ti_mo
65 lines
2.5 KiB
Matlab
65 lines
2.5 KiB
Matlab
% disp("Results Task 4:" + newline)
|
|
|
|
saveToFile = true;
|
|
|
|
ssid = "wlan fahren wir noch";
|
|
beaconInterval = 100;
|
|
band = 2.4;
|
|
channel = 1;
|
|
|
|
frameBodyConfig = wlanMACManagementConfig(BeaconInterval=beaconInterval, SSID=ssid);
|
|
|
|
dsElementID = 3;
|
|
dsInformation = dec2hex(channel, 2);
|
|
frameBodyConfig = frameBodyConfig.addIE(dsElementID, dsInformation);
|
|
|
|
beaconFrameConfig = wlanMACFrameConfig(FrameType="Beacon", ManagementConfig=frameBodyConfig, FromDS=false);
|
|
|
|
[mpduBits, mpduLength] = wlanMACFrame(beaconFrameConfig, OutputFormat="bits");
|
|
|
|
fc = wlanChannelFrequency(channel, band);
|
|
|
|
cfgNonHT = wlanNonHTConfig(PSDULength=mpduLength);
|
|
|
|
osf = 1;
|
|
tbtt = 1e-3;
|
|
txWaveform = wlanWaveformGenerator(mpduBits, cfgNonHT, OversamplingFactor=osf, NumPackets=5, IdleTime=tbtt);
|
|
|
|
Rs = wlanSampleRate(cfgNonHT,OversamplingFactor=osf);
|
|
|
|
if saveToFile
|
|
iq = txWaveform;
|
|
% store to pass filepath to analyzeTrace
|
|
save("traces/wlan_fahren_wir_noch_beacons.mat", "iq");
|
|
end
|
|
|
|
% parameters from task1.m
|
|
generatedTrace = analyzeTrace("traces/wlan_fahren_wir_noch_beacons.mat", channel, window, overlap, fft_precision, Rs);
|
|
|
|
generated_p_dB_min = prctile(generatedTrace.P_dB(:), 1);
|
|
generated_p_dB_max = prctile(generatedTrace.P_dB(:), 99.9);
|
|
|
|
plotSpectrogram(generatedTrace, 5, generated_p_dB_min, generated_p_dB_max);
|
|
|
|
%{
|
|
The first thing I noticed is that most of the spectrogram is shown in the
|
|
lowest color range. This is expected, because the generated waveform is a
|
|
synthetic signal and does not include receiver noise, interference, other
|
|
WiFi transmissions, or non-WiFi signals.
|
|
|
|
The only relevant signal components are the generated beacon frames. Between
|
|
the beacons, the waveform contains idle time, so the power is close to zero
|
|
and therefore appears at the lowest dB level in the spectrogram.
|
|
|
|
Over time, the spectrum only changes when a beacon frame is transmitted.
|
|
During these short intervals, the OFDM signal occupies the 20 MHz channel.
|
|
Between the beacon frames, there is no meaningful signal energy. Since the
|
|
generation is done under ideal conditions, the repeated beacons look very
|
|
similar and there are no random channel effects, noise floor variations, or
|
|
additional transmissions as in the recorded SDR traces.
|
|
|
|
For visualization, the idle time was reduced to 1 ms and NumPackets was set
|
|
to 5, so that multiple beacon frames are visible close to each other in the
|
|
spectrogram. This does not represent the normal beacon interval of 100 TU
|
|
(about 102.4 ms), but makes the generated frames easier to compare visually.
|
|
%} |