Added simple_agc_cc

csdr.c

@@ -135,6 +135,7 @@ char usage[]=
 "    duplicate_samples_ntimes_u8_u8 <sample_size_bytes> <ntimes>\n"
 "    bpsk_costas_loop_cc <samples_per_bits>\n"
 "    binary_slicer_f_u8\n"
+"    simple_agc_cc <rate> [reference [max_gain]]\n"
 "    ?<search_the_function_list>\n"
 "    =<evaluate_python_expression>\n"
 "    \n"
@@ -2652,7 +2653,7 @@ int main(int argc, char *argv[])
 		float samples_per_bits;
 		if(argc<=2) return badsyntax("need required parameter (samples_per_bits)");
 		sscanf(argv[2],"%f",&samples_per_bits);
-		if(samples_per_bits<=0) badsyntax("samples_per_bits should be >= 0");
+		if(samples_per_bits<=0) badsyntax("samples_per_bits should be > 0");
 
 		bpsk_costas_loop_state_t state = init_bpsk_costas_loop_cc(samples_per_bits);
 
@@ -2669,6 +2670,36 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	if(!strcmp(argv[1],"simple_agc_cc")) //<rate> [reference [max_gain]] 
+	{
+		float rate;
+		if(argc<=2) return badsyntax("need required parameter (rate)");
+		sscanf(argv[2],"%f",&rate);
+		if(rate<=0) badsyntax("rate should be > 0");
+
+		float reference = 1.;
+		if(argc>3) sscanf(argv[3],"%f",&reference);
+		if(reference<=0) badsyntax("reference should be > 0");
+
+		float max_gain = 65535.;
+		if(argc>4) sscanf(argv[4],"%f",&max_gain);
+		if(max_gain<=0) badsyntax("max_gain should be > 0");
+
+		float current_gain = 1.;
+
+		if(!initialize_buffers()) return -2;
+		sendbufsize(the_bufsize);
+
+		for(;;)
+		{
+			FEOF_CHECK;
+			FREAD_C;
+			simple_agc_cc((complexf*)input_buffer, (complexf*)output_buffer, the_bufsize, rate, reference, max_gain, &current_gain);
+			FWRITE_C;
+			TRY_YIELD;
+		}
+	}
+
 	if(!strcmp(argv[1],"none"))
 	{
 		return 0;

libcsdr.c

@@ -1990,6 +1990,26 @@ void bpsk_costas_loop_cc(complexf* input, complexf* output, int input_size, bpsk
 	}
 }
 
+void simple_agc_cc(complexf* input, complexf* output, int input_size, float rate, float reference, float max_gain, float* current_gain)
+{
+	float rate_1minus=1-rate;
+	int debugn = 0;
+	for(int i=0;i<input_size;i++)
+	{
+		float amplitude = sqrt(input[i].i*input[i].i+input[i].q*input[i].q);
+		float ideal_gain = (reference/amplitude);
+		if(ideal_gain>max_gain) ideal_gain = max_gain;
+		if(ideal_gain<=0) ideal_gain = 0;
+		//*current_gain += (ideal_gain-(*current_gain))*rate;
+		*current_gain = (ideal_gain-(*current_gain))*rate + (*current_gain)*rate_1minus;
+		if(debugn<100) fprintf(stderr, "cgain: %g\n", *current_gain), debugn++;
+		output[i].i=(*current_gain)*input[i].i;
+		output[i].q=(*current_gain)*input[i].q;
+	}
+}
+
+
+
 
 /*
   _____        _                                            _

libcsdr.h

@@ -337,3 +337,4 @@ typedef struct bpsk_costas_loop_state_s
 
 bpsk_costas_loop_state_t init_bpsk_costas_loop_cc(float samples_per_bits);
 void bpsk_costas_loop_cc(complexf* input, complexf* output, int input_size, bpsk_costas_loop_state_t* state);
+void simple_agc_cc(complexf* input, complexf* output, int input_size, float rate, float reference, float max_gain, float* current_gain);