Add Rsp config notes and fix max gain reduction

config/radar4.yml

@@ -3,10 +3,10 @@ capture:
   fc: 204640000
   device:
     type: "RspDuo"
-    agcSetPoint: -60
-    bandwidthNumber: 50
-    gainReduction: 40
-    lnaState: 4
+    agcSetPoint: -20
+    bandwidthNumber: 5
+    gainReduction: 59
+    lnaState: 1
     dabNotch: false
     rfNotch: false
   replay:

src/capture/rspduo/README.md

@@ -6,11 +6,11 @@ Here is a list of available config parameters:
 
 - **agcSetPoint** in dBfs has a default value of -60 dBfs, and can be set between -72 dBfs and 0 dBfs.
 
-- **bandwidthNumber** in Hz has a default value of 50 Hz, and can be 0, 5, 50 or 100 Hz.
+- **bandwidthNumber** in Hz has a default value of 50 Hz, and can be 0, 5, 50 or 100 Hz. This is the number of times per second the AGC makes gain adjustments by changing the gain reduction value. If setting to 0 then the AGC is effectively disabled.
 
-- **gainReduction** in dB has a default value of 40 dB, and can be set between 20 and 60.
+- **gainReduction** in dB has a default value of 40 dB, and can be set between 20 and 59. This is the initial value the gain reduction is set to, before the AGC changes this parameter to approach the AGC set point.
 
-- **lnaState** has a default value of 4, must be between 1 and 9.
+- **lnaState** has a default value of 4, must be between 1 and 9. A larger number means a larger gain reduction (attenuation). Maximum gain at LNA state 1 and minimum gain at LNA state 9.
 
 - **dabNotch** is a bool, true turns on the DAB band notch filter (default false).
 

src/capture/rspduo/RspDuo.cpp

@@ -16,7 +16,7 @@
 const double RspDuo::MAX_FREQUENCY_NR = 2000000000;
 const int RspDuo::MIN_AGC_SET_POINT_NR = -72;        // min agc set point
 const int RspDuo::MIN_GAIN_REDUCTION_NR = 20;        // min gain reduction
-const int RspDuo::MAX_GAIN_REDUCTION_NR = 60;        // max gain reduction
+const int RspDuo::MAX_GAIN_REDUCTION_NR = 59;        // max gain reduction
 const int RspDuo::MAX_LNA_STATE_NR = 9;              // max lna state
 const int RspDuo::DEF_SAMPLE_RATE_NR = 2000000;      // default sample rate