcvd, n_right)
>
>
> but no result ....
> Please advise me. 

The rx_callback function only gets called if a packet is seen, which means
correlating with the access code, so unless you're receiving packets, you'll
never enter this function. Hopefully the change in carrier frequency will
fix it.

Tom