Low-IF Receiver Adaptive Frequency Selection
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Solution Overview
Problem
Low-IF receivers in mobile communications face signal degradation due to spurious interference and image frequencies, which current technologies struggle to effectively mitigate without complicating the circuit structure.
Innovation Solution
A method where a low-IF receiver actively monitors for image frequencies and selects a local oscillator frequency to minimize their impact, shifting spurious interference outside the desired signal band and using adaptive intermediate frequency selection to reduce image frequency interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If low-IF reception is used to simplify receiver circuitry, then device complexity is reduced, but image frequencies are introduced that degrade signal integrity
Solution Approach 1:
The patent applies dynamics by making the intermediate frequency selection adaptive rather than fixed. The receiver dynamically selects from multiple possible intermediate frequencies based on monitoring signal conditions and detecting image frequency interference, allowing the system to adapt to different operational scenarios and maintain signal integrity while using simplified low-IF circuitry
Solution Approach 2:
The patent implements feedback mechanisms where the receiver actively monitors for image frequency interference and uses this information to adjust its operation. The monitoring of signal conditions and adaptive selection of intermediate frequencies based on detected interference creates a closed-loop system that compensates for the inherent limitations of low-IF reception
2Device complexity
If fixed intermediate frequency is used in low-IF reception, then device complexity is reduced, but adaptability to different signal conditions deteriorates
Solution Approach 1:
The patent transforms the static intermediate frequency selection into a dynamic process. Instead of using a single fixed intermediate frequency, the receiver is configured to select from multiple possible intermediate frequencies based on monitored signal conditions, providing adaptability without requiring complex real-time frequency synthesis mechanisms
Solution Approach 2:
The patent applies preliminary action by pre-defining multiple possible intermediate frequencies that the receiver can select from. This allows the system to have adaptive capabilities without requiring complex real-time decision-making mechanisms, as the choices are prepared in advance based on expected operational scenarios
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 robustness of low-IF receivers by reducing signal corruption from spurious and image frequencies, improving signal integrity and reception quality without increasing circuit complexity.
Implementation Method 1
a local oscillator component in an RF receiver with an oscillation frequency that substantially matches to the carrier frequency
Implementation Method 2
low intermediate frequency (low-IF) reception to receive and demodulate wirelessly received radio signals
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
A method of processing signals may include receiving a first signal being modulated on a first carrier frequency in a predefined frequency band; measuring a signal level of a received second signal at a frequency higher than the first carrier frequency; and measuring a signal level of a received third signal at a frequency being lower than the first carrier frequency. The method may further include selecting an intermediate mixing carrier frequency from a plurality of intermediate mixing carrier frequencies for processing at least a portion of the received first signal based on the signal level of the second signal and the signal level of the third signal. The method may additionally include performing intermediate frequency reception of at least a portion of the received first signal using the selected intermediate mixing carrier frequency.