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This report describes the hardware design of the TCAS Experimental Units (TEU's) constructed by Lincoln Laboratory to support the design and validation of the Traffic Alert and Collision Avoidance System (TCAS) for the FAA. Section 1.0 presents an overview of the operation of hte TEU's, in order to give some context for the hardware design. References are given to more extensive descriptions of the TCAS system operation and software design. Section 2.0 constitutes the bulk of the report, and is a detailed description of the TEU hardware design. The purpose of this description is to document the design details of the equipment which was used to develop and validate the signal processing techniques and algorithms which appear in the TCAS II Minimum Operational Performance Standard, the TCAS National Standard and various technical reports listed in the references. A second purpose is to provide design guidance to potential TCAS II manufacturers, in the form of a detailed description of a feasible design with documented performance. Finally, this document is a manual for future use and maintenance of the TEU's.

Experimental Traffic Alert and Collision Avoidance System (TCAS) avionics developed for the FAA at MIT Lincoln Laboratory are described. The objective of the program under which this equipment was developed was to assess the feasibility of providing a small, low-cost unit for general aviation usage. The experimental general aviation TCAS (GATCAS) avionics incorporates a new system architecture using a microprogrammed sequencer, a 16-bit microprocessor and a low-power, solid state sransmitter appropriate to the class of aircraft expected to employ GATCAS. The general aviatio unit is designed to operate below 10,000 feet in densities of up to 0.02 aircraft/nmi^2, and to provide a pilot warning time (TAUR) of 25 seconds. Assuming a track acquisition time of 10 seconds and a maximum closing speed of 300 knots, the required theoretical range of GATCAS is 3.4 nmi. The report includes (as an appendix) a cost analysis for general aviation TCAS avionics.