computeCI: Document hardcoded multiplier
Logarithm change of base rule is used. Document it so it's clear where
it comes from.
Change-Id: Ia588e8dafda4e1abe0721f12491661949339a1ba
diff --git a/Transceiver52M/sigProcLib.cpp b/Transceiver52M/sigProcLib.cpp
index 21978ff..df87f94 100644
--- a/Transceiver52M/sigProcLib.cpp
+++ b/Transceiver52M/sigProcLib.cpp
@@ -1478,7 +1478,13 @@
/* Esimate Carrier power */
C = xcorr.norm2() / ((N - 1) * sync->gain.abs());
- /* Interference = Signal - Carrier, so C/I = C / (S - C) */
+ /* Interference = Signal - Carrier, so C/I = C / (S - C).
+ * Calculated in dB:
+ * C/I_dB = 10 * log10(C/I)
+ * C/I_dB = 10 * (1/log2(10)) * log2(C/I)
+ * C/I_dB = 10 * 0.30103 * log2(C/I)
+ * C/I_dB = 3.0103 * log2(C/I)
+ */
return 3.0103f * log2f(C / (S - C));
}