Several administrations have studied and developed distress alerting systems using geostationary satellites, which are called as satellite EPIRB (Emergency Position Indicating Radio Beacon) systems. In order to evaluate L-band (1.6GHz) satellite EPIRB systems, international cooperative tests coordinated by the CCIR (International Radio Consultative Commitee) were conducted through 1982 and early in 1983.

We have developed an experimentel satellite EPIRB system and participated in these tests which consist of laboratory tests, land tests, simulation tests and sea trials. This report describes the details of the satellite EPIRB system and the results of laboratory tests.

The experimental satellite EPIRB is of a buoy type. The antenna is a quadrifilar helical one and is contained in the top of the buoy. The transmitter and storage batteries are enclosed in its lower half. The transmitting frequency is 1642.375 MHz and the maximum transmitting power is 9 dBW. Modulation is FSK with a frequency shift of ± 120 Hz and the transmission rate is 63 bps.

In the satellite EPIRB demodulator, received signals are detected by a pair of FSK asynchronous detectors. The detected signals are converted to the digital form and superposed. After superposition is repeated by a specified number of times, bit and frame synchronization are performed, and error correction by BCH code is carried out.

Laboratory tests were conducted to evaluate and optimise the design, including the analysis of performances in fading conditions, and to ensure the C/N₀ range for further tests. In laboratory tests, the IF signals of the satellite EPIRB transmitter are sent to the demodulator after down conversion. These tests show that the satellite EPIRB transmitter and the demodulator operate properly in both non-fading and fading conditions. Furthermore, 99% error free message probability was found to be achieved within 60 sec at C/N₀ of 19 dBHz. It also gives that the optimum C/N₀ range was 18∼24 dBHz.

This report describes outlines of an evaluation experiment of a prototype monopulse SSR and its results. The monopulse SSR was made to examine its effectiveness in improving the azimuth accuracy of a conventional SSR. The results show that the monopulse SSR has a 1/2 or 1/3 time smaller azimuth error deviation and a better target detection rate than the conventional one. The results also show better performance of the monopulse SSR in decoding code pulses of garbled targets. In addition, its performance with an interrogation rate of 200pps is almost equal to that of the current 350 pps operation.

The SARPs (Standards And Recommended Practices) for MLS (Microwave Landing System) are being established as ICAO standard. The research and development tasks on MLS have been performed to obtain data for its installation and operation.

This paper describes the ground tests and simple environmental tests, using MLS elevation subsystem and a ground test van at Sendai airport.

The MLS elevation subsystem employs a full solid state 15 W transmitter. Beam pattern of the scanning antenna is shaped, for vertical plane, 1.5 degree beam width and the centerline emphasis characteristics is used for holizontal plane.

The ground tests are carried out to investigate the performance of the subsystem and the multipath propagation problems. The location of the scanning antenna is chosen so that the error characteristics with and without the multipath wave from buildings can be measured at same site.

The elevation angle error without the multipath wave, 0.04 degree (2σ) stays at about 1/3 of the ICAO specifications. Large angle errors are observed due to the multipath wave by the buildings nearby. However, if the scanning antenna with the centerline emphasis pattern did not be employed, the errors would become much larger in the multipath region.

The environmental test results indicate that the static angle error is affected significantly by the heavy rain falls and the operation period of the air conditioner in the scanning antenna.

The results obtained here are expected to be the basic data to give MLS elevation subsystem specifications, siting criteria and operational procedures.