From 6c50362ccc7e0eaa617bab5b97fadca937791c67 Mon Sep 17 00:00:00 2001 From: Steven Franke Date: Sun, 5 Jun 2016 17:21:19 +0000 Subject: [PATCH] Tweak coarse frequency acquisition. git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6731 ab8295b8-cf94-4d9e-aec4-7959e3be5d79 --- lib/syncmsk144.f90 | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/lib/syncmsk144.f90 b/lib/syncmsk144.f90 index 9a8ddf58d..bbe1a91cb 100644 --- a/lib/syncmsk144.f90 +++ b/lib/syncmsk144.f90 @@ -73,7 +73,7 @@ subroutine syncmsk144(cdat,npts,msgreceived,fest) ! Coarse carrier frequency sync ! look for tones near 2k and 4k in the (analytic signal)**2 spectrum -! search range for coarse frequency error is +/- 200 Hz +! search range for coarse frequency error is +/- 100 Hz fs=12000.0 nfft=6000 !using a zero-padded fft to get 2 Hz bins df=fs/nfft @@ -97,17 +97,25 @@ subroutine syncmsk144(cdat,npts,msgreceived,fest) iloc=maxloc(tonespec,ismask) ilpk=iloc(1) al=tonespec(ilpk) - if( ah .ge. al ) then - ferr=(ihpk-2001)*df/2.0 - tot=sum(tonespec(1901:2101)) - q1=200*ah/(tot-tonespec(ihpk)) - else - ferr=(ilpk-1001)*df/2.0 - tot=sum(tonespec(901:1101)) - q1=200*al/(tot-tonespec(ilpk)) - endif fdiff=(ihpk-ilpk)*df - + ferrh=(ihpk-2001)*df/2.0 + ferrl=(ilpk-1001)*df/2.0 + if( abs(fdiff-2000) .le. 8.0 ) then ! we are pretty sure we've got the right peaks + if( ah .ge. al ) then + ferr=ferrh + else + ferr=ferrl + endif + else +! if fdiff is not 2000, then carrier acquisition is on shaky ground +! in this case, ignore amplitude and pick the peak that has the smallest ferr + if( abs(ihpk-2001) .le. abs(ilpk-1001) ) then + ferr=ferrh + else + ferr=ferrl + endif + endif + ! remove coarse freq error - should now be within a few Hz call tweak1(cdat,npts,-(1500+ferr),cdat)