International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / During engine and airfield performance testing it is often necessary to acquire weather data at the airfield where the test is being conducted. The airborne data acquisition system (DAS) acquires data associated with flight parameters. A separate system records airport weather conditions. Many times the separate system is an Automated Terminal Information Service (ATIS) or the ground crew relaying wind speed, wind direction and temperature from a weather station. To improve this system, the weather station is designed to acquire and store the data in memory. Utilizing a second DAS that is remote to the airborne DAS poses several problems. First, it is undesirable to have many different data acquisition systems from which to process data. The problem then develops into one of integrating the ground weather DAS with the existing airborne DAS. Other problems of system integrity, compatibility and FCC licensing exist. Complete system integration while maintaining integrity and compatibility is overcome by controlling signal format, flow and timing and is discussed in detail. Further discussion of the issue of transmission is overcome by a technique called spread-spectrum and is used in accordance with FCC rules and regulations.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The RAH-66 Comanche flight test program required a state of the art Airborne Data Acquisition System consisting of: 1) A modular distributed system that uses a series of software programmable building blocks capable of signal conditioning all types of sensors. 2) A digital multiplexing system capable of combining various types of digital streams at high rates including Synchronous and Asynchronous PCM, MIL-STD-1553B, and RS-422 data streams. 3) A Data Combiner Unit that accepts synchronous PCM data streams from one to eight sources at 4 MBPS or less and a frame size of up to 8128 words each that outputs four independent PCM streams at 8 MBPS or less and a frame size of up to 16384 words. 4) A Data System Control Unit that controls the tape recorder, serves as the interface to the Pilot’s Control Unit and monitors/reports status of the data acquisition system to the Pilots Control Unit. 5) An Airborne Computer that provides the control and interface to the pilot & copilot instrumentation displays. 6) A Cockpit Instrumentation Pilot Display System consisting of a Main Unit Multi- Function Display, a Load Factor/Hub Moment Display and a Right Wing Flight Control Position Display. The Main Unit Multi-Function Display has the capability to display multiple graphic pages generated by the Airborne Computer. 7) The ability to record high speed avionics buses from the (Mission Equipment Package) MEP such as MIL-STD-1553B, (High Speed Data Bus) HSDB, (Processor Interconnect) PI Bus, (Data Flow Network) DFN and PCM utilizing the Ampex DCRsi-107 Tape Recorder.