What is roaming? Is it useful? When will it be used?

Roaming refers to setting the radio to automatically move between repeaters based on which repeater has the strongest signal.
In a roaming system, you must set the RSSI (Received Signal Strength Indicator) threshold, which is the minimum signal strength that the radio will consider to be strong enough before the radio starts searching for a stronger signal.
Roaming is a limited use function, some people will need it, some people will not. This is a commercial function adapted to DMR amateur radio. Basically, that means you are driving from the south of the city to the north of the city, for example, there are 5 repeaters along the way. If you keep moving, the radio or car will automatically switch to the channel with the strongest signal and the repeater closest to you, because you are moving to the strongest repeater geographically.

But suppose you are using your mobile/car and Raspberry Pi hotspot devices at home, roaming will not help you, because your mobile or car does not need to change the frequency or channel, so the signal is constant.
Therefore, for some people, for example, you are traveling in a city and want your mobile radio or mobile radio to automatically roam to a nearby relay. If a mobile radio with roaming function is installed in your car, then It will be a good thing for you.

Roaming is like doing a smart scan of the repeater and using the available signal to maintain the same TG. Regardless of whether the signal strength is strong enough, the scan will usually stop on any carrier.

The difference between scanning and roaming is that scanning will continue to scan until a signal is received, while roaming radio will use repeaters in the roaming list to connect and remain locked on the channel until the signal is too weak.

Which Retevis DMR radio have roaming function?

1. Retevis RT73 20W mobile radio.