transceiver: Properly handle MAXDLY.

Previously MAXDLY value was applied to Normal Bursts, which was nice
when working with sloppy test equipment like CMD57, but useless for
real world usage. At the same time documentation and de facto usage
of MAXDLY in OsmoBTS and OpenBTS assumed that it actually applies to
Access Bursts (RACH). So this patch changes osmo-rx behavior to apply
MAXDLY to RACH bursts and introduces a new command MAXDLYNB for the
old behavior.

1 files changed, 5 insertions, 4 deletions

diff --git a/Transceiver52M/sigProcLib.cpp b/Transceiver52M/sigProcLib.cpp
index f3fa4f0..9674aa8 100644
--- a/Transceiver52M/sigProcLib.cpp
+++ b/Transceiver52M/sigProcLib.cpp
@@ -1816,21 +1816,22 @@ int detectGeneralBurst(signalVector &rxBurst,
  *
  * Correlation window parameters:
  *   target: Tail bits + RACH length (reduced from 41 to a multiple of 4)
- *   head: Search 4 symbols before target 
- *   tail: Search 10 symbols after target
+ *   head: Search 4 symbols before target
+ *   tail: Search 4 symbols + maximum expected delay
  */
 int detectRACHBurst(signalVector &rxBurst,
             float thresh,
             int sps,
             complex &amp,
-            float &toa)
+            float &toa,
+            unsigned maxTOA)
 {
   int rc, target, head, tail;
   CorrelationSequence *sync;
 
   target = 8 + 40;
   head = 4;
-  tail = 10;
+  tail = 4 + maxTOA;
   sync = gRACHSequence;
 
   rc = detectGeneralBurst(rxBurst, thresh, sps, amp, toa,