FIR Filter Calibration for Fast Transfer Function Replication
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Solution Overview
Problem
Deriving the transfer function of a signal processing device in a time-efficient manner to program a digital filter that replicates its behavior is challenging.
Innovation Solution
A detector device with a controllable finite-impulse-response (FIR) filter, frequency selection block, comparison block, feedback loop, and interpolation block is used to determine feedback control signals at different frequencies, which are then interpolated to derive calibration information for programming the digital filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional methods are used to derive the transfer function, then measurement accuracy can be maintained, but the calibration process becomes time-consuming and inefficient
Solution Approach 1:
The patent implements continuous frequency sweeping instead of discrete frequency measurements, allowing the transfer function to be derived continuously across the entire frequency range. This eliminates the time loss associated with stepping through individual frequencies and maintains measurement accuracy throughout the calibration process.
Solution Approach 2:
The patent employs a feedback mechanism where the measured transfer function is continuously compared with the desired transfer function, and the digital filter coefficients are adjusted in real-time to minimize the error. This feedback loop enables rapid convergence to the optimal calibration parameters without requiring multiple discrete measurements.
2Measurement precision
If comprehensive frequency measurements are taken to ensure accuracy, then the transfer function can be precisely determined, but the calibration process becomes more complex and resource-intensive
Solution Approach 1:
The patent replaces complex mechanical or manual measurement systems with a digital signal processing approach. A single controllable oscillator and digital filter are used to synthesize and analyze signals across the frequency range, eliminating the need for multiple physical measurement devices and reducing system complexity while maintaining precision.
Solution Approach 2:
The patent changes the operating parameters of a single digital filter dynamically to match different frequency components of the input signal. By adjusting the filter coefficients in real-time based on the input frequency, the system can accurately measure the transfer function across the entire frequency range using a single device rather than multiple fixed-frequency devices.
Data Source
AI summary
A detector device for calibrating a digital filter to replicate a transfer function of a signal processing apparatus, comprising: a first input to receive a first signal; a second input configured to receive a response signal of the signal processing apparatus to the first signal; a controllable FIR filter; a comparison-block to compare the phase and amplitude after a correction has been applied by the controllable FIR filter; a feedback loop; and an interpolation-block; wherein the at least one detector is configured to determine, at least, the feedback control signal at a first frequency and at a second frequency, and wherein the interpolation-block is configured to interpolate to determine calibration information for programming of the transfer function of said digital filter.