Basic PCM Digital Data Acquisition System PAM/FM/FM SYSTEMS

Transducer input signals constitute the PAM input. The PAM systems use an electronically switched network that samples up to 30 channels of trans­ducer inputs at 120 times a second. Deviations in transducer input voltages are represented as out­put pulses of varying amplitude for subsequent evaluation.

The SS/FM system is reserved for pertinent re­search requirements. Vibration and acoustical data needed for manned flight development will be trans­mitted by this system.

PCM/FM SYSTEM

The PCM/FM system (DDAS) is used during auto­matic checkout to provide data for the ground check­out computer. The system is also used to provide precise information concerning stage environment and performance of systems during flight.

Environmental Control Systems

AFT SKIRT AND INTERSTAGE THERMOCONDITIONING AND PURGE

The thermoconditioning and purge system purges the aft skirt and aft interstage of combustible gases andj distributes temperature controlled air or gas­eous nitrogen around electrical equipment in the aft skirt during the vehicle countdown.

The purging gas, supplied from a ground source through the umbilical, passes over the electrical equipment and flows into the aft interstage area. Some of the gas is directed through each of the auxiliary propulsion modules and exhausts into the interstage. A duct from the skirt manifold directs air or GN, to a thrust structure manifold. From the thrust structure manifold supply duct, a portion of air or GN, is directed to a shroud covering the hydraulic accumulator reservoir.

Temperature control is accomplished by two dual­element thermistor assemblies located in the gas­eous exhaust stream of each of the auxiliary propul­sion modules. Elements are wired in series to sense average temperature. Two series circuits are formed, each circuit utilizing one element from each thermistor assembly. One series is used for tem­perature control, the other for temperature record­ing.