Doppler Radars for Helicopter Navigation

The Challenge

To complete their missions successfully in hostile territory, helicopters must have accurate, jam-resistant navigation systems that are able to operate effectively and dependably in all mission scenarios. These conditions may require high-speed, low-level flight over featureless, unknown terrain, and in the presence of enemy jamming.

BAE Systems' Solution

BAE Systems' Doppler navigation systems provide accurate, independent, jam-resistant navigation in friendly and hostile environments, and in military operation situations where global positioning system (GPS) interference is likely.

BAE Systems’ AN/ASN-128 Doppler navigation system is used on more than 15,000 helicopters in 35 nations.

The ASN-128B/C provides a low-cost home for a single-card GPS receiver, minimizing the helicopter modifications needed to add GPS. The combined system displays navigation and guidance data to the flight crew in a format similar to the ASN-128, reducing training costs. Size and weight of the ASN-128 are unchanged. GPS receivers can be provided in either military P(Y) or civilian codes. The ASN-128B/C includes a MIL-STD-1553 interface card in the computer display unit to enable communication with other helicopter systems. Existing helicopter cabling is not affected by this change.

BAE Systems’ AN/ASN-157 provides velocity and navigation data to other avionics in the aircraft, including inertial navigation systems (INS) and combined INS and GPS. Microstrip antenna technology reduces antenna size, weight, and cost. All electronic circuits are integrated into one card, with reliability of 7,300 hours. The ASN-157 is integrated into the Apache Longbow GPS and INS, and is scheduled to replace the current ASN-128 and ASN-137 Dopplers on all Apaches.

Doppler navigation system variants:

• AN/ASN-128 Doppler navigation system
• AN/ASN-157 Doppler navigation set
• AN/ASN-128B/C Doppler and GPS navigation set
• AN/ASN-128D Doppler and GPS navigation set