Citation
Abstract
The ability to track very weak signals from distant spacecraft is limited by the phase instabilities of the received carrier signal and of the local oscillator employed by the receiver. These instabilities ultimately limit the minimum loop bandwidth that can be used in a phase-coherent receiver, and hence limit the ratio of received carrier power to noise spectral density which can be tracked phase-coherently. This article presents a method for near-real time estimation of the received carrier phase and additive noise spectrum, and: optimization of the phase locked loop bandwidth. The method was used with the breadbvard DSN Advanced Receiver to optimize tracking of very weak signals from the Pioneer 10 spacecraft, which is now more distant than the edge of the solar system. Tracking with bandwidths of 0.1 Hz to 1.0 Hz reduces tracking signal threshold and increases carrier loop SNR by 5 dB to 15 dB compared to the 3 Hz bandwidth of the receivers now used operationally in the DSN. This will enable the DSN to track Pioneer 10 until its power source fails near the end of the century.
Details
- Volume
- 42-91
- Published
- November 15, 1987
- Pages
- 141–157
- File Size
- 772.8 KB