Changeset 5465

Timestamp:

10/21/07 14:40:20 (6 years ago)

Author:

jgaeddert

Message:

adding frequency estimation to beginning of frame header; works over-the-air

Location:

experimental/components/SymbolSyncPoly/branches/SymbolSyncPoly-metadata/src

Files:

• FrameSynchronizer.cpp (modified) (2 diffs)
• FrameSynchronizerDSP.cpp (modified) (5 diffs)
• FrameSynchronizerDSP.h (modified) (3 diffs)
• MultirateSynchronizerDSP.cpp (modified) (1 diff)

experimental/components/SymbolSyncPoly/branches/SymbolSyncPoly-metadata/src/FrameSynchronizer.cpp

@@ -294 +294 @@
 
 #if 0
+        N_out = buf_len;
         // Main signal processing algorithm
         DEBUG(7, FrameSynchronizer, "Attempting to synchronize and decimate...")
@@ -299 +300 @@
             I_in, Q_in, N_in,
             I_out, Q_out, N_out);
-#endif
+        num_written = N_out;
+#endif
+#if 1
         DEBUG(7, FrameSynchronizer, "trying to find header...");
         FindFrameHeader(
             I_in, Q_in, N_in, num_read,
             I_out, Q_out, buf_len, num_written);
-        //printf("fs cv = %f\n", cv/(2*PI));
+        printf("fs cv = %f\n", cv/(2*PI));
+        //printf("fs q_hat_c = %f\n", q_hat_c);
+#endif
 
         DEBUG(7, FrameSynchronizer, "Emptying port buffer...")

experimental/components/SymbolSyncPoly/branches/SymbolSyncPoly-metadata/src/FrameSynchronizerDSP.cpp

@@ -53 +53 @@
     UpdateCostasLoopFilterCoefficients(0.02f);
 
+    e_i = 0;
+    e_q = Ac;
+    lock_zeta = 0.02;
+    header_phase_locked = false;
+    header_phase_lock_delay = 64;
+    header_phase_lock_delay_counter = 0;
+
 #ifdef FS_LOGGING
     input_log.open("framesync_input_log.dat");
@@ -68 +75 @@
 }
 
-// Find frame header
+// Find frame header using Costas loop
+bool FrameSynchronizerDSP::FindFrameHeaderCostasLoop(
+    short * I_in,
+    short * Q_in,
+    unsigned int input_length,
+    unsigned int &num_read,
+    short * I_out,
+    short * Q_out,
+    unsigned int output_length,
+    unsigned int &num_written)
+{
+    alpha_s = 0.027f;
+    beta_s = 1.02f;
+
+    int i(0);
+    short I, Q;
+    num_read = 0;
+    num_written = 0;
+    //printf("nco CV = %f\n", cv/(2*PI));
+
+    while ( i < (signed int) input_length ) {
+        v++;
+
+        // apply nco to input sample
+        ApplyNCO(I_in[i], Q_in[i], I, Q);
+        //I = I_in[i];
+        //Q = Q_in[i];
+        i++;
+
+        // push samples into buffer
+        PushInput(I, Q);
+
+        // compute filtered outputs (stored in mf_i, mf_q)
+        ComputeFilterBankOutputs();
+        
+        // compute costas loop phase error on matched-filter outputs
+        ///\todo matched filter output won't work because of delay
+        pd2_cl = GenerateCostasLoopPhaseError(I, Q);
+        //pd2_cl = GenerateCostasLoopPhaseError(mf_i, mf_q);
+        pd2_cl /= Ac;
+        
+        // advance costas loop filter
+        AdvanceCostasLoopFilter();
+
+        // update nco
+        UpdateNCO();
+            //I_out[num_written] = mf_i;
+            //Q_out[num_written] = mf_q;
+            //num_written++;
+
+        // decimate
+        if ( v >= (signed int) k ) {
+            // enable output
+            v -= k;
+            I_out[num_written] = mf_i;
+            Q_out[num_written] = mf_q;
+            num_written++;
+            //printf("I = %d, Q = %d\n", mf_i, mf_q);
+
+            // generate timing error
+            GenerateTimingError();
+
+            // advance timing loop filter
+            AdvanceTimingLoopFilter();
+
+            // compute filter bank index
+            ComputeFilterBankIndex();
+
+            // update v
+            switch (lc) {
+            case SHIFT:
+                // normal operation; do nothing
+                break;
+            case SKIP:
+                v--;
+                //printf("skip\n");
+                lc = SHIFT;
+                break;
+            case STUFF:
+                v++;
+                //printf("stuff\n");
+                lc = SHIFT;
+                break;
+            default:;
+            }
+
+            // push sample into buffer
+            inputBuffer.Push(mf_i);
+            r = CorrelateSequence( pnFrameSyncCode, 255 );
+
+            if ( abs(r) > int( Ac/2 ) ) {
+                r_frame_sync = abs(r);
+                std::cout << "PN FRAME SYNC CODE FOUND!!!" << std::endl;
+                std::cout << "  r = " << r_frame_sync << std::endl;
+
+                // check for phase inversion; if so inject pi radians into NCO
+                // [not sure how well this will work with band-limited pulse shapes]
+                if ( r<0 ) {
+                    std::cout << "  [Frame sync found negative PN code]" << std::endl;
+                    nco_control += PI;
+                }
+
+                operationalMode = EXTRACT_CONTROL_CODES;
+                inputBuffer.Release();
+                numControlCodesReceived = 0;
+
+                //num_read = i+1;
+                //return true;
+
+                // reduce bandwidth of loop filters for steady tracking mode
+                //UpdatePhaseLoopFilterCoefficients(0.0025f);
+                //UpdateTimingLoopFilterCoefficients(ALPHA_T_LO, BETA_T_LO);
+
+            }
+
+        }
+    }
+    
+    num_read = input_length;
+    return false;
+}
+
+// Extract frame header
+bool FrameSynchronizerDSP::ExtractFrameHeader(
+    short * I_in,
+    short * Q_in,
+    unsigned int input_length,
+    unsigned int &num_read,
+    short * I_out,
+    short * Q_out,
+    unsigned int output_length,
+    unsigned int &num_written)
+{
+    //unsigned int i;
+    //short I, Q;
+    //num_read = 0;
+    //num_written = 0;
+    return false;
+}
+
+
+// Find frame header using conventional method
 bool FrameSynchronizerDSP::FindFrameHeader(
     short * I_in,
@@ -79 +227 @@
     unsigned int &num_written)
 {
-    alpha_s = 0.027f;
-    beta_s = 1.02f;
-
-    int i(0);
-    short I, Q;
+    unsigned int i(0);
     num_read = 0;
     num_written = 0;
-    //printf("nco CV = %f\n", cv/(2*PI));
-
-    while ( i < (signed int) input_length ) {
+    alpha_c = 0.04f;
+    beta_c = 0.0028284f;
+
+    while ( i<input_length ) {
+        // Increment sample counter for output enable
         v++;
 
-        // apply nco to input sample
-        ApplyNCO(I_in[i], Q_in[i], I, Q);
-        //I = I_in[i];
-        //Q = Q_in[i];
-        i++;
-
-        // push samples into buffer
-        PushInput(I, Q);
-
-        // compute filtered outputs (stored in mf_i, mf_q)
-        ComputeFilterBankOutputs();
-        
-        // compute costas loop phase error on matched-filter outputs
-        ///\todo matched filter output won't work because of delay
-        //pd2_cl = GenerateCostasLoopPhaseError(I, Q);
-        pd2_cl = GenerateCostasLoopPhaseError(mf_i, mf_q);
-        pd2_cl /= Ac;
-        
-        // advance costas loop filter
-        AdvanceCostasLoopFilter();
-
-        // update nco
-        UpdateNCO();
-            //I_out[num_written] = mf_i;
-            //Q_out[num_written] = mf_q;
-            //num_written++;
-
-        // decimate
+        PushInputs( I_in, Q_in, i, input_length );
+
         if ( v >= (signed int) k ) {
-            // enable output
+            // Enable output
             v -= k;
+
+            // Decimate values; compute filter outputs mf_i, mf_q, dmf_i, dmf_q
+            ComputeFilterBankOutputs();
+
             I_out[num_written] = mf_i;
             Q_out[num_written] = mf_q;
             num_written++;
-            //printf("I = %d, Q = %d\n", mf_i, mf_q);
-
-            // generate timing error
-            GenerateTimingError();
-
-            // advance timing loop filter
-            AdvanceTimingLoopFilter();
-
-            // compute filter bank index
-            ComputeFilterBankIndex();
-
-            // update v
-            switch (lc) {
-            case SHIFT:
-                // normal operation; do nothing
-                break;
-            case SKIP:
-                v--;
-                //printf("skip\n");
-                lc = SHIFT;
-                break;
-            case STUFF:
-                v++;
-                //printf("stuff\n");
-                lc = SHIFT;
-                break;
-            default:;
-            }
-
-            // push sample into buffer
+
+            // push sample into buffer and correlate with frame sync code
             inputBuffer.Push(mf_i);
             r = CorrelateSequence( pnFrameSyncCode, 255 );
@@ -183 +279 @@
             }
 
+            // generate timing error
+            GenerateTimingError();
+
+            // advance timing loop filter
+            AdvanceTimingLoopFilter();
+
+            // compute filter bank index
+            ComputeFilterBankIndex();
+
+
+            // Update lock detection
+            e_i = lock_zeta*(float)(abs(mf_i)) + (1-lock_zeta)*e_i;
+            e_q = lock_zeta*(float)(abs(mf_q)) + (1-lock_zeta)*e_q;
+            header_phase_lock_delay_counter++;
+            lock_detect = e_i/e_q;
+            if ( header_phase_lock_delay_counter == header_phase_lock_delay &&
+                 lock_detect < 1.25f ) {
+                header_phase_lock_delay_counter = 0;
+                lock_detect = e_i/e_q;
+                printf("  lock_detect = %f\n", lock_detect);
+                //if ( lock_detect < 1.25 ) {
+                    unsigned int N_est = (input_length < 256) ? input_length : 256;
+                    wcTs = 2*PI*EstimateCarrierOffset(I_in, Q_in, N_est, false);
+                    printf("  estimate: %f\n", wcTs/(2*PI));
+                    cv = 0;
+                    nco_control = 0;
+                    q_c = 0;
+                    q_hat_c = 0;
+                    buff2_c = 0;
+                    q_prime_c = 0;
+                //}
+            } else {
+                // Calculate phase error
+
+                q_c = GeneratePhaseError( mf_i, mf_q );
+                q_c /= Ac;
+            }
+
+            AdvancePhaseLoopFilter();
+
         }
+        UpdateNCO();
+
     }
-    
+
     num_read = input_length;
     return false;
 }
 
-// Find frame header
-bool FrameSynchronizerDSP::ExtractFrameHeader(
-    short * I_in,
-    short * Q_in,
-    unsigned int input_length,
-    unsigned int &num_read,
-    short * I_out,
-    short * Q_out,
-    unsigned int output_length,
-    unsigned int &num_written)
-{
-    unsigned int i;
-    short I, Q;
-    num_read = 0;
-    num_written = 0;
-    return false;
-}
+
 
 // Main signal processing loop
@@ -392 +514 @@
             AdvancePhaseLoopFilter();
 
-            UpdateNCO();
-
         }
 
+        UpdateNCO();
+
     } // while
+
 }
 

experimental/components/SymbolSyncPoly/branches/SymbolSyncPoly-metadata/src/FrameSynchronizerDSP.h

@@ -54 +54 @@
 
     /// \brief Uses a CostasLoop to lock to the carrier, correlates with P/N sequence
+    bool FindFrameHeaderCostasLoop(
+        short * I_in,
+        short * Q_in,
+        unsigned int input_length,
+        unsigned int &num_read,
+        short * I_out,
+        short * Q_out,
+        unsigned int output_length,
+        unsigned int &num_written);
+
     bool FindFrameHeader(
         short * I_in,
@@ -133 +143 @@
     unsigned int r_frame_sync;
 
+    // Phase lock detect variables
+    float e_i;
+    float e_q;
+    float lock_zeta;
+    float lock_detect;
+    bool header_phase_locked;
+    unsigned int header_phase_lock_delay;
+    unsigned int header_phase_lock_delay_counter;
+
     // Costas loop methods
 
@@ -147 +166 @@
 
         ///\todo this is necessary because of the delay introduced by the filter
-        beta_cl /= 30.0f;
+        //beta_cl /= 30.0f;
     };
 

experimental/components/SymbolSyncPoly/branches/SymbolSyncPoly-metadata/src/MultirateSynchronizerDSP.cpp

@@ -243 +243 @@
 
 void MultirateSynchronizerDSP::UpdateNCO() {
-    cv = wcTs + q_hat_c;
+    cv = wcTs + q_hat_c/k;
 
     cv = ( cv >  PI/50 ) ?  PI/50 : cv;