SSB/DSB demodulator plugin

<h1>SSB/DSB demodulator plugin</h1>

<h2>Introduction</h2>

This plugin can be used to listen to a single sideband or double sidebands modulated signal. 

<h2>Interface</h2>

![SSB Demodulator plugin GUI](../../../doc/img/SSBDemod_plugin.png)

<h3>1: Frequency shift from center frequency of reception direction</h3>

The "+/-" button on the left side of the dial toggles between positive and negative shift.

<h3>2: Frequency shift from center frequency of reception value</h3>

Use the wheels to adjust the frequency shift in Hz from the center frequency of reception. Left click on a digit sets the cursor position at this digit. Right click on a digit sets all digits on the right to zero. This effectively floors value at the digit position.

<h3>3: Channel power</h3>

Average total power in dB relative to a +/- 1.0 amplitude signal received in the pass band.

<h3>4: Monaural/binaural toggle</h3>

  - Monaural: the scalar signal is routed to both left and right audio channels
  - Binaural: the complex signal is fed with the real part on the left audio channel and the imaginary part to the right audio channel
  
<h3>5: Invert left and right channels</h3>

Inverts left and right audio channels. Useful in binaural mode only.

<h3>6: SSB/DSB demodulation</h3>

Toggles between SSB (icon with one sideband signal) and DSB (icon with double sidebands signal)

<h3>7: Level meter in dB</h3>

  - top bar (green): average value
  - bottom bar (blue green): instantaneous peak value
  - tip vertical bar (bright green): peak hold value

<h3>8: Span</h3>

Signal span (i.e. sample rate) before demodulation. Baseband rate set in the sampling device panel is further decimated by powers of two.

<h3>9: Bandwidth</h3>

This is the upper limit in kHz of the signal filtered after demodulation. 

<h3>10: Bandwidth</h3>

SSB only: this is the lower limit in kHz of the signal filtered after demodulation. 

<h3>11: 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>12: Audio mute</h3>

Use this button to toggle audio mute for this channel.

<h3>13: Spectrum display</h3>

This is the spectrum display of the demodulated signal (SSB) or translated signal (DSB). Controls on the bottom of the panel are identical to the ones of the main spectrum display.