NZIF RF Demodulation Using Dynamic IF Spur Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RF demodulation methods fail to effectively mitigate the impact of clock harmonic spurs on RF signals, leading to reduced signal sensitivity in affected channels.
Innovation Solution
A method and circuit that dynamically set the intermediate frequency of a Near Zero Intermediate Frequency (NZIF) receiver to the difference between the central frequency of the received signal and its nearest harmonic, and employ signal processing techniques to filter and decimate the signals, thereby reducing the effect of harmonic spurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a NZIF receiver uses a fixed intermediate frequency, then the receiver structure is simple, but clock harmonic spurs fall within the received signal bandwidth causing degradation
Solution Approach 1:
The patent implements dynamic intermediate frequency selection by determining the nearest harmonic of the clock signal from the central frequency of the received signal band and setting the intermediate frequency to the difference between them. This dynamic adjustment ensures that the intermediate frequency always places harmonic spurs outside the received signal bandwidth, resolving the contradiction between simple fixed structure and harmonic spur avoidance.
2Reliability
If the intermediate frequency is set to avoid harmonic spurs, then signal quality improves, but additional frequency calculation and adjustment complexity is introduced
Solution Approach 1:
The patent changes the intermediate frequency parameter dynamically based on the relationship between the central frequency of the received signal band and the clock signal harmonics. By calculating the nearest harmonic and setting the intermediate frequency to their difference, the system adapts the frequency parameter to avoid spurs while maintaining manageable computational complexity through a systematic approach.
3Ease of operation
If traditional fixed intermediate frequency is used, then the demodulation process is straightforward, but signal sensitivity is reduced in channels affected by harmonic spurs
Solution Approach 1:
The patent performs preliminary determination of the nearest harmonic and calculation of the appropriate intermediate frequency before the demodulation process. This preliminary action ensures that the intermediate frequency is pre-configured to avoid harmonic spurs, thereby maintaining signal sensitivity without complicating the subsequent demodulation operations.
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
Significantly improves signal sensitivity in channels affected by harmonic spurs, reducing computational burden and maintaining signal quality.
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
Figure 1~2
Figure 3
Figure 4
AI summary
The present disclosure relates to a method for demodulating a RF signal comprising the steps of: determining the nearest harmonic of a clock signal from a central frequency (Frx) of a received frequency band; 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.