Speaker Line Inspection Device Dynamic Threshold Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing public address system loudspeaker line examination systems often make erroneous judgments regarding line breakage or short-circuiting due to inaccuracies in setting threshold values, particularly when the audio signal level is higher than the test signal level, leading to false alarms.
Innovation Solution
The system combines an analog test signal with the audio signal and uses impedance determining means to derive the impedance of the loudspeaker line, with threshold values adjusted based on the ratio of the composite signal to the test signal, and employs frequency analysis to accurately judge line breakage or impedance decrease, and includes a mechanism to revise threshold values dynamically to improve judgment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If threshold values are set accurately based on test signal only measurements, then detection accuracy for line breakage and short-circuiting is improved, but erroneous judgments occur when audio signal level is larger than test signal level
Solution Approach 1:
The threshold values are made dynamic rather than fixed. The judging means adjusts threshold values based on the ratio between composite signal level and test signal level. When the audio signal level is high relative to the test signal level, the threshold values are automatically adjusted to prevent erroneous judgments, while maintaining high detection accuracy when the test signal dominates.
Solution Approach 2:
The system changes the threshold parameters adaptively based on signal conditions. Instead of using fixed threshold values derived solely from test signal measurements, the threshold values are modified according to the composite signal to test signal ratio, allowing the detection system to accommodate varying audio signal levels while maintaining accurate fault detection.
2Productivity
If the audio signal level is higher than the test signal level, then the public address system operates effectively, but the impedance measurement accuracy deteriorates leading to false alarms
Solution Approach 1:
The system uses feedback from the signal level ratio detection to adjust threshold values. The judging means continuously monitors the ratio between composite signal and test signal levels, and uses this feedback information to dynamically adjust the threshold values, ensuring accurate impedance measurements even when audio signal levels are high.
Solution Approach 2:
The threshold parameters are changed adaptively based on the operating conditions. When the audio signal level exceeds the test signal level, the system automatically modifies the threshold values to compensate for the reduced measurement accuracy, preventing false alarms while maintaining system effectiveness.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
[Object] An audio signal from an audio signal source 2 is amplified in an amplifier 4, and the amplified audio signal is supplied through a loudspeaker line 6 to a plurality of loudspeakers 8 connected in parallel with each other. A test signal from a DSP 10 containing one or both of a frequency near the lowest frequency of the human audio frequency band and a frequency near the highest frequency, is combined with the audio signal in a combiner 13 and supplied to the loudspeaker line 6. Output signals of a current detecting circuit 14 and a voltage detecting circuit 16 disposed in the output of the amplifier 4 are supplied to a DSP 10 to analyze frequency components of the test signal, and a composite impedance of the loudspeakers 8 and the loudspeaker line 6 is computed based on the frequency component analysis. The DSP 10 compares the composite impedance with a threshold value to detect line breakage or decrease in impedance of the loudspeaker line.