From: drowe67 <drowe67@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Wed, 21 Nov 2012 22:03:13 +0000 (+0000)
Subject: reversed direction of freq shifter for consistency and exposed centre freq in fdmdv... 
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=e0f9d56ea7a1c7f35039dbb19929de48ac23b296;p=freetel-svn-tracking.git

reversed direction of freq shifter for consistency and exposed centre freq in fdmdv modem header file

git-svn-id: https://svn.code.sf.net/p/freetel/code@1044 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2-dev/src/fdmdv.c b/codec2-dev/src/fdmdv.c
index b16d8018..ca60e5ba 100644
--- a/codec2-dev/src/fdmdv.c
+++ b/codec2-dev/src/fdmdv.c
@@ -178,19 +178,19 @@ struct FDMDV * CODEC2_WIN32SUPPORT fdmdv_create(void)
     /* Set up frequency of each carrier */
 
     for(c=0; c<NC/2; c++) {
-	carrier_freq = (-NC/2 + c)*FSEP + FCENTRE;
+	carrier_freq = (-NC/2 + c)*FSEP + FDMDV_FCENTRE;
 	f->freq[c].real = cos(2.0*PI*carrier_freq/FS);
  	f->freq[c].imag = sin(2.0*PI*carrier_freq/FS);
     }
 
     for(c=NC/2; c<NC; c++) {
-	carrier_freq = (-NC/2 + c + 1)*FSEP + FCENTRE;
+	carrier_freq = (-NC/2 + c + 1)*FSEP + FDMDV_FCENTRE;
 	f->freq[c].real = cos(2.0*PI*carrier_freq/FS);
  	f->freq[c].imag = sin(2.0*PI*carrier_freq/FS);
     }
 	
-    f->freq[NC].real = cos(2.0*PI*FCENTRE/FS);
-    f->freq[NC].imag = sin(2.0*PI*FCENTRE/FS);
+    f->freq[NC].real = cos(2.0*PI*FDMDV_FCENTRE/FS);
+    f->freq[NC].imag = sin(2.0*PI*FDMDV_FCENTRE/FS);
 
     /* Generate DBPSK pilot Look Up Table (LUT) */
 
@@ -724,7 +724,7 @@ void CODEC2_WIN32SUPPORT fdmdv_freq_shift(COMP rx_fdm_fcorr[], COMP rx_fdm[], fl
     foff_rect->real = cos(2.0*PI*foff/FS);
     foff_rect->imag = sin(2.0*PI*foff/FS);
     for(i=0; i<nin; i++) {
-	*foff_phase_rect = cmult(*foff_phase_rect, cconj(*foff_rect));
+	*foff_phase_rect = cmult(*foff_phase_rect, *foff_rect);
 	rx_fdm_fcorr[i] = cmult(rx_fdm[i], *foff_phase_rect);
     }
 
@@ -1226,7 +1226,7 @@ void CODEC2_WIN32SUPPORT fdmdv_demod(struct FDMDV *fdmdv, int rx_bits[],
     
     if (fdmdv->coarse_fine == COARSE)
 	fdmdv->foff = foff_coarse;
-    fdmdv_freq_shift(rx_fdm_fcorr, rx_fdm, fdmdv->foff, &fdmdv->foff_rect, &fdmdv->foff_phase_rect, *nin);
+    fdmdv_freq_shift(rx_fdm_fcorr, rx_fdm, -fdmdv->foff, &fdmdv->foff_rect, &fdmdv->foff_phase_rect, *nin);
 	
     /* baseband processing */
 
diff --git a/codec2-dev/src/fdmdv.h b/codec2-dev/src/fdmdv.h
index e19fc696..a9c768f8 100644
--- a/codec2-dev/src/fdmdv.h
+++ b/codec2-dev/src/fdmdv.h
@@ -60,6 +60,7 @@ extern "C" {
 #define FDMDV_MAX_SAMPLES_PER_FRAME  200  /* max demod samples/frame, use this to allocate storage          */
 #define FDMDV_SCALE                 1000  /* suggested scaling for 16 bit shorts                            */
 #define FDMDV_NSYM                    15
+#define FDMDV_FCENTRE               1200  /* Centre frequency, Nc/2 carriers below this, Nc/2 carriers above (Hz) */
 
 /* 8 to 48 kHz sample rate conversion */
 
diff --git a/codec2-dev/src/fdmdv_internal.h b/codec2-dev/src/fdmdv_internal.h
index 34c9ab5b..9d4e0c30 100644
--- a/codec2-dev/src/fdmdv_internal.h
+++ b/codec2-dev/src/fdmdv_internal.h
@@ -43,7 +43,7 @@
 #define FS                    8000  /* sample rate in Hz                                                    */
 #define T                 (1.0/FS)  /* sample period in seconds                                             */
 #define RS                      50  /* symbol rate in Hz                                                    */
-#define NC                      14  /* number of carriers                                                   */
+#define NC                      14  /* number of data carriers (plus one pilot in the centre)               */
 #define NB                       2  /* Bits/symbol for QPSK modulation                                      */
 #define RB              (NC*RS*NB)  /* bit rate                                                             */
 #define M                  (FS/RS)  /* oversampling factor                                                  */
@@ -51,7 +51,6 @@
 #define NFILTER            (NSYM*M) /* size of tx/rx filters at sample rate M                               */
 
 #define FSEP                    75  /* Separation between carriers (Hz)                                     */
-#define FCENTRE               1200  /* Centre frequency, Nc/2 carriers below this, Nc/2 carriers above (Hz) */
 
 #define NT                       5  /* number of symbols we estimate timing over                            */
 #define P                        4  /* oversample factor used for initial rx symbol filtering               */
@@ -69,8 +68,10 @@
 
 #define COARSE                   0
 #define FINE                     1
-#define TRACK_COEFF              0.5
 
+/* averaging filter coeffs */
+
+#define TRACK_COEFF              0.5
 #define SNR_COEFF                0.9        /* SNR est averaging filter coeff */
 
 /*---------------------------------------------------------------------------*\
diff --git a/codec2-dev/src/fifo.c b/codec2-dev/src/fifo.c
index 6ac3dbac..4d224da7 100644
--- a/codec2-dev/src/fifo.c
+++ b/codec2-dev/src/fifo.c
@@ -6,7 +6,7 @@
                                                                              
   A FIFO design useful in gluing the FDMDV modem and codec together in
   integrated applications.  The unittest/tfifo indicates these
-  routines are thread safe without the need for syncronisisation
+  routines are thread safe without the need for syncronisation
   object, e.g. a different thread can read and write to a fifo at the
   same time.