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DAX IQ Streaming

Status

Status: Supported · Applies to: FlexRadio

DAX IQ delivers raw I/Q samples from the radio's digital down-converter to other SDR programs. Regular DAX Virtual Audio carries demodulated audio from a slice; DAX IQ carries the unprocessed complex signal of a panadapter, before any mode, filter or AGC. AetherSDR offers four IQ channels at 24, 48, 96 or 192 kHz. DAX IQ is a FlexRadio feature.

Typical uses:

  • Second-opinion SDR software: run SDR#, GQRX, SDR Console or similar alongside AetherSDR.
  • Skimmers: CW Skimmer and SDC take IQ through the TCI Server, up to four streams at once.
  • Recording and analysis: record raw IQ, or feed GNU Radio or your own DSP.
  • Satellite data: the built-in WFM demodulator (below).

Setup​

Choosing which panadapter feeds a channel​

IQ channels belong to panadapters, not slices. In the panadapter overlay, open the DAX flyout and pick the channel in IQ Ch (None, 1–4). The stream itself is switched on in the DAX IQ applet.

Starting a stream​

  1. Open the DAX IQ applet (applet-tray button IQ, closed by default).
  2. Choose a rate for the channel.
  3. Press On for that channel.

Using DAX IQ​

Getting IQ into other programs​

On Linux, each running channel appears as a virtual capture device named AetherSDR DAX IQ n (PulseAudio/PipeWire source aethersdr-iq-n): float32 stereo, I on the left channel and Q on the right, at the rate you chose.

  • SDR#: pick the audio IQ input, choose AetherSDR DAX IQ 1, and set the same sample rate.
  • GQRX: use a PulseAudio I/Q input on AetherSDR DAX IQ 1 at the matching rate.
  • GNU Radio: an Audio Source on aethersdr-iq-1 at the matching rate gives interleaved I/Q.

On other platforms, take IQ through the TCI Server instead, which is how CW Skimmer and SDC connect.

WFM demodulator (satellite data)​

AetherSDR can FM-demodulate a panadapter's DAX IQ stream on the computer, for G3RUH 9600-baud satellite data. The chain applies phase-continuous Doppler correction, resamples to exactly 48 kHz and uses a flat discriminator, then sends the audio to a virtual audio cable for a program such as HS-SoundModem.

  1. In the panadapter overlay DAX flyout, set IQ Ch first.
  2. Press WFM, directly below it. It works in any slice mode, on the flyout's slice.
  3. The first time, a Select WFM Audio Output Device dialog asks for the output. Choose a virtual cable (for example Hi-Fi Cable, BlackHole or a PipeWire null sink) and optionally remember the choice.

WFM needs a radio with DAX IQ; on other radios it is refused with a notice.

Reference​

The DAX IQ applet​

The applet has one row per channel, IQ 1 to IQ 4:

ControlWhat it does
Rate24k, 48k, 96k or 192k
Off / OnCreates or removes the IQ stream for that channel
Level meterSignal level in dBFS over a −70 to −10 dBFS window. Normal signals sit low; a full bar means you are near overload.

The rate and on/off state of each channel are saved and restored at startup.

Higher rates use more of the radio's resources and more network bandwidth.

Limits​

  • The radio reports how many IQ channels it can supply; four is the maximum.
  • Receivers on the same panadapter share that panadapter's IQ stream, so four independent band views need four panadapters.

Troubleshooting​

A program sees no AetherSDR DAX IQ device​

The device only exists on Linux, and only while that channel's stream is on.

  1. In the panadapter overlay DAX flyout, set IQ Ch for the panadapter you want.
  2. In the DAX IQ applet, press On for that channel.
  3. On macOS or Windows, connect the program through the TCI Server instead.
  4. Set the program's sample rate to the rate chosen in the applet.

WFM is refused with a notice​

The connected radio has no DAX IQ.

  1. Use a FlexRadio, which supplies DAX IQ.

See also​