An isochronous transmission, also called equidistant, is an asynchronous start-stop transmission over a synchronous data link. In such a transmission, there is always an integer number of steps between any two identification times.
In isochronous transmission, each bit is assigned a specific quantum of time during which it is present in the transmission. The transmitter and receiver agree on the length of the quantum. The time relation between transmitter and receiver is ensured by the clock rate in the form of marks on the transmission path. Isochronous transmission has high flexibility for bursty signals and supports real-time services with the corresponding bandwidth and delay requirements.
With isochronous, the network guarantees long-term clock stability for time-critical services such as voice and image transmissions.