DOPPLER OPTICAL NAVIGATOR.
Abstract
The objective of this program is to determine the feasibility of novel laser techniques for Doppler optical navigation. The performance goal is the measurement of ground speed with 5 m/sec accuracy at a maximum altitude of 300 mi. Analysis and experimental results indicate that amplitude modulation can be used to improve the coherence of the return signal. At optical frequencies the ground is a diffuse reflector whereas at a subcarrier frequency (or amplitude modulation frequency) it is not. As a result, a higher signal-to-noise ratio is realized with an amplitude-modulated wave, enabling velocity to be measured more accurately. Performance is optimized if a subcarrier frequency is chosen between 100 kc and 100 mc; but, theoretically, it makes no difference which frequency is chosen within this range. A comparison of the performance of cuprous chloride with hexamine electrooptic modulators indicated that hexamine shows more promise. An analysis of various filtering techniques showed that a subcarrier heterodyne receiver with a phase-locked oscillator filter will provide the best performance. Further, this analysis showed that optical heterodyne techniques will not improve the performance of the receiver. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 19, 1963
- Accession Number
- AD0426411
Entities
People
- G. Clubine
- L. J. Nicastro
- T. E. Penn
- W. J. Hannan