An Analysis of Modulation Techniques for the Simultaneous Measurement of Range and Reflectance Information by an Airborne Laser Scanner.
Abstract
The performance of an airborne laser terrain mapper, which measures both slant range and reflectance, depends on the method used to modulate the output power of the laser. This study analyzes four possible modulation techniques for a direct-detection scanner which utilizes a semiconductor laser. The first technique is sinusoidal modulation of the laser output. Range performance is found to improve as the frequency of the modulating sinusoid is increased. The second technique modulates the laser output with a subcarrier which is a periodic FM chirp pulse. Range performance improves as the frequency deviation of the chirp is increased. However, this also increases the required detector bandwidth. The third technique modulates the laser with a subcarrier which is phase-modulated by a periodic pseudonoise (PN) code.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1976
- Accession Number
- ADA035291
Entities
People
- Robert Charles Chapuran
Organizations
- Air Force Institute of Technology