Doppler Navigation System

The AN/ASN-128B is the US Army's standard lightweight helicopter airborne Doppler navigator and comprises three units: a receiver/transmitter/antenna, signal data converter and computer/display unit. A steering hover indicator can also be included as an option. With inputs from heading and vertical references, the system provides aircraft velocity, present position and steering information from ground level to above 10,000 ft. GEC-Marconi is under contract to the US Army to insert GPS capability into the AN/ASN-128. Identified as the AN/ASN-128B, the contract is to add a P/Y code GPS receiver, in the AN/ASN-128B signal data converter, and the modification of the computer display unit software to enable display of both Doppler navigation and GPS data. The contract is to modify 1,693 AN/ASN-128 systems currently installed in UH-60A/L Black Hawks and CH-47D Chinooks. These kits would also be applicable to most other AN/ASN-128 systems. GEC-Marconi has also developed a field kit enabling the AN/ASN-128 Doppler navigator to interface with a stand-alone Trimble GPS receiver, for continuous update of Doppler-derived present position with valid GPS data.


Volume: 20,724 cm
Weight: 13.61 kg
(hover indicator) 0.9 kg
Propagation: 4-beam configuration operating FM/continuous wave transmissions in K-band. Beam shaping eliminates the need for a land/sea switch. The single transmit/receive antenna uses full aperture in both modes to minimise beamwidth and reduce fluctuation noise
Number of waypoints: >100
Self-test: localisation of faults at LRU level by BITE
Reliability: (complete system) >2,100 h MTBF

Operational status : In production. Approximately 4,500 sets AN/ASN-128 have been manufactured, of which approximately 1,700 are AN/ASN-128B sets. In service with US Army Sikorsky UH-60A and UH-60L, Bell AH-1F, McDonnell Douglas AH-64A and Boeing CH-47D helicopters; also in Royal Australian Air Force Bell UH-1H, UH-60 and CH-47D, Hellenic Air Force UH-1H, Jordanian Army AH-1S, Pakistan AH-1S, South Korean CH-47, UH-60 and AH-1S, Spanish Army Eurocopter BO 105 and CH-47B, Taiwan Army CH-47B and Turkish UH-60. The system, with hover indicator, has been provided for the German Army Eurocopter BO 105, PAH-1, UH-1D and VBH helicopters. Also built under licence in Japan for the JASDF AH-1S and CH-47D. In use in Austria, Bahrain, Brunei, China, Denmark, Dubai, Egypt, Greece, Netherlands, Singapore, Spain, Taiwan and Thailand. Version kit deliveries started in the second quarter of 1996.

COMPANY NAME : GEC-Marconi Hazeltine Corp