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

[Tarun Tiwari]

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.

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.

Thank you again.

Regards,
Tarun

On 12/7/06, Tom Rondeau <address@hidden> wrote:

> From: discuss-gnuradio-bounces+trondeau=address@hidden
[mailto:address@hidden ] On Behalf Of Tarun
Tiwari
> Sent: Thursday, December 07, 2006 12:25 AM
> To: address@hidden
> Subject: [Discuss-gnuradio] Problem using benchmark_rx.py
>
> Hi,
>
> I am trying to transmit packets using benchamark_tx.py and recieve them
using benchmark_rx.py. As mentioned in README file I started first
benchmark_rx.py at one
> machine then started benchmark_tx.py on another machine, but I dont see
any print on receiver machine. I am using following commands:
>
> Tx Machine:
> address@hidden ~]# ./benchmark_tx.py -f 100e6 --tx-amplitude=3000 -M 2 -r
100e3 -s 1000
>
> Rx Machine:
> address@hidden ~]# ./benchmark_rx.py -f 100e6
> >>> gr_fir_fff: using SSE
>
> and I dont get any output.
>
> Can somebody guide me how to succesfully receive the transmitted packets?
>
> Thanks in advance.
>
> Tarun

Try using the '-v' (verbose) flag on both Rx and Tx, which will give you all
the information about the modulation, bit rate, etc. The most likely
candidate here is that you've specified the bit rate (100 kbps, GMSK) on the
transmitter but not the receiver. The receiver defaults to 500 kbps. Use the
'-r 100k' on your receiver as well.

Are you transmitting over the air, or connected over cable? And what
daughterboards are you using? This will impact the transmit amplitude you'll
need. What you've specified is a pretty good mid range for most setups. I
only point this out as the next place to look once you've corrected the bit
rate and it still doesn't work.

Tom