Power requirements for deep-space telecommunication links

The signal-to-noise ratio in a given equivalent bandwidth must be maintained above a minimum value during a deep-space mission in order to provide predictable performance, and in order to maintain effective telemetry communications with spacecraft at interplanetary distances it is necessary for earth stations to use maximum antenna gain. One solution is to extend telecommand range by reducing system noise temperature in the spacecraft receiver and reducing the bandwidth of the receiver's phase-lock loop. Low-noise preamplifiers have not yet been applied in planetary spacecraft in order to maintain simplicity and reliability. An answer to the problem seems to be high-power transmitters (earth-based) with outputs in the 1000-GW range.