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Tuning a Radio Interface

The Tuning tab of a node's page sets the audio levels and signaling of a SimpleUSB or USBRadio interface. It replaces the text tune menus (simpleusb-tune-menu and radio-tune-menu) with sliders, switches and live meters. See Audio Level Adjustment for the background on setting levels.

Open Nodes, click the node number, then the Tuning tab.

Tuning Tab

Changes Take Effect Immediately

Each setting reaches the radio interface as soon as you apply it. It isn't part of Review and save. Click Save settings to write the settings to the configuration file, so that they survive an Asterisk restart.

If the USB sound card isn't plugged in or isn't assigned to the node, a warning says so. The live meters and the test tone need the sound card. The other settings can still be changed.

Tuning Without a Sound Card

Live Activity

Live activity shows what the interface hears and does, as the driver sees it right now. Turn on Show live activity while you set the levels, then turn it off again. Nothing in this section changes a setting, but while it is on, nobody else can tune this node.

  • Receive level shows how loud the receiver audio is while a signal is being received. The markers show the 3 kHz and 5 kHz deviation points. Adjust the Receive Level Slider until the bar graph matches what you are sending in to the receiver with your service monitor (1kHz @ 3kHz deviation).
  • COS in and CTCSS in light when the radio's carrier detect (squelch open) and tone detect inputs are active.
  • Receiving lights when the node accepts the signal, based on the COS and CTCSS settings below.
  • PTT out lights when the node keys the transmitter.

A lamp reads "not used" when the interface is set to ignore that input. PTT out shows what the driver asks for, not what the transmitter does. With the wrong PTT polarity, the radio transmits while this lamp is clear.

Send test tone keys the transmitter three times for one second each, with a 1 kHz tone, to set the transmit level.

Levels

  • Receive level sets the audio level from the radio (0–999).
  • Transmit level, channel A and channel B set the audio level to the radio on each of the sound card's output channels (0–999).

Drag the slider or type a value, then click Apply.

Set Receive Level First!

Be sure to set the receive level first, to match the deviation being sent by your service monitor. Once that is set, adjust the transmit level.

This order is particularly important for full duplex repeater service, as the receive signal is split and sent to both the AllStarLink network, and the attached transmitter. A proper receive level ensures that other nodes on the AllStarLink network hear your audio at a consistent level with other nodes.

Settings

These match the settings of the text tune menu. For SimpleUSB:

  • Receive boost adds receive gain for low-level radios.
  • Transmit pre-emphasis and Receive de-emphasis apply the audio filters for radios with flat (unfiltered) audio.
  • Receive CTCSS (PL) filter removes sub-audible tones from received audio.
  • Invert PTT keys the transmitter by opening the PTT line instead of grounding it.
  • Carrier detect (COS) from and CTCSS detect from choose where carrier and tone detection come from: Not used, a USB input or a Parallel port input, each normal or inverted.
  • Receive on delay ignores carrier detect for this long (debounce).
  • Transmit off delay ignores received audio for this long after transmitting.
  • Echo mode repeats received audio back, for testing.

USBRadio interfaces have their own set: receive voice and squelch levels, transmit voice and CTCSS levels, the receive audio type (speaker or flat), what each transmit channel carries, and transmit pre-emphasis and limiting. They also have a Calibration section with guided steps for the noise, CTCSS and voice calibrations.

Saving and Undoing

  • Save settings writes the current settings to simpleusb.conf or usbradio.conf. A review shows what changed.
  • Undo this session's changes puts back the settings the interface had when you opened the tab.
  • Open the classic tune menu opens the text tune menu in a terminal, for anything this page doesn't cover.

One Tuning Session at a Time

Only one person can tune an interface at a time. If someone is using the text tune menu over SSH, the page warns you.

If the interface has an SA818 radio module (SHARI and similar), its frequency, tones and filters are set on the Hardware page.