phased.TwoRayChannel problem

I'm setting a radar simulation platform.

Since the multipath effect is considered, I use phased.TwoRayChannel instead of phased.FreeSpace

The size of xr, Radar Data Cube, is (1100,10,64) which means fast time samples, ULA sensors and number of sweeps respectively.

% Radar Data Cube (Time Domain Received Signal)
xr = complex(zeros(waveform.SampleRate*waveform.SweepTime,Num_of_channel,Nsweep));

    for m = 1:Nsweep
        % Update radar and target positions
        [radar_pos,radar_vel] = radarmotion(waveform.SweepTime);
        [tgt_pos,tgt_vel] = carmotion(waveform.SweepTime);

        % Transmit FMCW waveform
        sig = waveform();
        txsig = transmitter(sig);

        % Radiate the pulse toward the target
        txsig = radiator(txsig,tgtang);

        % Propagate the signal and reflect off the target
        txsig = txchannel(txsig,radar_pos,tgt_pos,radar_vel,tgt_vel);
        rxsig = cartarget(txsig);
        rxsig = rxchannel(rxsig,radar_pos,tgt_pos,radar_vel,tgt_vel);

        % Collect the echo from the incident angle at the antenna
        rxsig = collector(rxsig,tgtang);

        % Dechirp the received radar return
        rxsig = receiver(rxsig);
        dechirpsig = dechirp(rxsig,sig);

        % Visualize the spectrum
        % specanalyzer([txsig dechirpsig]);

        xr(:,:,m) = dechirpsig;
    end

The results I got is:

I have no idea why the results are correct only if I use phased.FreeSpace.

I guess the collector is the point.

Thank you for all your assistance !

[Honglei Chen]

Is there a questino about the two ray channel? thanks.

[Wei-Min Chen]

Sure, if I replace phased.TwoRayChannel with phased.FreeSpace, the simulation results are correct.

So I assumed that the point is phased.TwoRayChannel. (Or Collector, I mean maybe I shouldn't use phased.TwoRayChannel with ULA+Collect at the same time.)

Answer 1

[Kaushik Vasanth]

Hi,

Maybe this could give an idea.

This example in mathworks shows the two-ray propagation. "https://in.mathworks.com/examples/phased-array/mw/phased-ex90572992-radar-signal-simulation-and-processing-for-automated-driving?s_tid=srchtitle".

Here when you change from phased.FreeSpace to phased.TwoRayChannel, we need to model 2 different channels for Tx and Rx.

Just have a look through the code and it might be of some help.

Thanks!