DDS Synthesizer Phase Control for Stable Multi-Frequency Measurement
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Solution Overview
Problem
In measurement technology, especially in network analysis, achieving precise frequency and phase relationships between high-frequency signals is challenging, particularly when multiple signal generators are involved, leading to difficulties in maintaining accurate phase relationships during frequency changes, which results in low measuring speed and high software effort.
Innovation Solution
A measuring device equipped with a synthesizer device, including a direct digital synthesizer, and control devices with phase discriminators and integer frequency dividers, ensures precise generation and control of high-frequency signals with known phase relationships, using integer division factors to maintain stability and flexibility in signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fractional dividers are used to generate different frequencies from a common reference signal, then frequency flexibility is improved, but phase relationship stability deteriorates and measuring speed decreases due to slow phase correction
Solution Approach 1:
The patent divides the frequency synthesis function into separate direct digital synthesizer modules, each capable of generating signals with known phase relationships. By segmenting the system into independent DDS units rather than using a single reference signal with fractional dividers, the patent maintains phase coherence while achieving frequency flexibility through the DDS architecture.
Solution Approach 2:
The patent replaces the mechanical/phased-array approach of fractional dividers with a direct digital synthesis system. This substitution eliminates the need for slow software-based phase correction by inherently generating signals with known phase relationships through digital signal processing, thereby improving both phase stability and measuring speed.
2Adaptability or versatility
If multiple independent signal generators are used to generate signals of different frequencies, then frequency flexibility is improved, but phase relationship control deteriorates
Solution Approach 1:
The patent merges multiple signal generation functions into integrated direct digital synthesizer modules. Each DDS unit generates multiple signals with known phase relationships, combining the frequency flexibility of independent generators with the phase coherence of a unified system, thereby eliminating the need for complex external phase synchronization.
Solution Approach 2:
The direct digital synthesizer modules are designed to be multi-functional, capable of generating signals at different frequencies while maintaining known phase relationships. This universal approach allows the same hardware to serve both frequency flexibility and phase control requirements, unlike independent signal generators that require additional synchronization infrastructure.
3Measurement precision
If phase correction is performed after frequency changes using software methods, then phase relationship accuracy is improved, but measuring speed deteriorates due to slow correction processes
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing phase correction values in lookup tables within the direct digital synthesizer. When frequency changes occur, the system immediately switches to the pre-computed phase values without requiring slow software-based correction, thereby maintaining high phase accuracy while preserving fast measuring speed.
Solution Approach 2:
The system uses periodic updating of phase correction values at predetermined intervals or frequency steps. This periodic action allows the system to maintain accurate phase relationships through pre-computed values rather than continuous software correction, improving measuring speed while preserving phase accuracy at critical measurement points.
Data Source
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AI summary
The invention relates to a measuring apparatus having a synthesizer device (49c), at least two control devices (86c, 86d), and at least two controlled oscillators (64c, 64d). The synthesizer device (49c) comprises at lest one direct digital synthesizer (50c, 50d) and generates at least two signals of known phase ratios. Signals generated by the synthesizer device (49c) form reference signals of at least one control device (86c, 86d). Signals formed by the control devices (86c, 86d) control the controlled oscillators (64c, 64d). The measuring apparatus comprises only frequency dividers dividing by whole-number dividing factors.