Polar Modulator Amplitude Up-Sampling for Origin-Crossing Interpolation
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Solution Overview
Problem
Polar modulator architectures experience poor performance at higher data sampling frequencies due to signal discontinuities and high frequency information introduced by rapid dips and rises in polar amplitude and phase transitions, which conventional interpolation methods fail to address effectively.
Innovation Solution
An up-sampling process is employed in polar modulators that involves identifying origin crossings in the IQ plane, selectively applying inversion to the polar amplitude sample stream, interpolating, and removing the inversion to generate an up-sampled polar amplitude sample stream, using a controlled inverter and interpolator to smooth signal discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional interpolation methods are used to up-sample the polar amplitude sample stream, then the processing speed is maintained, but the interpolation accuracy deteriorates due to signal discontinuities and high frequency information
Solution Approach 1:
The patent applies preliminary action by identifying origin crossings in the IQ plane before performing interpolation. The system detects when the signal passes through the origin and selectively inverts the polar amplitude sample stream at these critical points. This preliminary preparation removes signal discontinuities before the interpolation process, ensuring that conventional interpolation methods achieve high accuracy without requiring complex processing.
Solution Approach 2:
The patent employs inversion by selectively inverting the polar amplitude sample stream at origin crossings. Instead of directly interpolating the original signal with discontinuities, the system inverts the signal segments that contain high frequency information, then performs interpolation on the inverted signal. This inversion technique transforms the problematic discontinuous signal into a form that is easier to interpolate accurately, effectively removing high frequency artifacts while maintaining processing speed.
2Reliability
If the polar amplitude sample stream is up-sampled at higher data sampling frequencies, then the modulation performance is improved, but the signal discontinuities and high frequency information increase
Solution Approach 1:
The patent implements feedback by continuously monitoring the polar amplitude sample stream to identify origin crossings. The system uses feedback from the signal itself to determine when inversion is needed. By detecting origin crossings in real-time and selectively inverting the signal at these points, the system adapts to the actual signal characteristics, removing discontinuities and high frequency information that would otherwise degrade modulation performance at higher sampling frequencies.
Data Source
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AI summary
Systems and methods for up-sampling a polar amplitude sample stream in a polar modulator are disclosed. In some embodiments, an example process includes receiving, at a polar modulator, an in-phase sample stream and a quadrature sample stream which together characterize a data signal in an IQ plane. The process includes generating a polar amplitude sample stream and a polar phase sample stream. The process includes generating an up-sampled polar amplitude sample stream by: identifying an origin crossing of the data signal in the IQ plane; responsively adjusting an inversion trigger; selectively applying an inversion to the polar amplitude sample stream based on the inversion trigger; interpolating the selectively inverted polar amplitude sample stream; and removing the inversion from the interpolated selectively inverted polar amplitude sample stream. The process includes modulating a carrier signal using the up-sampled polar amplitude stream and the polar phase sample stream.