Instrumentation - RF transmitter - S-band transmitter. Transducers - for anything that needs to be measured (pressure, voltage, stress, temperature). Tracking - C-Band transponder for range safety. Ground radar emits interrogation bulses spaced 6 microseconds apart. The signal is received by antennas on the Centaur tank. The transponder sends back signals in response to interrogation from ground. The round trip transit time of the pulsed signal is used to determine the range of the vehicle. Elevation and azimuth angles of the returning signals are processed to determine vheicle location. Multiplexer - handles 100 inputs, multiplexer selects an input and digitizes Instrumentation Elements: - Digital Computer Unit (DCU) - Remote Multiplexer Units (RMUs) - Signal Conditioner - Telemetry Transmitter (S-band) - Ring Coupler and Antennas Functions: - Collects and Transmits Vehicle Status - Reports Status during Vehicle Checkout - Provides Data for Post Flight Analysis Pulse code modulated (PCM) telemetry characterizes the instrumentation and telemetry function on Centaur D-1. Measurements that are not digital in nature are converted to digital representations and transmitted in a serial format. Measurements of several types are accommodated by signal conditioners that convert measurements to voltages usable by the PCM formatting hardware. The PCM format (sequence of transmission) and bit rate are each selectable from four choices by the program being executed by the DCU. Flexibility in formatting permits any reasonable choice of sequence. For prelaunch checkout of several airborne packages and general astrionics status monitoring, the PCM data are sent to the computer controlled launch set (CCLS) via a hardwire link through the PCM ground station. The S-band telemetry ground station network is provided and operated by the Eastern and Western Test Range. The facilities used depend on the specific mission profile and needs, and can include downrange ground stations, ships, or aircraft. SYSTEM OPERATION. The instrumentation and telemetry function collects, digitizes, and sends to the ground measurements made on the airborne systems. These measurements are sent in a preprogrammed PCM format. During the prelaunch activity, this PCM data is used to check out and establish the flight readiness of most of the on-board astrionics. For this function, the data downlink is via a coax in one of the umbilical cables. During flight, the PCM data are sent to the ground by radio frequency (RF) link for post-flight analysis. Measurements, made directly or by transducers, are collected by the remote multiplexer unit (RMU). Analog signals are scaled by the signal conditioners before reaching the RMUs, where they are digitized. Event signals go directly to the RMUs. The RMUs identify signals by addresses, and when addressed by a central controller unit (CCU) send these measurements to a central controller unit. Each PCM data word has eight bits. Analog signals are converted to digital by eight-bit converters that cover the signal range being serviced pow, mid, or high). Events are grouped in clusters of eight, all of which are reported when that group is addressed. Formatting, or the sequencing of PCM addresses, is done by programming a dedicated area of DCU memory. Up to four formats may be stored, and the one in use at any time is selected by the DCU program being executed. Four bit rates may be selected by the DCU program. The maximum selectable is 267K bits per second. This provides the capability to send about 30, 000 measurements per second. Growth. Over 1000 measurements are available for use in a format that can accommodate an additional 4000 measurements per second. These can be accommodated by adding circuit boards or RMUs and extra signal conditioners and by the inclusion of these measurements in the PCM format.