Citation
Abstract
We derive a simple, approximate link equation for a direct-detected, pulseposition-modulated (PPM) optical link. To enable this, we utilize a fixed field-of-view parameter. Scaling laws are determined from the link equation, and we show that the link may be divided into three regions as a function of the link parameters: a signal-powerdominant regime, a background-noise-dominant regime, and a bandwidth-limited regime. As a function of the range R, with all other parameters held constant, the data rate goes as 1/R2 in the signal-dominant regime, as 1/R4 in the noise-dominant regime, and saturates in the bandwidth-limited regime. An approximation to the optimum modulation order is determined for the signal-dominant case. The accuracy of the link equation is demonstrated by comparing its predictions with those produced by a link budget tool developed at JPL, showing good agreement. Finally, the equation is used to derive a critical data rate and noise power at which the link transitions from signal dominant to noise dominant.
Details
- Volume
- 42-199
- Published
- November 15, 2014
- Pages
- 1–14
- File Size
- 248.4 KB