Digital Frequency Measurement Using Phase Delay Correlation
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Solution Overview
Problem
Existing frequency measurement devices, both analogue and digital, face challenges such as high cost, power consumption, and complexity, particularly in covering wide frequency bands, with digital methods requiring complex signal processing and analogue methods being bulky and expensive.
Innovation Solution
A method and apparatus using digital components to measure signal frequency by digitizing the phase of a received signal, delaying it, calculating the phase difference, and determining the frequency without requiring expensive signal processing techniques or mixers, utilizing a Field Programmable Gate Array for efficient implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Delay Line Correlator is used for frequency measurement, then frequency measurement capability is achieved, but manufacturing cost and power consumption increase
Solution Approach 1:
The patent replaces the mechanical/analog Delay Line Correlator system with a digital implementation using a Field Programmable Gate Array (FPGA). The analog components (delay lines, mixers, correlators) are substituted with digital logic circuits that perform the same frequency measurement function through digital signal processing, thereby reducing manufacturing cost and complexity while maintaining measurement capability
Solution Approach 2:
The patent changes the operational parameters by using digital sampling and processing instead of continuous analog processing. The FPGA implements digital delay elements and correlators that operate on sampled signals, transforming the system from analog to digital domain and achieving cost reduction while preserving the frequency measurement function
2Measurement precision
If a Delay Line Correlator is used for frequency measurement, then frequency measurement capability is achieved, but physical volume increases
Solution Approach 1:
The patent merges multiple discrete analog components (delay lines, mixers, correlators, filters) into a single integrated digital system implemented in an FPGA. This consolidation integrates the functions of multiple separate components into one compact device, significantly reducing the physical volume required for frequency measurement while maintaining the same measurement precision
Solution Approach 2:
The FPGA-based implementation provides multi-functionality by able to perform frequency measurement across wide bandwidths and can be reconfigured for different measurement requirements. This universal platform replaces multiple specialized analog circuits with a single reconfigurable digital device, reducing overall system volume
3Measurement precision
If digital frequency measurement devices use Fourier transforms on sampled signals, then frequency analysis capability is achieved, but processing complexity increases
Solution Approach 1:
The patent extracts and implements only the essential frequency measurement function without requiring full-spectrum Fourier transform processing. By using a simplified digital correlator approach that specifically targets frequency measurement, the system achieves the necessary frequency analysis capability with reduced processing complexity compared to general-purpose FFT-based analyzers
Solution Approach 2:
The patent applies partial action by implementing a streamlined digital processing approach that performs only the necessary correlator operations for frequency measurement rather than complete spectral analysis. This selective processing reduces computational complexity while maintaining adequate frequency measurement precision for the intended application
4Adaptability or versatility
If wideband digital frequency measurement is implemented, then frequency range coverage is improved, but ADC complexity and processing requirements increase
Solution Approach 1:
The patent segments the wide frequency band into multiple narrower sub-bands and processes each sub-band separately using the digital correlator method. This segmentation allows the use of simpler ADCs and processors for each sub-band while collectively achieving wideband frequency measurement coverage through parallel or sequential processing of the divided bands
Solution Approach 2:
The patent implements dynamic frequency range selection where the measurement bandwidth and sampling rate can be adjusted based on the specific measurement requirements. This dynamic operation allows the system to optimize performance for different frequency ranges, using higher resolution for narrowband measurements and broader coverage for wideband applications, thereby reducing the need for maximum-capability components
Data Source
AI summary
A method of measuring the frequency of a received signal comprising the steps of: generating a first phase signal by digitising the phase of the received signal; delaying the first phase signal by a predetermined amount to generate a second phase signal; calculating a phase difference between the first and the second phase signals; and calculating the frequency of the input signal from the phase difference.