DTMF Decoder Segments Audio for Routing Data Extraction
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Solution Overview
Problem
Traditional DTMF decoders are unable to differentiate telephone routing data from other audio content, particularly in law enforcement contexts where only routing data should be captured, without prior knowledge of the data's location within the audio.
Innovation Solution
A device that groups DTMF symbols based on timing and volume information, partitions audio into sections, and uses a filter to identify and output telephone numbers or routing data, discarding non-relevant sections like voice or silence, ensuring compliance with legal metadata capture requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional DTMF decoding is used, then all DTMF symbols in the audio are captured, but routing data cannot be differentiated from other content
Solution Approach 1:
The patent segments the audio stream into distinct sections by detecting silence periods and voice activity. DTMF symbols are captured only during identified routing sections, while voice and other non-routing content is excluded. This segmentation enables precise differentiation of routing data from other audio content without losing relevant information.
Solution Approach 2:
The system performs preliminary analysis of the audio stream to identify routing sections based on silence detection and voice activity detection before capturing DTMF symbols. By pre-identifying which sections contain routing data, the system can selectively capture only relevant symbols, improving measurement precision while avoiding capture of non-routing content.
2Reliability
If all DTMF symbols are captured without filtering, then complete audio content is recorded, but legal compliance for metadata-only capture is violated
Solution Approach 1:
The patent extracts and captures only DTMF symbols that occur during identified routing sections, while explicitly excluding voice content and other non-routing audio. This extraction approach ensures legal compliance by capturing only metadata (routing data) without recording conversational content, while maintaining reliability through systematic filtering based on audio analysis.
Solution Approach 2:
The system introduces an intermediary analysis layer that detects silence periods and voice activity to determine whether DTMF symbols should be captured. This intermediary mechanism mediates between the raw audio stream and the capture output, ensuring that only routing-related symbols are recorded while maintaining legal compliance with metadata-only requirements.
3Measurement precision
If DTMF symbols are grouped without audio analysis, then processing is simple, but accuracy in identifying routing data decreases
Solution Approach 1:
The patent implements dynamic grouping of DTMF symbols based on real-time audio conditions. Instead of static grouping, the system adjusts which symbols are captured by continuously monitoring silence periods and voice activity. This dynamic approach improves accuracy of routing data identification while managing complexity through efficient audio analysis algorithms that adapt to changing audio conditions.
Data Source
AI summary
A dual-tone multi-frequency (DTMF) decoder may decode DTMF symbols received in an audio input and transfer the symbols to a buffer. A volume accumulator may determine whether the audio input includes audio with volume above a predetermined threshold. The buffer may receive instructions from the timer or volume accumulator to transfer stored DTMF symbols to a filter, which may identify a characteristic of information conveyed by the DTMF symbols and send the identified characteristic information to an output device. The timer may determine a time associated with when each DTMF symbol was received and transfer each associated time to the buffer, which may transfer each associated time to a group boundary detector that may determine a predetermined number of longest time durations in between the DTMF symbols. The presence of a predetermined number of longest time durations in between the DTMF symbols may indicate a telephone number format.