From: baobrien <baobrien@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Thu, 7 Sep 2017 03:32:15 +0000 (+0000)
Subject: Began sketching out TDMA pilot RX path
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=ad6cabc77ad95250dc9bda49abf0dbea6cbb8d74;p=freetel-svn-tracking.git

Began sketching out TDMA pilot RX path


git-svn-id: https://svn.code.sf.net/p/freetel/code@3360 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2-dev/src/tdma.c b/codec2-dev/src/tdma.c
index 2dd625db..6674e662 100644
--- a/codec2-dev/src/tdma.c
+++ b/codec2-dev/src/tdma.c
@@ -101,6 +101,50 @@ u32 tdma_get_N(struct TDMA_MODEM * tdma){
     return slot_size * (Fs/Rs);
 }
 
-void tdma_rx(struct TDMA_MODEM * tdma, COMP * samps){
+void tdma_rx_no_sync(struct TDMA_MODEM * tdma, COMP * samps, u64 timestamp){
+    mode = tdma->settings;
+    u32 Rs = mode.sym_rate;
+    u32 Fs = mode.samp_rate;
+    u32 slot_size = mode.slot_size;
+    //u32 frame_size = mode.frame_size;
+    u32 n_slots = mode.n_slots;
+    u32 M = mode.fsk_m;
+    u32 Ts = Fs/Rs;
+    u32 bits_per_sym = M==2?1:2;
+
+    //Number of bits per pilot modem chunk (half a slot)
+    u32 n_pilot_bits = (slot_size/2)*bits_per_sym;
+    //We look at a full slot for the UW
+    u8 pilot_bits[n_pilot_bits*2];
+
+    /*
+    Pseudocode:
+        copy into samp buffer (? may want to let the downstream stuff do this; We may not even really need a local samp buffer)
+        demod a half slot
+        look for UW in slot-wide bit buffer
+        if UW found
+          change to pilot sync state
+          set slot offset to match where a frame should be
+          go to slot_sync_rx to try and decode found frame
+        else  
+          set up for next half slot, repeat        
+   */
+}
 
+void tdma_rx(struct TDMA_MODEM * tdma, COMP * samps,u64 timestamp){
+
+    /* Staate machine for TDMA modem */
+    switch(tdma->state){
+        no_sync:
+            tdma_rx_no_sync(tdma,samps,timestamp);
+            break;
+        pilot_sync:
+            break;
+        slot_sync;
+            break;
+        master_sync:
+            break;
+        default:
+            break;
+    }
 }
\ No newline at end of file
diff --git a/codec2-dev/src/tdma.h b/codec2-dev/src/tdma.h
index 1357555b..7e473b9c 100644
--- a/codec2-dev/src/tdma.h
+++ b/codec2-dev/src/tdma.h
@@ -36,8 +36,9 @@
 
 /* TODO: Replace these types with their full names */
 /* I'm just feeling lazy right now */
+typedef uint64_t u64;
 typedef uint32_t u32;
-typedef  int32_t i32;
+typedef int32_t  i32;
 typedef uint8_t  u8;
 typedef float    f32;