Telemetering through leaky waveguides is a combination of cable transmission and atmospheric transmission. This system carries radio signals in a confined space tube thus making signal transmission through tunnels, mines, and buildings possible. This paper discusses the history of development, the types of leaky waveguide, the transmission characteristics, and the performance evaluation methods.

A key problem in establishing and maintaining high quality communication repeater links among users, where the vehicle for retransmission is a synchronous orbit communications satellite, is that of enhancing the limited effective radiated power (ERP) capabilities of the smaller user against the not always so limited ERP capabilities of co-users or other sources of rf interference. The adaptive array which can supply narrow high gain custom shaped individualized beams weighted to reflect the ratio of user power to thermal noise and at the same time minimize the capacity reducing effects of intentional or unintentional rf interference emitters appears to be the most effective means of improving overall performance at least system cost.

Poisson particle flux is considered which intensity is a random process. The equations are presented for the construction of the intensity realization estimate corresponding to the minimum of a mean-square reconstruction error. The condition is derived the filfulment of which assures the existence of the optimal accumulation time minimising the reconstruction error. The calculation results are given to illustrate the dependence of a mean-square reconstruction error on the accumulation time.

With the implementation of a nationwide Air Traffic Control (ATC) automation system nearly completed the Department of Transportation/Federal Aviation Administration is devoting considerable attention to the integration of a data link capability into the system. This paper presents a description of the universal data link system and details of the system’s characteristics. A possible configuration of the data link system with the ATC automation system is also presented.

The data acquisition system of today’s research aircraft generally consists of a multiplicity of “black boxes” linked together by wiring cables of various lengths and sizes. This approach offers the user an “off-the shelf” type of flexibility to which he has become accustomed. It does not, however, provide for all the needs of an results demanded by today’s technology. The rising costs of flight test hours, the sophisticated airframes, and the minimum flight time allotted for actual flight test indicate a need to review existing data acquisition system technology and apply up-to-date technology. The NASA Flight Research Center at Edwards, California, initiated a review of its needs in the area of airborne data acquisition systems. The result was a new and powerful system called “AIFTDS-4000” (Airborne Integrated Flight Test Data System). AIFTDS is a high speed computer-controlled PCM system comprised of three basic units, the remote multiplexer de-multiplexer unit, the PCM processor, and the memory unit. The three units were designed and tested to meet the requirements of pertinent Mil-Specs for high performance aircraft. The signal conditioning, sensor excitation, and time code generator were designed as an integral part of the system and are not separate chassis. This paper discusses the design objectives established prior to actual hardware construction and compares these objectives with the final hardware.

AIFTDS-4000 has been developed as a modularly expandable instrumentation and control system primarily for use in aircraft and system flight test. The bidirectional data processing capacity of Remote Multiplexer/Demultiplexer Unit, however, permits the system to be applied to data processing and control loop functions as well as the classical role of a data gathering system. The basic system was developed for NASA-FRC under three different contracts; NAS4-1848 (the ACS and RMDU’s), NAS4-1940 (the integrated signal conditioner cards) and, NAS4-1943 (the expanded test set). The system comprises Airborne Hardware, Ground Support Equipment and Software. The Airborne Hardware is divided into two major elements; The Airborne Computing System (ACS), and the Remote Multiplexer/Demultiplexer Unit (RMDU). Ground Support Equipment is presently restricted to the ACS Test Set (ACS/TS) which permits total checkout of the ACS without the RMDU’s or checkout of the full AIFTDS, as well as performing the function of an autonomous mini-data reduction ground station and the Portable Address Generator which permits testing of one RMDU (or one zone of the airplane) without the ACS or the ACS/TS. Software may be grouped into System Checkout and Diagnostic Software, Flight Test Program Software and Quick Look/Reduction Software. The prototype AIFTDS-4000 was qualified in two stages; the RMDU was qualified in October 1972 with the ACS qualified in April 1973. The Expanded Test Set and supporting software were delivered in May 1973.

New generation satellites such as ERTS present a new challenge to the data recording industry. Continuous wideband data creates an enormous storage/retrieval problem. Recently developed high density tape storage solves the volume problem but does not provide fast access. Clearly, some cartridge type device is required. A similar problem faced the broadcast T.V. industry. Cartridge equipment was developed to allow automatic programming of short segments. This paper describes application of this technology to present and future data storage requirements. With the technique described, ERTS data can be segmented into blocks of ten frames each and stored in easily accessed tape cartridges.

Concepts of VHF analog magnetic recording are discussed; problem areas are reviewed; and solutions are outlined. Attention is drawn to the conductive-gap-spacer recording head. The unique field contours of this recording head with Alfesil pole faces are analyzed in relation to the recording of very short wavelengths. The field gradients of the unloaded head are computed for various conditions such as maximum magnetization depths, positions in the tape coating, and gap lengths. Comparison of the driven-gap-spacer head using Alfesil pole faces with the ferrite driven-gap-spacer head and the conventional ring-core head shows the Alfesil type to be the most effective for a-c bias VHF recording at very short wavelengths. Problems associated with short-wavelength recording and reproduction are reviewed. In spite of good short-wavelengths capabilities of the Alfesil head, the requirement for a high head-to-tape speed continues to be mandatory to minimize wavelength reproduction losses.

The two most basic requirements for air traffic control are surveillance and communications. The surveillance system in use today is the Air Traffic Control Radar Beacon System. It is based on World War II technology and is experiencing severe difficulties as the number of aircraft carrying transponders increases. This paper outlines the present FAA program to develop a new surveillance system which will eliminate the problems, will be compatible with the existing system and will also provide a digital data-link for collision avoidance and air traffic control purposes.

Results of an experiment involving the synchronous satellite relay of digital information at L-band between a ground station and a jet aircraft are described. Specific tests studied the performance of PSK signalling in conjunction with three distinct detection strategies for both the classical additive noise channels and the composite multipath channel (direct signal plus multipath). Tests were conducted at various signalto-noise ratios and direct signal-to-multipath ratios. Reasonable agreements with available non-fading and Rician fading channel theory is shown. Implications for the operational aeronautical satellite case are discussed.