Low Probability of Intercept Altimeters (LPIA)

The LPIA was developed and tested by the U.S. Navy for tri-service use. At its core is a high-speed digital signal processor and RF module operating on a frequency-hopped, spread spectrum, phase encoded, low-power signal waveform.

This highly effective waveform and signal processing allows the LPIA to extend altimeter accuracy, performance envelope (roll, pitch, and altitude), jamming resistance, and low probability of intercept capabilities far beyond existing altimeters.

High gain achieved in the receive signal processing allows for very low power output, resulting in a very simple RF design, eliminating multiple power amplifier circuits. These unique features help drive the in-field reliability to greater than 6800 hours.

The LPIA modular design allows for 100% backward compatibility with existing installations of the APN-194, APN-232, APN-209 and APN-171, eliminating A-kit costs by using interchangeable front panels, mounting plates, analog I/O cards and reuse of existing antennas. High reliability and extensive BIT coverage support cost-effective maintenance with minimal replacement and pipeline spare requirements. A common design reuses five of the seven subassemblies in all configurations. This allows users to share cost savings from a broader production base. Waveform and signal processing are all software controlled, allowing custom performance. Software is field-reprogrammable, keeping new install and software maintenance costs low.

LPIA benefits:

• Minimal probability of detection provided by low-wattage beam, increasing mission success
• High jam resistance
• Low life cycle cost and high dependability
• Reduced logistics burden through enhanced testability features
• Very high accuracy at all altitudes and attitudes
• Software-based processing allows for easy modification to meet new requirements
• High commonality across system variants