Artifact: Up-Data Link (UDL) Equipment, Digital, Apollo Command Module, Block II

Apollo Command Module Up-Data Link Equipment (Manufactured by Motorola) This 21-pound device is 6 by 18.3 by 9.6 inches. It received, verifies, and distributed digital updating information sent to the spacecraft from the Manned Space Flight Network at various times throughout the mission to update or change the modes of the telecommunications systems.

Data was received by the S-band receiver and routed to the up-data link. The up-data link equipment received, verified and distributed digital information sent to the spacecraft by the ground to update or change the status of operational systems. The up-data link consists of detecting and decoding circuitry, a buffer storage unit, output relay drivers, and a power supply and provides the means for the ground to update the computer and the central timing equipment, and to select certain vehicle function.

Up-data information was transmitted to the spacecraft as part of the 2-gigaHertz S-band signal. When this signal was received by the unified S-band receiver, the 70-kiloHertz subcarrier containing the up-data information was extracted and sent to the up-data discriminator in the pre-modulation processor. The resulting composite-audio frequency signal was routed to the sub-bit detector in the up-data link which converted it to a serial digital signal. The digital output from the sub-bit detector was fed to the remaining up-data link circuitry, which checked and stored the digital data, determined its proper destination, and transferred it to the appropriate system or equipment.