Satellite-to-Ground Link Quality From Partial-Burst Telemetry
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Solution Overview
Problem
Existing satellite communication systems face challenges in estimating signal power and quality with low complexity, low cost, and rapid accuracy, particularly due to the limitations of Continuous Waveform pilot signals and the resource-intensive recovery of downlink symbol streams.
Innovation Solution
A partial burst demodulation and decoding method is employed, utilizing a partial burst signal quality estimation and synchronization system that analyzes a portion of the burst header for signal quality estimation, avoiding the need for full burst demodulation and decoding, thereby reducing computational burden and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a CW pilot signal is used for terrestrial station monitoring of downlink signal quality, then the signal is easily recovered and analyzed at the terrestrial station, but the high power spectral density creates interference of other communication channels and regulatory problems
Solution Approach 1:
The patent extracts only the necessary portion of the downlink signal (preamble or header containing known symbols) for quality estimation purposes, rather than using a separate CW pilot signal. This allows signal quality monitoring without the harmful high power spectral density of dedicated CW pilots, as the estimation is performed on existing signal portions that are already being transmitted for other purposes.
Solution Approach 2:
The patent makes the preamble/header symbols serve multiple functions: they are used both for signal quality estimation and as part of the normal data transmission structure. This eliminates the need for separate CW pilot signals, as the existing signal structure is made multi-functional to perform both data transmission and quality monitoring tasks.
2Measurement precision
If the downlink symbol stream is recovered and analyzed for signal quality estimation, then accurate quality metrics can be obtained, but significant resource costs are incurred due to complex modulation, encoding, and encryption
Solution Approach 1:
The patent extracts only the preamble or header portion of the downlink signal for quality estimation, which contains known symbols that do not require full demodulation and decoding. By taking out only this essential subset for analysis, the system achieves accurate quality metrics without the significant resource costs of processing the entire complex modulated and encrypted symbol stream.
Solution Approach 2:
The patent applies partial action by performing quality estimation on only a portion of the signal (preamble/header with known symbols) rather than the complete downlink stream. This partial processing approach provides sufficient accuracy for quality monitoring while dramatically reducing the computational resources needed compared to full symbol stream recovery and analysis.
3Measurement precision
If full burst demodulation and decoding is performed for signal quality estimation, then complete signal analysis is achieved, but high processing complexity and computational burden result
Solution Approach 1:
The patent extracts only the essential preamble or header portion containing known symbols for quality estimation purposes. This extraction approach provides sufficient measurement precision for signal quality monitoring while avoiding the high processing complexity and computational burden of performing full burst demodulation and decoding of the entire signal.
Solution Approach 2:
The patent implements partial action by performing quality estimation on a subset of the signal (preamble/header) rather than the complete burst. This partial processing achieves the necessary measurement precision for quality monitoring while significantly improving productivity by reducing the computational burden compared to full demodulation and decoding.
Data Source
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AI summary
Disclosed methods of terrestrial station monitoring of downlink signal quality include receiving a sequence of samples of reference symbol slots of a downlink burst, and estimating a time offset between a local clock and a timing of a symbol pattern carried by the reference symbol slots, using a local copy of the reference symbol pattern. A corresponding time correction is applied to the sequence of samples to form time corrected samples of symbols carried by the reference symbol slots. A frequency offset between the time corrected samples of the symbols carried by the reference symbol slots and a local clock is estimated. A corresponding frequency compensation is applied to the time corrected samples, forming time/frequency compensated samples of the symbols carried by the reference symbol slots. A signal to noise plus interference ratio (SNIR) estimation data, and corresponding estimate of signal path, is generated, based on moments of the time/frequency compensated samples.