BAD REFERENCE SIGNALS ERROR IN TDOA
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WARNING: BAD REFERENCE SIGNALS: ref delays differ by more than 2 samples!
taking ref with higher reliability, i.e. ref check (reliability: 0.00017386(ref) < 0.0054402(ref check)
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Walter Roberson
on 20 Apr 2021
What code are you using? https://www.mathworks.com/help/lte/ug/time-difference-of-arrival-positioning-using-prs.html ?
Answers (1)
Walter Roberson
on 21 Apr 2021
It looks like you are using a system that has three signals total, two of which are intended to be the same reference signal, and the third is probably the signal whose distance is to be judged. But the correlation between the two reference signals is more than 2 samples. If your sampling frequency is 22100 Hz, that would correspond to 1/11050 seconds; at 343 meters per second in air, that would be
format long g
Fs = 22100; %samples/second
SoS = 343; %m/s
Nsamp = 2; %samples
distance_m = Nsamp / Fs * SoS
distance_cm = distance_m * 100
But if your sampling frequency is 8000:
Fs = 8000; %samples/second
SoS = 343; %m/s
Nsamp = 2; %samples
distance_m = Nsamp / Fs * SoS
distance_cm = distance_m * 100
I would guess that you are intended to place your microphone at the same distance relative to two speakers that are emitting the same sound, in order to calibrate, but that you have not done that placement accurately enough.
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