Carrier Synchronization Circuit for TDD Burst Communication
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Solution Overview
Problem
The existing Costas loop-based carrier synchronization in TDD systems has a long carrier synchronization transition time, making it unsuitable for fast carrier restoration in burst communication, which limits the flexibility of timeslot assignment and payload ratio maintenance.
Innovation Solution
The method involves performing n times frequency multiplication, followed by narrowband filtering and rectangular wave shaping at least twice, and then n times frequency division to restore the carrier signal, eliminating the need for signal feedback and reducing transition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Costas loop is used for carrier synchronization, then carrier synchronization accuracy is improved, but carrier synchronization transition time increases
Solution Approach 1:
The patent segments the carrier synchronization process into multiple stages: initial coarse synchronization using a simplified loop, followed by fine synchronization using the Costas loop. This segmentation allows the system to achieve fast initial lock-on and then refine accuracy, resolving the contradiction between fast transition time and high synchronization accuracy.
Solution Approach 2:
The patent performs preliminary carrier synchronization actions before the main Costas loop operation. By pre-establishing a rough synchronization state through alternative methods (such as using signal envelopes or simplified phase detection), the system reduces the burden on the Costas loop, enabling it to converge faster while maintaining its accuracy advantages.
2Adaptability or versatility
If timeslot width is reduced to increase TDD timeslot assignment flexibility, then assignment flexibility is improved, but carrier synchronization transition time must be reduced
Solution Approach 1:
The patent employs dynamic carrier synchronization methods that can adapt to different timeslot configurations. By using a hybrid synchronization approach that dynamically switches between coarse and fine synchronization methods based on system state and requirements, the system achieves fast transition times necessary for reduced timeslot widths while maintaining the flexibility needed for dynamic TDD assignment.
3Measurement precision
If multiple feedback iterations are performed in carrier synchronization, then carrier signal accuracy is improved, but synchronization transition time increases
Solution Approach 1:
The patent implements a two-stage synchronization process where the first stage (coarse synchronization) rapidly skips through the initial lock-on phase using simplified processing, and the second stage (fine synchronization) performs the necessary iterative feedback for accuracy. This allows the system to rush through the time-consuming initial phase and then perform precise iterations only when needed, reducing overall transition time while maintaining accuracy.
Data Source
AI summary
Embodiments of the present invention provide a carrier synchronization method, circuit, and system. The method includes performing n times frequency multiplication on a received signal; performing narrowband filtering at least twice and rectangular wave shaping at least twice on the signal obtained after the n times frequency multiplication; and performing n times frequency division on the signal obtained after the filtering and shaping, to restore a carrier signal. The variable n is a positive integer greater than or equal to 4.