On 29/03/2023 01:36, sor...@ayecka.com wrote:
I’ve uploaded a sample of the signal I generate at:
https://mega.nz/file/jEEgnBZL#Kr-qjSUXlYDNBmuVfFvSOwy1CJCBelmxsSsnS2a4aDQ
The file is binary. The signal is sampled at 5.76 MHz. The signal is
complex interleaved, 16 bits signed.
I gather the signal as it is transmitted to the B205.
I use: linux; GNU C++ version 9.4.0; Boost_107100; UHD_4.4.0.0-0-g5fac246b
Gain 80 db. BW 10 MHz. lo-offset 3e6. Rate 5.76MHz.
I measure an output power of 3 dbm. Image rejection about 25 db only.
I copied the code for the initialization of the USRP:
std::string device_args("num_send_frames=256");
std::string subdev("A:A");
std::string ant("TX/RX");
std::string ref("external");
std::cout << boost::format("Creating the usrp device with: %s...") %
device_args << std::endl;
uhd::usrp::multi_usrp::sptr usrp =
uhd::usrp::multi_usrp::make(device_args);
// Lock mboard clocks
std::cout << boost::format("Lock mboard clocks: %f") % ref << std::endl;
usrp->set_clock_source(ref);
//always select the subdevice first, the channel mapping affects the
other settings
std::cout << boost::format("subdev set to: %f") % subdev << std::endl;
usrp->set_tx_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;
}
// set sample rate
std::cout << boost::format("Setting TX Rate: %f Msps...") % (rate /
1e6) << std::endl;
usrp->set_tx_rate(rate);
std::cout << boost::format("Actual RX Rate: %f Msps...") %
(usrp->get_tx_rate() / 1e6) << std::endl << std::endl;
// set freq
std::cout << boost::format("Setting RX Freq: %f MHz...") % (freq /
1e6) << std::endl;
uhd::tune_request_t tune_request(freq,lo_offset);
usrp->set_tx_freq(tune_request);
std::cout << boost::format("Actual TX Freq: %f MHz...") %
(usrp->get_tx_freq() / 1e6) << std::endl << std::endl;
// set the rf gain
std::cout << boost::format("Setting TX Gain: %f dB...") % gain <<
std::endl;
usrp->set_tx_gain(gain);
std::cout << boost::format("Actual TX Gain: %f dB...") %
usrp->get_tx_gain() << std::endl << std::endl;
// set the IF filter bandwidth
std::cout << boost::format("Setting TX Bandwidth: %f MHz...") % (bw /
1e6) << std::endl;
usrp->set_tx_bandwidth(bw);
std::cout << boost::format("Actual TX Bandwidth: %f MHz...") %
(usrp->get_tx_bandwidth() / 1e6) << std::endl << std::endl;
// set the antenna
std::cout << boost::format("Setting TX Antenna: %s") % ant << std::endl;
usrp->set_tx_antenna(ant);
std::cout << boost::format("Actual TX Antenna: %s") %
usrp->get_tx_antenna() << std::endl << std::endl;
std::string cpu_format ="sc16";
std::string wirefmt="sc16";
uhd::stream_args_t stream_args(cpu_format, wirefmt);
std::vector<size_t> channel_nums;
channel_nums.push_back(boost::lexical_cast<size_t>("0"));
stream_args.channels = channel_nums;
It would be great to know how to get it work properly.
Thank you,
Sorin
You should be able to use the tx_samples_from_file example for this
simple test, which includes the ability to set an LO offset.
This will tell you whether its your setup or something else.
Make sure that your sample amplitudes aren't saturated (that is, don't
approach more than perhaps +/- 20000 or so).
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