Abstract: A data communications link uses a multi-power level optical source to encode and transmit data words along a communications channel to a receiver station. A received signal condition monitor senses the level of a pre-determined characteristic and transmits a control signal to a controller which controls the power output of the optical source.

Abstract: An isochronous output data stream format which is time multiplexed and has a fixed time period where input isochronous data streams are multiplexed into the output isochronous data stream and the output data stream is the same data rate as the fastest input isochronous data stream. One or more of the input data streams contain a code which has been run length limited and/or has a zero running digital sum with banded disparity. In another embodiment, an isochronous output data stream format which is time multiplexed and has a fixed time period where input isochronous data streams are multiplexed into the output isochronous data stream and the output data stream is the sum of the maximum input isochronous data streams. One or more of the data streams contain a code which has been run length limited and/or has a zero running digital sum with banded disparity.

Abstract: An isochronous output data stream format in which a single n bit word is transmitted as m multiple synchronous data streams where the length of the word transmitted in each data stream is n/m, the output data stream containing multiple isochronous different data rate data streams and one or more asynchronous data stream or streams. One bit from each of the m multiple synchronous data streams are combined and transmitted as a single signal at one of 2m analog levels. Data which is it desired to have a lower error rate than other data is transmitted in the synchronous data stream corresponding to the most significant bit associated with the 2m analog levels. Calibration data is transmitted in the synchronous data stream corresponding to the most significant bit associated with the 2m analog levels, the calibration data also being transmitted distributed over each of the m synchronous data streams.