Widening Synchronization Range in DMT Single Pilot Tone Systems
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Solution Overview
Problem
Discrete multitone (DMT) multicarrier single pilot tone systems face synchronization errors exceeding 360°, leading to system resets and undesirable jitter when correcting for phase errors and temperature drift, as conventional protocols do not allow for error detection beyond 360° using a single pilot tone.
Innovation Solution
Combining phase errors from a second two-bit constellation data channel with the pilot tone channel, converting the data channel's phase error to a 0-90° range, and using a resolver circuit to calculate the actual phase error up to and beyond 360°, allowing for wider synchronization range without introducing jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pilot tone channel is used for synchronization, then the system complexity is reduced, but the synchronization range is limited to within 360° and cannot detect errors beyond this range
Solution Approach 1:
The patent combines the phase error information from the single pilot tone channel with phase error information from a data channel to achieve wider synchronization range detection. By merging these two sources of phase error data, the system can detect errors beyond 360° while still using only one pilot tone channel, thus maintaining low system complexity while improving measurement precision.
Solution Approach 2:
The patent uses a second error detector circuit as an intermediary to extract phase error information from the data channel. This intermediary component enables the system to obtain additional phase error measurements without adding a second pilot tone channel, allowing the single pilot tone system to achieve extended synchronization range through the mediating data channel analysis.
2Reliability
If conventional phase error correction is applied repeatedly, then synchronization is maintained for small errors, but temperature drift causes errors to exceed 360° and introduces undesirable jitter
Solution Approach 1:
The patent transitions from a single-dimensional phase error measurement (0-360° from pilot tone alone) to a multi-dimensional measurement by incorporating phase error data from the data channel. This dimensional expansion allows the system to distinguish between small phase errors and large drift errors exceeding 360°, enabling correction without introducing jitter while maintaining reliability.
Solution Approach 2:
The patent replaces the conventional mechanical phase-locked loop correction mechanism with a computational approach that uses resolver circuits to calculate actual phase errors beyond 360°. This substitution eliminates the jitter introduced by repeated conventional corrections while maintaining synchronization accuracy, as the computational method can handle large drift errors without the mechanical limitations of traditional PLL circuits.
3Measurement precision
If a second pure tone channel is added for error detection beyond 360°, then the synchronization range is extended, but conventional protocols do not permit this additional channel
Solution Approach 1:
The patent makes the data channel serve a dual function: its primary function for data transmission and a secondary function for phase error measurement. By using the data channel for both purposes, the system achieves extended error detection capability without adding a dedicated second pilot tone channel, thus extending measurement precision while avoiding increased device complexity.
Solution Approach 2:
The patent enables the data channel to serve itself by extracting phase error information from its own signal. The data channel's own phase variations are utilized for synchronization error detection, eliminating the need for an additional dedicated channel while achieving the desired extended measurement range. This self-service approach allows one channel to provide multiple functions.
Data Source
AI summary
A system and method of widening the synchronization range for a discrete multitone multicarrier single pilot tone system includes detecting a first phase error in a received pilot tone; detecting a second phase error in a received second two bit constellation data channel; converting the second phase error to a first quadrant angle between 0-90° and combining the first phase error and the converted phase error to obtain the actual phase error up to and beyond 360°.