Adaptive Reference Frequency Correction for Fast Signal Synchronization
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Solution Overview
Problem
Existing radio communication devices face challenges in generating a stable reference frequency due to variations in crystal oscillators and require additional control circuitry for frequency correction, leading to increased costs and space requirements, as well as non-linear control characteristics.
Innovation Solution
A synchronization apparatus and method that uses a frequency error to convert an uncorrected reference frequency to an exact reference frequency through a frequency conversion unit, eliminating the need for external control means and achieving a linear control characteristic by decoupling from phase locked loop arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If crystal oscillators are used as reference oscillators, then frequency stability is improved, but frequency deviations occur due to temperature variations and non-linearities in the control path
Solution Approach 1:
The patent implements an automatic frequency control mechanism that continuously monitors the frequency deviation of the reference oscillator and applies corrective feedback. A frequency error detector measures the deviation from the nominal frequency, and a control signal is generated to adjust the oscillator frequency, thereby maintaining both stability and accuracy over temperature variations and time.
Solution Approach 2:
The patent employs temperature compensation techniques that dynamically adjust the oscillator parameters based on detected temperature changes. By changing the operating parameters of the crystal oscillator in response to temperature variations, the system maintains frequency accuracy while preserving the inherent stability of the crystal oscillator.
2Measurement precision
If automatic frequency control circuitry is added to correct frequency deviations, then frequency accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the frequency control functions with the existing phase-locked loop architecture. The frequency error detection and correction mechanisms are integrated into the PLL structure, sharing common components such as the voltage-controlled oscillator and feedback pathways. This merging approach provides accurate frequency control while minimizing additional circuitry and complexity.
Solution Approach 2:
The control circuitry designed in the patent serves multiple functions: it corrects reference oscillator frequency deviations, maintains PLL lock, and provides frequency synthesis. By making the control mechanism universal and multi-functional, the patent avoids dedicated separate circuits for each function, thereby reducing overall device complexity while maintaining frequency accuracy.
3Object-affected harmful factors
If extensive decoupling networks are used to reduce noise, then noise performance is improved, but device area and cost increase
Solution Approach 1:
The patent extracts and removes unnecessary decoupling components from the traditional frequency control circuitry. By carefully analyzing the noise sources and transmission paths, the invention identifies which decoupling elements are essential and which can be eliminated or minimized, thereby reducing the overall circuit area while maintaining adequate noise performance through optimized placement of essential decoupling capacitors.
Solution Approach 2:
The patent replaces extensive passive RC decoupling networks with active filtering and digital signal processing techniques. By using electronic noise cancellation and digital filtering in the frequency error detection path, the system achieves low noise performance without requiring large physical decoupling networks, thus reducing board area and component count.
4Ease of operation
If analog control signals are applied to varactor diodes for frequency correction, then frequency tuning is achieved, but linear control characteristic is lost
Solution Approach 1:
The patent replaces the analog varactor diode tuning mechanism with a digital frequency control approach. Instead of using voltage-controlled capacitance changes in varactor diodes, the system employs digital signal processing and programmable frequency synthesis to achieve frequency tuning. This substitution provides both the required frequency tuning capability and a linear, predictable control characteristic through digital algorithms.
Solution Approach 2:
The patent changes the control parameter from analog voltage to digital frequency words. By controlling the VCO through digital frequency specifications rather than analog voltage levels, the system achieves linear control characteristics where the output frequency is directly proportional to the input control value, eliminating the non-linear capacitance-voltage relationship of varactor diodes.
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 solution allows for precise frequency synchronization without additional tracking or control circuitry, reducing current consumption and enabling fast channel switching, while maintaining spectral purity and reducing costs and space requirements.
Implementation Method 1
a frequency conversion unit (90) that converts the uncorrected reference frequency to the exact reference frequency
Implementation Method 2
A Digital-to-Analog-Converter (DAC) is used to obtain an analog control signal. This analog control signal is applied to a varactor diode which changes its capacitance in dependence of the applied voltage and therefore the frequency of the crystal oscillator changes
Data Source
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AI summary
The present invention relates to an apparatus and method for providing synchronization of an output signal to a synchronization information. The synchronization is accomplished by providing coupling of a correction control information that controls a signal generating means, e.g. a phase locked loop arrangement (30) or a direct digital synthesis arrangement, to its exact frequency to a frequency conversion unit (90) that converts an uncorrected reference frequency to a correct or exact reference frequency. Thereby, the uncorrected reference frequency for the signal generating means (30) can be provided by a simple crystal oscillator (2) without any means for frequency control. The setting of the signal generating means (30) and the frequency conversion unit (90) can be done in a predetermined sequence which enables a user equipment to synchronize its reference frequency to the synchronization information emitted by a communication network.