uhd/host/utils/uhd_cal_tx_dc_offset.cpp

//
// Copyright 2010,2012,2014 Ettus Research LLC
//
// SPDX-License-Identifier: GPL-3.0
//

#include "usrp_cal_utils.hpp"
#include <uhd/utils/thread.hpp>
#include <uhd/utils/safe_main.hpp>
#include <uhd/utils/paths.hpp>
#include <uhd/utils/algorithm.hpp>
#include <uhd/usrp/multi_usrp.hpp>
#include <boost/program_options.hpp>
#include <boost/format.hpp>
#include <boost/thread/thread.hpp>
#include <boost/math/special_functions/round.hpp>
#include <iostream>
#include <complex>
#include <ctime>

namespace po = boost::program_options;

/***********************************************************************
 * Transmit thread
 **********************************************************************/
static void tx_thread(uhd::usrp::multi_usrp::sptr usrp, const double tx_wave_freq, const double tx_wave_ampl)
{
    uhd::set_thread_priority_safe();

    // set max TX gain
    usrp->set_tx_gain(usrp->get_tx_gain_range().stop());

    //create a transmit streamer
    uhd::stream_args_t stream_args("fc32"); //complex floats
    uhd::tx_streamer::sptr tx_stream = usrp->get_tx_stream(stream_args);

    //setup variables and allocate buffer
    uhd::tx_metadata_t md;
    md.has_time_spec = false;
    std::vector<samp_type> buff(tx_stream->get_max_num_samps()*10);

    //values for the wave table lookup
    size_t index = 0;
    const double tx_rate = usrp->get_tx_rate();
    const size_t step = boost::math::iround(wave_table_len * tx_wave_freq / tx_rate);
    wave_table table(tx_wave_ampl);

    //fill buff and send until interrupted
    while (not boost::this_thread::interruption_requested())
    {
        for (size_t i = 0; i < buff.size(); i++)
            buff[i] = table(index += step);
        tx_stream->send(&buff.front(), buff.size(), md);
    }

    //send a mini EOB packet
    md.end_of_burst = true;
    tx_stream->send("", 0, md);
}

/***********************************************************************
 * Tune RX and TX routine
 **********************************************************************/
static double tune_rx_and_tx(uhd::usrp::multi_usrp::sptr usrp, const double tx_lo_freq, const double rx_offset)
{
    //tune the transmitter with no cordic
    uhd::tune_request_t tx_tune_req(tx_lo_freq);
    tx_tune_req.dsp_freq_policy = uhd::tune_request_t::POLICY_MANUAL;
    tx_tune_req.dsp_freq = 0;
    usrp->set_tx_freq(tx_tune_req);

    //tune the receiver
    double rx_freq = usrp->get_tx_freq() - rx_offset;
    double min_fe_rx_freq = usrp->get_fe_rx_freq_range().start();
    double max_fe_rx_freq = usrp->get_fe_rx_freq_range().stop();
    uhd::tune_request_t rx_tune_req(rx_freq);
    rx_tune_req.dsp_freq_policy = uhd::tune_request_t::POLICY_MANUAL;
    rx_tune_req.dsp_freq = 0;
    if (rx_freq < min_fe_rx_freq)
        rx_tune_req.dsp_freq = rx_freq - min_fe_rx_freq;
    else if (rx_freq > max_fe_rx_freq)
        rx_tune_req.dsp_freq = rx_freq - max_fe_rx_freq;
    usrp->set_rx_freq(rx_tune_req);

    //wait for the LOs to become locked
    boost::this_thread::sleep(boost::posix_time::milliseconds(50));
    boost::system_time start = boost::get_system_time();
    while (not usrp->get_tx_sensor("lo_locked").to_bool() or not usrp->get_rx_sensor("lo_locked").to_bool())
    {
        if (boost::get_system_time() > start + boost::posix_time::milliseconds(100))
            throw std::runtime_error("timed out waiting for TX and/or RX LO to lock");
    }

    return usrp->get_tx_freq();
}

/***********************************************************************
 * Main
 **********************************************************************/
int UHD_SAFE_MAIN(int argc, char *argv[])
{
    std::string args, subdev, serial;
    double tx_wave_freq, tx_wave_ampl, rx_offset;
    double freq_start, freq_stop, freq_step;
    size_t nsamps;
    double precision;

    po::options_description desc("Allowed options");
    desc.add_options()
        ("help", "help message")
        ("verbose", "enable some verbose")
        ("args", po::value<std::string>(&args)->default_value(""), "device address args [default = \"\"]")
        ("subdev", po::value<std::string>(&subdev), "Subdevice specification (default: first subdevice, often 'A')")
        ("tx_wave_freq", po::value<double>(&tx_wave_freq)->default_value(507.123e3), "Transmit wave frequency in Hz")
        ("tx_wave_ampl", po::value<double>(&tx_wave_ampl)->default_value(0.7), "Transmit wave amplitude")
        ("rx_offset", po::value<double>(&rx_offset)->default_value(.9344e6), "RX LO offset from the TX LO in Hz")
        ("freq_start", po::value<double>(&freq_start), "Frequency start in Hz (do not specify for default)")
        ("freq_stop", po::value<double>(&freq_stop), "Frequency stop in Hz (do not specify for default)")
        ("freq_step", po::value<double>(&freq_step)->default_value(default_freq_step), "Step size for LO sweep in Hz")
        ("nsamps", po::value<size_t>(&nsamps), "Samples per data capture")
        ("precision", po::value<double>(&precision)->default_value(default_precision), "Correction precision (default=0.0001)")
    ;

    po::variables_map vm;
    po::store(po::parse_command_line(argc, argv, desc), vm);
    po::notify(vm);

    //print the help message
    if (vm.count("help")){
        std::cout << boost::format("USRP Generate TX DC Offset Calibration Table %s") % desc << std::endl;
        std::cout <<
            "This application measures leakage between RX and TX on a transceiver daughterboard to self-calibrate.\n"
            "Note: Not all daughterboards support this feature. Refer to the UHD manual for details.\n"
            << std::endl;
        return EXIT_FAILURE;
    }

    // Create a USRP device
    uhd::usrp::multi_usrp::sptr usrp = setup_usrp_for_cal(args, subdev, serial);

    if (not vm.count("nsamps"))
        nsamps = size_t(usrp->get_rx_rate() / default_fft_bin_size);

    //create a receive streamer
    uhd::stream_args_t stream_args("fc32"); //complex floats
    uhd::rx_streamer::sptr rx_stream = usrp->get_rx_stream(stream_args);

    //create a transmitter thread
    boost::thread_group threads;
    threads.create_thread(boost::bind(&tx_thread, usrp, tx_wave_freq, tx_wave_ampl));

    //re-usable buffer for samples
    std::vector<samp_type> buff;

    //store the results here
    std::vector<result_t> results;

    if (not vm.count("freq_start")) freq_start = usrp->get_fe_tx_freq_range().start();
    if (not vm.count("freq_stop")) freq_stop = usrp->get_fe_tx_freq_range().stop();

    //check start and stop frequencies
    if (freq_start < usrp->get_fe_tx_freq_range().start())
    {
        std::cerr << "freq_start must be " << usrp->get_fe_tx_freq_range().start() << " or greater for this daughter board" << std::endl;
        return EXIT_FAILURE;
    }
    if (freq_stop > usrp->get_fe_tx_freq_range().stop())
    {
        std::cerr << "freq_stop must be " << usrp->get_fe_tx_freq_range().stop() << " or less for this daughter board" << std::endl;
        return EXIT_FAILURE;
    }

    //check rx_offset
    double min_rx_offset = usrp->get_rx_freq_range().start() - usrp->get_fe_tx_freq_range().start();
    double max_rx_offset = usrp->get_rx_freq_range().stop() - usrp->get_fe_tx_freq_range().stop();
    if (rx_offset < min_rx_offset or rx_offset > max_rx_offset)
    {
        std::cerr << "rx_offset must be between " << min_rx_offset << " and "
            << max_rx_offset << " for this daughter board" << std::endl;
        return EXIT_FAILURE;
    }

    std::cout << boost::format("Calibration frequency range: %d MHz -> %d MHz") % (freq_start/1e6) % (freq_stop/1e6) << std::endl;

    //set RX gain
    usrp->set_rx_gain(0);

    for (double tx_lo_i = freq_start; tx_lo_i <= freq_stop; tx_lo_i += freq_step)
    {
        const double tx_lo = tune_rx_and_tx(usrp, tx_lo_i, rx_offset);

        //frequency constants for this tune event
        const double actual_rx_rate = usrp->get_rx_rate();
        const double actual_tx_freq = usrp->get_tx_freq();
        const double actual_rx_freq = usrp->get_rx_freq();
        const double bb_dc_freq = actual_tx_freq - actual_rx_freq;

        //reset TX DC offset
        usrp->set_tx_dc_offset(std::complex<double>(0, 0));

        //capture initial uncorrected value
        capture_samples(usrp, rx_stream, buff, nsamps);
        const double initial_dc_dbrms = compute_tone_dbrms(buff, bb_dc_freq/actual_rx_rate);

        //bounds and results from searching
        double i_corr_start = -1.0;
        double i_corr_stop = 1.0;
        double i_corr_step = (i_corr_stop - i_corr_start)/(num_search_steps+1);
        double q_corr_start = -1.0;
        double q_corr_stop = 1.0;
        double q_corr_step= (q_corr_stop - q_corr_start)/(num_search_steps+1);
        double best_dc_dbrms = initial_dc_dbrms;
        double best_i_corr = 0;
        double best_q_corr = 0;
        while (i_corr_step >= precision or q_corr_step >= precision)
        {
            for (double i_corr = i_corr_start + i_corr_step; i_corr <= i_corr_stop - i_corr_step; i_corr += i_corr_step)
            {
                for (double q_corr = q_corr_start + q_corr_step; q_corr <= q_corr_stop - q_corr_step; q_corr += q_corr_step)
                {
                    const std::complex<double> correction(i_corr, q_corr);
                    usrp->set_tx_dc_offset(correction);

                    //receive some samples
                    capture_samples(usrp, rx_stream, buff, nsamps);
                    const double dc_dbrms = compute_tone_dbrms(buff, bb_dc_freq/actual_rx_rate);

                    if (dc_dbrms < best_dc_dbrms)
                    {
                        best_dc_dbrms = dc_dbrms;
                        best_i_corr = i_corr;
                        best_q_corr = q_corr;
                    }
                }
            }

            i_corr_start = best_i_corr - i_corr_step;
            i_corr_stop = best_i_corr + i_corr_step;
            i_corr_step = (i_corr_stop - i_corr_start)/(num_search_steps+1);
            q_corr_start = best_q_corr - q_corr_step;
            q_corr_stop = best_q_corr + q_corr_step;
            q_corr_step = (q_corr_stop - q_corr_start)/(num_search_steps+1);
        }

        if (best_dc_dbrms < initial_dc_dbrms)   //keep result
        {
            result_t result;
            result.freq = tx_lo;
            result.real_corr = best_i_corr;
            result.imag_corr = best_q_corr;
            result.best = best_dc_dbrms;
            result.delta = initial_dc_dbrms - best_dc_dbrms;
            results.push_back(result);
            if (vm.count("verbose"))
                std::cout << boost::format("TX DC: %f MHz: lowest offset %f dB, corrected %f dB") % (tx_lo/1e6) % result.best % result.delta << std::endl;
            else
                std::cout << "." << std::flush;
        }

    }

    std::cout << std::endl;

    //stop the transmitter
    threads.interrupt_all();
    boost::this_thread::sleep(boost::posix_time::milliseconds(500));    //wait for threads to finish
    threads.join_all();

    store_results(results, "TX", "tx", "dc", serial);

    return EXIT_SUCCESS;
}