Accession Number : AD0683093

Title :   SYSTEM OF COMMUNICATION WITH INTERPLANETARY SPACE VEHICLES,

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : Khodarev,Yu. K.

Report Date : 19 AUG 1968

Pagination or Media Count : 6

Abstract : A communications system used during deep-space probes (Zond, Mars, and Venera) is described. The equipment in the Deep-Space Communications Center (usually one point) provides communications for all deep-space probes. Communication is periodic and scheduled. When the interval between communication-exchange sequences is long enough (15 days), receiver tuning problems arise because of the Doppler frequency shift and signal delay. To avoid these problems, deep-space communications systems in the USSR have a programmed control for correcting the ground-based transmitter and receiver (heterodyne) frequencies. This control uses the real-time parameters from the space-flight trajectory and velocity. The control system determines the difference between measured and predicted system frequency and signal-delay time. The accuracy of the frequency control is about 0.25 Hz with a phase shift of 1--2 degrees, and the accuracy of signal-delay time is 1--2 msec. A noncoherent detector is used in the space receiver because the ground transmitter imparts about 100 kw of power to the antenna. The ground receiver has a coherent receiver, and the message from space is modulated by a code-FM-PM or code PM-PM system. Practical use of the communication system described shows that it provides communication without additional receiver-frequency adjustment and is recommended for use in deep-space communications. (Author)

Descriptors :   (*SPACE COMMUNICATIONS, SPACE PROBES), RADIOFREQUENCY, CONTROL SYSTEMS, CORRECTIONS, MODULATION, USSR

Subject Categories : Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE