[USRP-users] Re: B205 mini i very high lo-leakage, image rejection and aggressive DC correction.

[soring]

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

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