NFM demodulator plugin: documentation as readme

plugins/channel/demodnfm/readme.md

@@ -0,0 +1,53 @@
+<h1>NFM demodulator plugin</h1>
+
+<h2>Introduction</h2>
+
+This plugin can be used to listen to a narrowband FM modulated signal. By "narrowband" it means that the bandwidth can vary from 5 to 40 kHz.
+
+<h2>Interface</h2>
+
+![NFM Demodulator plugin GUI](/doc/img/NFMdemod_plugin.png)
+
+<h3>1: Frequency shift from center frequency of reception</h3>
+
+Use the wheels to adjust the frequency shift in Hz from the center frequency of reception. Use the "+/-" button on the left side to toggle between positive and negative shift.
+
+<h3>2: Channel power</h3>
+
+Total power in dB relative to a +/- 1.0 amplitude signal received in the pass band.
+
+<h3>3: RF bandwidth</h3>
+
+This is the bandwidth in kHz of the channel signal before demodulation. It can be set in steps as 5, 6.25, 8.33, 10, 12.5, 15, 20, 25 and 40 kHz.
+
+<h3>4: AF bandwidth</h3>
+
+This is the bandwidth of the audio signal in kHz (i.e. after demodulation). It can be set in continuous kHz steps from 1 to 20 kHz.
+
+<h3>5: Volume</h3>
+
+This is the volume of the audio signal from 0.0 (mute) to 10.0 (maximum). It can be varied continuously in 0.1 steps using the dial button.
+
+<h3>6: Squelch threshold</h3>
+
+This is the squelch threshold in dB. The total power received in the signal bandwidth before demodulation is compared to this value and the squelch input is open above this value. It can be varied continuously in 0.1 dB steps from 0.0 to -100.0 dB using the dial button.
+
+<h3>7: Squelch gate</h3>
+
+This is the squelch gate in milliseconds. The squelch input must be open for this amount of time before the squelch actually opens. This prevents the opening of the squelch by parasitic transients. It can be varied continuously in 10ms steps from 10 to 500ms using the dial button.
+
+<h3>8: CTCSS on/off</h3>
+
+Use the checkbox to toggle CTCSS activation. When activated it will look for a tone squelch in the demodulated signal and display its frequency (see 10). 
+
+<h3>9: CTCSS tone</h3>
+
+This is the tone squelch in Hz. It can be selected using the toolbox among the usual CTCSS values and `--` for none. When a value is given and the CTCSS is activated the squelch will open only for signals with this tone squelch.
+
+<h3>10: CTCSS tone value</h3>
+
+This is the value of the tone squelch received when the CTCSS is activated. It displays `--` if the CTCSS system is de-activated.
+
+<h3>11: Audio mute</h3>
+
+Use this button to toggle audio mute for this channel. The button will light up in green if the squelch is open. This helps identifying which channels are active in a multi-channel configuration.

plugins/channel/udpsrc/readme.md

@@ -24,7 +24,7 @@ Combo box to specify the type of samples that are sent over UDP.
 
   - `S16LE I/Q`: Raw I/Q samples on signed 16 bits integers with Little Endian layout. Use it with software that accepts I/Q data as input like GNUradio with the `UDP source` block
   - `S16LE SSB`: AF of SSB demodulated signal as 16 bits signed integers with Little Endian layout. Use it with software that uses a SSB demodulated signal as input i.e. software that is based on the audio output of a SSB radio.
-  - `S16LE NFM`: AF of FM demodulated signal as 16 bits signed integers with Little Endian layout. Use it with software that takes FM demodulated audio or discriminator output as input. Make sure you specify the appropriate signal bandwidth (see 7) according to the AF bandwidth needs.
+  - `S16LE NFM`: AF of FM demodulated signal as 16 bits signed integers with Little Endian layout. Use it with software that takes the FM demodulated audio or the discriminator output of a radio as input. Make sure you specify the appropriate signal bandwidth (see 7) according to the AF bandwidth needs.
   
 <h3>4: Signal sample rate</h3>