Importing timeseries with different sampling rate into simulink loses data?

Hello all,

I have been seeing some spooky effect in my simulations, I could have traced it to what I think is the importing of the time series into simulink. Let's me show what I do,

• I create a 802.11p signal with wlan tool box

    cfgNHT = wlanNonHTConfig;
    cfgNHT.ChannelBandwidth = 'CBW10';
    cfgNHT.PSDULength = psduLen;
    cfgNHT.MCS = mcs;
    %% Packet parameters
    % Create random data; PSDULength is in bytes
    savedState = rng(0); % Set random state
    data = randi([0 1],cfgNHT.PSDULength*8*numPackets,1);
    % Generate a multi-packet waveform
    waveForm80211p = wlanWaveformGenerator(data,cfgNHT, 'NumPackets',100,'IdleTime',3.6e-3/10);
    fs = wlanSampleRate(cfgNHT);

• Convert that signal into a timeseries to import into simulink

    s = timeseries(txWaveform,1:length(txWaveform));
    s.Time = s.Time/fs;

• Import s signal into simulink via a From Workspace block using sample time 1/fs
• Change the sample rate of s within simulink to 1/(64*fs) using a RateTransition block since my model runs with that simulation step

Something as shown below

• Run the simulation

Then what I observe is that for certain 802.11p signals, its SFT are not looking as they supposed to look like, they look like this ( yellow signal)

whereas they should looke like this

THe above two scrreenshots are coming from the same simulation as shown below

So it seems that sometimes the timeseries s is not properly either imported or re-sampled by simulink, since if I plot out.s_simulink I get this

Any ideas why is this happening? Is a bug in Simulink when importing the timeseries to an different sampling rate model?

Answer 1

[Stefanie Schwarz]

This is probably the result of the Interpolation settings in your From Workspace block. Please see the following MATLAB Answers post regarding why it looks like data is being lost when you disble interpolation:

https://uk.mathworks.com/matlabcentral/answers/93802-why-are-some-of-my-values-repeated-when-using-the-from-workspace-block-without-interpolation-in-simu