Citation
Abstract
A carrier-arraying technique was demonstrated at Goldstone in May 1990. The Block IIE receivers of two 34-m antennas, DSS 12 and DSS 15, were arrayed together to receive S-band (2.3-GHz) signals from the Pioneer 11 spacecraft. Carrier phases m the two receivers were synchronized by the analog phase-lock loops, and carrier signals were added at an intermediate frequency to enhance tracking performance. The receiver at DSS 15, which had been unable to lock up and track the Pioneer 11 signal by itself due to a wider tracking loop bandwidth and a higher system temperature, was now able to track the carrier and produce usable baseband signals. The receiver at DSS 12 achieved a reduction of the rms phase error, increasing the telemetry symbol SNR by an average of 0.35 dB. The baseband signals from both antennas were then synchronized and combined using the existing Baseband Assembly, thereby achieving a total symbol SNR increase of 2.5 + 0.7 dB relative to DSS 12 alone. Baseband combining would have been impossible without carrier arraying In this case. In analyzing the performance of carrier arraying, previous models only treated the rms phase errors caused by the ground receiver thermal noises. But as very narrow tracking loops were employed, the contribution of phase noises transmitted from the spacecraft or generated in the ground-receiver oscillators should be included. In this article, a more comprehensive model is presented to permit evajuation of both thermal and phase-nolse effects. The analysis agrees well with observed data.
Details
- Volume
- 42-106
- Published
- August 15, 1991
- Pages
- 307–334
- File Size
- 1.0 MB