Accessory Control Tones With Calibration for Noise-Free Audio Control
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Solution Overview
Problem
Existing methods for controlling electronic devices using accessories, such as headsets, often interfere with audio signals and produce undesirable noise effects due to the need to ground microphone lines for control signals, and face challenges in accurately generating control tones with low-cost components.
Innovation Solution
The system employs a tone generator in the accessory to produce inaudible control tones and calibration sequences, which are sent to the electronic device, using a zero-crossing detector and period measurement to compensate for errors and execute actions, thereby avoiding noise interference and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the microphone line is grounded to send control signals, then control functionality is achieved, but audio signals are interfered with and noise effects occur
Solution Approach 1:
The patent introduces an ultrasonic carrier wave as an intermediary to transmit control signals. Instead of directly grounding the microphone line, the system modulates control information onto an ultrasonic carrier (above human hearing range) and transmits it through the audio pathway without interfering with audible audio signals. The electronic device detects these ultrasonic modulations to interpret control commands.
Solution Approach 2:
The patent replaces the mechanical/electrical grounding method with an acoustic field-based transmission method. Control signals are transmitted through acoustic waves (ultrasonic frequencies) rather than direct electrical grounding, substituting a field-based approach for a contact-based approach to avoid audio interference.
2Ease of manufacture
If low-cost components are used in the accessory, then manufacturing cost is reduced, but accuracy in generating control tones deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the electronic device measures the actual frequency of the control tone generated by the accessory and compares it to the target frequency. The device then compensates for frequency deviations by adjusting its interpretation of the control signals based on the measured actual frequency, ensuring accurate control despite component tolerances.
Solution Approach 2:
The patent changes the approach from requiring precise fixed-frequency generation to accepting variable frequencies and compensating through measurement and calculation. The system measures the actual frequency parameter of the generated tone and uses this information to adjust control signal interpretation, allowing low-cost components with frequency variations to function accurately.
3Object-affected harmful factors
If control tones are made inaudible using ultrasonic frequencies, then user experience is improved, but detection and measurement difficulty increases
Solution Approach 1:
The patent uses periodic modulation of the ultrasonic carrier wave to encode control information. Control signals are transmitted by varying the amplitude or frequency of the ultrasonic wave in periodic patterns corresponding to different button presses or control commands. This periodic structure makes the ultrasonic signals detectable through zero-crossing detection and frequency analysis despite being inaudible.
Solution Approach 2:
The patent includes a calibration sequence transmitted before actual control tones to establish baseline frequency and timing information. This preliminary action allows the electronic device to pre-configure its detection parameters and measurement windows, optimizing its ability to detect and measure subsequent ultrasonic control tones with high accuracy.
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 approach allows for reliable and noise-free control of electronic devices using accessories without interfering with audio signals, enhancing the accuracy of control tone interpretation and reducing the impact of component inaccuracies.
Implementation Method 1
generate a corresponding control tone... ultrasonic tones and calibration sequences
Implementation Method 2
including a zero-crossing detector operable to determine at least one of a start or an ending of each of the calibration sequence and the control tone
Implementation Method 3
having a circuit operable to determine the periods of the calibration sequence and the control tone based on the zero-crossing detector output
Data Source
AI summary
A system for controlling an electronic device, including an accessory coupled to the device having a control interface for receiving at least one input and a tone generator, the accessory configured to, in response to an input, generate a corresponding control tone using the tone generator, and send the control tone and a calibration sequence to the device. The device is operable to receive the calibration sequence and control tone. The device includes a zero-crossing detector operable to determine at least one of the start or ending of each of the calibration sequence and the control tone and having a circuit operable to determine the periods of the calibration sequence and the control tone based on the zero-crossing detector output.