EQAM Phase Synchronization for Multiple Reference Clocks
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Solution Overview
Problem
Bypassing the M-CMTS core in cable modem termination systems requires EQAMs to synchronize multiple reference clocks, complicating system design and causing timing and phase information loss during data transmission.
Innovation Solution
Implementing phase synchronizers in EQAM devices that operate at a common system clock, using edge detectors, phase-locked loops, and phase accumulators to synchronize modulated symbol phases with multiple independent reference clocks, allowing modulators to align symbol phases with corresponding reference clocks while maintaining system clock operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple independent reference clocks are synchronized in EQAM devices to support multiple data sources, then the system can deliver rich multimedia content from multiple sources, but the system complexity increases significantly
Solution Approach 1:
The patent divides the synchronization task into separate phase synchronizer modules, each handling one reference clock independently. Each phase synchronizer is a self-contained unit that receives a specific reference clock and generates corresponding phase information, allowing multiple clocks to be managed through modular segmentation rather than a complex centralized system.
Solution Approach 2:
The patent creates a universal phase synchronizer module that can handle any reference clock regardless of its source or characteristics. This multi-functional module serves multiple purposes: it synchronizes to different reference clocks, generates phase information for various modulators, and maintains timing alignment across diverse data sources, thereby reducing overall system complexity through standardization.
2Productivity
If data is transmitted over packet-based IP networks, then cost is reduced and bandwidth is increased, but timing and phase information is lost
Solution Approach 1:
The patent performs preliminary synchronization by recovering reference clocks from incoming data streams before the actual data processing occurs. The phase synchronizers are configured in advance to lock onto reference clocks and generate phase information proactively, ensuring that timing and phase alignment are established before data transmission through the packet network, thus preventing information loss.
Solution Approach 2:
The patent implements feedback mechanisms where the phase synchronizers continuously monitor and adjust phase information based on the recovered reference clocks. This closed-loop feedback ensures that even as data travels through the packet-based network, the timing and phase information is continuously corrected and maintained, compensating for network-induced variations.
3Productivity
If EQAMs bypass the M-CMTS core to receive content directly from multiple data sources, then M-CMTS core capacity requirements are reduced, but synchronization of multiple reference clocks becomes necessary
Solution Approach 1:
The patent extracts the synchronization function from the M-CMTS core and places it directly in the EQAM devices. By taking out the clock recovery and phase synchronization capabilities from the core and embedding them in the EQAMs, the system allows EQAMs to independently handle multiple reference clocks, thereby reducing the burden on the M-CMTS core while managing synchronization complexity at the edge where it is most needed.
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
This approach enables efficient synchronization of multiple reference clocks, reducing system complexity and ensuring accurate timing and phase alignment, thereby supporting increased bandwidth demands for rich multimedia content delivery without the need for additional M-CMTS cores.
Implementation Method 1
each modulator is provided with a phase synchronizer. The phase synchronizer synchronizes the modulated symbol phases to the corresponding reference clock
Implementation Method 2
Each phase synchronizer has a source reference clock input, a system clock input, and an output coupled to the respective modulator
Data Source
AI summary
Efficient synchronization techniques that support multiple reference clocks in an EQAM device. Consider a plurality of different modulators in the EQAM device receiving data from a corresponding plurality of different sources having corresponding different timing references (i.e., different source reference clocks). To accommodate this, the modulators all operate using a common system clock, and each modulator is provided with a phase synchronizer. The phase synchronizer synchronizes the modulated symbol phases to the corresponding reference clock.