Analog Audio Data Transmission via Frequency Modulation
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Solution Overview
Problem
Existing methods for transmitting digital data with analog audio signals suffer from significant distortion, particularly when using USB connectors, leading to noticeable harmonics and DC bias distortion.
Innovation Solution
The system employs a frequency modulator to convert digital data into an analog signal with distinct frequencies above the audible range, which are superimposed onto an audio channel using a capacitor and transmitter amplifier, minimizing total harmonic distortion by using high-frequency sine or square waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital data is transmitted with analog audio signals using conventional methods, then data communication functionality is achieved, but significant distortion occurs in the analog audio signal
Solution Approach 1:
The patent introduces a capacitor as an intermediary coupling element between the data signal source and the audio channel. This capacitor blocks DC components while allowing AC signal components to pass, thereby preventing DC bias distortion from affecting the audio signal while still enabling data transmission through the audio channel.
Solution Approach 2:
The patent employs frequency modulation to encode digital data onto an analog carrier signal. By varying the frequency of the carrier signal according to the data bits, the system achieves robust data transmission that is less susceptible to distortion and interference, maintaining audio quality while enabling reliable data communication.
2Productivity
If data pulses are placed on audio signals at frequencies within the audible band, then data transmission is achieved, but total harmonic distortion exceeds acceptable levels
Solution Approach 1:
The patent transitions from using audible frequency modulation to ultrasonic frequency modulation for data encoding. By moving the data carrier frequency above the human audible range (>20 kHz), the system eliminates audible distortion while maintaining data transmission capability through the same audio channel.
3Adaptability or versatility
If USB connectors are used for simultaneous digital data and analog audio communication, then device functionality is enhanced, but noticeable harmonics and DC bias distortion occur
Solution Approach 1:
The patent extracts and removes the DC bias component from the data signal before coupling it to the audio channel. By using a capacitor to block DC components and employing AC-coupled circuitry, the system eliminates DC bias distortion and reduces harmonic generation, allowing USB connectors to simultaneously handle both digital data and analog audio without the harmful effects previously observed.
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 reduces total harmonic distortion to levels undetectable by most users, achieving low distortion in transmitting digital data with analog audio signals, with THD less than 0.00035% over the audible frequency range of 20 Hz to 20 kHz.
Implementation Method 1
a capacitor coupled to a first conductor of the audio channel, the capacitor configured to couple an analog representation of a digital data signal with an analog audio signal on the audio channel
Implementation Method 2
a frequency modulator configured to receive the digital data signal and to modulate a frequency of an output signal of the frequency modulator based on a logic level of the digital data signal
Data Source
AI summary
This application discusses among other things, apparatus and method for transmitting data with an analog signal without significantly distorting the analog signal. In an example, an apparatus can include an audio channel, a capacitor coupled to a first conductor of the audio channel, the capacitor configured to couple an analog representation of a digital data signal with an analog audio signal on the audio channel, and a frequency modulator configured to receive the digital data signal and to modulate a frequency of an output signal of the frequency modulator based on a logic level of the digital data signal, wherein the analog representation of the digital data signal includes the frequency of the output signal of the frequency modulator.