Change in osmo-trx[master]: computeCI: Document hardcoded multiplier

This is merely a historical archive of years 2008-2021, before the migration to mailman3.

A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/gerrit-log@lists.osmocom.org/.

pespin gerrit-no-reply at lists.osmocom.org
Fri Sep 3 11:52:15 UTC 2021


pespin has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-trx/+/25331 )


Change subject: computeCI: Document hardcoded multiplier
......................................................................

computeCI: Document hardcoded multiplier

Logarithm change of base rule is used. Document it so it's clear where
it comes from.

Change-Id: Ia588e8dafda4e1abe0721f12491661949339a1ba
---
M Transceiver52M/sigProcLib.cpp
1 file changed, 7 insertions(+), 1 deletion(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-trx refs/changes/31/25331/1

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));
 }
 

-- 
To view, visit https://gerrit.osmocom.org/c/osmo-trx/+/25331
To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings

Gerrit-Project: osmo-trx
Gerrit-Branch: master
Gerrit-Change-Id: Ia588e8dafda4e1abe0721f12491661949339a1ba
Gerrit-Change-Number: 25331
Gerrit-PatchSet: 1
Gerrit-Owner: pespin <pespin at sysmocom.de>
Gerrit-MessageType: newchange
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osmocom.org/pipermail/gerrit-log/attachments/20210903/c0834435/attachment.htm>


More information about the gerrit-log mailing list