uhd: added tx dc offset calibration + tweaks

6 files changed, 325 insertions, 49 deletions

diff --git a/host/lib/usrp/common/apply_corrections.cpp b/host/lib/usrp/common/apply_corrections.cpp
index c3ac4256a..720c51633 100644
--- a/host/lib/usrp/common/apply_corrections.cpp
+++ b/host/lib/usrp/common/apply_corrections.cpp
@@ -142,7 +142,14 @@ void uhd::usrp::apply_tx_fe_corrections(
             sub_tree,
             "dboards/" + slot + "/tx_eeprom",
             "tx_frontends/" + slot + "/iq_balance/value",
-            "tx_fe_cal_v0.1_",
+            "tx_iq_cal_v0.1_",
+            lo_freq
+        );
+        apply_fe_corrections(
+            sub_tree,
+            "dboards/" + slot + "/tx_eeprom",
+            "tx_frontends/" + slot + "/dc_offset/value",
+            "tx_dc_cal_v0.1_",
             lo_freq
         );
     }
@@ -162,7 +169,7 @@ void uhd::usrp::apply_rx_fe_corrections(
             sub_tree,
             "dboards/" + slot + "/rx_eeprom",
             "rx_frontends/" + slot + "/iq_balance/value",
-            "rx_fe_cal_v0.1_",
+            "rx_iq_cal_v0.1_",
             lo_freq
         );
     }
diff --git a/host/utils/CMakeLists.txt b/host/utils/CMakeLists.txt
index 1185b06cc..6c17be22c 100644
--- a/host/utils/CMakeLists.txt
+++ b/host/utils/CMakeLists.txt
@@ -37,8 +37,9 @@ ENDFOREACH(util_source)
 SET(util_share_sources
     usrp_burn_db_eeprom.cpp
     usrp_burn_mb_eeprom.cpp
-    usrp_gen_rx_fe_cal_table.cpp
-    usrp_gen_tx_fe_cal_table.cpp
+    usrp_gen_rx_iq_cal_table.cpp
+    usrp_gen_tx_iq_cal_table.cpp
+    usrp_gen_tx_dc_cal_table.cpp
 )
 
 IF(ENABLE_USB)
diff --git a/host/utils/usrp_cal_utils.hpp b/host/utils/usrp_cal_utils.hpp
index 3cfe2b2ed..c9695d305 100644
--- a/host/utils/usrp_cal_utils.hpp
+++ b/host/utils/usrp_cal_utils.hpp
@@ -28,7 +28,7 @@
 
 namespace fs = boost::filesystem;
 
-struct result_t{double freq, real_corr, imag_corr, sup;};
+struct result_t{double freq, real_corr, imag_corr, best, delta;};
 
 /***********************************************************************
  * Constants
@@ -39,6 +39,8 @@ static const size_t wave_table_len = 8192;
 static const size_t num_search_steps = 5;
 static const size_t num_search_iters = 7;
 static const size_t skip_initial_samps = 20;
+static const double default_freq_step = 13.7e3;
+static const size_t default_num_samps = 10000;
 
 /***********************************************************************
  * Sinusoid wave table
@@ -99,7 +101,8 @@ static void store_results(
     uhd::usrp::multi_usrp::sptr usrp,
     const std::vector<result_t> &results,
     const std::string &XX,
-    const std::string &xx
+    const std::string &xx,
+    const std::string &what
 ){
     //extract eeprom serial
     uhd::property_tree::sptr tree = usrp->get_device()->get_tree();
@@ -112,7 +115,7 @@ static void store_results(
     fs::create_directory(cal_data_path);
     cal_data_path = cal_data_path / "cal";
     fs::create_directory(cal_data_path);
-    cal_data_path = cal_data_path / (xx + "_fe_cal_v0.1_" + db_eeprom.serial + ".csv");
+    cal_data_path = cal_data_path / str(boost::format("%s_%s_cal_v0.1_%s.csv") % xx % what % db_eeprom.serial);
     if (fs::exists(cal_data_path)){
         fs::rename(cal_data_path, cal_data_path.string() + str(boost::format(".%d") % time(NULL)));
     }
@@ -124,14 +127,15 @@ static void store_results(
     cal_data << boost::format("timestamp, %d\n") % time(NULL);
     cal_data << boost::format("version, 0, 1\n");
     cal_data << boost::format("DATA STARTS HERE\n");
-    cal_data << "lo_frequency, iq_correction_real, iq_correction_imag, measured_suppression\n";
+    cal_data << "lo_frequency, correction_real, correction_imag, measured, delta\n";
 
     for (size_t i = 0; i < results.size(); i++){
         cal_data
             << results[i].freq << ", "
             << results[i].real_corr << ", "
             << results[i].imag_corr << ", "
-            << results[i].sup << "\n"
+            << results[i].best << ", "
+            << results[i].delta << "\n"
         ;
     }
 
diff --git a/host/utils/usrp_gen_rx_fe_cal_table.cpp b/host/utils/usrp_gen_rx_iq_cal_table.cpp
index a365c9be7..71c447e65 100644
--- a/host/utils/usrp_gen_rx_fe_cal_table.cpp
+++ b/host/utils/usrp_gen_rx_iq_cal_table.cpp
@@ -128,8 +128,8 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
         ("tx_offset", po::value<double>(&tx_offset)->default_value(.9344e6), "TX LO offset from the RX LO in Hz")
         ("tx_gain", po::value<double>(&tx_gain)->default_value(0), "TX gain in dB")
         ("rx_gain", po::value<double>(&rx_gain)->default_value(0), "RX gain in dB")
-        ("freq_step", po::value<double>(&freq_step)->default_value(10e6), "Step size for LO sweep in Hz")
-        ("nsamps", po::value<size_t>(&nsamps)->default_value(10000), "Samples per data capture")
+        ("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)->default_value(default_num_samps), "Samples per data capture")
     ;
 
     po::variables_map vm;
@@ -183,6 +183,18 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
     for (double rx_lo_i = freq_range.start()+50e6; rx_lo_i < freq_range.stop()-50e6; rx_lo_i += freq_step){
         const double rx_lo = tune_rx_and_tx(usrp, rx_lo_i, tx_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_tone_freq = actual_tx_freq - actual_rx_freq;
+        const double bb_imag_freq = -bb_tone_freq;
+
+        //capture initial uncorrected value
+        usrp->set_rx_iq_balance(std::polar<double>(1.0, 0.0));
+        capture_samples(usrp, rx_stream, buff);
+        const double initial_suppression = compute_tone_dbrms(buff, bb_tone_freq/actual_rx_rate) - compute_tone_dbrms(buff, bb_imag_freq/actual_rx_rate);
+
         //bounds and results from searching
         std::complex<double> best_correction;
         double phase_corr_start = -.3, phase_corr_stop = .3, phase_corr_step;
@@ -203,22 +215,10 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
                 //receive some samples
                 capture_samples(usrp, rx_stream, buff);
 
-                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_tone_freq = actual_tx_freq - actual_rx_freq;
-                const double bb_imag_freq = -bb_tone_freq;
-
                 const double tone_dbrms = compute_tone_dbrms(buff, bb_tone_freq/actual_rx_rate);
                 const double imag_dbrms = compute_tone_dbrms(buff, bb_imag_freq/actual_rx_rate);
                 const double suppression = tone_dbrms - imag_dbrms;
 
-                //std::cout << "bb_tone_freq " << bb_tone_freq << std::endl;
-                //std::cout << "bb_imag_freq " << bb_imag_freq << std::endl;
-                //std::cout << "tone_dbrms " << tone_dbrms << std::endl;
-                //std::cout << "imag_dbrms " << imag_dbrms << std::endl;
-                //std::cout << "suppression " << (tone_dbrms - imag_dbrms) << std::endl;
-
                 if (suppression > best_suppression){
                     best_correction = correction;
                     best_suppression = suppression;
@@ -243,13 +243,14 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
             result.freq = rx_lo;
             result.real_corr = best_correction.real();
             result.imag_corr = best_correction.imag();
-            result.sup = best_suppression;
+            result.best = best_suppression;
+            result.delta = best_suppression - initial_suppression;
             results.push_back(result);
+            if (vm.count("verbose")){
+                std::cout << boost::format("%f MHz: best suppression %fdB, corrected %fdB") % (rx_lo/1e6) % result.best % result.delta << std::endl;
+            }
+            else std::cout << "." << std::flush;
         }
-        if (vm.count("verbose")){
-            std::cout << boost::format("%f MHz: best suppression %fdB") % (rx_lo/1e6) % best_suppression << std::endl;
-        }
-        else std::cout << "." << std::flush;
 
     }
     std::cout << std::endl;
@@ -258,7 +259,7 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
     threads.interrupt_all();
     threads.join_all();
 
-    store_results(usrp, results, "RX", "rx");
+    store_results(usrp, results, "RX", "rx", "iq");
 
     return 0;
 }
diff --git a/host/utils/usrp_gen_tx_dc_cal_table.cpp b/host/utils/usrp_gen_tx_dc_cal_table.cpp
new file mode 100644
index 000000000..570203496
--- /dev/null
+++ b/host/utils/usrp_gen_tx_dc_cal_table.cpp
@@ -0,0 +1,262 @@
+//
+// Copyright 2010 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+#include "usrp_cal_utils.hpp"
+#include <uhd/utils/thread_priority.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();
+
+    //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<std::complex<float> > 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);
+
+    //fill buff and send until interrupted
+    while (not boost::this_thread::interruption_requested()){
+        for (size_t i = 0; i < buff.size(); i++){
+            buff[i] = float(tx_wave_ampl) * wave_table_lookup(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
+    usrp->set_rx_freq(usrp->get_tx_freq() - rx_offset);
+
+    //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();
+}
+
+/***********************************************************************
+ * Data capture routine
+ **********************************************************************/
+static void capture_samples(uhd::usrp::multi_usrp::sptr usrp, uhd::rx_streamer::sptr rx_stream, std::vector<std::complex<float> > &buff){
+    uhd::stream_cmd_t stream_cmd(uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE);
+    stream_cmd.num_samps = buff.size();
+    stream_cmd.stream_now = true;
+    usrp->issue_stream_cmd(stream_cmd);
+    uhd::rx_metadata_t md;
+    const size_t num_rx_samps = rx_stream->recv(&buff.front(), buff.size(), md);
+
+    //validate the received data
+    if (md.error_code != uhd::rx_metadata_t::ERROR_CODE_NONE){
+        throw std::runtime_error(str(boost::format(
+            "Unexpected error code 0x%x"
+        ) % md.error_code));
+    }
+    if (num_rx_samps != buff.size()){
+        throw std::runtime_error("did not get all the samples requested");
+    }
+}
+
+/***********************************************************************
+ * Main
+ **********************************************************************/
+int UHD_SAFE_MAIN(int argc, char *argv[]){
+    std::string args;
+    double rate, tx_wave_freq, tx_wave_ampl, rx_offset, freq_step, tx_gain, rx_gain;
+    size_t nsamps;
+
+    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 = \"\"]")
+        ("rate", po::value<double>(&rate)->default_value(12.5e6), "RX and TX sample rate in Hz")
+        ("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 in counts")
+        ("rx_offset", po::value<double>(&rx_offset)->default_value(.9344e6), "RX LO offset from the TX LO in Hz")
+        ("tx_gain", po::value<double>(&tx_gain)->default_value(0), "TX gain in dB")
+        ("rx_gain", po::value<double>(&rx_gain)->default_value(0), "RX gain in dB")
+        ("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)->default_value(default_num_samps), "Samples per data capture")
+    ;
+
+    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 Frontend Calibration Table %s") % desc << std::endl;
+        std::cout <<
+            "This application measures leakage between RX and TX on an XCVR daughterboard to self-calibrate.\n"
+            << std::endl;
+        return ~0;
+    }
+
+    //create a usrp device
+    std::cout << std::endl;
+    std::cout << boost::format("Creating the usrp device with: %s...") % args << std::endl;
+    uhd::usrp::multi_usrp::sptr usrp = uhd::usrp::multi_usrp::make(args);
+
+    //set the antennas to cal
+    if (not uhd::has(usrp->get_rx_antennas(), "CAL") or not uhd::has(usrp->get_tx_antennas(), "CAL")){
+        throw std::runtime_error("This board does not have the CAL antenna option, cannot self-calibrate.");
+    }
+    usrp->set_rx_antenna("CAL");
+    usrp->set_tx_antenna("CAL");
+
+    //set the sample rates
+    usrp->set_rx_rate(rate);
+    usrp->set_tx_rate(rate);
+
+    //set midrange rx gain, default 0 tx gain
+    usrp->set_tx_gain(tx_gain);
+    usrp->set_rx_gain(rx_gain);
+
+    //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<std::complex<float> > buff(nsamps);
+
+    //store the results here
+    std::vector<result_t> results;
+
+    const uhd::meta_range_t freq_range = usrp->get_tx_freq_range();
+    for (double tx_lo_i = freq_range.start()+50e6; tx_lo_i < freq_range.stop()-50e6; 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;
+
+        //capture initial uncorrected value
+        usrp->set_tx_dc_offset(std::complex<double>(0, 0));
+        capture_samples(usrp, rx_stream, buff);
+        const double initial_dc_dbrms = compute_tone_dbrms(buff, bb_dc_freq/actual_rx_rate);
+
+        //bounds and results from searching
+        double dc_i_start = -.01, dc_i_stop = .01, dc_i_step;
+        double dc_q_start = -.01, dc_q_stop = .01, dc_q_step;
+        double lowest_offset = 0, best_dc_i = 0, best_dc_q = 0;
+
+        for (size_t i = 0; i < num_search_iters; i++){
+
+            dc_i_step = (dc_i_stop - dc_i_start)/(num_search_steps-1);
+            dc_q_step = (dc_q_stop - dc_q_start)/(num_search_steps-1);
+
+            for (double dc_i = dc_i_start; dc_i <= dc_i_stop + dc_i_step/2; dc_i += dc_i_step){
+            for (double dc_q = dc_q_start; dc_q <= dc_q_stop + dc_q_step/2; dc_q += dc_q_step){
+
+                const std::complex<double> correction(dc_i, dc_q);
+                usrp->set_tx_dc_offset(correction);
+
+                //receive some samples
+                capture_samples(usrp, rx_stream, buff);
+
+                const double dc_dbrms = compute_tone_dbrms(buff, bb_dc_freq/actual_rx_rate);
+
+                if (dc_dbrms < lowest_offset){
+                    lowest_offset = dc_dbrms;
+                    best_dc_i = dc_i;
+                    best_dc_q = dc_q;
+                }
+
+            }}
+
+            //std::cout << "best_dc_i " << best_dc_i << std::endl;
+            //std::cout << "best_dc_q " << best_dc_q << std::endl;
+            //std::cout << "lowest_offset " << lowest_offset << std::endl;
+
+            dc_i_start = best_dc_i - dc_i_step;
+            dc_i_stop = best_dc_i + dc_i_step;
+            dc_q_start = best_dc_q - dc_q_step;
+            dc_q_stop = best_dc_q + dc_q_step;
+        }
+
+        if (lowest_offset < -90){ //most likely valid, keep result
+            result_t result;
+            result.freq = tx_lo;
+            result.real_corr = best_dc_i;
+            result.imag_corr = best_dc_q;
+            result.best = lowest_offset;
+            result.delta = initial_dc_dbrms - lowest_offset;
+            results.push_back(result);
+            if (vm.count("verbose")){
+                std::cout << boost::format("%f MHz: lowest offset %fdB, corrected %fdB") % (tx_lo/1e6) % result.best % result.delta << std::endl;
+            }
+            else std::cout << "." << std::flush;
+        }
+
+    }
+    std::cout << std::endl;
+
+    //stop the transmitter
+    threads.interrupt_all();
+    threads.join_all();
+
+    store_results(usrp, results, "TX", "tx", "dc");
+
+    return 0;
+}
diff --git a/host/utils/usrp_gen_tx_fe_cal_table.cpp b/host/utils/usrp_gen_tx_iq_cal_table.cpp
index bf19e4a37..a2b98d8e6 100644
--- a/host/utils/usrp_gen_tx_fe_cal_table.cpp
+++ b/host/utils/usrp_gen_tx_iq_cal_table.cpp
@@ -130,8 +130,8 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
         ("rx_offset", po::value<double>(&rx_offset)->default_value(.9344e6), "RX LO offset from the TX LO in Hz")
         ("tx_gain", po::value<double>(&tx_gain)->default_value(0), "TX gain in dB")
         ("rx_gain", po::value<double>(&rx_gain)->default_value(0), "RX gain in dB")
-        ("freq_step", po::value<double>(&freq_step)->default_value(10e6), "Step size for LO sweep in Hz")
-        ("nsamps", po::value<size_t>(&nsamps)->default_value(10000), "Samples per data capture")
+        ("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)->default_value(default_num_samps), "Samples per data capture")
     ;
 
     po::variables_map vm;
@@ -185,6 +185,18 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
     for (double tx_lo_i = freq_range.start()+50e6; tx_lo_i < freq_range.stop()-50e6; 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_tone_freq = actual_tx_freq + tx_wave_freq - actual_rx_freq;
+        const double bb_imag_freq = actual_tx_freq - tx_wave_freq - actual_rx_freq;
+
+        //capture initial uncorrected value
+        usrp->set_tx_iq_balance(std::polar<double>(1.0, 0.0));
+        capture_samples(usrp, rx_stream, buff);
+        const double initial_suppression = compute_tone_dbrms(buff, bb_tone_freq/actual_rx_rate) - compute_tone_dbrms(buff, bb_imag_freq/actual_rx_rate);
+
         //bounds and results from searching
         std::complex<double> best_correction;
         double phase_corr_start = -.3, phase_corr_stop = .3, phase_corr_step;
@@ -205,22 +217,10 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
                 //receive some samples
                 capture_samples(usrp, rx_stream, buff);
 
-                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_tone_freq = actual_tx_freq + tx_wave_freq - actual_rx_freq;
-                const double bb_imag_freq = actual_tx_freq - tx_wave_freq - actual_rx_freq;
-
                 const double tone_dbrms = compute_tone_dbrms(buff, bb_tone_freq/actual_rx_rate);
                 const double imag_dbrms = compute_tone_dbrms(buff, bb_imag_freq/actual_rx_rate);
                 const double suppression = tone_dbrms - imag_dbrms;
 
-                //std::cout << "bb_tone_freq " << bb_tone_freq << std::endl;
-                //std::cout << "bb_imag_freq " << bb_imag_freq << std::endl;
-                //std::cout << "tone_dbrms " << tone_dbrms << std::endl;
-                //std::cout << "imag_dbrms " << imag_dbrms << std::endl;
-                //std::cout << "suppression " << (tone_dbrms - imag_dbrms) << std::endl;
-
                 if (suppression > best_suppression){
                     best_correction = correction;
                     best_suppression = suppression;
@@ -245,13 +245,14 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
             result.freq = tx_lo;
             result.real_corr = best_correction.real();
             result.imag_corr = best_correction.imag();
-            result.sup = best_suppression;
+            result.best = best_suppression;
+            result.delta = best_suppression - initial_suppression;
             results.push_back(result);
+            if (vm.count("verbose")){
+                std::cout << boost::format("%f MHz: best suppression %fdB, corrected %fdB") % (tx_lo/1e6) % result.best % result.delta << std::endl;
+            }
+            else std::cout << "." << std::flush;
         }
-        if (vm.count("verbose")){
-            std::cout << boost::format("%f MHz: best suppression %fdB") % (tx_lo/1e6) % best_suppression << std::endl;
-        }
-        else std::cout << "." << std::flush;
 
     }
     std::cout << std::endl;
@@ -260,7 +261,7 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
     threads.interrupt_all();
     threads.join_all();
 
-    store_results(usrp, results, "TX", "tx");
+    store_results(usrp, results, "TX", "tx", "iq");
 
     return 0;
 }