DATV demod: updated readme with DVB-S2 information

plugins/channelrx/demoddatv/readme.md

@@ -14,6 +14,8 @@ This plugin can be used to view digital amateur analog television transmissions
 
 The whole bandwidth available to the channel is used. That is it runs at the device sample rate possibly downsampled by a power of two in the source plugin.
 
+⚠ Note that DVB-S2 support is experimental. You may need to move some settings back and forth to achieve constellation lock and decode. For exmple change mode or slightly move back adn forth center frequency.
+
 <h2>Interface</h2>
 
 ![DATV Demodulator plugin GUI](../../../doc/img/DATVDemod_plugin.png)
@@ -42,19 +44,27 @@ Power of signal received in the channel (dB)
 
 This is the constellation of the PSK or QAM synchronized signal. When the demodulation parameters are set correctly (modulation type, symbol rate and filtering) and signal is strong enough to recover symbol synchronization the purple dots appear close to the white crosses. White crosses represent the ideal symbols positions in the I/Q plane.
 
-<h4>B.2a: DATV signal settings</h4>
+<h4>B.2a: DATV signal settings (all standards)</h4>
 
 ![DATV Demodulator plugin DATV2 GUI](../../../doc/img/DATVDemod_pluginDATV2.png)
 
 <h5>B.2a.1: DATV standard</h5>
 
-For now only the DVB-S standard is available
+  - DVB-S: DVB-S
+  - DVB-S2: DVB-S3 and some DVB-S2X
 
 <h5>B.2a.2: Modulation type</h5>
 
+Depends on the standard.
+
+  - DVB-S: Normally only QPSK and BPSK (later addition) are supported in the standard but amateur radio use has a little bit abused of the standard so PSK6, QAM16, QAM64 and QAM256 are also supported
+  - DVB-S2: QPSK, PSK8, APSK16, APSK32, APSK64e (DVB-S2X)
+
+The constallations are as follows:
+
   - BPSK: binary phase shift keying. Symbols are in &#960;/4 and -3&#960;/4 positions.
   - QPSK: quadrature phase shift keying. Symbols are in &#960;/4, 3&#960;/4, -3&#960;/4 and -&#960;/4 positions.
-  - 8PSK: 8 phase shift keying a.k.a. &#960;/4 QPSK. Symbols are in 0, &#960;/4, &#960;/2, 3&#960;/4, &#960;, -3&#960;/4, -&#960;/2 and -&#960;/4 positions
+  - PSK8: 8 phase shift keying a.k.a. &#960;/4 QPSK. Symbols are in 0, &#960;/4, &#960;/2, 3&#960;/4, &#960;, -3&#960;/4, -&#960;/2 and -&#960;/4 positions
   - APSK16: amplitude and phase shift keying with 16 symbols
   - APSK32: amplitude and phase shift keying with 32 symbols
   - APSK64e: amplitude and phase shift keying with 64 symbols
@@ -64,29 +74,36 @@ For now only the DVB-S standard is available
 
 <h5>B.2a.3: Symbol rate</h5>
 
-This controls the expected symbol rate
+This controls the expected symbol rate in symbols per second
 
 <h5>B.2a.4: FEC rate</h5>
 
-Choice between 1/2 , 2/3 , 3/4, 5/6 and 7/8.
+Dpends on the standard and modulation
+
+  - DVB-S with all modulations: 1/2 , 2/3 , 3/4, 5/6 and 7/8.
+  - DVB-S2 and QPSK: 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9, 9/10
+  - DVB-S2 and PSK8: 3/5, 2/3, 3/4, 5/6, 8/9, 9/10
+  - APSK16 (DVB-S2): 2/3, 3/4, 4/5, 5/6, 8/9, 9/10
+  - APSK32 (DVB-S2): 3/4, 4/5, 5/6, 8/9, 9/10
+  - APSK64E (DVB-S2): 4/5, 5/6
 
 <h5>B.2a.5: Notch filter</h5>
 
 LeanSDR feature: attempts to fix signal spectrum shape by eliminating peaks. This is the number of peaks to be tracked. It is safer to keep the 0 default (no notch).
 
-<h5>B.2a.6: Fast lock</h5>
+<h5>B.2a.6: Fast lock (DVB-S only)</h5>
 
 Faster signal decode but may yield more errors at startup.
 
-<h5>B.2a.7: Allow drift</h5>
+<h5>B.2a.7: Allow drift (DVB-S only)</h5>
 
 Small frequency drift compensation.
 
-<h5>B.2a.8: Hard metric</h5>
+<h5>B.2a.8: Hard metric (DVB-S only)</h5>
 
 Constellation hardening (LeanSDR feature).
 
-<h5>B.2a.9: Viterbi</h5>
+<h5>B.2a.9: Viterbi (DVB-S only)</h5>
 
 Viterbi decoding. Be aware that this is CPU intensive. Should be limited to FEC 1/2 , 2/3 and 3/4 in practice.
 
@@ -110,17 +127,33 @@ Automatically adjusts unit (kB, MB, ...)
 
 Gauge that shows percentage of buffer queue length
 
-<h4>B.2b: DATV video stream</h4>
+<h4>B.2b: DATV signal settings (DVB-S2 specific)</h4>
+
+![DATV Demodulator plugin DATV3 GUI](../../../doc/img/DATVDemod_pluginDATV3.png)
+
+<h5>B.2b.3: MODCOD status</h5>
+
+In addition to the controls a MODCOD status text appears on the right of the standard selector (1) that give the mode and code rate as retrieved from MODCOD information. When the MODCOD information has triggered the automatic mode and rate selection (2) and (4) the text background turns to green.
+
+<h5>B.2b.2 and 4: Mode and rate selection</h5>
+
+The mode and rate selection can be done manually but if a discrepancy in the number of bits per symbol appears compared to the MODCOD information then the MODCOD information takes precedence and the selection is changed automatically and the status background (3) turns to green.
+
+<h5>B.2b.5: DVB-S specific controls</h5>
+
+The controls specific to DVB-S are disabled and greyed out. These are: Fast Lock, Allow Drift, Hard Metric and Viterbi.
+
+<h4>B.2c: DATV video stream</h4>
 
 ![DATV Demodulator plugin video GUI](../../../doc/img/DATVDemod_pluginVideo.png)
 
-<h5>B.2b.1: Image</h5>
+<h5>B.2c.1: Image</h5>
 
 The decoded video is displayed here
 
-<h5>B.2b.2: Stream information</h5>
+<h5>B.2c.2: Stream information</h5>
 
-<h5>B.2b.3: Stream decoding status</h5>
+<h5>B.2c.3: Stream decoding status</h5>
 
 These non clickable checkboxes report the decoding status (checked when OK):
 
@@ -129,7 +162,7 @@ These non clickable checkboxes report the decoding status (checked when OK):
   - video: video data detected
   - decoding: video being decoded
 
-<h5>B.2b.4: Video mute</h5>
+<h5>B.2c.4: Video mute</h5>
 
 Toggle button to pause/run video decoding. This also indicates the video status:
 
@@ -137,7 +170,7 @@ Toggle button to pause/run video decoding. This also indicates the video status:
   - Green: a video stream is present and successfully decoded
   - Red: a video stream is present but decoding fails
 
-<h5>B.2b.5: Audio mute</h5>
+<h5>B.2c.5: Audio mute</h5>
 
 Toggle button to pause/run audio decoding. This also indicates the audio status:
 
@@ -147,11 +180,11 @@ Toggle button to pause/run audio decoding. This also indicates the audio status:
 
 In addition right clicking on the button will give you access to the audio device selection dialog
 
-<h5>B.2b.6: Audio volume</h5>
+<h5>B.2c.6: Audio volume</h5>
 
 Show the audio volume on a 0 to 100 scale. The actual coefficient applied to the audio samples follows a logarithmic rule where 0 corresponds to 0.01, 50 to 0.1 and 100 to 1.0
 
-<h5>B.2b.7: Audio volume control</h5>
+<h5>B.2c.7: Audio volume control</h5>
 
 Use this slider to control the value (0 to 100) of the audio volume.