RTL: Add input gain adjustments during ncurses session using g/G and update example usage (credit: ki4hyf);

Group trunking shortcut key changed from g to T;

examples/Example_Usage.md

@@ -190,7 +190,7 @@ y - toggle scanner (needs either rtl input, or rigctl connection)
 1 - Toggle Voice Synthesis in TDMA Slot 1 or FDMA Conventional Voice
 2 - Toggle Voice Synthesis in TDMA Slot 2
 w - Toggle Trunking/Playback White List (Allow A Groups Only) / Black List (Block B or DE groups only) Mode
-g - Toggle Trunking Tuning to Group Calls (DMR T3, Con+, Cap+, P25, NXDN)
+T - Toggle Trunking Tuning to Group Calls (DMR T3, Con+, Cap+, P25, NXDN)
 u - Toggle Trunking Tuning to Private Calls (DMR T3, Cap+, P25)
 d - Toggle Trunking Tuning to Data Calls (DMR T3, NXDN)
 e - Toggle Trunking Tuning to Encrypted Calls (P25)
@@ -222,6 +222,12 @@ N - Toggle Passband  Filter on Analog Voice or Raw Signal Monitoring
 
 v - Cycle RTL Input Volume Multiplier 1X, 2X, 3X (lower v)
 
+g - Manually decrease RTL gain
+G - Manually increase RTL gain
+
+{ - Manually decrease PPM
+} - Manually increase PPM
+
 ```
 
 ## Sending Audio to a Icecast 2 Server via FFmpeg (Windows)

include/dsd.h

@@ -364,6 +364,7 @@ typedef struct
   int unmute_encrypted_p25;
   int rtl_dev_index;
   int rtl_gain_value;
+  int rtl_gain_actual;
   int rtl_squelch_level;
   int rtl_volume_multiplier;
   int rtl_udp_port;

src/dsd_main.c

@@ -689,6 +689,7 @@
    //all RTL user options -- enabled AGC by default due to weak signal related issues
    opts->rtl_dev_index = 0;        //choose which device we want by index number
    opts->rtl_gain_value = 0;     //mid value, 0 - AGC - 0 to 49 acceptable values
+   opts->rtl_gain_actual = -100; //mirror dongle.gain actual values -100 is AUTO_GAIN, else nearest_gain(dongle.dev, dongle.gain);
    opts->rtl_squelch_level = 100; //100 by default, but only affects NXDN and dPMR during framesync test, compared to RMS value
    opts->rtl_volume_multiplier = 2; //sample multiplier; This multiplies the sample value to produce a higher 'inlvl' for the demodulator
    opts->rtl_udp_port = 0; //set UDP port for RTL remote -- 0 by default, will be making this optional for some external/legacy use cases (edacs-fm, etc)

src/dsd_ncurses_handler.c

@@ -594,7 +594,7 @@ uint8_t ncurses_input_handler(dsd_opts * opts, dsd_state * state, int c)
     else opts->trunk_tune_enc_calls = 1;
   }
 
-  if (opts->p25_trunk == 1 && c == 103) //'g' key, toggle tune group calls
+  if (opts->p25_trunk == 1 && c == 84) //'T' key, toggle tune group calls
   {
     if (opts->trunk_tune_group_calls == 1) opts->trunk_tune_group_calls = 0;
     else opts->trunk_tune_group_calls = 1;
@@ -918,6 +918,26 @@ uint8_t ncurses_input_handler(dsd_opts * opts, dsd_state * state, int c)
   if (c == 123)
     opts->rtlsdr_ppm_error--;
 
+  //RTL Gain Manual Adjustment
+  if (c == 103)
+  {
+    if (opts->rtl_gain_value > 0)
+    {
+      opts->rtl_gain_value--;
+      opts->rtl_gain_actual = 0;
+    }
+  }
+
+  if (c == 71)
+  {
+    if (opts->rtl_gain_value < 49)
+    {
+      opts->rtl_gain_value++;
+      opts->rtl_gain_actual = 0;
+    }
+  }
+    
+
   //anything with an entry box will need the inputs and outputs stopped first
   //so probably just write a function to handle c input, and when c = certain values
   //needing an entry box, then stop all of those

src/dsd_ncurses_printer.c

@@ -245,10 +245,10 @@ ncursesPrinter (dsd_opts * opts, dsd_state * state)
   if (opts->audio_in_type == 3)
   {
     printw ("| RTL: %d;", opts->rtl_dev_index);
-    if (opts->rtl_gain_value == 0)
+    if (opts->rtl_gain_actual == -100)
       printw (" G: AGC;");
     else
-      printw (" G: %idB;", opts->rtl_gain_value);
+      printw (" G: %i/%i;", opts->rtl_gain_value, opts->rtl_gain_actual);
     printw (" V: %iX;", opts->rtl_volume_multiplier);
     printw (" PPM: %i;", opts->rtlsdr_ppm_error); //Adjust manually now with { and }
     printw (" SQ: %i;", opts->rtl_squelch_level);
@@ -363,7 +363,7 @@ ncursesPrinter (dsd_opts * opts, dsd_state * state)
   {
     printw ("| Trunking -");
     if (opts->trunk_tune_group_calls == 0) attron(COLOR_PAIR(2));
-    printw (" Group(g)");
+    printw (" Group(T)");
     attron(COLOR_PAIR(4));
     if (opts->trunk_tune_private_calls == 0) attron(COLOR_PAIR(2));
     printw (" Private(u)");
@@ -382,8 +382,8 @@ ncursesPrinter (dsd_opts * opts, dsd_state * state)
   if (opts->p25_trunk == 1 && (opts->use_rigctl == 1 || opts->audio_in_type == 3) )
   {
     printw ("| Trunking -");
-    if (opts->trunk_tune_group_calls == 0) printw (" group(g)");
-    else printw (" GROUP(g)");
+    if (opts->trunk_tune_group_calls == 0) printw (" group(T)");
+    else printw (" GROUP(T)");
     if (opts->trunk_tune_private_calls == 0) printw (" private(u)");
     else printw (" PRIVATE(u)");
     if (opts->trunk_tune_data_calls == 0) printw (" data(d)");

src/rtl_sdr_fm.cpp

@@ -1031,6 +1031,7 @@ void open_rtlsdr_stream(dsd_opts *opts)
 
 	//this needs to be initted first, then we set the parameters
   dongle_init(&dongle);
+
 	//init with low pass if decoding P25 or EDACS/Provoice
 	if (opts->frame_p25p1 == 1 || opts->frame_p25p2 == 1 || opts->frame_provoice == 1)
   	demod_init_ro2(&demod);
@@ -1089,7 +1090,7 @@ void open_rtlsdr_stream(dsd_opts *opts)
 		verbose_auto_gain(dongle.dev);
 		fprintf (stderr, "Setting RTL Autogain. \n");
 	} else {
-		dongle.gain = nearest_gain(dongle.dev, dongle.gain);
+		opts->rtl_gain_actual = dongle.gain = nearest_gain(dongle.dev, dongle.gain);
 		verbose_gain_set(dongle.dev, dongle.gain);
 		// fprintf (stderr, "Setting RTL Nearest Gain to %d. \n", dongle.gain); //seems to be working now
 	}
@@ -1151,6 +1152,26 @@ int get_rtlsdr_sample(int16_t *sample, dsd_opts * opts, dsd_state * state)
 		verbose_ppm_set(dongle.dev, dongle.ppm_error);
 	}
 
+	//if Gain or AGC Value is Manually Changed, Change it here now
+	if (opts->rtl_gain_actual != dongle.gain && opts->rtl_gain_value != 0)
+	{
+		dongle.gain = (opts->rtl_gain_value * 10);
+		opts->rtl_gain_actual = dongle.gain = nearest_gain(dongle.dev, dongle.gain);
+		verbose_gain_set(dongle.dev, dongle.gain);
+
+		//debug
+		// fprintf (stderr, "\n Dongle Gain Set: %d; \n", dongle.gain);
+	}
+
+	else if (opts->rtl_gain_value == 0 && dongle.gain != AUTO_GAIN)
+	{
+		opts->rtl_gain_actual = dongle.gain = AUTO_GAIN;
+		verbose_auto_gain(dongle.dev);
+
+		//debug
+		// fprintf (stderr, "\n AGC Set; \n");
+	}
+
 	while (output.queue.empty())
 	{
 		struct timespec ts;