The Apollo Unified S-Band System
The Manned Space Flight Network antennas operated in the S-Band, on frequencies around 2.2 GHz. The system employed was known as the Unified S-Band System (USB). This system combined tracking and ranging; command, voice and television into a single antenna.
S-Band frequencies were minimally attenuated by the Earths atmosphere and were suitable for both Earth orbit and Lunar use.
A USB-equipped antenna could transmit and receive simultaneously. Voice, telemetry and television were all received together. From the Lunar Module, for example, slow-scan television was frequency modulated on the carrier, and telemetry was phase modulated on the the subcarriers. In addition, the system allowed for very accurate ranging to determine the distance of the spacecraft from Earth.
Bill Wood notes:
Proceedings of the Apollo Unified S-Band Conference, July 1965.
In July 1965, the Goddard Space Flight Center hosted the Apollo Unified S-Band Technical Conference. The proceedings were published in this famous Unified S-band green book.
Although some details changed before the first Apollo flights, this remains the most comprehensive record of the USB system.
Bill Wood (ex-Goldstone) and Neil Sandford (ex-Honeysuckle) have worked together to produce this high quality PDF version of the book, NASA SP-87 from Neils copy, numbered 00030.
It is a 23MB download. 316 pages.
Collins Radio Unified S-Band Project Director George F. Mansur wrote this 1 page article about the USB system in Autumn 1964.
Provided by Alan Gilham (ex-Carnarvon.) Click the image for a 370kb enlargement.