On Wed, Feb 08, 2012 at 06:39:24PM -0500, Nazmul Islam wrote: > Hello, > > I am running the benchmark_tx.py codes and looking at the spectrum of the > signals using uhd_fft.py. I am using the latest image of GNU radio > (GNUradio 3.5) and I have XCVR2450 daughterboards. I ran the > benchmark_tx.py code in three transmitter nodes and surprisingly, all of > them are transmitting with 1 MHz frequency offset! I have attached two > screenshots with the email (I hope that they go through). I give the > following input parameters to run the benchmark_tx code. > > ./benchmark_tx.py -f 2.4G -r 1M -m gmsk -M 10 -a "addr = 192.168.10.2" > > Both uhd_fft.py and the spectrum analyzer of my laboratory show that the > received signal is centered at 2.401 GHz. I varied the frequency to 2.45 > GHz, 2.41 GHz, but this 1 MHz frequency shift persists. > > When I run the benchmark_rx.py code at the receiver nodes, they don't > receive/detect any packets (due to the frequency offset, I guess). I even > tried to run the transmitter at 2.4 GHz and the receiver at 2.401 GHz. > However, that did not help either! > > I will try to modify the control loop gain parameters using Tom's blogs > suggestions and see if that helps. However, I am really surprised to see > how all three different transmitter nodes can transmit with almost exactly > 1 MHz frequency offset. Any suggestion will be appreciated. >
Can you tell us which version of UHD you are using? (uhd_usrp_probe --version) We have heard reports of such an issue and my best guess is that it was related to an accidental swap of I and Q in the XCVR2450 transmitter code. This went in after the 3.3.2 release and is fixed on latest UHD master since 837437c65ce36d418cceb3df5b093f9497b3af5f Jason _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
