This is a little trick which many portable receivers and transceivers do. When a receiver is listening to comms traffic, sometimes nothing can happen for minutes, maybe hours at a time. If it went to sleep during this time it would miss a call. What it does instead is go to sleep most of the time but wake up for just enough to check that there is still no activity and then goes back to sleep again.

It does all this quite rapidly but the net effect is a reasonable extension of battery life. Not that the R20 needs too much help in this department but if you are away from a source of power for an extended time you may want to consider putting power save into AUTO mode.

The down side to power save mode is that the receiver may take longer to notice a signal and respond by waking up. This means you may miss the beginning of a transmission when power save is engaged.

The R20 is quite smart though and has a two level power save. After 5 seconds of no audio, it will go into mild power save with a 1:4 (125ms:500ms) ratio, and after a further 60 seconds of no activity, it will go into a deeper power save mode with a ratio of 1:8 (125ms:1000ms)