From 80526be3ed44f458403b1acfc57245976398918d Mon Sep 17 00:00:00 2001
From: lwvmobile <59371473+lwvmobile@users.noreply.github.com>
Date: Tue, 15 Feb 2022 11:00:03 -0500
Subject: [PATCH] NXDN48/96 Modulation Fix

Change NXDN to C4FM Modulation and change RF_mod type.
Not sure if it actually affects performance, but its the correct type.
Decoding relies more on samplesPerSymbol than anything.
---
 src/dsd_main.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/dsd_main.c b/src/dsd_main.c
index f81c6b1..cfd5941 100644
--- a/src/dsd_main.c
+++ b/src/dsd_main.c
@@ -786,8 +786,8 @@ main (int argc, char **argv)
               opts.frame_dstar = 1;
               opts.frame_x2tdma = 1;
               opts.frame_p25p1 = 1;
-              opts.frame_nxdn48 = 0;
-              opts.frame_nxdn96 = 0;
+              opts.frame_nxdn48 = 0; //turn it on, doesn't work due to symbol rate difference
+              opts.frame_nxdn96 = 0; //causes false positives, leave on 0 
               opts.frame_dmr = 1;
               opts.frame_provoice = 0; //turn it on, doesn't work due to symbol rate difference
             }
@@ -852,14 +852,16 @@ main (int argc, char **argv)
               opts.frame_nxdn96 = 0;
               opts.frame_dmr = 0;
               opts.frame_provoice = 0;
+              //I think I've got it to decode on proper modulation now c4fm, not really sure what the difference is in DSD, seems to work either way for some reason
               state.samplesPerSymbol = 20;
               state.symbolCenter = 10;
-              opts.mod_c4fm = 0;
+              opts.mod_c4fm = 1; // was 0
               opts.mod_qpsk = 0;
-              opts.mod_gfsk = 1; //was 1 with others on zero
-              state.rf_mod = 2; //was 2
+              opts.mod_gfsk = 0; //was 1 with others on zero
+              state.rf_mod = 0; //was 2
               //opts.symboltiming = 2400; //NXDN48 uses 2400 symbol rate
               fprintf (stderr,"Setting symbol rate to 2400 / second\n");
+              fprintf (stderr,"Enabling only C4FM modulation optimizations.\n");
               fprintf (stderr,"Decoding only NXDN 4800 baud frames.\n");
             }
           else if (optarg[0] == 'n')
@@ -871,11 +873,12 @@ main (int argc, char **argv)
               opts.frame_nxdn96 = 1;
               opts.frame_dmr = 0;
               opts.frame_provoice = 0;
-              opts.mod_c4fm = 0;
+              opts.mod_c4fm = 1; //was 0
               opts.mod_qpsk = 0;
-              opts.mod_gfsk = 1;
-              state.rf_mod = 2;
-              fprintf (stderr,"Enabling only GFSK modulation optimizations.\n");
+              opts.mod_gfsk = 0; //was 1
+              state.rf_mod = 0; //was 2
+              //fprintf (stderr,"Enabling only GFSK modulation optimizations.\n");
+              fprintf (stderr,"Enabling only C4FM modulation optimizations.\n");
               fprintf (stderr,"Decoding only NXDN 9600 baud frames.\n");
             }
           else if (optarg[0] == 'r')