Robust satellite beacon receiver
A beacon receiver including: a Digital Fourier Transform (DFT) module including bins to acquire and to track a beacon signal; an acquisition processor to find acquisition frequency estimates of the beacon signal, to improve the acquisition frequency estimates with a generalized complex interpolator and to linearize the acquisition frequency estimates; and a tracking filter to track the acquired beacon signal and to calculate a tracking frequency estimates; and a synchronization manager to apply a frequency correction, to an oscillator, based on the acquisition frequency estimates or the tracking frequency estimates, wherein the DFT module uses a first bin size for the bins to acquire, a second bin size for the bins to track, and the first bin size is greater than the second bin size.
1. A beacon receiver comprising:
a Digital Fourier Transform (DFT) module comprising bins to acquire and to track a beacon signal;
an acquisition processor to find acquisition frequency estimates of the beacon signal, to improve the acquisition frequency estimates with a generalized complex interpolator and to linearize the acquisition frequency estimates; and
a tracking filter to track the acquired beacon signal and to calculate a tracking frequency estimates; and
a synchronization manager to apply a frequency correction, to an oscillator, based on the acquisition frequency estimates or the tracking frequency estimates,
wherein the DFT module uses a first bin size for the bins to acquire, a second bin size for the bins to track, and the first bin size is greater than the second bin size.
2. The beacon receiver of claim 1 , wherein the first bin size is greater than 6 Hz.
3. The beacon receiver of claim 1 , wherein a frequency correction error of the first bin size is greater than 0.1 Hz when the beacon signal has a frequency range of +/−1.5 kHz.
4. The beacon receiver of claim 1 , further comprising a Square Root Raised Cosine (SRRC) filter operating on a beacon symbol in the beacon signal at a symbol rate that is an integer multiple of a beacon symbol rate.
5. The beacon receiver of claim 1 , further comprising a Generalized Complex Lagrange (GCL) interpolator to improve the tracking frequency estimates.
6. The beacon receiver of claim 1 , wherein the acquisition processor improves the acquisition frequency estimates with a Generalized Complex Lagrange (GCL) interpolator.
7. The beacon receiver of claim 1 , further comprising a Signal-Noise Ratio (SNR) estimator to provide an SNR estimate to the acquisition processor.
8. The beacon receiver of claim 1 , further comprising a control to detect loss of the beacon signal and an SNR estimator to provide an SNR estimate to the control.
9. The beacon receiver of claim 6 , further comprising a control to restore a known good state for the acquisition processor when transitioning from an outage.
10. The beacon receiver of claim 9 , further comprising a beacon redundancy module, wherein the beacon signal comprises redundant beacon signals, and a control to switch from a first beacon signal of the redundant beacon signals to a second beacon signals of the redundant beacon signals, when an outage of the first beacon signal is detected.
11. The beacon receiver of claim 1 , wherein the DFT module to acquire the beacon signal and the DFT module to track the beacon signal are same.
12. The beacon receiver of claim 1 , wherein the tracking filter is a first order filter having an α feedback control set to 0.1.
13. The beacon receiver of claim 1 , wherein the beacon signal comprises a beacon symbol rate of 23.4 kilo symbols per second (ksps) signal, wherein the beacon signal comprises a frame having a duration of less than or equal to 100 ms.
14. The beacon receiver of claim 1 , wherein the first bin size is 30 Hz, and wherein the second bin size is 1 Hz.
15. The beacon receiver of claim 1 , wherein the beacon signal comprises a satellite beacon signal.
16. The beacon receiver of claim 1 , further comprising a Received Signal Strength Indicator (RSSI) estimator to provide a linearized RSSI estimate, wherein the RSSI estimator operates at a signal rate of the beacon signal.
17. A method for receiving a beacon signal comprising:
transforming, to acquire and to track, the beacon signal using a Digital Fourier Transform (DFT) module comprising bins;
acquiring the beacon signal by finding acquisition frequency estimates of the beacon signal, improving the acquisition frequency estimates using generalized complex interpolator, and linearizing the acquisition frequency estimates;
tracking the acquired beacon signal and calculating tracking frequency estimates; and
synchronizing an oscillator by applying a frequency correction based on the acquisition frequency estimates or the tracking frequency estimates,
wherein the DFT module uses a first bin size for the bins for the acquiring, a second bin size for the bins for the tracking, and the first bin size is greater than the second bin size.
18. The method of claim 17 , further comprising improving the tracking frequency estimates using a Generalized Complex Lagrange (GCL) interpolator.
19. The method of claim 17 , wherein a DFT module for acquiring the beacon signal and a DFT module for tracking the beacon signal are same.
20. The method of claim 17 , wherein the beacon signal comprises redundant beacon signals, and the method further comprises switching from a first beacon signal of the redundant beacon signals to a second beacon signals of the redundant beacon signals, when an outage of the first beacon signal is detected.