Low-Intermediate Frequency Receiver Dynamic LO Switching
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Solution Overview
Problem
Low-intermediate frequency receivers face poor blocking performance and adjacent channel selectivity issues due to sensitivity to I/Q unbalance and interference, which are not adequately addressed by existing zero-intermediate frequency or static low-intermediate frequency solutions.
Innovation Solution
A method involving selecting a local oscillator signal from a preset frequency set for frequency mixing, determining the energy ratio of interference to useful signal, and switching to another local oscillator signal if the ratio exceeds a preset threshold to reduce adjacent channel interference, thereby improving adjacent channel selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a zero-intermediate frequency solution is adopted, then integration is improved and volume is reduced, but blocking performance deteriorates by 19 dB compared to superheterodyne solution
Solution Approach 1:
The patent implements dynamic local oscillator frequency switching based on signal detection. The receiver dynamically adjusts the local oscillator frequency between two preset values (f1 and f2) depending on whether an interfering signal is detected, transforming the static zero-IF architecture into a dynamic system that adapts to interference conditions to maintain blocking performance while preserving integration benefits
Solution Approach 2:
The patent changes the operating parameter (local oscillator frequency) of the receiver system. By switching the local oscillator frequency between two different values, the system alters the frequency relationship between the desired signal and interfering signals, thereby improving blocking performance without sacrificing the compact integrated design of the zero-IF architecture
2Reliability
If a static low-intermediate frequency solution is adopted, then blocking performance is improved to approximate superheterodyne solution, but adjacent channel selectivity deteriorates by about 24 dB
Solution Approach 1:
The patent employs dynamic switching of the local oscillator frequency between two preset values based on real-time signal detection. This dynamic approach allows the system to maintain good blocking performance by selecting appropriate frequency offsets, while preserving adjacent channel selectivity by avoiding fixed frequency positions that would cause 24 dB degradation
Solution Approach 2:
The patent implements periodic switching between two local oscillator frequencies (f1 and f2). By alternating between these frequencies based on interference detection, the system achieves both good blocking performance and maintained adjacent channel selectivity, avoiding the continuous degradation seen in static solutions
3Measurement precision
If local oscillator is switched cyclically to determine offset direction, then interference determination is achieved, but cyclic error codes occur due to calling state
Solution Approach 1:
The patent uses feedback from signal energy detection to control local oscillator frequency switching. The system detects the energy of received signals and uses this feedback information to determine whether to switch between frequency f1 and f2, thereby accurately determining interference presence without generating cyclic error codes that plague purely cyclic switching approaches
Solution Approach 2:
The patent performs preliminary signal energy detection before switching the local oscillator frequency. By detecting the presence and characteristics of interfering signals in advance, the system determines the appropriate frequency offset to use, avoiding the cyclic error code problem that occurs when switching is performed without prior signal assessment
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
This approach enhances the adjacent channel selectivity and blocking performance of low-intermediate frequency receivers by dynamically adjusting the local oscillator signal to minimize interference, outperforming static solutions and zero-intermediate frequency receivers in anti-blocking performance.
Implementation Method 1
selecting a local oscillator signal from a preset local oscillator frequency set as an initial local oscillator signal to perform frequency mixing on an input signal, so as to obtain a low-intermediate frequency signal
Data Source
AI summary
Disclosed in the present application are a method for improving performance of a low-intermediate frequency receiver, a storage medium, and a receiver. The method comprises: selecting a local oscillator signal from a preset local oscillator frequency set as an initial local oscillator signal to perform frequency mixing processing on an input signal, so as to obtain a low-intermediate frequency signal comprising a low-intermediate frequency useful signal and a low-intermediate frequency interference signal; determining whether an energy ratio of the low-intermediate frequency interference signal to the low-intermediate frequency useful signal is greater than a first preset ratio; and if the energy ratio is greater than the first preset ratio, selecting another local oscillator frequency from the preset local oscillator frequency set as the current local oscillator signal to process the input signal. In this way, the present application can improve the adjacent channel selectivity of a low-intermediate frequency receiver.