test-case: check-alsabat.sh: Lower the threshold for detecting tones

The default parameter sigma k is 3.0 when omitted from command line.
This patch drops the threshold to half with 1.5 to better detect
distortion in playback. Alsabat judges spectral components above the
threshold as sine frequencies.

This change should increase the probability fail a test to avoid
green failures to happen.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

Author: singalsu

test-case/check-alsabat.sh

@@ -36,6 +36,9 @@ OPT_HAS_ARG['c']=1             OPT_VAL['c']=''
 OPT_NAME['f']='frequency'       OPT_DESC['f']='target frequency'
 OPT_HAS_ARG['f']=1             OPT_VAL['f']=821
 
+OPT_NAME['k']='sigmak'		OPT_DESC['k']='sigma k value'
+OPT_HAS_ARG['k']=1             OPT_VAL['k']=1.5
+
 OPT_NAME['n']='frames'          OPT_DESC['n']='test frames'
 OPT_HAS_ARG['n']=1             OPT_VAL['n']=240000
 
@@ -50,6 +53,7 @@ pcm_c=${OPT_VAL['c']}
 rate=${OPT_VAL['r']}
 channel_c=${OPT_VAL['C']}
 frequency=${OPT_VAL['f']}
+sigmak=${OPT_VAL['k']}
 frames=${OPT_VAL['n']}
 
 if [ "$pcm_p" = "" ]||[ "$pcm_c" = "" ];
@@ -91,16 +95,16 @@ arecord -Dplug$pcm_c -d 1 /dev/null -q || die "Failed to capture on PCM: $pcm_c"
 
 # alsabat test
 # hardcode the channel number of playback to 2, as sof doesnot support mono wav.
-dlogc "alsabat -P$pcm_p --standalone -n $frames -r $rate -c 2 -F $frequency"
-alsabat -P$pcm_p --standalone -n $frames -c 2 -r $rate -F $frequency & playPID=$!
+dlogc "alsabat -P$pcm_p --standalone -n $frames -r $rate -c 2 -F $frequency -k $sigmak"
+alsabat -P$pcm_p --standalone -n $frames -c 2 -r $rate -F $frequency -k $sigmak & playPID=$!
 
 # playback may have low latency, add one second delay to aviod recording zero at beginning.
 sleep 1
 
 # We use different USB sound cards in CI, part of them only support 1 channel for capture,
 # so make the channel as an option and config it in alsabat-playback.csv
-dlogc "alsabat -C$pcm_c -c $channel_c -r $rate -F $frequency"
-alsabat -C$pcm_c -c $channel_c -r $rate -F $frequency || {
+dlogc "alsabat -C$pcm_c -c $channel_c -r $rate -F $frequency -k $sigmak"
+alsabat -C$pcm_c -c $channel_c -r $rate -F $frequency -k $sigmak || {
         # upload failed wav file
         __upload_wav_file
         # dump amixer contents for more debugging