VoIP Tone Signal Phase Synchronization via Intermediary Generator
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Solution Overview
Problem
In Voice over IP communication networks, the compression of tone signals can cause undesired changes in fax/modem tone signals, leading to misinterpretations and transmission failures due to phase reversals or amplitude modulations, especially when signals are transmitted through multiple networks using RFC 2833 protocol.
Innovation Solution
The method involves inserting tone signals into data packets with specific tone information, generating the tone signal on the receiving side, and adjusting the phase difference to match a predefined value to prevent phase shifts, allowing for synchronized insertion of the tone signal without constant active phase detection, and storing only the last two bit patterns for efficient synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tone signal is transmitted through multiple networks using RFC 2833 protocol with compression, then the tone signal can be transmitted over IP networks, but phase reversals or amplitude modulations occur causing misinterpretations and transmission failures
Solution Approach 1:
The patent introduces an intermediary tone generator that recreates the tone signal from transmitted tone information, and a phase detector that acts as a mediator to compare and synchronize the phase between transmitted and generated tone signals. This intermediary mechanism ensures accurate tone reproduction without direct transmission of the original signal through multiple networks.
Solution Approach 2:
The patent implements a feedback mechanism where the phase detector continuously monitors the phase difference between the transmitted tone signal and the generated tone signal, and this phase information is fed back to adjust and synchronize the generated signal, ensuring transmission accuracy.
2Measurement precision
If phase detection is constantly active to synchronize tone signals, then phase accuracy is maintained, but processing time and system complexity increase
Solution Approach 1:
The patent employs periodic action by activating the phase detector only at specific intervals when tone signals are being transmitted and need synchronization, rather than maintaining constant phase detection. This reduces processing time while maintaining necessary phase accuracy.
Solution Approach 2:
The system uses self-service by leveraging the already-transmitted tone signal as a reference for phase detection, eliminating the need for external synchronization sources and reducing additional processing requirements.
3Measurement precision
If the last two bit patterns are stored for synchronization, then phase comparison is enabled, but memory usage increases
Solution Approach 1:
The patent applies local quality by storing only the specific bit patterns that are locally relevant for phase comparison (the last two transmitted bit patterns), rather than storing entire tone signals or excessive data. This minimizes memory usage while enabling necessary phase measurement.
Data Source
AI summary
In addition to the transmission of a tone signal (ts) according to the RFC standard 2833 via a network using Internet protocol, the tone signal is transmitted in the data packets (dp). Subsequently, the phase difference (Δφ) between the transmitted tone signal (ts) and the generated tone signal (ts′) is ascertained, before beginning the insertion of the generated tone signal (ts′) in the data packets (dp), and compared to a predetermined phase difference (φν). If the ascertained phase difference exceeds the predetermined phase difference (Δφ,φν), the phase of the generated tone signal (ts′) is changed by a predetermined phase (φ) with the aid of the tone generator (TG). The ascertainment of the phase differences (Δφ) and the change of the phase (φ) of the generated tone signal (ts′) is repeated until the ascertained phase difference is less than the predetermined phase difference (Δφ,φν), upon which instead of the transmitted tone signal (ts), the generated tone signal (ts) is inserted into the data packets (dp). A substantial advantage of the invention can be seen in that a phase detector does not have to be continuously active for the synchronization, but rather the synchronization must only be performed if a tone signal (ts) or tone information (ti) is received and the insertion of the generated tone signal (ts′) is imminent.