Vehicle Emergency Call Audio Path Testing Without External Signal Leakage
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Solution Overview
Problem
Existing methods for testing the functional capability of emergency call devices in transportation vehicles do not ensure that only signals generated by the device are heard by the external receiving station, making it difficult to verify the device's functionality during certification processes.
Innovation Solution
A method is proposed where the emergency call device can be placed in a test mode, generating specific audio signals for the interior of the vehicle, which are then transmitted to an external monitoring station, ensuring that only these signals are heard, and not external audio signals, allowing for reliable testing of the device's functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the emergency call device operates in normal mode transmitting all audio signals to external station, then external communication is maintained, but testing reliability deteriorates due to interference from external audio signals
Solution Approach 1:
The emergency call device dynamically changes its signal transmission behavior based on the operational mode. In test mode, the device transmits only internally generated audio signals while blocking external audio signals from the loudspeaker. This dynamic adaptability allows the same device to serve both testing and normal operational requirements without compromising either function.
Solution Approach 2:
The audio signal transmission path is segmented into different channels based on signal origin. The system separates internally generated test signals from externally sourced audio signals, allowing selective transmission of only the desired signal type to the external station depending on the operational mode. This segmentation enables reliable testing while maintaining normal communication capabilities.
2Measurement precision
If the emergency call device blocks external audio signals during testing, then testing accuracy improves, but normal communication functionality deteriorates
Solution Approach 1:
The device dynamically adjusts its signal filtering characteristics based on operational mode. During test mode, external audio signals are blocked to ensure testing accuracy. During normal operation mode, the blocking is removed and full communication functionality is restored. This dynamic behavior resolves the contradiction between testing accuracy and communication ease of operation.
3Ease of operation
If the emergency call device transmits all audio signals including external ones, then complete audio communication is maintained, but signal source identification deteriorates
Solution Approach 1:
The audio signal path is segmented into distinct transmission channels based on signal origin. The system identifies whether audio signals originate from internal generation (microphone input) or external sources (loudspeaker output) and transmits them selectively. This segmentation preserves complete audio communication capability while ensuring accurate signal source identification for testing purposes.
Data Source
AI summary
A method for testing the functional capability of an emergency call device of a transportation vehicle. In an emergency mode, at least one specific audio signal is generated for a vehicle passenger by the emergency call device and emitted to the interior of the transportation vehicle. For testing, the emergency call device is put into a testing mode in which the at least one audio signal intended for the emergency is generated and wherein, in the testing mode, the generated audio signal passes, within the vehicle-internal emergency call device, through a signal path which is modified compared with the emergency mode.