On Wed, Oct 16, 2013 at 10:22 PM, Aditya Dhananjay <adi...@cs.nyu.edu>wrote:
> Hi All, > > I have two USRP N210 devices connected by an attenuator cable. I set up > the following experiments. > > -- BEGIN EXPERIMENT 1 > > Step 1) Use benchmark_tx on one of the USRPs and send 100 packets. At the > receiver, I simply record the incoming samples and save them into a file > called samples1.dat. This file is static and does not change from now on. > > Step 2) Run benchmark_rx with the --from-file=samples1.dat option. The > other parameters (modulation, fft-length, occupied-tones, etc) are > identical to those I used at the transmitter in Step 1. Measure the packet > delivery rate. > > Step 3) Repeat Step 2 a bunch of times. Sometimes, I notice differences in > the packet delivery ratios, even though all runs of the experiment use the > identical 'samples1.dat' file and an identical set of parameters These > differences are small (1-2 packet difference), but I don't understand why > they exist. > > Is this normal behavior? If so, could someone please let me know what the > probable causes are? > > -- END EXPERIMENT 1 > > The next experiment does not use either of the USRP devices. > > -- BEGIN EXPERIMENT 2 > > 1) Use benchmark_tx to generate 100 packets, and write the samples into a > file (samples2.dat) using the --to-file option. > > 2) Use benchmark_rx with the --from-file=samples2.dat option and check the > packet delivery rate. The parameters used (fft-length, etc) are obviously > identical to those used to generate the samples in Step 1. I observe that > the delivery rate is never even close to 100%. > > 3) Change to a different parameter set and repeat steps 1 and 2. Across > different runs, I observe that the delivery rate is anywhere between 30% > and 85%. > > This cannot be the expected behavior. Any pointers on what I'm > doing wrong would be much appreciated! > > -- END EXPERIMENT 2 > > Thanks! > > Aditya > I should have made a brief mention of my environment: GNU Radio 3.7.1 installed from source Ubuntu 12.04 LTS (64-bit) Thanks! Aditya
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