Re: [USRP-users] Gain difference in 4 RX on N310

[Baroch Oren via USRP-users]

Hi Marcus, thank you for the reply. I've built and installed UHD using AN-445 "Building and Installing the USRP Open-Source Toolchain (UHD and GNU Radio) on Linux" instructions (https://kb.ettus.com/Building_and_Installing_the_USRP_Open-Source_Toolchain_(UHD_and_GNU_Radio)_on_Linux) Do you think that a gain setting bug is possible when I set the gain using this code? and the screen output says all channels are set to same gain (60dB)? This code is an adaptation of the rx_multi_samples.cpp example.     // detect which channels to use & init them     std::vector<std::string> channel_strings;     std::vector<size_t> channel_nums;     boost::split(channel_strings, channel_list, boost::is_any_of("\"',"));     int current_channel = 0;     for (size_t ch = 0; ch < channel_strings.size(); ch++) {         size_t chan = std::stoi(channel_strings[ch]);         if (chan >= usrp->get_rx_num_channels()) {             throw std::runtime_error("Invalid channel(s) specified.");         } else {         current_channel = std::stoi(channel_strings[ch]);             channel_nums.push_back(current_channel);             //set the rx center frequency         std::cout << boost::format("Setting RX chan%d Freq: %f Mhz... ") % current_channel % (freq/1e6);             usrp->set_rx_freq(freq, current_channel);             std::cout << boost::format("Actual: %f Mhz") % (usrp->get_rx_freq()/1e6) << std::endl;             // set the rf gain             if (vm.count("gain")) {                 std::cout << boost::format("Setting RX chan%d Gain: %f dB... ") % current_channel % gain;                 usrp->set_rx_gain(gain, current_channel);                 std::cout << boost::format("Actual RX Gain: %f dB...")                          % usrp->get_rx_gain(current_channel)                   << std::endl;             }     }     } Thanks, Baroch On 25/12/2019 16:18, Marcus Müller wrote: Hi Baroch, oh, that's interesting and I must admit I don't really know where to start looking into this, but let's take this top-down: How are you setting the gain, and how are you doing the capturing? My gut feeling tells me there's something in UHD not handling multi- channel gain setting right, but lacking an N310 on my desk right now, I can't just trace this with a debugger. How did you build and install your UHD? Best regards, Marcus On Wed, 2019-12-25 at 15:29 +0200, Baroch Oren via USRP-users wrote: Hello. I've been capturing with N310 on 4 channels simultaneously. A strange behavioure occurs: First experiment: capturing on a single channel when all the other 3 rx channels are terminated, I get a similar captured gain on every one of the RX channels. Second experiment: capturing simultaneously, channel 3 (RF2 RX2) shows a decreased capture gain in about -14db. all other channels show capture gain similar to first experiment. Third experiment: capturing simultaneously on 4 channels, all inputs terminated: thermal noise of same gain on all 4 channels. Anyone has any clue for direction to further research this? My setup: UHD_3.14.1.HEAD-0-g0347a6d8 on Ubuntu Thanks, Baroch Oren _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com -- ברוך אורן بروح اورن Baroch Oren טל' 058-7799233 cell תמכו באקטיביזם שלי support my activism

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