Wireless Station Frequency Correction Without CNR Degradation
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Solution Overview
Problem
Existing wireless communication systems face challenges in correcting frequency errors in RF signals during operation, particularly in simulcast communication systems, where high frequency accuracy is required, and existing correction methods impair the carrier-to-noise ratio or require multiple voltage control circuits.
Innovation Solution
A wireless station equipped with an oscillator, error calculator, modulation data generator, and modulator that calculates frequency errors using a Global Navigation Satellite System (GNSS) signal and adjusts modulation data to correct frequency errors in real-time by conducting frequency modulation, allowing for continuous operation without degrading the carrier-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage control circuits are used to correct frequency errors in oscillators, then frequency accuracy is improved, but the carrier-to-noise ratio is impaired
Solution Approach 1:
The patent introduces a phase modulation signal as an intermediary to transmit frequency error correction information between the wireless station and the oscillator. Instead of directly controlling the oscillator voltage (which degrades carrier-to-noise ratio), the system modulates phase information onto a carrier wave, allowing frequency error correction data to be transmitted without directly interfering with the oscillator's carrier signal and thus preserving the carrier-to-noise ratio.
Solution Approach 2:
The patent replaces the direct voltage control mechanism (electrical/mechanical system) with a phase modulation communication system. Instead of using voltage control circuits to directly adjust oscillator frequency (which introduces noise), the system uses phase-modulated signals to convey frequency error information, substituting a cleaner signal processing approach for the noisy voltage control approach.
2Measurement precision
If multiple voltage control circuits are implemented to correct frequency errors, then frequency accuracy is improved, but device complexity increases
Solution Approach 1:
The patent makes the phase modulation signal serve multiple functions: it carries both the primary communication data and the frequency error correction information simultaneously. This multi-functionality eliminates the need for separate dedicated control circuits for frequency correction, as the same communication infrastructure is used for both purposes, thereby reducing overall device complexity while maintaining frequency accuracy.
Solution Approach 2:
The patent merges the frequency error correction function with the existing communication signal transmission function. By combining frequency correction data with regular communication data in a single phase-modulated signal, the system eliminates the need for separate voltage control circuits, reducing device complexity while achieving frequency accuracy improvement.
3Measurement precision
If frequency error correction is performed during operation, then frequency accuracy is improved, but the system requires additional correction apparatus
Solution Approach 1:
The patent implements a self-service mechanism where the wireless station automatically generates, transmits, and processes frequency error correction signals without requiring external correction apparatus. The system monitors its own frequency errors through phase modulation and autonomously adjusts its operation, eliminating the need for separate external correction devices while maintaining high frequency accuracy during operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables real-time correction of frequency errors in the reference signal output from the oscillator, maintaining the center frequency of the RF signal at the target value and ensuring stable operation without impairing the carrier-to-noise ratio.
Implementation Method 1
The modulator includes a voltage controlled oscillator into which the reference signal and the modulation data are input, the voltage controlled oscillator providing an oscillation frequency varying depending on the modulation data.
Data Source
AI summary
A wireless station includes at least one oscillator to output a reference signal, and an error calculator to calculate a frequency of the reference signal and calculate a frequency error by subtracting a target frequency of the reference signal from the calculated frequency of the reference signal. The wireless station further includes a modulation data generator to generate modulation data by adding a correction value, varying in negative correlation with the frequency error calculated by the error calculator, to data to be transmitted, and a modulator to conduct frequency modulation on the basis of the modulation data and the reference signal.