ASCEE/lasp
ASCEE/lasp
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Negative time constant for single pole lowpass filter means no time-weighting at all.

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This commit is contained in:
Anne de Jong 2020-01-21 21:06:17 +01:00
parent 29dc70fad3
commit bd88882f25
1 changed files with 159 additions and 136 deletions
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53
lasp/c/lasp_slm.c
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@ -20,10 +20,7 @@ Slm *Slm_create(Sosfilterbank *prefilter, Sosfilterbank *bandpass, const d fs,
assertvalidptr(downsampling_fac);
Slm *slm = NULL;
if (tau <= 0) {
WARN("Invalid time constant");
return NULL;
} else if (ref_level <= 0) {
if (ref_level <= 0) {
WARN("Invalid reference level");
return NULL;
} else if (fs <= 0) {
@ -41,10 +38,15 @@ Slm *Slm_create(Sosfilterbank *prefilter, Sosfilterbank *bandpass, const d fs,
/// documentation for the computation of its minus 20 dB point. We set the
/// reduction in its 'sampling frequency' such that its noise is at a level
/// of 20 dB less than its 'signal'.
if (tau > 0) {
const d fs_slm = 1 / (2 * number_pi * tau) * (1 - 0.01) / 0.01;
slm->downsampling_fac = (us)(fs / fs_slm);
slm->cur_offset = 0;
*downsampling_fac = slm->downsampling_fac;
} else {
*downsampling_fac = 1;
slm->downsampling_fac = 1;
}
/// Create the single pole lowpass
us filterbank_size;
@ -54,6 +56,8 @@ Slm *Slm_create(Sosfilterbank *prefilter, Sosfilterbank *bandpass, const d fs,
filterbank_size = 1;
}
if (tau > 0) {
vd lowpass_sos = vd_alloc(6);
d b0 = 1.0 / (1 + 2 * tau * fs);
*getvdval(&lowpass_sos, 0) = b0;
@ -70,6 +74,10 @@ Slm *Slm_create(Sosfilterbank *prefilter, Sosfilterbank *bandpass, const d fs,
Sosfilterbank_setFilter(slm->splowpass[ch], 0, lowpass_sos);
}
vd_free(&lowpass_sos);
} else {
/// No low-pass filtering. Tau set to zero
slm->splowpass = NULL;
}
feTRACE(15);
return slm;
@ -106,19 +114,26 @@ dmat Slm_run(Slm *slm, vd *input_data) {
iVARTRACE(15, samples_bandpassed);
us cur_offset = slm->cur_offset;
/// Compute the number of samples output
int nsamples_output = (samples_bandpassed - cur_offset) / downsampling_fac;
while(nsamples_output*downsampling_fac + cur_offset < samples_bandpassed)
while (nsamples_output * downsampling_fac + cur_offset < samples_bandpassed)
nsamples_output++;
if(nsamples_output < 0) nsamples_output = 0;
if (nsamples_output < 0)
nsamples_output = 0;
iVARTRACE(15, nsamples_output);
iVARTRACE(15, cur_offset);
dmat levels = dmat_alloc(nsamples_output, filterbank_size);
dmat levels;
if (slm->splowpass) {
levels = dmat_alloc(nsamples_output, filterbank_size);
} else {
levels = dmat_alloc(samples_bandpassed, filterbank_size);
}
for (us ch = 0; ch < bandpassed.n_cols; ch++) {
iVARTRACE(15, ch);
cur_offset = slm->cur_offset;
vd chan = dmat_column(&bandpassed, ch);
/// Inplace squaring of the signal
for (us sample = 0; sample < bandpassed.n_rows; sample++) {
tmp = getdmatval(&bandpassed, sample, ch);
@ -127,7 +142,8 @@ dmat Slm_run(Slm *slm, vd *input_data) {
// Now that all data for the channel is squared, we can run it through
// the low-pass filter
vd chan = dmat_column(&bandpassed, ch);
if (slm->splowpass) {
cur_offset = slm->cur_offset;
/// Apply single-pole lowpass filter for current filterbank channel
vd power_filtered = Sosfilterbank_filter(slm->splowpass[ch], &chan);
@ -135,25 +151,32 @@ dmat Slm_run(Slm *slm, vd *input_data) {
/// Output resulting levels at a lower interval
us i = 0;
d level;
while (cur_offset < samples_bandpassed) {
iVARTRACE(10, i);
iVARTRACE(10, cur_offset);
level = 10 * d_log10(*getvdval(&power_filtered, cur_offset) / ref_level /
ref_level);
/// Compute level
d level = 10 * d_log10(*getvdval(&power_filtered, cur_offset) /
ref_level / ref_level);
*getdmatval(&levels, i++, ch) = level;
cur_offset = cur_offset + downsampling_fac;
}
iVARTRACE(15, cur_offset);
iVARTRACE(15, i);
dbgassert(i == nsamples_output, "BUG");
dbgassert(i == (int) nsamples_output, "BUG");
vd_free(&chan);
vd_free(&power_filtered);
}
}
slm->cur_offset = cur_offset - samples_bandpassed;
if (!slm->splowpass) {
/// Raw copy of to levels. Happens only when the low-pass filter does not
/// have to come into action.
dmat_copy(&levels, &bandpassed);
}
vd_free(&prefiltered);
dmat_free(&bandpassed);
feTRACE(15);
@ -166,7 +189,6 @@ void Slm_free(Slm *slm) {
if (slm->prefilter) {
Sosfilterbank_free(slm->prefilter);
}
assertvalidptr(slm->splowpass);
us filterbank_size;
if (slm->bandpass) {
@ -175,11 +197,12 @@ void Slm_free(Slm *slm) {
} else {
filterbank_size = 1;
}
if (slm->splowpass) {
for (us ch = 0; ch < filterbank_size; ch++) {
Sosfilterbank_free(slm->splowpass[ch]);
}
a_free(slm->splowpass);
}
a_free(slm);
feTRACE(15);