Editing Lua extension API (section)

== Modulation declaration ==
{| class="wikitable"
! Field !! Default !! Meaning
|-
| <code>name</code> || Required || Display name.
|-
| <code>description</code> || Empty || User-facing description.
|-
| <code>bandwidth</code> || 3000 for IQ, usual width for audio output || Suggested initial transmit bandwidth in hertz. The operator may change it.
|-
| <code>controls</code> || Empty || List of controls described below.
|-
| <code>input</code> || <code>"audio"</code> || Shorthand for one input. <code>"none"</code> and <code>"generator"</code> declare a source-free mode.
|-
| <code>inputs</code> || One required audio input || List of declared inputs. It cannot be combined with <code>input</code>.
|-
| <code>output</code> || <code>"iq"</code> || <code>"iq"</code>, <code>"audio"</code>, or <code>{type="audio", modulation="USB"}</code>.
|-
| <code>start</code> || None || Optional <code>function(ctx)</code> called once when a session starts.
|-
| <code>process</code> || Required || <code>function(ctx)</code> called for each output block. <code>modulate</code> is an alias.
|-
| <code>stop</code> || None || Optional <code>function(ctx)</code> called once when the session closes.
|}

An IQ-output mode produces complex baseband directly. An audio-output mode produces mono audio and then uses a built-in RF modulation selected by the operator. The default built-in modulation is USB. Any built-in mode other than IQ may be used.

The callback object is documented in [[Lua modulation API]].