Dahdio

Guide · input

How to connect
your radio.

Dahdio decodes best from the radio’s own audio, fed straight in. Any of the first three ways below is a direct connection. The microphone is not.

  1. 01USB audio interface
  2. 02Headset socket
  3. 03Radio’s own USB
  4. 04Level
  5. 05Hum
  6. 06Other inputs

01 Recommended

A USB audio interface

Connect the radio’s headphone, line or data output to a USB audio interface or USB sound-card adapter, and plug that into the phone (with a USB-C or OTG adapter if needed) or the computer.

Dahdio uses a USB input automatically when one is plugged in and Input is set to Automatic.

Use the adapter’s microphone or line input. A line input suits a data or line output; a microphone input needs the radio’s volume kept low.

The radio's headphone, line or data output goes by cable into a USB audio interface, which plugs into the phone or computer running Dahdio. 14.030 Radio phones, line or data out USB audio interface mic or line input Phone or computerrunning Dahdio
Radio output → USB audio interface → phone or computer. Plugged in mid-session? Press Stop, then Listen.

02

A cable into the headset socket

On a phone with a 3.5 mm headset socket, a TRRS cable or adapter takes the radio’s audio into the headset’s microphone contact.

Headset inputs expect a small signal: keep the radio’s volume low, or use a cable with an attenuator.

The radio's audio goes through a cable, with an optional attenuator, into the phone's 3.5 mm headset socket. On the four-contact TRRS plug, the radio's audio goes to the sleeve, the microphone contact, and the radio's ground to the second ring. 7.030 Radio phones or line out Attenuator optional Headset socket 3.5 mm, four contacts tip Lring Rring gndradio groundsleeve micradio audio
The four-contact plug as most current phones wire it. Check your adapter’s wiring if it is unmarked.

03

A radio with built-in USB audio

Many modern radios have a USB sound card of their own: one USB cable carries the receive audio.

On Android the phone must support USB OTG (host mode), and the radio then appears as a USB input. On a computer it appears as a sound input like any other.

A radio with its own USB sound card connects to the phone with one USB cable through a USB OTG adapter; the receive audio travels on that cable. 7.030 OTG Radio with USB audio its own sound card one USB cable USB OTG adapter Phone or computer appears as a USB input

04

Setting the level

Start with the volume low and raise it until the signals are clearly heard.

Too loud is worse than too quiet: a clipped input distorts every signal in it at once.

Too quiet
About right
Clipped
The same keyed signal at three input levels. Clipping flattens the tops, and every station in the audio suffers with it.

05

Hum and ground loops

A steady hum or buzz, especially with the phone or computer on a charger, is usually a ground loop between the radio and the phone or computer.

An audio isolation transformer in the audio lead breaks the loop. Running on battery also helps.

A ground loop: the audio lead, the phone's charger and the radio's power supply make a loop through the mains. An audio isolation transformer in the audio lead breaks it. 7.030 mains: the radio’s power supply and the charger Isolation transformer breaks the loop looploop Radio

06

Other inputs

Dahdio can also listen through Bluetooth or the built-in microphone. Neither is a direct connection, and copy suffers for it.

Not recommended for weak signals

Bluetooth

Bluetooth is a narrowband voice link, and many headsets add noise suppression. Strong signals decode almost as well as over a cable; weak ones noticeably worse. For weak-signal work use a cable or USB.

A quick try only

The built-in microphone

With nothing connected, Dahdio listens through the microphone. It works for a quick try, but copy is much weaker than with a cable or USB interface: the room adds noise and echo, and the phone’s own processing works against weak signals.

Stuck?

Tell us your radio and your phone or computer, and we’ll do our best to help you get it connected.

Email support