Record cockpit audio with a Lightspeed Zulu 4 on Android

The Lightspeed Zulu 4 is the headset TowerOwl was built on, and the only one verified so far. It needs no cable and no iPhone.

Setup

1. Open the battery door on the controller. Set DIP switch 6 (“Record Comm”) ON. This mixes the intercom into the Bluetooth call channel. While it is ON and the headset is plugged into the panel, anyone you phone through the headset hears the intercom too.
2. If you test on the ground without the headset plugged into a panel, DIP switches 3 and 4 (“Cell mic bias”) must be ON, otherwise the boom microphone is unpowered and silent.
3. Pair the headset with your phone. In Android's Bluetooth settings keep both “Phone calls” and “Media audio” enabled.
4. Open TowerOwl and tap Record. The status line should read “VOICE_COMMUNICATION → Zulu 4 / BT_SCO”.

Good to know

• Audio quality is Bluetooth call quality (16 kHz wideband on most phones): fine for radio speech, which is band-limited anyway.
• While recording, the phone's media plays through the call channel. The Zulu 4 pairs with two devices at once, so run your EFB on a tablet and record with the phone.
• Replay works into the headset while the recording continues. If replayed audio shows up twice in your recordings, enable “Mute recording during replay” in Settings.