diff options
| -rw-r--r-- | host/examples/tx_waveforms.cpp | 62 |
1 files changed, 43 insertions, 19 deletions
diff --git a/host/examples/tx_waveforms.cpp b/host/examples/tx_waveforms.cpp index e9cf210bb..22975da96 100644 --- a/host/examples/tx_waveforms.cpp +++ b/host/examples/tx_waveforms.cpp @@ -20,6 +20,7 @@ #include <uhd/usrp/simple_usrp.hpp> #include <boost/program_options.hpp> #include <boost/thread/thread_time.hpp> //system time +#include <boost/math/special_functions/round.hpp> #include <boost/format.hpp> #include <iostream> #include <complex> @@ -32,7 +33,7 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){ //variables to be set by po std::string args, wave_type; - size_t total_duration, amspb; + size_t total_duration, mspb; double rate, freq, wave_freq; float ampl, gain; @@ -42,7 +43,7 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){ ("help", "help message") ("args", po::value<std::string>(&args)->default_value(""), "simple uhd device address args") ("duration", po::value<size_t>(&total_duration)->default_value(3), "number of seconds to transmit") - ("amspb", po::value<size_t>(&amspb)->default_value(10000), "approximate mimimum samples per buffer") + ("mspb", po::value<size_t>(&mspb)->default_value(10000), "mimimum samples per buffer") ("rate", po::value<double>(&rate)->default_value(100e6/16), "rate of outgoing samples") ("freq", po::value<double>(&freq)->default_value(0), "rf center frequency in Hz") ("ampl", po::value<float>(&l)->default_value(float(0.3)), "amplitude of the waveform") @@ -88,33 +89,56 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){ } //error when the waveform is not possible to generate - if (std::abs(wave_freq)/sdev->get_tx_rate() < 0.5/amspb){ + if (std::abs(wave_freq)/sdev->get_tx_rate() < 0.5/mspb){ throw std::runtime_error("wave freq/tx rate too small"); } if (std::abs(wave_freq) > sdev->get_tx_rate()/2){ throw std::runtime_error("wave freq out of Nyquist zone"); } - //fill a buffer with one period worth of samples - std::vector<float> period(size_t(sdev->get_tx_rate()/std::abs(wave_freq))); - std::cout << boost::format("Samples per waveform period: %d") % period.size() << std::endl; - for (size_t n = 0; n < period.size(); n++){ - if (wave_type == "CONST") period[n] = ampl; - else if (wave_type == "SQUARE") period[n] = (n > period.size()/2)? ampl : 0; - else if (wave_type == "RAMP") period[n] = float((n/double(period.size()-1)) * 2*ampl - ampl); - else if (wave_type == "SINE") period[n] = ampl*float(std::sin(2*M_PI*n/double(period.size()))); - else throw std::runtime_error("unknown waveform type: " + wave_type); + //how many periods should we have per buffer to mimimize error + double samps_per_period = sdev->get_tx_rate()/std::abs(wave_freq); + std::cout << boost::format("Samples per waveform period: %d") % samps_per_period << std::endl; + size_t periods_per_buff = std::max<size_t>(1, mspb/samps_per_period); + while (true){ + double num_samps_per_buff = periods_per_buff*samps_per_period; + double sample_error = num_samps_per_buff - boost::math::round(num_samps_per_buff); + if (std::abs(sample_error/num_samps_per_buff) < 1e-5) break; + periods_per_buff++; } //allocate data to send (fill with several periods worth of IQ samples) - const size_t periods_per_buff = std::max<size_t>(1, amspb/period.size()); - std::vector<std::complex<float> > buff(period.size()*periods_per_buff); + std::vector<std::complex<float> > buff(samps_per_period*periods_per_buff); + const double i_ahead = (wave_freq > 0)? samps_per_period/4 : 0; + const double q_ahead = (wave_freq < 0)? samps_per_period/4 : 0; std::cout << boost::format("Samples per send buffer: %d") % buff.size() << std::endl; - const size_t i_ahead = (wave_freq > 0)? period.size()/4 : 0; - const size_t q_ahead = (wave_freq < 0)? period.size()/4 : 0; - for (size_t n = 0; n < buff.size(); n++) buff[n] = std::complex<float>( - period[(n+i_ahead)%period.size()], period[(n+q_ahead)%period.size()] //I,Q - ); + if (wave_type == "CONST"){ + for (size_t n = 0; n < buff.size(); n++){ + buff[n] = std::complex<float>(ampl, ampl); + } + } + else if (wave_type == "SQUARE"){ + for (size_t n = 0; n < buff.size(); n++){ + float I = (std::fmod(n+i_ahead, samps_per_period) > samps_per_period/2)? ampl : 0; + float Q = (std::fmod(n+q_ahead, samps_per_period) > samps_per_period/2)? ampl : 0; + buff[n] = std::complex<float>(I, Q); + } + } + else if (wave_type == "RAMP"){ + for (size_t n = 0; n < buff.size(); n++){ + float I = float(std::fmod(n+i_ahead, samps_per_period)/samps_per_period * 2*ampl - ampl); + float Q = float(std::fmod(n+q_ahead, samps_per_period)/samps_per_period * 2*ampl - ampl); + buff[n] = std::complex<float>(I, Q); + } + } + else if (wave_type == "SINE"){ + for (size_t n = 0; n < buff.size(); n++){ + float I = float(ampl*std::sin(2*M_PI*(n+i_ahead)/samps_per_period)); + float Q = float(ampl*std::sin(2*M_PI*(n+q_ahead)/samps_per_period)); + buff[n] = std::complex<float>(I, Q); + } + } + else throw std::runtime_error("unknown waveform type: " + wave_type); //setup the metadata flags uhd::tx_metadata_t md; |