Ok. I couldn't seem to duplicate with the stock "rx_samples_to_file", but
with the following minor mods, I see some of the bad behavior. This sure
looks like a UHD bug to me.
I simply added timed commands around the set_rx_freq() function (see
snippet below as well as attached source code). Is this the correct way to
do it? If so, then I believe there is a bug because I get changing spectra
just by changing the LO offset.
uhd::time_spec_t cmd_time = usrp->get_time_now()+0.1;
usrp->set_command_time(cmd_time);
usrp->set_rx_freq(tune_request, channel); // this line not modified
usrp->clear_command_time();
My command line was
rx_samples_to_file --nsamps 500000 --rate 50e6 --freq 2450e6 --lo-offset
-10e6
If I change just the LO offset (always keeping "--freq 2450e6"), the known
CW tone that I supply as an input signal moves around the spectrum.
This is the correct spectrum achieved with --lo-offset 0. Note the CW tone
at 5 MHz which is correct because my sig gen is transmitting at 2455 MHz.
[image: image.png]
This is the spectrum received with --lo-offset -10e6. Note that the tone
(which did not change from the example above) shows up at 15 MHz instead of
the correct location at 5 MHz.
[image: image.png]
Rob
On Thu, Apr 18, 2019 at 1:53 PM Rob Kossler <rkoss...@nd.edu> wrote:
> I do see in the documentation that the tune result "target_rf_freq"
> will match the tune request "rf_freq", which it does in my example
> below. So, I suppose the output shown is as expected for my request.
> Unfortunately, this doesn't solve my problem of the actual spectrum
> being wrong. I may have to construct a test case to show that the
> problem is in UHD....
>
> On Thu, Apr 18, 2019 at 1:50 PM Marcus D. Leech via USRP-users
> <usrp-users@lists.ettus.com> wrote:
> >
> > On 04/18/2019 01:44 PM, Rob Kossler via USRP-users wrote:
> >
> > Hi,
> > I am seeing some strange (and unrepeatable) behavior with an
> X310/UBX-160 and the multi_usrp->set_rx_freq() function. I call this
> function with a tune_request that I create with a desired target frequency
> & lo_offset. The output below shows a "pp_string" of the request and the
> result (for the request, I had to create my own "pp_string" function but
> for the result, I used the existing Ettus function).
> >
> > I can tell from the resulting spectrum (not provided) that the
> frequencies / offsets are often not getting set correctly because I have a
> CW tone at a known frequency coming in. But, what I am presently
> interested in is the output shown below. In this example, I requested a
> target frequency of 2450 MHz with a 5 MHz LO offset. The tune request
> looks like I would expect. However, for the tune result, shouldn't the
> "Target RF freq" match the "Target freq" from the request (i.e., 2450 MHz
> rather than 2455 MHz)?
> > Rob
> >
> > // This is essentially the code executed
> > tune_request_t tune_req(2450e6,5e6);
> > tune_result_t tune_res = usrp->set_rx_freq(tune_req,0);
> >
> > // here is the output showing to_pp_string()
> > Tune request
> > RF Policy: M
> > Target freq: 2450.000000 (MHz)
> > RF freq: 2455.000000 (MHz)
> > DSP Policy: A
> > DSP freq: 0.000000 (MHz)
> > args:
> >
> > Tune Result:
> > Target RF Freq: 2455.000000 (MHz)
> > Actual RF Freq: 2455.006105 (MHz)
> > Target DSP Freq: 5.006105 (MHz)
> > Actual DSP Freq: 5.006105 (MHz)
> >
> > The "Target RF Frequency" is the frequency setting of the LO, which if
> you are requesting a 5MHz LO offset, will be somewhere around 5MHz away from
> > your target "sky" frequency. The DSP arranges to "mop up" the
> difference.
> >
> >
> > _______________________________________________
> > USRP-users mailing list
> > USRP-users@lists.ettus.com
> > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
//
// Copyright 2010-2011,2014 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: GPL-3.0-or-later
//
#include <uhd/exception.hpp>
#include <uhd/types/tune_request.hpp>
#include <uhd/usrp/multi_usrp.hpp>
#include <uhd/utils/safe_main.hpp>
#include <uhd/utils/thread.hpp>
#include <boost/format.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/program_options.hpp>
#include <chrono>
#include <complex>
#include <csignal>
#include <fstream>
#include <iostream>
#include <thread>
namespace po = boost::program_options;
static bool stop_signal_called = false;
void sig_int_handler(int)
{
stop_signal_called = true;
}
template <typename samp_type>
void recv_to_file(uhd::usrp::multi_usrp::sptr usrp,
const std::string& cpu_format,
const std::string& wire_format,
const size_t& channel,
const std::string& file,
size_t samps_per_buff,
unsigned long long num_requested_samples,
double time_requested = 0.0,
bool bw_summary = false,
bool stats = false,
bool null = false,
bool enable_size_map = false,
bool continue_on_bad_packet = false)
{
unsigned long long num_total_samps = 0;
// create a receive streamer
uhd::stream_args_t stream_args(cpu_format, wire_format);
std::vector<size_t> channel_nums;
channel_nums.push_back(channel);
stream_args.channels = channel_nums;
uhd::rx_streamer::sptr rx_stream = usrp->get_rx_stream(stream_args);
uhd::rx_metadata_t md;
std::vector<samp_type> buff(samps_per_buff);
std::ofstream outfile;
if (not null)
outfile.open(file.c_str(), std::ofstream::binary);
bool overflow_message = true;
// setup streaming
uhd::stream_cmd_t stream_cmd((num_requested_samples == 0)
? uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS
: uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE);
stream_cmd.num_samps = size_t(num_requested_samples);
stream_cmd.stream_now = true;
stream_cmd.time_spec = uhd::time_spec_t();
rx_stream->issue_stream_cmd(stream_cmd);
typedef std::map<size_t, size_t> SizeMap;
SizeMap mapSizes;
const auto start_time = std::chrono::steady_clock::now();
const auto stop_time =
start_time + std::chrono::milliseconds(int64_t(1000 * time_requested));
// Track time and samps between updating the BW summary
auto last_update = start_time;
unsigned long long last_update_samps = 0;
// Run this loop until either time expired (if a duration was given), until
// the requested number of samples were collected (if such a number was
// given), or until Ctrl-C was pressed.
while (not stop_signal_called
and (num_requested_samples != num_total_samps or num_requested_samples == 0)
and (time_requested == 0.0 or std::chrono::steady_clock::now() <= stop_time)) {
const auto now = std::chrono::steady_clock::now();
size_t num_rx_samps =
rx_stream->recv(&buff.front(), buff.size(), md, 3.0, enable_size_map);
if (md.error_code == uhd::rx_metadata_t::ERROR_CODE_TIMEOUT) {
std::cout << boost::format("Timeout while streaming") << std::endl;
break;
}
if (md.error_code == uhd::rx_metadata_t::ERROR_CODE_OVERFLOW) {
if (overflow_message) {
overflow_message = false;
std::cerr
<< boost::format(
"Got an overflow indication. Please consider the following:\n"
" Your write medium must sustain a rate of %fMB/s.\n"
" Dropped samples will not be written to the file.\n"
" Please modify this example for your purposes.\n"
" This message will not appear again.\n")
% (usrp->get_rx_rate(channel) * sizeof(samp_type) / 1e6);
}
continue;
}
if (md.error_code != uhd::rx_metadata_t::ERROR_CODE_NONE) {
std::string error = str(boost::format("Receiver error: %s") % md.strerror());
if (continue_on_bad_packet) {
std::cerr << error << std::endl;
continue;
} else
throw std::runtime_error(error);
}
if (enable_size_map) {
SizeMap::iterator it = mapSizes.find(num_rx_samps);
if (it == mapSizes.end())
mapSizes[num_rx_samps] = 0;
mapSizes[num_rx_samps] += 1;
}
num_total_samps += num_rx_samps;
if (outfile.is_open()) {
outfile.write((const char*)&buff.front(), num_rx_samps * sizeof(samp_type));
}
if (bw_summary) {
last_update_samps += num_rx_samps;
const auto time_since_last_update = now - last_update;
if (time_since_last_update > std::chrono::seconds(1)) {
const double time_since_last_update_s =
std::chrono::duration<double>(time_since_last_update).count();
const double rate = double(last_update_samps) / time_since_last_update_s;
std::cout << "\t" << (rate / 1e6) << " Msps" << std::endl;
last_update_samps = 0;
last_update = now;
}
}
}
const auto actual_stop_time = std::chrono::steady_clock::now();
stream_cmd.stream_mode = uhd::stream_cmd_t::STREAM_MODE_STOP_CONTINUOUS;
rx_stream->issue_stream_cmd(stream_cmd);
if (outfile.is_open()) {
outfile.close();
}
if (stats) {
std::cout << std::endl;
const double actual_duration_seconds =
std::chrono::duration<float>(actual_stop_time - start_time).count();
std::cout << boost::format("Received %d samples in %f seconds") % num_total_samps
% actual_duration_seconds
<< std::endl;
const double rate = (double)num_total_samps / actual_duration_seconds;
std::cout << (rate / 1e6) << " Msps" << std::endl;
if (enable_size_map) {
std::cout << std::endl;
std::cout << "Packet size map (bytes: count)" << std::endl;
for (SizeMap::iterator it = mapSizes.begin(); it != mapSizes.end(); it++)
std::cout << it->first << ":\t" << it->second << std::endl;
}
}
}
typedef std::function<uhd::sensor_value_t(const std::string&)> get_sensor_fn_t;
bool check_locked_sensor(std::vector<std::string> sensor_names,
const char* sensor_name,
get_sensor_fn_t get_sensor_fn,
double setup_time)
{
if (std::find(sensor_names.begin(), sensor_names.end(), sensor_name)
== sensor_names.end())
return false;
auto setup_timeout = std::chrono::steady_clock::now()
+ std::chrono::milliseconds(int64_t(setup_time * 1000));
bool lock_detected = false;
std::cout << boost::format("Waiting for \"%s\": ") % sensor_name;
std::cout.flush();
while (true) {
if (lock_detected and (std::chrono::steady_clock::now() > setup_timeout)) {
std::cout << " locked." << std::endl;
break;
}
if (get_sensor_fn(sensor_name).to_bool()) {
std::cout << "+";
std::cout.flush();
lock_detected = true;
} else {
if (std::chrono::steady_clock::now() > setup_timeout) {
std::cout << std::endl;
throw std::runtime_error(
str(boost::format(
"timed out waiting for consecutive locks on sensor \"%s\"")
% sensor_name));
}
std::cout << "_";
std::cout.flush();
}
std::this_thread::sleep_for(std::chrono::milliseconds(100));
}
std::cout << std::endl;
return true;
}
int UHD_SAFE_MAIN(int argc, char* argv[])
{
uhd::set_thread_priority_safe();
// variables to be set by po
std::string args, file, type, ant, subdev, ref, wirefmt;
size_t channel, total_num_samps, spb;
double rate, freq, gain, bw, total_time, setup_time, lo_offset;
// setup the program options
po::options_description desc("Allowed options");
// clang-format off
desc.add_options()
("help", "help message")
("args", po::value<std::string>(&args)->default_value(""), "multi uhd device address args")
("file", po::value<std::string>(&file)->default_value("usrp_samples.dat"), "name of the file to write binary samples to")
("type", po::value<std::string>(&type)->default_value("short"), "sample type: double, float, or short")
("nsamps", po::value<size_t>(&total_num_samps)->default_value(0), "total number of samples to receive")
("duration", po::value<double>(&total_time)->default_value(0), "total number of seconds to receive")
("time", po::value<double>(&total_time), "(DEPRECATED) will go away soon! Use --duration instead")
("spb", po::value<size_t>(&spb)->default_value(10000), "samples per buffer")
("rate", po::value<double>(&rate)->default_value(1e6), "rate of incoming samples")
("freq", po::value<double>(&freq)->default_value(0.0), "RF center frequency in Hz")
("lo-offset", po::value<double>(&lo_offset)->default_value(0.0),
"Offset for frontend LO in Hz (optional)")
("gain", po::value<double>(&gain), "gain for the RF chain")
("ant", po::value<std::string>(&ant), "antenna selection")
("subdev", po::value<std::string>(&subdev), "subdevice specification")
("channel", po::value<size_t>(&channel)->default_value(0), "which channel to use")
("bw", po::value<double>(&bw), "analog frontend filter bandwidth in Hz")
("ref", po::value<std::string>(&ref)->default_value("internal"), "reference source (internal, external, mimo)")
("wirefmt", po::value<std::string>(&wirefmt)->default_value("sc16"), "wire format (sc8, sc16 or s16)")
("setup", po::value<double>(&setup_time)->default_value(1.0), "seconds of setup time")
("progress", "periodically display short-term bandwidth")
("stats", "show average bandwidth on exit")
("sizemap", "track packet size and display breakdown on exit")
("null", "run without writing to file")
("continue", "don't abort on a bad packet")
("skip-lo", "skip checking LO lock status")
("int-n", "tune USRP with integer-N tuning")
;
// clang-format on
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("UHD RX samples to file %s") % desc << std::endl;
std::cout << std::endl
<< "This application streams data from a single channel of a USRP "
"device to a file.\n"
<< std::endl;
return ~0;
}
bool bw_summary = vm.count("progress") > 0;
bool stats = vm.count("stats") > 0;
bool null = vm.count("null") > 0;
bool enable_size_map = vm.count("sizemap") > 0;
bool continue_on_bad_packet = vm.count("continue") > 0;
if (enable_size_map)
std::cout << "Packet size tracking enabled - will only recv one packet at a time!"
<< std::endl;
// 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);
// Lock mboard clocks
usrp->set_clock_source(ref);
// always select the subdevice first, the channel mapping affects the other settings
if (vm.count("subdev"))
usrp->set_rx_subdev_spec(subdev);
std::cout << boost::format("Using Device: %s") % usrp->get_pp_string() << std::endl;
// set the sample rate
if (rate <= 0.0) {
std::cerr << "Please specify a valid sample rate" << std::endl;
return ~0;
}
std::cout << boost::format("Setting RX Rate: %f Msps...") % (rate / 1e6) << std::endl;
usrp->set_rx_rate(rate, channel);
std::cout << boost::format("Actual RX Rate: %f Msps...")
% (usrp->get_rx_rate(channel) / 1e6)
<< std::endl
<< std::endl;
// set the center frequency
if (vm.count("freq")) { // with default of 0.0 this will always be true
std::cout << boost::format("Setting RX Freq: %f MHz...") % (freq / 1e6)
<< std::endl;
std::cout << boost::format("Setting RX LO Offset: %f MHz...") % (lo_offset / 1e6)
<< std::endl;
uhd::tune_request_t tune_request(freq, lo_offset);
if (vm.count("int-n"))
tune_request.args = uhd::device_addr_t("mode_n=integer");
uhd::time_spec_t cmd_time = usrp->get_time_now() + uhd::time_spec_t(0.1);
usrp->set_command_time(cmd_time);
usrp->set_rx_freq(tune_request, channel);
usrp->clear_command_time();
std::cout << boost::format("Actual RX Freq: %f MHz...")
% (usrp->get_rx_freq(channel) / 1e6)
<< std::endl
<< std::endl;
}
// set the rf gain
if (vm.count("gain")) {
std::cout << boost::format("Setting RX Gain: %f dB...") % gain << std::endl;
usrp->set_rx_gain(gain, channel);
std::cout << boost::format("Actual RX Gain: %f dB...")
% usrp->get_rx_gain(channel)
<< std::endl
<< std::endl;
}
// set the IF filter bandwidth
if (vm.count("bw")) {
std::cout << boost::format("Setting RX Bandwidth: %f MHz...") % (bw / 1e6)
<< std::endl;
usrp->set_rx_bandwidth(bw, channel);
std::cout << boost::format("Actual RX Bandwidth: %f MHz...")
% (usrp->get_rx_bandwidth(channel) / 1e6)
<< std::endl
<< std::endl;
}
// set the antenna
if (vm.count("ant"))
usrp->set_rx_antenna(ant, channel);
std::this_thread::sleep_for(std::chrono::milliseconds(int64_t(1000 * setup_time)));
// check Ref and LO Lock detect
if (not vm.count("skip-lo")) {
check_locked_sensor(usrp->get_rx_sensor_names(channel),
"lo_locked",
[usrp, channel](const std::string& sensor_name) {
return usrp->get_rx_sensor(sensor_name, channel);
},
setup_time);
if (ref == "mimo") {
check_locked_sensor(usrp->get_mboard_sensor_names(0),
"mimo_locked",
[usrp](const std::string& sensor_name) {
return usrp->get_mboard_sensor(sensor_name);
},
setup_time);
}
if (ref == "external") {
check_locked_sensor(usrp->get_mboard_sensor_names(0),
"ref_locked",
[usrp](const std::string& sensor_name) {
return usrp->get_mboard_sensor(sensor_name);
},
setup_time);
}
}
if (total_num_samps == 0) {
std::signal(SIGINT, &sig_int_handler);
std::cout << "Press Ctrl + C to stop streaming..." << std::endl;
}
#define recv_to_file_args(format) \
(usrp, \
format, \
wirefmt, \
channel, \
file, \
spb, \
total_num_samps, \
total_time, \
bw_summary, \
stats, \
null, \
enable_size_map, \
continue_on_bad_packet)
// recv to file
if (wirefmt == "s16") {
if (type == "double")
recv_to_file<double> recv_to_file_args("f64");
else if (type == "float")
recv_to_file<float> recv_to_file_args("f32");
else if (type == "short")
recv_to_file<short> recv_to_file_args("s16");
else
throw std::runtime_error("Unknown type " + type);
} else {
if (type == "double")
recv_to_file<std::complex<double>> recv_to_file_args("fc64");
else if (type == "float")
recv_to_file<std::complex<float>> recv_to_file_args("fc32");
else if (type == "short")
recv_to_file<std::complex<short>> recv_to_file_args("sc16");
else
throw std::runtime_error("Unknown type " + type);
}
// finished
std::cout << std::endl << "Done!" << std::endl << std::endl;
return EXIT_SUCCESS;
}
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