Frequency Difference Estimator for Asynchronous Antenna Signals
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Solution Overview
Problem
Existing technologies face challenges in measuring and minimizing frequency offsets between signals from separate antennas that do not share a common local oscillator reference, which is essential for coherent combining of signals.
Innovation Solution
A device and method that utilize a frequency meter with a phase meter, quadrant transition state machine, and frequency meter counter to measure the frequency difference between signals from two antennas by detecting phase differences, quadrant transitions, and accumulating these transitions over a desired interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signals from multiple antennas are coherently combined to improve signal to noise ratio, then signal quality is improved, but frequency offset between antennas with asynchronous local oscillator references must be minimized which increases system complexity
Solution Approach 1:
The patent introduces a frequency offset measurement device as an intermediary component that measures the frequency offset between signals from multiple antennas. This device includes a phase meter to measure phase difference, a frequency counter to count cycles, and calculates frequency offset based on the relationship: frequency offset = (phase difference change over time) / (2π). By providing an automated measurement mechanism, the system can compensate for frequency offsets without requiring complex manual calibration or synchronization hardware.
2Measurement precision
If frequency offset measurement device is added to enable coherent combining of signals from antennas with asynchronous local oscillators, then signal alignment is improved, but device complexity increases
Solution Approach 1:
The frequency offset measurement device performs multiple functions using a unified architecture: it measures phase difference between signals, counts frequency cycles, calculates frequency offset, and can be applied to any number of antennas with asynchronous local oscillators. The device uses standard components (phase meter, frequency counter, processor) that can handle various signal frequencies and antenna configurations, making it a universal solution rather than requiring specialized hardware for each antenna pair.
Solution Approach 2:
The patent replaces complex mechanical frequency synchronization systems with an electronic measurement and calculation approach. Instead of using mechanical frequency references or synchronized oscillators, the system electronically measures the phase difference between signals using a phase meter, counts frequency cycles using a frequency counter, and computationally determines the frequency offset. This substitution of mechanical systems with electronic and computational methods reduces physical complexity while maintaining measurement precision.
Data Source
AI summary
A device and method for estimating the frequency difference between antennas having asynchronized local oscillator references includes a frequency meter configured for connection with radio frequency signals from two antennas and configured to output a measured frequency difference between baseband filtered signals of two antennas. The frequency meter includes a phase meter, a quadrant transition, and a frequency meter counter. The phase meter receives in-phase and quadrature pairs of filtered signals and output a phase difference between the pairs. The quadrant transition state machine receives the phase difference, detects a quadrant associated with the phase difference, and detects a change between the detected quadrant and a previously detected quadrant. The frequency meter counter then accumulates the quadrant transitions and direction over a desired interval to establish a measure of the frequency difference between the two radio frequency signals input into phase meter.