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From: | Yahya Ezzeldin |
Subject: | Re: [Discuss-gnuradio] False Packets for benchmark TX/RX |
Date: | Wed, 5 Dec 2012 03:15:37 +0200 |
On 04/12/12 07:47 PM, Yahya Ezzeldin wrote:The usual reason for this is frequency-offset between RX and TX. In the 'real world' this is a constant problem,_______________________________________________ Discuss-gnuradio mailing list address@hidden https://lists.gnu.org/mailman/listinfo/discuss-gnuradioI am pretty aware this had been covered in alot of question in the Mailing List but after going through alot of them I am unable to find a solution.
Currently, I am trying to establish the benchmark connection between two USRP 1 nodes. Both Laptop stations have GnuRadio 3.6.2 installed on Ubuntu 12.04.
Now the facts:****************
1) The codes I use at Node 1 is :
./benchmark_tx.py -f 900M -m gmsk -r 250k --tx-amplitude=0.5 --tx-gain=20
The codes I use at Node 2 is :
./benchmark_rx.py -f 900M -m gmsk -r 250k --rx-gain=152) I edited the threshold in the receive_path.py from 30 to -70. This is based on the FFT_plot that I get when transmitting the packets. Is this wrong ?
3) My USRPs are placed approx. 50cm apart.
4) I get this as output on Node 2 when running benchmark_rx command
ok = False pktno = 215 n_rcvd = 1 n_right = 0ok = False pktno = 217 n_rcvd = 2 n_right = 0ok = False pktno = 219 n_rcvd = 3 n_right = 0ok = False pktno = 221 n_rcvd = 4 n_right = 0ok = False pktno = 165 n_rcvd = 5 n_right = 0ok = False pktno = 230 n_rcvd = 6 n_right = 0ok = False pktno = 227 n_rcvd = 7 n_right = 0ok = False pktno = 233 n_rcvd = 8 n_right = 0ok = False pktno = 239 n_rcvd = 9 n_right = 0ok = False pktno = 236 n_rcvd = 10 n_right = 0ok = False pktno = 252 n_rcvd = 11 n_right = 0ok = False pktno = 240 n_rcvd = 12 n_right = 0ok = False pktno = 241 n_rcvd = 13 n_right = 0ok = False pktno = 246 n_rcvd = 14 n_right = 0ok = False pktno = 243 n_rcvd = 15 n_right = 0ok = False pktno = 225 n_rcvd = 16 n_right = 0
I hope anyone can guide me as to what to do regarding this
Best Regards,--Yahya Ezzeldin
which is why complete, market-ready, radio-based digital comms systems have a frequency locking mechanism
in the receiver.
Try offseting the RX frequency in small amounts in either direction, and see if you can get good packets.
-- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
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