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Diffstat (limited to 'util/spkmodem_decode/spkmodem-decode.c')
-rw-r--r--util/spkmodem_decode/spkmodem-decode.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/util/spkmodem_decode/spkmodem-decode.c b/util/spkmodem_decode/spkmodem-decode.c
index af60f997..a1a197bc 100644
--- a/util/spkmodem_decode/spkmodem-decode.c
+++ b/util/spkmodem_decode/spkmodem-decode.c
@@ -571,6 +571,14 @@ detect_tone(struct decoder_state *st)
if (st->learn_frames != LEARN_FRAMES)
return;
+ /*
+ * If the observed frequencies are too close,
+ * learning likely failed (only one tone seen).
+ * Keep the default threshold.
+ */
+ if (st->freq_max - st->freq_min < 2)
+ return;
+
st->freq_threshold =
(st->freq_min + st->freq_max) / 2;