DTMF Tone Synchronization with Ring Cycle Pauses
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Solution Overview
Problem
Mobile devices face challenges in detecting DTMF tones during the ring portion of a ring tone cycle, especially when a data channel is not available, and there is a need to avoid users hearing control and status tones sent over voice channels.
Innovation Solution
The solution involves using DTMF tones sent from the mobile device to the PBX server to estimate the delay on the voice channel, allowing the server to synchronize the sending of status or control information during ring off periods by restarting the local ring tone and using verification tones to determine the start of the ring cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If DTMF tones are sent over the voice channel to convey control and status information, then communication capability is improved, but the user can hear the tones which is harmful
Solution Approach 1:
The system utilizes the periodic ring-off periods of the mobile device's ring tone cycle to send DTMF tones. The server schedules tone transmission to coincide with these natural silence intervals, allowing information communication without the user hearing the tones during audible ring portions.
Solution Approach 2:
The mobile device restarts its local ring tone and sends verification tones before the server begins transmitting control and status information. This preliminary action establishes synchronization, allowing the server to estimate the ring cycle timing and schedule subsequent tones during appropriate pause periods.
2Productivity
If DTMF tones are sent during the ring portion of the ring tone cycle, then communication efficiency is improved, but the mobile device cannot detect the tones accurately
Solution Approach 1:
The system schedules DTMF tone transmission during the ring-off periods of the mobile device's ring tone cycle. These periodic pause periods provide quiet intervals where the mobile device can accurately detect incoming tones without interference from its own ring tone generation.
Solution Approach 2:
The mobile device sends verification tones to the server to confirm successful reception of transmitted tones. This feedback mechanism allows the server to assess detection accuracy and adjust timing if needed, ensuring reliable communication during the ring cycle.
3Loss of time
If the server sends status information immediately without synchronization, then response time is improved, but the tones may be audible to the user
Solution Approach 1:
The mobile device restarts its local ring tone and sends verification tones before the server begins transmitting control and status information. This preliminary synchronization allows the server to estimate the ring cycle timing and schedule subsequent tones during appropriate pause periods without significant delay.
Solution Approach 2:
The server dynamically adjusts the timing of DTMF tone transmission based on the estimated ring cycle timing from verification tones. This dynamic scheduling allows the system to maintain optimal response times while ensuring tones are delivered during audible pause periods rather than fixed intervals.
Data Source
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AI summary
Mobile devices use a PBX and application servers associated with the PBX to access voice services. Some mobile devices can support simultaneous data and voice channels, with the PBX and application server respectively. Where a data channel is unavailable, a control and status updating mechanism is needed. One approach is to signal over the voice channel with DTMF tones. DTMF tones should be timed to cause the tones to arrive at the mobile device during a pause period of a ring cycle. However, it also is desirable to avoid unnaturally long silence periods or other pauses during system usage. Aspects relate to enhancing a user experience in these situations and successful transmission/reception of control and status information over a voice channel using DTMF tones.