Accession Number : AD0660377

Title :   INTERIM REPORT OF PRECIPITATION EFFECTS ON OMEGA AIRCRAFT RECEIVERS.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Eisenberg,R. L. ; Williams,M. F.

Report Date : 10 AUG 1967

Pagination or Media Count : 50

Abstract : Omega is a very-low-frequency (VLF) radio navigation system which is characterized by very-long-range capability and relatively high accuracy. Fixes with an accuracy of one to two miles can be obtained by ships, aircraft and submerged submarines within a range of more than 5000 nautical miles. Propagation studies have shown that eight stations will provide radio navigation information over the entire earth. The performance studies of the Naval Research Laboratory's Omega aircraft receivers indicate that the use of the Omega navigation system for aircraft is entirely practical. Evaluation flights demonstrate that in good weather and in areas of reasonable signal strength Omega provides excellent navigation for aircraft. In flight the aircraft position is continuously and readily available from counters on the front panel. However, precipitation static effects have had a detrimental effect on receiver operation. Experiments were conducted to determine the effect of precipitation on the reception of VLF in aircraft. On the majority of the NRL flights a two-foot vertical blade antenna has been used (the AN/104AX). This antenna, because of its high base-to-ground impedance, is susceptible to signal output reduction when the base insulator is wetted. A two-foot polyethylene insulated rod antenna has improved characteristics under wetting conditions, but both the blade and the insulated rod are still susceptible to static pickup. A loop antenna appears to have improved characteristics with respect to both wetting and static pickup. The blade and the loop antennas were evaluated in the laboratory and in flight. Oscilloscope pictures demonstrate the results discussed. (Author)

Descriptors :   (*RADIO RECEIVERS, *RADIO NAVIGATION), (*PRECIPITATION STATIC, RADIO RECEIVERS), RADIO EQUIPMENT, VERY LOW FREQUENCY, AIRCRAFT ANTENNAS, AIRBORNE, PERFORMANCE(ENGINEERING)

Subject Categories : Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE