Digital radio

The invention concerns a digital radio (2) for pseudo-duplex radio communication, and a method of transmission time mediation for pseudo-duplex radio communication. A digital radio (2) is in time division duplex communication with a second digital radio (4). The digital radio (2) derives a source signal activity parameter (VAD) indicating the likelihood of there being a source signal for transmission by the digital radio (2) to the second digital radio (4) over a single radio channel. The digital radio (2) also derives a first value (VADDir1) of a signal direction parameter (VADDir) in dependence on both the value of the signal activity parameter (VAD) for the digital radio (2) and a second value (VADDir2) of the signal direction parameter (VADDir) received from the second digital radio (4); The digital radio (2) selects the proportions of time for transmission and reception over the single radio channel in dependence on the first value (VADDir1) of the signal direction parameter (VADDir). The digital radio (2) also transmits the first value (VADDir1) of the signal direction parameter (VADDir) to the second digital radio (4), to allow the second digital radio (4) to perform an analogous update of its value of the signal direction parameter (VADDir). The apparatus and method of the invention are robust to radio channel and VAD value imperfections.