All FM transmissions are digital. What differentiates this FM station from some of those in service is its clarity and its ability to simultaneously send a text message with its audio broadcasts. This could be the name of the station or something like that. No special radios are required to recieve its broadcasts.
So far, I have seen only a handful of car sterios that are capable of recieving the visual text signature of the station. City limits FM station is also a digital FM station and I believe it is the first in The Gambia.