The output samples file is parsed into raw i/q values and plotted in gnuplot.
Currently, the loopback is done via just direct RF cable between RF0 TX/RX radio and RF1 RX2 radio with 30 db of attenuation inline. Lenny From: "Marcus D. Leech" <mle...@ripnet.com> Date: Tuesday, July 17, 2018 at 8:54 PM To: Leonid Veytser <veyt...@ll.mit.edu>, "usrp-users@lists.ettus.com" <usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Setting N310 TX and RX bandwidth On 07/17/2018 02:13 PM, Veytser, Leonid - 0665 - MITLL wrote: I tried various gain settings, including both 0 and 30 for TX and 0 and 30 for RX. I also tried setting clock and time sources to “internal” but it didn’t seem to make a difference. How are you inspecting the file that it produces to see if the signal is there or not? How are you doing the loopback? From: "Marcus D. Leech" <mle...@ripnet.com> Date: Tuesday, July 17, 2018 at 1:02 PM To: Leonid Veytser <veyt...@ll.mit.edu>, "usrp-users@lists.ettus.com" <usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Setting N310 TX and RX bandwidth On 07/17/2018 12:22 PM, Veytser, Leonid - 0665 - MITLL wrote: I tried both of your suggestions – increasing RX gain and offsetting RX frequency. However, neither seem to be working. Lenny What gain setting are you using for both TX and RX? What happens if you don't use external time and clock sources? From: "Marcus D. Leech" <mle...@ripnet.com> Date: Monday, July 16, 2018 at 10:08 PM To: Leonid Veytser <veyt...@ll.mit.edu>, "usrp-users@lists.ettus.com" <usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Setting N310 TX and RX bandwidth On 07/16/2018 06:53 PM, Veytser, Leonid - 0665 - MITLL wrote: Hi Marcus, Thanks for your answer. Perhaps this is not my issue then. I am having issue with sending and receiving a simple sine wave using N310. In the simplest case, I can take X310 run txrx_loopback_to_file with the arguments below, plot reals and imaginaries of the stored files and I can see the sine wave. If I do the exact same command against a N310, I appear to just see noise, which seems to be highly quantized. Just values in the range between -4 and 4. ./txrx_loopback_to_file --tx-args "addr=192.168.20.2,clock_source=external,time_source=external" --rx-args "addr=192.168.20.2,clock_source=external,time_source=external" --tx-rate 1.25e6 --rx-rate 1.25e6 --tx-freq 1800e6 --rx-freq 1800e6 --tx-channels "0" --rx-channels "1" --wave-type SINE --wave-freq 1e3 Any help or suggestion is greatly appreciated! Thanks, Lenny The gain-control range on the AD9371 is much larger than on cards you'll find on the X310. Try increasing the RX gain, and offset the RX frequency a bit -- you may be losing some in DC-offset removal for a carrier that is right on top of the "DC" region. From: USRP-users <usrp-users-boun...@lists.ettus.com> on behalf of "Marcus D. Leech via USRP-users" <usrp-users@lists.ettus.com> Reply-To: "Marcus D. Leech" <mle...@ripnet.com> Date: Monday, July 16, 2018 at 3:20 PM To: "usrp-users@lists.ettus.com" <usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Setting N310 TX and RX bandwidth On 07/16/2018 02:46 PM, Veytser, Leonid - 0665 - MITLL via USRP-users wrote: I am unable to set either RX or TX bandwidth on N310. When attempting to set, I get the following warning: Setting TX Bandwidth: 40.000000 MHz... [WARNING] [0/Radio_0] set_tx_bandwidth take no effect on AD9371. Default analog bandwidth is 100MHz Actual TX Bandwidth: 0.000000 MHz... and Setting RX Bandwidth: 40.000000 MHz... [WARNING] [0/Radio_0] set_rx_bandwidth take no effect on AD9371. Default analog bandwidth is 100MHz Actual RX Bandwidth: 100.000000 MHz... When looking through the UHD code, I tracked down to these FIXME comments: https://github.com/EttusResearch/uhd/blob/master/host/lib/usrp/dboard/magnesium/magnesium_radio_ctrl_impl.cpp#L322 Is this some sort of limitation with the N310 and the AD9371 tranceiver? Does this mean I am unable to set TX and RX bandwidth at all? Thanks, Lenny Based purely on the comment, I'm guessing that there are notionally registers to control this in the AD9371, but they don't apparently work as documented, hence the warning message. Keep in mind that *internally*, the AD9371 samples the analog mixer outputs at several hundred MHz, so if the internal anti-alias filters are set-up for 100MHz by default, there's no danger of aliases appearing in the outputs, regardless of your ultimate sample-rate delivered to the host.
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