IQ Baseband Correction Filters for Speaker-Drive Signal Purity
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Solution Overview
Problem
Radios that convert RF signals to in-phase and quadrature phase (IQ) baseband components face errors due to interference from other signals, leading to amplitude and phase discrepancies, which affect the quality of the output used to drive a speaker.
Innovation Solution
A device and method that control a local oscillator of an RF downmixing device to multiple baseband frequency offsets to determine and correct amplitude ratio and phase errors in IQ baseband components, using filter coefficients to compensate for these errors and generate corrected IQ baseband components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF signals are converted to IQ baseband components using a local oscillator, then the RF signal can be processed at lower frequencies, but interfering signals cause amplitude ratio errors and phase errors in the IQ baseband components
Solution Approach 1:
The patent applies preliminary action by measuring amplitude ratio errors and phase errors at multiple baseband frequency offsets before actual signal processing. These measurements are used to pre-calculate compensation filter coefficients that are then applied to correct IQ baseband components, preventing interference-related errors from affecting processing accuracy
Solution Approach 2:
The patent changes parameters by measuring errors at multiple baseband frequency offsets rather than a single offset. This multi-point measurement approach captures the frequency-dependent nature of interference effects, allowing for more accurate compensation filter coefficient calculation that adapts to different operating conditions
2Measurement precision
If filter coefficients are generated to compensate for amplitude ratio error and phase error, then IQ baseband component accuracy improves, but device complexity increases due to multiple frequency offset measurements and calculations
Solution Approach 1:
The patent applies self-service by having the system automatically perform error measurements at multiple frequency offsets and self-generate the appropriate compensation filter coefficients without external intervention. This automated self-calibration process reduces the need for manual configuration and simplifies operation despite the complex underlying calculations
Solution Approach 2:
The patent implements feedback by using measured amplitude ratio errors and phase errors from multiple frequency offsets to generate compensation filter coefficients. These coefficients are then applied to correct IQ baseband components, creating a closed-loop system where measurement results directly inform correction actions
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 effectively reduces errors in IQ baseband components, ensuring that the amplitudes are equal and phases are 90° out of phase, improving the quality of the output to drive a speaker by filtering out interference-related artefacts.
Implementation Method 1
controlling a local oscillator of a radio frequency downmixing device to a plurality of baseband frequency offsets over a range that includes a given baseband frequency offset
Implementation Method 2
converting a radio frequency signal to in-phase and quadrature phase baseband components
Data Source
AI summary
A device and method for correcting in-phase and quadrature phase (IQ) baseband components to drive a speaker is provided. The device: controls a local oscillator of an RF downmixing device to a plurality of baseband frequency offsets over a range that includes a given baseband frequency offset; determines, at the plurality of baseband frequency offsets, for a received RF signal, amplitude ratio error and phase error for respective IQ baseband components of the received RF signal; generates, using the amplitude ratio error and the phase error for the respective IQ baseband components, for the given offset, filter coefficients for a given baseband frequency range which compensates for respective amplitude ratio error and respective phase error for the given baseband frequency range; and filters, with the filter coefficients, IQ baseband components of the received RF signal, with the local oscillator operating at the given offset, to generate corrected IQ baseband components.