Notification
While the radio is on, its notification shows the channel, frequency and what is happening (ready, receiving, transmitting, scanning) with three buttons: previous channel, scan or stop scan, next channel. Tap the notification to open the app.
Home-screen widget
Device → Home widget asks the home screen to add it (confirm with Add), or long-press the home screen, choose Widgets, find SignalDeck and drag the Radio widget out. It can be resized. It shows the channel number and name and the same status line, with previous, scan, next and Talk buttons. Tap the channel to open the app.
Talk from the widget
A widget cannot feel a held finger, so Talk works tap to start, tap to stop: the button turns red while you transmit. Transmitting stops by itself after 28 seconds. The radio's own limit is 120 seconds. Receive-only channels refuse it.
When the radio is off
The buttons need the app to own the radio. If it does not, they say so; tap the channel to open the app.