Delay circuit for the time delay of a radio-frequency signal and device for reducing interferences using said circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing interference cancellation systems for radio communication systems are ineffective in eliminating broadband noise and high-speed communication signal interference due to limited frequency range and stability issues in phase and amplitude adjustments, leading to degraded communication quality.
Innovation Solution
A delay circuit with an all-pass filter and two anti-resonant circuits is used to linearize phase shift over a wide frequency range, allowing precise adjustment of phase, amplitude, and time shift of the compensation signal, enabling effective interference cancellation across a broader frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional all-pass filter is used for delay circuit, then the phase shift is linearized over a narrow frequency range, but the frequency range for effective interference cancellation is limited
Solution Approach 1:
The patent combines multiple all-pass filter sections with different central frequencies (first all-pass filter section with central frequency f1, second all-pass filter section with central frequency f2) to create a composite delay circuit. This merging of multiple filter sections with overlapping frequency ranges extends the overall frequency range over which the phase shift remains linear, allowing effective interference cancellation across a broader spectrum while maintaining phase linearity in each individual section.
2Reliability
If the time delay between direct signal and transmitted signal is not precisely adjusted, then the cancellation effectiveness is reduced to approximately 30 dB, but adjusting time delay requires precise frequency-dependent control
Solution Approach 1:
The patent changes the parameter of central frequency for each all-pass filter section (f1, f2, etc.) to create overlapping frequency coverage. By selecting central frequencies such that f2 - f1 < 30% of f1, the filters work together to maintain consistent time delay characteristics across a wider frequency range, reducing the need for complex frequency-dependent time delay adjustment while achieving cancellation effectiveness greater than 30 dB.
3Object-affected harmful factors
If broadband noise is emitted by the transmitter, then interference occurs across the entire receiving frequency band, but conventional cancellation systems only work in a reduced frequency range
Solution Approach 1:
The patent segments the broadband frequency range into multiple overlapping frequency bands, each handled by a dedicated all-pass filter section. The first all-pass filter section handles frequencies around f1, the second section handles frequencies around f2, and their overlapping coverage ensures continuous cancellation across the entire broadband range. This segmentation approach transforms a single wideband problem into multiple manageable narrowband problems that can be solved independently and combined.
4Measurement precision
If amplitude and phase are perfectly adjusted at a central frequency, then cancellation is effective at that frequency, but frequency deviations of 50 MHz cause significant performance degradation
Solution Approach 1:
The patent creates a multi-functional delay circuit where each all-pass filter section serves multiple purposes: it provides phase linearity for its own central frequency while also contributing to the overall frequency coverage when combined with other sections. This universal approach allows the same circuit structure to handle multiple frequency ranges effectively, increasing frequency tolerance from ±50 MHz around a single frequency to a much broader range when multiple sections are combined.
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 solution provides improved stability and constant delay over a wider frequency range, effectively eliminating interference between radio communication systems, particularly in scenarios with diverse communication protocols like LTE and Tetrapol, enhancing communication quality.
Implementation Method 1
an all-pass filter having a given central frequency configured to linearize the phase shift of the output signal with respect to the input signal as a function of the frequency over a first frequency range
Implementation Method 2
a first anti-resonant circuit having a first central frequency and a second anti-resonant circuit having a second central frequency, the all-pass filter and the two anti-resonant circuits being configured and arranged to linearize the phase shift of the output signal with respect to the signal d input as a function of frequency over a second frequency range including the first range
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The delay circuit (10) for the time shift of an input radio frequency signal (Vin), said delay circuit (10) comprising an all-pass filter (1) having a given center frequency (f0) configured to linearize the phase shift of the output signal (Vout) with respect to the input signal (Vin) as a function of frequency over a first frequency range (B1) and characterized in that it comprises a first anti-resonant circuit (2) having a first center frequency (f1) and a second anti-resonant circuit (3) having a second center frequency (f2), the all-pass filter (1) and the two anti-resonant circuits (2, 3) being configured and arranged to linearize the phase shift of the output signal (Vout) with respect to the input signal (Vin) as a function of frequency over a second frequency range (B2) including the first range (B1).