Multi-Format Frame Synchronization Using Differential Alignment Sequences
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Solution Overview
Problem
Conventional frame synchronization modules in digital communication systems are not compatible with multiple modulation formats, such as OOK, DPSK, and DBS, limiting their ability to accurately synchronize and determine the polarity of received digital streams across different formats.
Innovation Solution
A frame synchronization module with a search engine for differential frame alignment sequences (DFAS) and an inverter, capable of detecting and aligning frames in digital streams using OOK, DPSK, or DBS modulation formats, which determines the polarity of the received stream and bit-inverts it if necessary to achieve synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional frame synchronization modules are used, then the system works with a single modulation format, but it cannot support multiple modulation formats (OOK, DPSK, DBS) simultaneously
Solution Approach 1:
The patent implements a universal frame synchronization module that can handle multiple modulation formats (OOK, DPSK, DBS) through a single integrated architecture. The module uses a differential frame alignment sequence (DFAS) search engine that adapts its detection logic based on the modulation format, eliminating the need for separate synchronization modules for each format while maintaining full functionality across all supported formats.
Solution Approach 2:
The patent changes the operational parameters of the frame synchronization module by introducing a differential processing stage that transforms the received signal into a differential domain. This parameter transformation allows the same hardware architecture to process different modulation formats uniformly, as the differential operation normalizes the signal characteristics across OOK, DPSK, and DBS formats.
2Measurement precision
If specialized frame synchronization algorithms are used for each modulation format, then accurate synchronization is achieved for that format, but the system cannot determine polarity for DPSK and DBS formats
Solution Approach 1:
The patent performs preliminary differential processing on the received signal before frame synchronization detection. By computing the differential of the received signal in advance, the system prepares the signal in a form that simultaneously enables both accurate frame detection and polarity determination for DPSK and DBS formats, without requiring separate processing stages.
Solution Approach 2:
The differential frame alignment sequence (DFAS) acts as an intermediary between the received signal and the frame synchronization decision. The DFAS search engine correlates the differential processed signal with expected differential alignment sequences, enabling the system to simultaneously achieve frame synchronization and polarity determination through a single detection mechanism.
Data Source
AI summary
A method and apparatus for frame synchronization in digital communication systems using multiple modulation formats perform a search for a differential frame alignment sequence (FAS) to frame-align the received digital stream and determine the polarity of the stream. Embodiments of the invention are compatible with Differential Phase Shift Keying (DPSK), Duobinary Signaling (DBS), and ON/OFF Keying (OOK) modulation formats.