Hi All: I am new to GNU Radio and I am experiencing a few anomalies. My experimental setup is as follows:
- I am using USPR2 with GNU Radio ver. 3.2 installed on an Intel 64-bit Quad Core machine with GigEthernet. - I am using XCVR2450 daughter card and the latest firmware on the USRP2s. - I am running benchmark_rx.py and benchmark_tx.py using two USPR2s. - I have wired the two USRPs using a 60 dB attenuator. My Observations: - The maximum bit rate I could achieve was 12.5 Mbps corresponding to samples/symbol = 2 and interpolation and decimation factor set to 4 - The minimum bit rate I could see was 120 Kbps in the 2.4GHz band and 250 Kbps on the 5GHz band. I have the following questions: 1. What is the minimum and maximum bit rates that USPR2 can support ? My immediate guess for minimum bitrate is that it depends on the ADC/DAC sampling rates, samples/symbol and interpolation and decimation factor. So with least interpolation (4) and least Samples/Sym (2), the calculations give 12.5 Mbps (for GMSK - 1bit/sample/Hz). The maximum bit rate is limited by the host processor; whether it can churn out as many packets as the USPR2 wants in a second. Is my analysis correct ? 2. Why does the minimum bit rate depend on the carrier frequency ? I tried changing the Tx amplitude and Tx gain at 5G but it still didn't change anything. 3. How to perform benchmark_rx/tx in BERT mode ( from digital-bert folder) ? Looks like the scripts are written for USRP1. How to modify them to make it work on USRP2 ? Can anyone please help me resolve these issues ? Thanks, Srinivas Graduate Student, WINLAB, Rutgers University, NJ
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