An Interplanetary Communication System

Exploring of space by means of space probes poses some challenging problems if all useful data acquired at the probe´s location is to be made available on earth. There exists a monotonic relationship for every communication system between the received energy required per unit of received information. The quantity of received data can be increased by an increase in the received energy or more subtly by varying this monotonic relationship through the choice of a more efficient communication system. Proper screening and processing of data before their transmission can increase the amount of useful information received at the expense of other data not so valuable and can ease ground data handling problems. A telemetry system, entitled ``Telebit,´´ which makes use of some of these principles, and is a forerunner to the application of others, is described.