diff options
| author | Sylvain Munaut <tnt@246tNt.com> | 2011-10-16 17:07:38 +0200 |
|---|---|---|
| committer | Sylvain Munaut <tnt@246tNt.com> | 2011-10-16 17:07:38 +0200 |
| commit | 02b2575adc2bcbab135d9e9b924d0136dc31dcff (patch) | |
| tree | eba0a6ece21830e87ae97a4d4b02658eaf5baaa8 /src/sdr | |
| parent | b6fc11d17c4624d875b9c5b87799910f66a9c7a5 (diff) | |
sdr/fcch: Add safety to FCCH multi rough detection for period discovery
We try to find the periodicity, but in some case, for some signals
this can fail and we need to ensure Lp is valid and within bounds
since it's used as offset.
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Diffstat (limited to 'src/sdr')
| -rw-r--r-- | src/sdr/fcch.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/src/sdr/fcch.c b/src/sdr/fcch.c index 9f49f47..5ce6553 100644 --- a/src/sdr/fcch.c +++ b/src/sdr/fcch.c @@ -285,7 +285,7 @@ gmr1_fcch_rough_multi(struct osmo_cxvec *search_win_in, int sps, float freq_shif struct osmo_cxvec *corr = NULL; float *corr_pwr = NULL; float pwr_max, pwrs[2], peaks[2], avg, stddev, th, peaks_pwr[N]; - int Lw, Lp, i, pwr_max_idx, a, peaks_cnt; + int Lw, Lp, nLp, i, pwr_max_idx, a, peaks_cnt; int rv; /* Safety : need 650 ms of signal */ @@ -314,7 +314,9 @@ gmr1_fcch_rough_multi(struct osmo_cxvec *search_win_in, int sps, float freq_shif goto err; } - Lw = (330 * GMR1_SYM_RATE) / 1000; /* Len window */ + Lw = (320 * GMR1_SYM_RATE) / 1000; /* Len window */ + Lw += GMR1_FCCH_SYMS; + Lp = (320 * GMR1_SYM_RATE) / 1000; /* Len period */ pwr_max_idx = 0; @@ -354,7 +356,15 @@ gmr1_fcch_rough_multi(struct osmo_cxvec *search_win_in, int sps, float freq_shif peaks[0] /= pwrs[0]; peaks[1] /= pwrs[1]; - Lp = (int)round(peaks[1] - peaks[0]); + nLp = (int)round(peaks[1] - peaks[0]); + + /* Safety */ + if (abs(nLp - Lp) > 10) { + rv = -EINVAL; + goto err; + } + + Lp = nLp; /* 'Mix' the two cycles to improve signal. Compute avg at the same time */ avg = 0.0f; |