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FM Broadcast modulator baseband decimation factor

조회 수: 8 (최근 30일)
Emilija Lazdanaite
Emilija Lazdanaite 2018년 3월 29일
답변: Trey Shenk 2022년 12월 13일
Does anyone have experience with the FM Broadcast block in Simulink? I keep getting the error "The signal length (number of rows) must be a multiple of the decimation factor:[...]", but the online explanation of what the decimation factor is is not really clear.

답변 (2개)

Abhishek Ballaney
Abhishek Ballaney 2018년 3월 29일
https://in.mathworks.com/help/comm/ref/fmbroadcastmodulatorbaseband.html
  댓글 수: 2
Emilija Lazdanaite
Emilija Lazdanaite 2018년 3월 29일
yes, I've read the documentation, it does not explain what the decimation factor is. It only says "The input length of the audio signal must be an integer multiple of the audio decimation factor." Is the decimation factor then the audioLength/audioSampleRate? Because the number i get as the decimation factor in the error message is not that ratio.
Quenten Switten
Quenten Switten 2020년 4월 8일
Have you find the solution on this question?
I ask this because I have the same problem.

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Trey Shenk
Trey Shenk 2022년 12월 13일
You can find the decimation factor using the comm.FMBroadcastModulator system function "info." Here's a modified version of the Mathworks FM example, with the input truncated so that you need to adjust the length.
audio_data = audioread('guitartune.wav');
audio_fs = 44.1e3; %sampling rate of audio
fs = 240e3; % modulated output sampling rate
fmbMod = comm.FMBroadcastModulator( ...
'AudioSampleRate',audio_fs, ...
'SampleRate',fs);
% truncate audio_data so that it we need to adjust length for demo
audio_data = audio_data(1:661100);
% get the decimation factor
mod_info = fmbMod.info;
dec_factor = mod_info.AudioDecimationFactor;
% zero-pad if needed
zpad_num = dec_factor - mod(length(audio_data), dec_factor);
audio_data = padarray(audio_data, zpad_num, 'post');
% generate modulated signal
sig = fmbMod(audio_data);
% demodulate and listen to confirm settings
fmbDemod = comm.FMBroadcastDemodulator( ...
'AudioSampleRate',audio_fs, ...
'SampleRate',fs,'PlaySound',true);
fmbDemod(sig);

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