In-band modem sample slip detection via correlation tracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing communication systems face challenges in efficiently transmitting data over speech channels due to limitations in vocoder models, which are inadequate for modeling tone signals, leading to unreliable data transfer and synchronization issues, especially at higher data rates.
Innovation Solution
A method for synchronizing and tracking sample slip conditions in an in-band modem by receiving a synchronization sequence, correlating it with a reference signal, and identifying sample slip based on correlation peaks, ensuring accurate synchronization and data transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vocoders are used to model tone signals for data transmission, then data can be transmitted over speech channels, but the modeling is insufficient leading to unreliable data transfer
Solution Approach 1:
The patent introduces an in-band modem as an intermediary device that operates within the speech channel infrastructure. The modem includes a modulator that embeds data within speech packets and a demodulator that extracts it, allowing reliable data transmission without requiring the vocoder to model tone signals directly. This mediator bypasses the vocoder's modeling limitations while utilizing the existing speech channel.
Solution Approach 2:
The patent replaces the mechanical signal modeling approach of vocoders with an electronic data embedding approach. Instead of relying on the vocoder to accurately model tone signals, the system uses digital modulation techniques to embed data within the speech packet structure, substituting the analog modeling mechanism with a digital data encoding mechanism that is more reliable for data transmission.
2Productivity
If data transmission rate is increased by changing tones quickly, then higher data rates are achieved, but detection accuracy deteriorates and complex schemes are needed
Solution Approach 1:
The patent replaces the tone-based modulation mechanism with a packet-based data embedding mechanism. The modulator embeds data directly into the speech packet structure using bit mapping, and the demodulator extracts it through correlation detection. This substitution eliminates the need for rapid tone changes while maintaining high data rates, and the correlation-based detection provides robust accuracy even in noisy environments.
Solution Approach 2:
The patent implements synchronization tracking with correlation detection that provides feedback on detection confidence. The demodulator correlates received packets with expected patterns and can detect synchronization status, allowing the system to adjust and maintain detection accuracy. This feedback mechanism enables reliable operation at high data rates without requiring overly complex error correction schemes.
3Reliability
If synchronization tracking is implemented in in-band modem, then sample slip conditions can be managed, but system complexity increases
Solution Approach 1:
The patent introduces a synchronization tracking module as an intermediary component within the in-band modem. This module includes a correlator that compares received synchronization sequences with local references and a tracker that monitors sample alignment. By embedding this dedicated synchronization intermediary, the system achieves reliable sample slip detection and correction without requiring complex external synchronization infrastructure.
Solution Approach 2:
The patent uses correlation copying where the demodulator creates local copies of expected synchronization sequences and data patterns. By comparing received signals against these local copies, the system can detect synchronization status and correct sample slips. This copying approach provides robust synchronization tracking using simple comparison logic rather than complex algorithms.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Processing the synchronization of an inband modem to detect sample slip conditions is disclosed. The processing comprises correlation of a pseudorandom sequence. Decision logic reliably detects the sample slip condition while minimizing the number of false alarms.