Multi-Stage Frequency Conversion Circuit for Radio Wave Timepiece
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Solution Overview
Problem
Conventional multiband radio wave receiving apparatuses face issues such as increased size and cost due to multiple oscillating circuits, instability in local oscillating circuits, and inaccurate frequency conversion leading to poor detection accuracy.
Innovation Solution
A radio wave receiving apparatus that employs a multi-stage frequency conversion circuit without local oscillating or PLL circuits, using a frequency divider circuit to sequentially convert received signals into lower frequencies for accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple local oscillating circuits are provided for receiving different frequency standard radio waves, then the receiving capability for multiple bands is improved, but the circuit size and cost increase
Solution Approach 1:
The patent merges multiple local oscillating circuits into a single shared circuit. The frequency division circuit divides the reference frequency signal into multiple different frequencies, which are then supplied to a single local oscillating circuit. This single circuit can sequentially generate different local oscillating frequencies corresponding to different standard radio wave frequencies, eliminating the need for multiple separate oscillating circuits while maintaining multiband receiving capability.
Solution Approach 2:
The single local oscillating circuit is designed to perform multiple functions by generating different oscillating frequencies based on control signals. Instead of being dedicated to a single frequency, the circuit can adaptively generate local oscillating signals for receiving standard radio waves at different frequencies (e.g., 60 kHz, 77.5 kHz, 100 kHz), making it a universal component that replaces multiple specialized circuits.
2Measurement precision
If a PLL circuit is used for frequency synthesis, then the frequency accuracy is improved, but the power consumption and circuit complexity increase
Solution Approach 1:
The patent extracts and eliminates the PLL circuit from the frequency synthesis process. Instead of using a PLL circuit to generate the local oscillating signal, the system uses a frequency division circuit that simply divides a stable reference frequency signal to generate multiple precise frequencies. This removes the complex feedback control mechanism of the PLL while maintaining frequency accuracy through the stability of the reference frequency source.
Solution Approach 2:
The patent replaces the mechanical/feedback-based PLL system with a simpler digital frequency division approach. The frequency division circuit uses basic digital counting and division operations to generate precise frequencies from a reference signal, substituting the analog feedback control mechanism of the PLL with a more straightforward digital frequency synthesis method that consumes less power and has lower complexity.
3Adaptability or versatility
If the oscillatory frequency of the local oscillating circuit is changed by switching, then the adaptability to different frequencies is improved, but the stability and response time deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-calculating and preparing the frequency division ratios needed for different standard radio wave frequencies. The frequency division circuit is configured in advance to divide the reference frequency by specific integers to generate the exact frequencies needed for each band. This pre-prepared frequency division scheme allows rapid switching between frequencies without the stabilization time required by PLL circuits, as the division ratios are simply changed rather than the oscillation frequency being adjusted.
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 results in a stable, accurate, and cost-effective radio wave receiving apparatus with reduced power consumption and chip size, capable of receiving multiple standard radio waves with high precision.
Implementation Method 1
a frequency division circuit for dividing the reference frequency signal by frequency division ratios respectively, and outputting frequency division signals
Implementation Method 2
a mixer circuit for synthesizing a received signal with a frequency division signal, and outputting a synthesized signal
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
In the radio-wave receiving apparatus according to the invention, a signal received by a receiving antenna (621) is amplified and the amplified received signal is input into a multi-stage frequency conversion circuit (623) including a plurality of basic circuits (624n) connected in series. The multi-stage frequency conversion circuit (625) converts the frequency of the received signal from the antenna into frequencies based on signals (gn) input from the frequency divider circuit sequentially, thereby to output a signal "a" which is obtained by conversions into gradually lower frequencies. Detection is performed by a detection circuit (626) on the basis of the signal. Thereby, a radio-wave receiving apparatus which requires no local oscillating circuit nor a PLL circuit and is also stable in operation and high in accuracy is realized.