How to transmit and receive a sinusoid using BPSK modulation and demodulation schemes utilizing the built in Family Radio Service (FRS) Full-Duplex Transceiver with USRP® Hardware?

Hi, I am trying to utilize the built in code for the Family Radio Service (FRS) Full-Duplex Transceiver with USRP® Hardware environment. I want to run the tests for several modulation and demodulation schemes. I am using USRP N210 Loop back connection. I believe the transmitter end works well and I am facing problems in recovering the data from the receiver side. I am copying the code below. I will be very grateful if someone can help me with this. Thank you.

clear all

close all

clc

%Discover Radio

connectedRadios = findsdru;

if strncmp(connectedRadios(1).Status, 'Success', 7)

radioFound = true;

platform = connectedRadios(1).Platform;

switch connectedRadios(1).Platform

case {'B200','B210'}

address = connectedRadios(1).SerialNum;

case {'N200/N210/USRP2','X300','X310'}

address = connectedRadios(1).IPAddress;

end

else

radioFound = false;

address = '192.168.10.2';

platform = 'N200/N210/USRP2';

end

% Transmitter Initialization

rfTxFreq = 15e6; % RF Transmitter Center Frequency (Hz)

frsFDTxParams = configureFDTx(platform, rfTxFreq);

% Receiver Initialization

rfRxFreq = 15e6; % RF Receiver Center Frequency (Hz)

rfRxFreqCorrection = -4e3; % Frequency calibration compensation value (Hz)

rfRxFreqActual = rfRxFreq + rfRxFreqCorrection;

frsFDRxParams = configureFDRx(platform, rfRxFreqActual);

% Create a data source to transmit the contents of a sound file at a

% sampling frequency of 8 kHz.

% source = FRSGMRSDemoSource('Sound file', frsFDTxParams.SourceSampleRate);

% source.AudioFileName = 'speech_dft.avi';

source = FRSGMRSDemoSource('Pure Tone', frsFDTxParams.SourceSampleRate);

% PP=source();

% source.AudioFileName = 'speech_dft.avi';

% The Continuous Tone-Coded Squelch System (CTCSS) filters out

% undesired communication or interference from these other users by

% generating a tone between 67 Hz and 250 Hz and transmitting it along with

% the source signal.

ctcss = dsp.SineWave(frsFDTxParams.CTCSSAmplitude, ...

frsFDTxParams.CTCSSToneFrequencies(frsFDTxParams.CTCSSCode), ...

'SampleRate', frsFDTxParams.SourceSampleRate, ...

'SamplesPerFrame', frsFDTxParams.SourceFrameLength, ...

'OutputDataType', 'single');

% The interpolator and BPSK modulator convert the sampling rate of the sum of

% the modulating signal and the CTCSS tone to match the USRP(R) hardware

% sampling rate of 200 kHz.

interpolator = dsp.FIRInterpolator(frsFDTxParams.InterpolationFactor, ...

frsFDTxParams.InterpolationNumerator);

BPSKMod = comm.BPSKModulator;

BPSKMod.PhaseOffset = pi/4;

% Set up transmitter radio object to use the found radio

switch platform

case {'B200','B210'}

radioTx = comm.SDRuTransmitter('Platform', platform, ...

'SerialNum', address, ...

'MasterClockRate', frsFDTxParams.RadioMasterClockRate, ...

'CenterFrequency', frsFDTxParams.CenterFrequency,...

'Gain', frsFDTxParams.RadioGain, ...

'InterpolationFactor', frsFDTxParams.RadioInterpolationFactor)

case {'X300','X310'}

radioTx = comm.SDRuTransmitter('Platform', platform, ...

'IPAddress', address, ...

'MasterClockRate', frsFDTxParams.RadioMasterClockRate, ...

'CenterFrequency', frsFDTxParams.CenterFrequency,...

'Gain', frsFDTxParams.RadioGain, ...

'InterpolationFactor', frsFDTxParams.RadioInterpolationFactor)

case {'N200/N210/USRP2'}

radioTx = comm.SDRuTransmitter('Platform', platform, ...

'IPAddress', address, ...

'CenterFrequency', frsFDTxParams.CenterFrequency,...

'Gain', frsFDTxParams.RadioGain, ...

'InterpolationFactor', frsFDTxParams.RadioInterpolationFactor)

end

% Set up transmitter radio object to use the found radio

switch platform

case {'B200','B210'}

radioRx = comm.SDRuReceiver('Platform', platform, ...

'SerialNum', address, ...

'MasterClockRate', frsFDRxParams.RadioMasterClockRate, ...

'CenterFrequency', frsFDRxParams.CenterFrequency,...

'Gain', frsFDRxParams.RadioGain, ...

'DecimationFactor', frsFDRxParams.RadioDecimationFactor, ...

'SamplesPerFrame', frsFDRxParams.RadioFrameLength, ...

'OutputDataType', 'single')

case {'X300','X310'}

radioRx = comm.SDRuReceiver('Platform', platform, ...

'IPAddress', address, ...

'MasterClockRate', frsFDRxParams.RadioMasterClockRate, ...

'CenterFrequency', frsFDRxParams.CenterFrequency,...

'Gain', frsFDRxParams.RadioGain, ...

'DecimationFactor', frsFDRxParams.RadioDecimationFactor, ...

'SamplesPerFrame', frsFDRxParams.RadioFrameLength, ...

'OutputDataType', 'single')

case {'N200/N210/USRP2'}

radioRx = comm.SDRuReceiver('Platform', platform, ...

'IPAddress', address, ...

'CenterFrequency', frsFDRxParams.CenterFrequency,...

'Gain', frsFDRxParams.RadioGain, ...

'DecimationFactor', frsFDRxParams.RadioDecimationFactor, ...

'SamplesPerFrame', frsFDRxParams.RadioFrameLength, ...

'OutputDataType', 'single')

end

% AGC

agc = comm.AGC;

% Low pass filter for channel separation

channelFilter = frsFDRxParams.ChannelFilter;

% BPSK demodulator

% Decimation filter to resample to 8 kHz

decimator = dsp.FIRDecimator(frsFDRxParams.DecimationFactor, ...

frsFDRxParams.DecimationNumerator);

% The CTCSS decoder compares the estimated received code with the

% preselected code and then sends the signal to the audio device if the two

% codes match.

decoder = FRSGMRSDemoCTCSSDecoder(...

'MinimumBlockLength', frsFDRxParams.CTCSSDecodeBlockLength, ...

'SampleRate', frsFDRxParams.AudioSampleRate);

% High pass filter to filter out CTCSS tones

audioFilter = frsFDRxParams.AudioFilter;

% Audio device writer

audioPlayer = audioDeviceWriter(frsFDRxParams.AudioSampleRate);

% Perform stream processing if a radio is found.

if radioFound

% Loop until the example reaches the target stop time.

timeCounter = 0;

while timeCounter < frsFDTxParams.StopTime

% Transmitter stream processing

% -----------------------------------------------------------------

dataTx = step(source); % Generate audio waveform

dataWTone = dataTx + step(ctcss); % Add CTCSS tones

% Interpolation BPSK modulation

outResamp = step(interpolator, dataWTone); % Resample to 200 kHz

KK=zeros(1,length(outResamp));

NN=KK';

for i=1:length(outResamp)

if outResamp(i)>0

NN(i)=1;

else NN(i)=0;

end

end

outMod = step(BPSKMod, NN);

% plot(outMod)

step(radioTx, outMod); % Transmit to USRP(R) radio

% Receiver stream processing

% -----------------------------------------------------------------

[dataRx, lenRx] = step(radioRx);

if lenRx > 0

outAGC = step(agc, dataRx); % AGC

outChanFilt = step(channelFilter, outAGC); % Adjacent channel filtering

rxAmp = mean(abs(outChanFilt));

if rxAmp > frsFDRxParams.DetectionThreshold

outThreshold = outChanFilt;

else

outThreshold = complex(single(zeros(frsFDRxParams.RadioFrameLength, 1)));

end

BPSKDemod=comm.BPSKDemodulator;

BPSKDemod.PhaseOffset = pi/4;

% BPSK demodulation and decimation

outBPSKDemod = step(BPSKDemod, outThreshold); % BPSK demodulate

outDecim = step(decimator, outBPSKDemod); % Resample to 8 kHz

% CTCSS decode and conditionally send to audio output

rcvdCode = step(decoder, outDecim);

if (rcvdCode == frsFDRxParams.CTCSSCode) || (frsFDRxParams.CTCSSCode == 0)

rcvdSig = outDecim;

else

rcvdSig = single(zeros(frsFDRxParams.AudioFrameLength, 1));

end

audioSig = step(audioFilter, rcvdSig); % Filter out CTCSS tones

step(audioPlayer, audioSig); % Audio output

timeCounter = timeCounter + frsFDRxParams.RadioFrameTime;

end

end

else

warning(message('sdru:sysobjdemos:MainLoop'))

end

% Release all SDRu and audio resources, FM Modulator and Demodulator

release(BPSKMod)

release(radioTx)

release(BPSKDemod)

release(radioRx)

release(audioPlayer)