Did you see this note in the May 29 tech bulletin?
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1.Repeater: V9.00.10.100.iM
Fixes the noise issue when repeater is working in analog mode
Fixes the issue on statis registration when using AIS for repeater
Fixes B843 message sequence issue when using API for repeater
I applied this FW update to my RD982 repeaters and it fixed the analog audio noise issue.
The analog audio noise issue manifested itself as a buzz heard on the repeater during the hang time. The last valid frame of audio data was not being flushed out and replaced with a digital representation of silence whenever the audio is muted. The last frame of audio data was being continuously played during the hang time. When a signal was strong into the repeater, i.e., dead full quieting (DFQ), no buzz or a very faint buzz was heard during the hang time. A weak/noisy signal into the repeater would leave an annoyingly loud buzz during the hang time because the last frame of audio data was noisy analog audio. Whatever the last valid frame of audio contained when audio muted, that frame of data was played repeatedly during the hang time. The digital to analog converter (DAC) continuously outputs data and it was repeating the last valid frame of analog audio data instead of outputting empty frames of data during the hang time. The FW update fixed this behavior.
As an experiment to help test my theory, I put a full quieting signal into the repeater using a cheap Chinese radio (CCR). I held down a DTMF digit and then turned power OFF on the radio so the transmitter would un-key without transmitting a reverse burst for squelch tail elimination. A distorted buzzy version of the DTMF tone was heard on the repeater during the hang time. In this case the last valid frame of analog audio data played out during the hang time was the DTMF tone.
The good news is the FW update fixed the analog noise issue.
