RF Receiver Interference Removal Using Segmented PSK Demodulation
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Solution Overview
Problem
Existing RF receivers struggle to effectively identify and remove interfering higher-order PSK signal components due to intermodulation and multiplication of signals and noise, which complicates the determination of carrier frequency and symbol rate.
Innovation Solution
The RF receiver employs a lower-order PSK demodulation circuit to generate locking parameters, which are then used by a higher-order PSK demodulation circuit to lock onto and demodulate the RF receive signal, thereby determining the interfering PSK signal component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional delay and multiply circuits are used to determine carrier frequency and symbol rate of interfering signals, then lower-order interfering signals can be identified, but higher-order modulated signals cannot be effectively processed due to noise floor growth from intermodulation
Solution Approach 1:
The patent segments the interference excision process into two distinct stages: first using a lower-order PSK demodulation circuit to generate locking parameters, then using a higher-order PSK demodulation circuit with those parameters to determine the interfering signal characteristics. This segmentation allows each circuit to operate in its optimal range, resolving the contradiction between measurement precision for lower-order signals and adaptability to higher-order signals.
Solution Approach 2:
The lower-order PSK demodulation circuit performs preliminary action by generating locking parameters (carrier frequency and symbol rate estimates) before the higher-order PSK demodulation circuit attempts to determine the interfering signal characteristics. This preliminary action provides a foundation that enables accurate processing of higher-order signals that would otherwise be obscured by noise.
2Adaptability or versatility
If complex demodulator and remodulator circuits are incorporated to handle higher-order signals, then signal processing capability improves, but system complexity increases and may not operate adequately
Solution Approach 1:
The patent divides the complex demodulation task into two separate circuits: a lower-order PSK demodulation circuit for generating locking parameters and a higher-order PSK demodulation circuit for determining interfering signal characteristics. This segmentation reduces the complexity burden on any single circuit while maintaining the ability to process higher-order signals.
Solution Approach 2:
The lower-order PSK demodulation circuit acts as an intermediary that generates locking parameters, which then serve as input to the higher-order PSK demodulation circuit. This intermediary approach simplifies the overall system architecture by breaking down the complex task into manageable stages with clear interfaces between components.
3Productivity
If interference excision is performed on higher-order PSK signals without preliminary locking, then direct processing is attempted, but the noise floor grows due to intermodulation making rate line discernment difficult
Solution Approach 1:
The patent implements preliminary action by using the lower-order PSK demodulation circuit to generate locking parameters before the higher-order PSK demodulation circuit attempts to discern rate lines and determine interfering signal characteristics. This preliminary locking action prevents noise floor growth from obscuring the rate lines, maintaining measurement precision while enabling productive interference removal.
Solution Approach 2:
The lower-order PSK demodulation circuit provides beforehand cushioning by generating accurate locking parameters that protect the higher-order demodulation process from noise floor growth. This cushioning effect ensures that rate lines remain discernible even when processing higher-order modulated signals with interfering components.
Data Source
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AI summary
A Radio Frequency (RF) receiver 30 may include a lower-order phase shift keying (PSK) demodulation circuit 40 configured to generate at least one locking parameter when performing a lower-order PSK demodulation of an RF receive signal having an interfering PSK signal component. A higher-order PSK demodulation circuit 44 has a higher order than the lower-order PSK demodulation circuit 40, and locks to the RF receive signal using the at least one locking parameter from the lower-order PSK demodulation circuit. The higher-order PSK demodulation circuit 44 performs the higher-order PSK demodulation of the RF receive signal based upon locking to the RF receive signal to determine the interfering PSK signal component.