Seismic Data Acquisition Using Frequency Adapter and Interpolation
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Solution Overview
Problem
Conventional seismic data acquisition systems face challenges with high energy consumption, computing load, and memory requirements due to the use of voltage-controlled crystal oscillators and complex interpolation filters, making them difficult and expensive to implement.
Innovation Solution
A data acquisition apparatus utilizing a temperature-compensated crystal oscillator (TCXO) with a sigma-delta modulator and an interpolation filter to achieve accurate data acquisition while minimizing energy consumption and computational complexity, using a frequency adapter to set the sampling frequency and compensating for frequency drift with a linear or quadratic interpolation function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage-controlled crystal oscillator (VCXO) controlled by a phase-locked loop (PLL) is used to maintain sampling clock frequency, then sampling frequency stability is improved, but energy consumption and hardware complexity increase significantly
Solution Approach 1:
The patent extracts the frequency control function from the VCXO-PLL system and relocates it to a software-based frequency adapter that operates on a simple crystal oscillator. This removes the complex VCXO and PLL hardware while preserving the frequency stability function through digital correction algorithms.
Solution Approach 2:
The patent replaces the mechanical/electrical VCXO-PLL frequency control system with a software-based frequency adaptation mechanism. The frequency adapter uses digital signal processing to compensate for frequency deviations, substituting complex hardware control with computational correction.
2Measurement precision
If a high-degree interpolation filter is used to correct sampling frequency errors, then data acquisition accuracy is improved, but computing load and memory requirements increase
Solution Approach 1:
The patent implements a dynamic frequency adaptation mechanism where the frequency adapter continuously adjusts interpolation parameters based on real-time frequency error measurements. This allows the system to use lower-degree filters while maintaining accuracy through adaptive parameter adjustment rather than relying on fixed high-degree filtering.
Solution Approach 2:
The patent changes the approach from using high-degree filter polynomials to using dynamic parameter adjustment in the interpolation process. The frequency adapter modifies interpolation coefficients based on measured frequency deviations, achieving accurate correction with computationally efficient low-degree filters.
3Measurement precision
If satellite-based positioning system gauging is continuously performed to correct local clock frequency error, then sampling synchronization is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic frequency gauging using satellite positioning signals at predetermined intervals rather than continuous gauging. The frequency adapter periodically corrects the crystal oscillator frequency based on satellite time references, achieving synchronization while allowing the system to operate in low-power mode between correction intervals.
Solution Approach 2:
The system uses its own periodic satellite signal reception to self-correct frequency drift without requiring continuous external power-intensive synchronization mechanisms. The local crystal oscillator maintains frequency between corrections, and the system autonomously adjusts based on periodic satellite time stamps.
Data Source
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AI summary
The invention concerns a data acquisition apparatus and method. According to the invention, - a first means providing a series of first digital sampled data (X) at an imperfect sampling frequency (FE) provided by a local clock (2) comprises sigma-delta modulation means (3) arranged to produce said series of first digital sigma-delta modulated data (X), - a second gauging means (50) for measuring the frequency error of the local clock (2) in view of a reference clock (6), - a third means for correcting the first data based at least on the measured frequency error, which comprises at least an interpolation means (4) to produce second digital data (Y) based on at least an interpolation of said first series (X) and compensating the measured frequency error (FD), and at least a decimation filter (7) for producing third digital data (A) based on said second digital data (Y), are provided.