Bluetooth RDF Phase Data via Single Receiver Chain
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Solution Overview
Problem
Providing radio direction finding (RDF) capability in mobile devices using Bluetooth signals is challenging due to the high cost and physical space requirements of multiple Bluetooth antennas with separate receiver chains, and the fast switching speed needed to sample signals within a single symbol period is not feasible.
Innovation Solution
A method and apparatus that sample signals from multiple antennas within each period of constant frequency, determine data symbol values, and use these values to eliminate phase variations, allowing for the generation of relative phase data without the need for simultaneous sampling or fast switching, utilizing a single RF receive chain and exploiting known data patterns in Bluetooth signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple Bluetooth antennas with separate receiver chains are provided, then RDF capability is achieved, but cost and physical space increase prohibitively
Solution Approach 1:
The patent merges multiple antenna signals into a single receiver chain by sequentially connecting each antenna to the same receiver through switching. This combining approach maintains RDF capability while eliminating the need for multiple separate receiver chains, thereby reducing hardware complexity and physical space requirements
Solution Approach 2:
The single receiver chain is designed to handle signals from multiple antennas universally. The receiver can be configured to receive and process signals from any of the multiple antennas in sequence, making it a multi-functional component that replaces what would traditionally require multiple dedicated receivers
2Measurement precision
If antennas are switched at high speed to sample within a single symbol period, then simultaneous sampling is achieved, but switching speed requirements are not feasible
Solution Approach 1:
The patent applies preliminary action by capturing and storing signal samples from each antenna in sequential order before processing. Instead of requiring simultaneous sampling through high-speed switching, the system preliminarily accumulates samples from each antenna during its turn, then processes them together to achieve the equivalent of simultaneous sampling measurement
Solution Approach 2:
The system uses periodic action by cycling through each antenna in sequence at a manageable switching speed. Each antenna is connected to the receiver for a complete symbol period, allowing sampling at feasible switching rates while maintaining measurement accuracy through the periodic collection and subsequent joint processing of all antenna samples
3Device complexity
If a single receiver chain is used for multiple antennas, then hardware requirements are reduced, but phase variations between samples must be eliminated
Solution Approach 1:
The patent uses feedback by determining data symbol values from the received signals and using this determined information to compensate for and eliminate phase variations. The system feeds back the symbol value information to correct the phase differences introduced by sequential sampling, thereby recovering accurate relative phase data between antennas
Solution Approach 2:
The determined data symbol values act as an intermediary that mediates between the sequentially sampled signals from different antennas. By using these symbol values to eliminate phase variations, the system creates a reference framework that allows accurate comparison of phase relationships despite the sequential sampling process
Data Source
AI summary
A method of determining relative phase data of a signal received at multiple antennas, the signal being a phase-modulated data signal having a plurality of periods of constant frequency, the method comprising: within each period of constant frequency, sampling the signal received by a first one of the multiple antennas and sampling the signal received by at least one different one of the multiple antennas; determining from the received samples a data symbol value represented by the received signal for each of the periods of constant frequency; and using the determined data symbol value information to eliminate phase variations between the samples received by the different antennas within each constant frequency period arising from the modulation of the data signal to generate relative phase data for said different antennas.