Channels

A channel takes a Device's IQ and turns one frequency into audio, messages, or pictures. Which channel you pick decides the mode: AM, WFM, ADS-B, and so on. The Decoders page lists them all.

Add a channel

Press + Add and pick a mode.
Wire Device iq to the channel's iq.
Set the channel frequency.
Wire the outputs you need:

Output	Wire to	You get
`audio`	Speaker	Live sound
`audio`	Audio recorder	A WAV file
`audio`	Audio FX	Filtered, denoised or levelled sound
`events`	Readout	Current state: station text, aircraft table
`events`	Decoder log	Message history
`events`	Map	Positions
`events`	Export	CSV or JSON of logged rows
`video`	Video	ATV frames or SSTV pictures
`baseband`	Baseband scope, recorder, or Network IQ	The channel's filtered IQ

To swap the mode, right-click the channel and choose Replace with…. The frequency and squelch stay; wires the new mode has no port for are dropped. m and M cycle the analog modes.

A Device on auto tuning moves its window to cover its channels. A Device tuned by hand only carries the channels inside its window. The rest stay configured and resume when the radio covers them again. See Tuning.

Wire a channel to more than one Device and it runs on whichever radio hears it. Radios on auto tuning split their channels between them so as many as possible are heard. A channel wired to only one radio stays on that radio. The channel face names the radio carrying it.

While a scanner, signal hunt, recording, or network export uses a channel, it stays on its radio until that stops.

Tune

Use the channel dial, drag its marker on the Scope, or use the keyboard. Typed frequencies are in MHz unless you add kHz, MHz, or GHz. The step buttons move by 5 or 25 kHz.

The lock beside a dial freezes that frequency. Locking a channel does not lock its Device.

You can set channel frequencies before a radio is connected. The Device opens over them.

Sample rate

Each channel runs at its own fixed rate. The Device's IQ is resampled to match, so any Device rate works for any channel, as long as the channel's full bandwidth fits inside the Device's window. If it does not fit, retune the Device, move the channel, or raise the sample rate.

When the Device rate equals the channel rate, resampling is skipped: ADS-B runs at 2.4 MS/s, DAB and GNSS at 2.048 MS/s, ATV at 16 MS/s. Use the lowest rate that covers your signals. It saves USB bandwidth and CPU.

Squelch

Squelch mutes audio when nothing is there. Only channels with audio have it. Data decoders use their own detection threshold.

Mode	Opens
Off	Always
Manual	Above a fixed level
Auto	A set number of dB above the measured noise floor

The level meter marks the threshold. Auto learns the floor while the channel is quiet, so a signal that never stops can be mistaken for noise. Once squelch is open, the floor cannot rise and cut off a long transmission. Switching back to Manual restores your last manual level.

NFM also has tone squelch:

Setting	Behaviour
Detect	Shows the CTCSS tone or DCS code, never mutes
CTCSS	Opens only for the chosen tone
DCS	Opens only for the chosen code

Compander expands audio 2:1 for links that compress it. Leave it off for ordinary NFM.

Noise blanker

The channel's Blanker removes impulse noise from the IQ before filtering. A lower threshold removes more, but can damage the signal. AM and SSB level their own volume.

Audio FX

Wire a channel's audio through an Audio FX node to process what you hear. The channel's raw audio stays available on its own wires, so a recorder can keep it while a Speaker plays the cleaned version. Chain several nodes to stack effects. Stages run in this order, all off by default:

Stage	Does
De-click	Removes short clicks from the audio.
Passband	Cuts audio below and above two frequencies.
Notches	Removes up to four chosen tones, each with its own width.
Auto notch	Finds and removes steady tones.
Denoise	Spectral: attenuates noise by up to 20 dB, light on CPU. Neural: the DPDFNet speech model, stronger on voice, about 10% of a core per stream.
AGC	Levels the volume. Slow suits SSB speech, fast suits tuning around.

Neural denoise is trained on speech. Leave it off for music, data tones and CW.

Where decoded events go

Every event carries its source, frequency, and time. Use Readout for what is happening now, Decoder log for history, Map for positions, and Export to save rows. The log keeps a bounded history.

Filter events

Put an Event filter between a decoder and its outputs. Every rule you set must match.

Mode	Passes
Keep	Only matching events
Drop	Everything except matching events

A rule that does not apply to an event is ignored: a talkgroup rule never judges an aircraft. A drop filter with no rules drops nothing. Chain filters to combine them, for example keep POCSAG, then drop messages containing TEST.

A filter only affects events that arrive after it is set. Rows already in the log stay.

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