Clock Multiplexing for AFC-Corrected Cellular and Stable GPS Timing
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Solution Overview
Problem
Current multi-functional cellular applications require separate clock references for cellular transceiver and GPS receiver modules, leading to increased complexity and cost due to the need for two independent clock modules, one of which is not AFC-corrected, causing abrupt frequency changes that are not acceptable to the GPS receiver.
Innovation Solution
A system with a single clock module generating an AFC-uncorrected clock reference shared between both modules, where the cellular transceiver performs AFC to generate an AFC-corrected clock reference internally, reducing the need for separate clock modules and minimizing abrupt frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single clock module is used for both cellular transceiver and GPS receiver, then device complexity and cost are reduced, but abrupt frequency changes from AFC correction disrupt GPS receiver operation
Solution Approach 1:
The clock reference signal is segmented into two paths: one for GPS receiver that maintains stability, and another for cellular transceiver that accepts AFC correction. The GPS clock reference is extracted directly from the single clock module without AFC processing, while the cellular transceiver receives a separate AFC-corrected clock reference generated internally.
Solution Approach 2:
An intermediary clock distribution architecture is introduced where the single clock module provides a base clock reference that is then processed differently for each receiver. The GPS receiver receives the unprocessed reference while the cellular transceiver generates its own AFC-corrected reference, acting as an intermediary solution between the conflicting requirements.
2Reliability
If a second non-AFC-corrected clock module is added for GPS receiver, then GPS operation stability is improved, but device cost and complexity increase
Solution Approach 1:
The patent merges the clock generation functions by using a single clock module to provide the base clock reference for both GPS and cellular transceiver. The cellular transceiver internally generates the AFC-corrected clock reference from this shared reference, eliminating the need for a separate dedicated GPS clock module while maintaining stability.
Solution Approach 2:
The single clock module serves multiple functions by providing a universal clock reference that can be used directly by the GPS receiver while also serving as the basis for generating the AFC-corrected reference for the cellular transceiver. This multi-functional approach reduces the total number of clock modules required.
Data Source
AI summary
A wireless communications system includes a clock module, a communications module, a receiver module, and a baseband module. The clock module is configured to generate a first clock reference. The communications module is configured to operate in response to the first clock reference and independent of a corrected clock reference. The corrected clock reference is generated by performing automatic frequency correction on the first clock reference according to an automatic frequency correction signal. The receiver module is configured to (i) receive radio frequency signals from a wireless medium, and (ii) in response to the corrected clock reference, generate baseband signals based on the received radio frequency signals. The baseband module is configured to (i) receive the baseband signals, and (ii) in response to a selected one of the first clock reference and the corrected clock reference, generate the automatic frequency correction signal based on the baseband signals.