Citation
Abstract
This work establishes the threshold performance of noncausal smoothing filters used for tracking residual carrier signals when performance is limited by both phase process noise and additive receiver noise. Previous work [1] based entirely on linear theory predicts significant improvements in phase estimation by using smoothing filters as compared with using causal phase-locked loops (PLLs). For phase process noise having a 1=f3 spectral density, which is typical of many oscillators, linear theory predicts a reduction in phase estimation error of 5 dB for the same phasenoise and receiver-noise magnitudes. Alternatively, linear theory predicts the ability of a smoother to track a 7.5-dB weaker signal with the same mean-square phase error, under the same conditions of phase process noise. Simulations show that the smoothers achieve an efiective loop signal-to-noise ratio (SNR) within 0.5 dB of linear theory when the linear theory predicts an efiective loop SNR as low as 11.4 dB. Under the same conditions, an optimum PLL would have a linear-model efiective loop SNR of only 6.4 dB and would perform more than 1-dB worse that this, with many cycle slips.
Keywords
Details
- Volume
- 42-141
- Published
- May 15, 2000
- Pages
- 1–16
- File Size
- 390.6 KB