Receiver Noise Squelch Control for Low-Latency Audio
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Solution Overview
Problem
Conventional receivers face a trade-off between sensitivity and noise reduction, where high threshold values increase sensitivity but allow more noise, and low threshold values decrease sensitivity and lengthen voice latency, making it difficult to balance noise suppression and reception quality.
Innovation Solution
A receiver with a noise squelch processor that integrates a rectified signal using a low-pass filter to adjust the noise level and generate a determination signal, along with a carrier detector and audio controller to mute or unmute the voice signal based on signal strength, and an integrator controller that dynamically adjusts the cutoff frequency of the low-pass filter to optimize noise suppression and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the threshold value is set high, then the receiver sensitivity increases, but noises increase since the reception signal tends to be unmuted even when an electric field is weak
Solution Approach 1:
The patent applies dynamics by making the threshold value variable rather than fixed. The threshold is dynamically adjusted based on the strength of the reception signal: when the reception signal is strong, the threshold is set high to improve sensitivity; when the reception signal is weak, the threshold is set low to prevent noise. This resolves the contradiction by adapting the threshold to operating conditions, allowing high sensitivity without excessive noise.
2Object-generated harmful factors
If the threshold value is set low, then the noise suppression improves, but the receiver sensitivity decreases and the latency of voice is lengthened
Solution Approach 1:
The patent uses dynamic threshold adjustment based on reception signal strength. When the reception signal is weak, the threshold is automatically lowered to prevent noise, and when the reception signal is strong, the threshold is raised to improve sensitivity. This dynamic adaptation resolves the contradiction between noise suppression and sensitivity by optimizing the threshold for current operating conditions.
3Object-generated harmful factors
If the threshold value is set low, then the noise suppression improves, but the latency of voice is lengthened
Solution Approach 1:
The patent dynamically adjusts the threshold based on reception signal strength to optimize both noise suppression and voice latency. When the reception signal is strong, a high threshold reduces voice latency by quickly unmuting valid signals. When the reception signal is weak, a low threshold prevents noise while maintaining acceptable latency. This dynamic adaptation resolves the contradiction between noise suppression and voice latency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces noise while maintaining high receiver sensitivity and minimizing voice latency, ensuring consistent and comfortable audio output across varying signal strengths.
Implementation Method 1
a noise level decreasing from an initial value to a predetermined convergence value by integrating, by an integrator composed of a low-pass filter, a rectified signal obtained by extracting and rectifying a signal outside a band of a voice
Data Source
AI summary
A noise squelch processor generates a noise squelch determination signal by comparing a noise level and a threshold value with each other. A carrier detector generates a carrier determination signal indicating whether or not a reception signal is present based on a signal strength of the reception signal. An integrator controller controls an integrator to set a cutoff frequency of the integrator to a second cutoff frequency higher than a first cutoff frequency at a first timing when the carrier detector generates a carrier determination signal indicating that the reception signal is present, and to switch the cutoff frequency of the integrator from the second cutoff frequency to the first cutoff frequency at a second timing after an elapse of a predetermined period from the first timing.