NZIF RF Demodulation With Adaptive Harmonic Spur Avoidance
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Solution Overview
Problem
Existing RF demodulation methods fail to effectively mitigate the impact of clock harmonic spurs in RF receivers, particularly in Near Zero Intermediate Frequency (NZIF) architectures, leading to reduced signal sensitivity in affected channels.
Innovation Solution
A method and circuit that determine the nearest harmonic of a clock signal from the central frequency of a received frequency band and set the intermediate frequency of the NZIF receiver to the difference between the central frequency and the nearest harmonic, or a nominal value if it's out of the frequency band, followed by signal amplification, mixing, filtering, and digital processing to suppress the harmonic spurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a NZIF receiver uses a fixed nominal intermediate frequency, then the receiver structure is simple, but clock harmonic spurs fall within the frequency band and degrade signal sensitivity
Solution Approach 1:
The patent applies dynamics by making the intermediate frequency adjustable rather than fixed. The system dynamically determines the nearest clock harmonic to the central frequency and sets the intermediate frequency to their difference, allowing the receiver to adapt to different operating conditions and avoid harmonic spurs while maintaining simple overall architecture
Solution Approach 2:
The patent changes the intermediate frequency parameter based on the relationship between clock signal frequency and received signal central frequency. By calculating the difference between these frequencies and setting the intermediate frequency accordingly, the system optimizes performance and eliminates harmonic interference without requiring complex additional hardware
2Object-affected harmful factors
If the intermediate frequency is set to the difference between central frequency and nearest harmonic, then harmonic spurs are suppressed, but additional frequency determination and calculation steps are required
Solution Approach 1:
The system performs self-service by automatically determining the nearest clock harmonic and calculating the appropriate intermediate frequency without external intervention. The receiver uses its own clock signal and received signal characteristics to autonomously configure the optimal intermediate frequency, eliminating the need for external calibration or complex additional hardware
Solution Approach 2:
The patent changes the intermediate frequency parameter based on the relationship between clock signal frequency and received signal central frequency. By calculating the difference between these frequencies and setting the intermediate frequency accordingly, the system optimizes performance and eliminates harmonic interference
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 proposed method significantly reduces the effect of clock harmonic spurs, improving signal sensitivity in channels affected by these spurs, thereby enhancing overall demodulation performance.
Implementation Method 1
mixing the amplified RF signal, in the first path, with an in-phase signal of a local oscillator frequency corresponding to the sum of said central frequency and of the intermediate frequency, and mixing the amplified RF signal, in the second path, with a quadrature signal of said local oscillator frequency
Data Source
AI summary
The present disclosure relates to a method for demodulating a radio frequency (RF) signal comprising the steps of determining the nearest harmonic of a clock signal from a central frequency (Frx) of a received frequency band; and, if said nearest harmonic is in said frequency band, setting an intermediate frequency (IF) of a Near Zero Intermediate Frequency (NZIF) receiver to the difference (SpurOffset) between said central frequency (Frx) and said nearest harmonic.