# Benchmark test between two USRPs have different performances in two directions **URL:** \ **Category:** GNU Radio\ **Created:** [August 3, 2012, 9:45pm UTC](https://www.ruby-forum.com/t/benchmark-test-between-two-usrps-have-different-performances-in-two-directions/221901 "2012-08-03T21:45:59Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![aris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/258eb7/32.png) [@aris](https://www.ruby-forum.com/u/aris)\ **Post date:** [August 3, 2012, 9:45pm UTC](https://www.ruby-forum.com/t/benchmark-test-between-two-usrps-have-different-performances-in-two-directions/221901/1 "2012-08-03T21:45:59Z")
I run benchmark\_tx in USRP A, and benchmark\_rx in USRP B: A: ./benchmark\_tx.py -f 2.46G -r 0.5M --tx-gain=-30 B: ./benchmark\_rx.py -f 2.46G -r 0.5M The n\_right/n\_recvd is 549/628. But when I rx in USRP A and tx in USRP B with the same parameters, the n\_right/n\_recvd is always pretty bad: 0/275. What might be the reasons? I am using USRP N210 and XCVR2450. ---
**Author:** ![Weixian\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/6de8d8/32.png) [@Weixian\_Z](https://www.ruby-forum.com/u/Weixian_Z)\ **Post date:** [August 4, 2012, 7:53pm UTC](https://www.ruby-forum.com/t/benchmark-test-between-two-usrps-have-different-performances-in-two-directions/221901/2 "2012-08-04T19:53:58Z")
On 08/03/2012 03:45 PM, Weixian Z. wrote: > I run benchmark\_tx in USRP A, and benchmark\_rx in USRP B: > A: ./benchmark\_tx.py -f 2.46G -r 0.5M --tx-gain=-30 > B: ./benchmark\_rx.py -f 2.46G -r 0.5M > The n\_right/n\_recvd is 549/628. > But when I rx in USRP A and tx in USRP B with the same parameters, the > n\_right/n\_recvd is always pretty bad: 0/275. > What might be the reasons? 0/275 doesnt sound like a performance difference. Something is just not working, or incorrect setup, antenna issues. Before experimenting with the mac layer examples in gnuradio, it might be good to verify setup connectivity and signal integrity, etc. have you verified functionality of your setup with a simple test tone? Check the the correct antennas are used. correct frequency comes out, reasonable power level. cheers, -josh ---
**Author:** ![Weixian\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/6de8d8/32.png) [@Weixian\_Z](https://www.ruby-forum.com/u/Weixian_Z)\ **Post date:** [August 8, 2012, 7:32pm UTC](https://www.ruby-forum.com/t/benchmark-test-between-two-usrps-have-different-performances-in-two-directions/221901/3 "2012-08-08T19:32:48Z")
Hi Josh, The tone test works. And I have tried to use different antennas. The following is the result: > **[benchmark test](https://docs.google.com/spreadsheets/d/19QxmDtqhDrAc6IG9n4zIuiO5030X54WO0xpPSbdy1Sw/edit?pli=1&pli=1)** > > Aug 13 > > receiver,sender,n\_rcvd/n\_right > USRP A: ./benchmark\_rx.py -f 2.42G -r 0.5M,USRP C: ./benchmark\_tx.py -f 2.42G -r 0.5M --tx-gain=-30,269/0 > 282/0 > 291/0 > USRP A: ./benchmark\_rx.py -f 5.1G -r 0.5M,USRP C: ./benchmark\_tx.py -f 5.1G -r 0.5M... The results are very different even with same antennas. The n\_rcvd/n\_right is 626/623, and 289/0 sometimes. What might be the reason? ---
**Author:** ![Weixian\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/6de8d8/32.png) [@Weixian\_Z](https://www.ruby-forum.com/u/Weixian_Z)\ **Post date:** [August 10, 2012, 7:38pm UTC](https://www.ruby-forum.com/t/benchmark-test-between-two-usrps-have-different-performances-in-two-directions/221901/4 "2012-08-10T19:38:16Z")
Hi Josh, I was testing benchmark\_tx.py at tx end and uhd\_fft at rx end at 5.0GHz frequency: ./benchmark\_tx.py -f 5.0G -r 0.5M -A J1 --tx-gain=-30 And the received spectrums don’t look like have frequency offset, check the attached. ---
**Author:** ![Weixian\_Z](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/6de8d8/32.png) [@Weixian\_Z](https://www.ruby-forum.com/u/Weixian_Z)\ **Post date:** [August 9, 2012, 3:53am UTC](https://www.ruby-forum.com/t/benchmark-test-between-two-usrps-have-different-performances-in-two-directions/221901/5 "2012-08-09T03:53:59Z")
On 08/08/2012 10:31 AM, Weixian Z. wrote: > Hi Josh, > The tone test works. And I have tried to use different antennas. The > following is the result: > **[benchmark test](https://docs.google.com/spreadsheets/d/19QxmDtqhDrAc6IG9n4zIuiO5030X54WO0xpPSbdy1Sw/edit?pli=1&pli=1)** > > This Sheet is private > The results are very different even with same antennas. The n\_rcvd/n\_right > is 626/623, and 289/0 sometimes. What might be the reason? There will be a slight frequency offset between devices. Often with some of the example apps, this offset will cause the signal to be outside of the filter pass band. It would be good to make sure that the received spectrum appears at the expected frequency: some faq on this: [http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#I-have-two-USRPs-and-when-I-transmit-on-one-and-receive-on-the-other-at-the-same-frequency-I-get-an-offset](http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#I-have-two-USRPs-and-when-I-transmit-on-one-and-receive-on-the-other-at-the-same-frequency-I-get-an-offset) In general, it looks like you are seeing a lot of dropped packets or checksum errors. You have to diagnose the issue at a lower level. How does the received spectrum look? How-about the received constellation? Any obvious distortions, etc? -josh