GNSS Receiver Signal Correlator Time Division Multiplexing
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Solution Overview
Problem
Current GNSS receivers face increased complexity, cost, and power consumption when supporting a larger number of ranging codes to improve reliability, as each additional code requires more hardware and signal decoding circuits.
Innovation Solution
A GNSS receiver design incorporating a code generator, signal correlator circuit with a circular buffer, and processor that uses a time division multiplexing scheme and multiple clock rates to efficiently cross-correlate signals with multiple ranging codes, allowing sharing of correlator circuit modules and reducing the number of required hardware components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of supported ranging codes is increased to improve reliability, then the receiver can decode signals from more satellite transmitters, but the hardware complexity, cost, and power consumption increase
Solution Approach 1:
A single signal correlator circuit is designed to perform multiple functions by supporting a large number of ranging codes through time division multiplexing. The correlator circuit can be configured to correlate with different ranging codes at different time intervals, allowing one hardware unit to replace what would traditionally require multiple separate correlator circuits. This multi-functional design enables the receiver to support more satellite transmitters while avoiding proportional increases in hardware complexity.
Solution Approach 2:
The signal correlator circuit employs dynamic time division multiplexing to switch between different ranging codes during operation. By dynamically allocating time slots to different code correlations and using a second clock rate that is a multiple of the first clock rate, the system can adaptively manage the correlation process for multiple codes without requiring static dedicated hardware for each code. This dynamic approach reduces overall system complexity while maintaining the ability to process multiple codes.
2Adaptability or versatility
If the number of signal decoding circuits is increased to support more ranging codes, then more satellite signals can be decoded, but power consumption increases
Solution Approach 1:
The signal correlator circuit serves as a universal decoding unit that can handle multiple ranging codes through time division multiplexing. Instead of having separate power-consuming decoding circuits for each code, a single circuit is shared across multiple codes by switching between them in time slots. This significantly reduces the total power consumption while maintaining support for a large number of ranging codes and corresponding satellite transmitters.
Solution Approach 2:
The system uses periodic time division multiplexing with a second clock rate that is a multiple of the first clock rate to cycle through different ranging code correlations. This periodic switching allows the single correlator circuit to systematically process multiple codes over time, ensuring that each code receives adequate processing attention while avoiding the need for continuous operation of multiple parallel circuits, thereby reducing overall power consumption.
Data Source
AI summary
A global navigation satellite system (GNSS) receiver can include a code generator, a signal correlator circuit, and a processor. The code generator can generate samples of a plurality of ranging codes associated with corresponding GNSS transmitters. The signal correlator circuit can receive, according to a first clock rate, samples of a signal from a GNSS transmitter, and update, according to a second clock rate and a time division multiplexing scheme, cross-correlation values indicative of cross-correlations between the signal and a subset of the plurality of ranging codes. The second clock rate can be equal to at least multiple times the first clock rate. The signal correlator circuit can determine final results of the cross-correlation values based on the updating of the cross-correlation values, and a processor can identify the GNSS transmitter among the plurality of GNSS transmitters based on the final results of the cross correlation values.