Clock Snapshot Synchronization for Multiple Network Timebases
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Solution Overview
Problem
Traditional television broadcasting, both analog and digital, faces challenges in managing timing and synchronization, particularly in preventing buffer underflows and overflows, and maintaining audio-video synchronization, which existing technologies have not adequately addressed.
Innovation Solution
A method for conveying and reproducing independent timebases in a network by distributing a common measuring clock and counter, locking the master clock counter to an external input, taking periodic snapshots, and transmitting these snapshots to other cards to synchronize clock rates, allowing for precise adjustment of clock counters without physical clock wires, enabling synchronization of multiple channels within a single data packet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional physical wiring is used for clock distribution, then synchronization can be achieved, but the system complexity and wiring requirements increase dramatically
Solution Approach 1:
The patent replaces the mechanical/physical clock wiring system with an electronic data packet transmission system. Instead of physically connecting thousands of clock wires between master and slave cards, the system uses standard data packets containing timestamp information to convey timing data. This substitution dramatically reduces physical wiring complexity while maintaining synchronization accuracy through software-based timestamp processing.
Solution Approach 2:
The patent introduces timestamps as an intermediary element between the master clock and slave cards. Rather than directly transmitting clock signals through physical wires, the system uses timestamps embedded in data packets as a mediator to convey timing information. This intermediary approach allows synchronization to be achieved through standard data communication infrastructure, eliminating the need for dedicated clock distribution wiring.
2Adaptability or versatility
If multiple independent timebases are managed, then versatility increases, but the quantity of clock wires required increases exponentially
Solution Approach 1:
The patent makes the data packet transmission system universal by enabling it to carry timing information for multiple independent timebases simultaneously. A single data packet can contain timestamps from multiple master cards, and slave cards can process these universal packets to synchronize to any of the timebases. This multi-functionality allows the system to manage thousands of timebases using the same infrastructure, eliminating the need for separate wiring for each timebase.
Solution Approach 2:
The patent merges multiple clock distribution functions into a single data packet transmission system. Instead of having separate wire systems for each master-slave card pair, the system combines all timing information into standardized data packets that can be routed to multiple destinations. This merging reduces the total quantity of wiring required while maintaining the ability to manage multiple independent timebases.
3Device complexity
If clock snapshots are transmitted as data packets, then wiring requirements are reduced, but timing precision may be affected by network latency
Solution Approach 1:
The patent applies preliminary action by having master cards generate and embed timestamps in data packets before the actual timing measurement point. The timestamps are calculated in advance based on the master clock state, and slave cards use these pre-calculated timestamps to synchronize their clocks. This preliminary timestamp generation compensates for network transmission delays, as the timestamp reflects the actual clock state at a known past moment, allowing slave cards to adjust their timing accordingly.
Solution Approach 2:
The system uses feedback mechanisms where slave cards receive timestamps from master cards, compare their local clock state against the received timestamps, and adjust their clock rates accordingly. This closed-loop feedback ensures that even though data packets are transmitted through a network with variable latency, the slave cards can continuously correct their timing to maintain synchronization accuracy with the master timebases.
Data Source
AI summary
Disclosed are methods and systems of conveying and reproducing independent timebases in a network. The methods include distributing a common measurement clock and a common measurement clock counter to a plurality of cards in a master chassis in the network. Distributed master clock counters are locked to an external input signal in each of the plurality of cards. Periodic snapshots of a count value generated by the master clock counter are taken. A counter speed of the master clock counter is analyzed to create a future snapshot of the count value. The future snapshot of the count value is transmitted from the master chassis to at least one receiving chassis in the network. The association between master counters and slave counters is programmable by various means including modifying the routing of the snapshot packets.