[Discuss-gnuradio] [UHD] tx_from_file.cpp (sending a file formed 802.11 packet using UHD)

[Sangho Oh]

Hello,

The goal is to send a full 802.11 packet using UHD.

1. I have created a complex samples of 802.11 packet using MATLAB and saved it into a file.

- final: 1440 complex samples

file_name='in.dat';

fid = fopen(file_name,'w');

new_save = reshape([real(final);imag(final)],1,2*length(final));

F = fwrite(fid,new_save,'float');

fclose all;

2. current tx_from_file.cpp does not compile, so modified a little bit

- I think I messed up the data formats.

/*-------------------------------------------------------------------------------*/

    //allocate data to send

    std::vector<std::complex<float> > buff;

    uhd::tx_metadata_t md;

    std::cout << "Read data to send from file: in.dat" << std::endl;

    std::ifstream infile("in.dat", std::ifstream::binary);

    while (!infile.eof()) {

        std::complex<float> c;

        infile.read((char *)&c, sizeof(std::complex<float>));

        if (!((c.real() == 0) && (c.imag() == 0))) {

            buff.push_back(c); 

//std::cout << "C = " << c << std::endl;

        }

    }

    samps_per_packet = buff.size();

    infile.close();

    std::cout << "Number of samples in file: " << samps_per_packet << std::endl;

    //send the data in multiple packets

    size_t num_packets = (total_num_samps+samps_per_packet-1)/samps_per_packet;

    for (size_t i = 0; i < num_packets; i++){

        //setup the metadata flags and time spec

        md.start_of_burst = true;                  //always SOB (good for continuous streaming)

        md.end_of_burst   = (i == num_packets-1);  //only last packet has EOB

        md.has_time_spec  = (i == 0);              //only first packet has time

        md.time_spec = uhd::time_spec_t(seconds_in_future);

        size_t samps_to_send = std::min(total_num_samps - samps_per_packet*i, samps_per_packet);

        //send the entire packet (driver fragments internally)

        size_t num_tx_samps = dev->send(

            &buff.front(), samps_to_send, md,

            uhd::io_type_t::COMPLEX_FLOAT32,

            uhd::device::SEND_MODE_FULL_BUFF

        );

        if(verbose) std::cout << std::endl << boost::format("Sent %d samples") % num_tx_samps << std::endl;

    }

    //finished

    std::cout << std::endl << "Done!" << std::endl << std::endl;

3. I don't know what the the proper sample rate is for 802.11 6Mbps data frame. I set the rate as 6e6 and got following message

Warning:

    The hardware does not support the requested TX sample rate:

    Target sample rate: 6.000000 MSps

    Actual sample rate: 5.882353 MSps

    

Actual TX Rate: 5.882353 Msps...

--
From: Sangho Oh

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