Telemetry Signal Date-Stamping via Coherent Phase Demodulation
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Solution Overview
Problem
Current ranging signal receivers for aircraft and spacecraft location suffer from insufficient date-stamping accuracy, leading to location errors of several kilometers due to time-based jitter introduced by re-sampling processes, which is inadequate for precise positioning.
Innovation Solution
A method and receiver system that utilize coherent demodulation and phase locking to accurately determine the transition dates of a modulated signal, reducing variance in bit transitions and improving synchronization, allowing for more precise date-stamping by integrating demodulated samples over symbol periods and resolving phase ambiguities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If re-sampling is used to synchronize with symbol rate, then symbol synchronization is achieved, but time-based jitter increases date-stamping error
Solution Approach 1:
The patent replaces the mechanical re-sampling process with a mathematical phase extraction method. Instead of physically re-sampling the signal at symbol rates, the invention extracts phase information directly from the received signal using correlation with a local replica of the pseudo-random code, thereby eliminating the time-based jitter inherent in re-sampling operations.
Solution Approach 2:
The patent changes the parameter used for synchronization from time-based re-sampling to phase-based correlation. By measuring the phase difference between the received signal and a local replica across multiple code periods and averaging these measurements, the system achieves sub-microsecond date-stamping accuracy without the jitter problems of traditional re-sampling methods.
2Use of energy by moving object
If passive ranging techniques are used to save resources, then transmission resources are reduced, but signal presence and data processing complexity increase
Solution Approach 1:
The patent extracts the ranging information directly from the existing communication signal by correlating the received signal with a local replica of the transmitted pseudo-random code. This extraction process isolates the phase information needed for ranging while discarding the rest of the communication data, thereby simplifying the processing complexity despite using passive techniques.
3Ease of manufacture
If conventional date-stamping methods are used, then processing is simple, but location accuracy is insufficient
Solution Approach 1:
The patent continuously measures and averages the phase difference over multiple code periods rather than relying on a single measurement. This continuous observation and averaging process maintains processing simplicity while significantly improving location accuracy by reducing the impact of random noise and jitter on the date-stamping measurement.
Data Source
AI summary
A method of date-stamping reception of digital data of a signal coherently modulating the carrier or sub-carrier, and utilizing the properties of such a modulation to improve the date-stamping thereof. Thereby accurately correcting the date-stamping of a pilot sequence (known pattern), and reducing the variance on the date-stamping of the transitions of the bits.