FIR Filter Calibration via Feedback and Interpolation
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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, phase and amplitude comparators, and an interpolation block determines feedback control signals at different frequencies to calibrate a digital filter, using discrete Fourier transforms and interpolation to derive calibration information for programming the filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional 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 a feedback loop where the detector device measures the transfer function of the signal processing device, and the measured data is used to program the digital filter. This closed-loop approach enables iterative optimization of the calibration process, allowing the system to converge to accurate results more quickly than conventional open-loop methods.
Solution Approach 2:
The patent creates a digital copy of the analog signal processing device's transfer function by measuring it with the detector device and programming the digital filter with the derived calibration data. This digital replica allows for rapid re-calibration and adjustment without requiring physical changes to the analog components, significantly reducing calibration time.
2Adaptability or versatility
If a digital filter is programmed to replicate the transfer function, then system adaptability is improved, but the complexity of deriving and programming the filter increases
Solution Approach 1:
The detector device is integrated within the signal processing system itself, allowing the system to perform self-calibration without requiring external measurement equipment. The detector uses the system's own components (signal generator, signal processing device, ADC) to measure and derive the transfer function, reducing external complexity while maintaining adaptability.
Solution Approach 2:
The detector device serves multiple functions: it acts as a signal generator, a measurement instrument, and a calibration tool. By combining these functions into a single integrated device, the patent reduces the overall system complexity while enabling the digital filter to be programmed with accurate transfer function data for improved adaptability.
3Measurement precision
If frequent re-calibration is performed to maintain system performance, then measurement precision is maintained, but energy consumption increases
Solution Approach 1:
The patent enables periodic re-calibration of the digital filter by using the detector device to measure the transfer function at intervals. This periodic measurement approach maintains measurement precision over time while allowing the system to return to normal low-power operation between calibration events, thus managing energy consumption effectively.
Data Source
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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.