Delta-Sigma Audio Transmission with High-Bit Code Modulation
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Solution Overview
Problem
Existing transmission systems that use delta-sigma modulation for analog signals face noise deterioration due to noise components superimposed on the sampling clock and ground, requiring additional circuitry for pseudo-random signal demodulation, which increases circuit area and noise interference.
Innovation Solution
A transmission system that includes a delta-sigma modulator and a code modulator to selectively code-modulate high-order bits of delta-sigma modulated signals based on low-order bits, reducing noise interference without the need for additional output terminals and circuitry, by performing code modulation only on high-order bits and transmitting them along with unmodified low-order bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pseudo-random signals are transmitted for demodulation, then signal transmission quality is improved, but circuit area increases due to extra output terminals
Solution Approach 1:
The patent extracts only the necessary portion of the signal (high-order bits) for code modulation while leaving low-order bits unmodulated. This selective extraction allows demodulation to be performed without requiring additional output terminals, thus reducing circuit area while maintaining signal transmission quality.
Solution Approach 2:
The patent segments the multi-bit signal into high-order bits and low-order bits, applying code modulation only to the high-order bits. This segmentation allows the system to perform selective demodulation without requiring extra circuitry for the entire signal, resolving the contradiction between transmission quality and circuit area.
2Object-affected harmful factors
If code modulation is applied to reduce noise, then noise interference is reduced, but circuit complexity increases
Solution Approach 1:
The patent applies code modulation only to high-order bits rather than the entire signal. This local application of modulation reduces noise interference in the critical high-order portions while avoiding the complexity of modulating all bits, thus reducing overall circuit complexity.
Solution Approach 2:
The patent performs partial code modulation on only the high-order bits rather than the complete signal. This partial action is sufficient to reduce noise interference in the most significant portions of the signal while minimizing the added circuit complexity.
Data Source
AI summary
In a transmission system of an audio signal etc., circuit enlargement is suppressed and deterioration of transmitting signal is reduced. A transmission system including a transmitting apparatus including a first delta-sigma modulator outputting first multi-bit delta-sigma modulated signals of three or more bits and a first code modulator code-modulating first signals of two or more bits located in bit positions higher than a predetermined bit position of the first multi-bit delta-sigma modulated signals based on at least part of a second signal located in one or more bit positions not higher than the predetermined bit position and outputting a plurality of modulated signals; a transmission path transmitting the second signal and the plurality of modulated signals; and a receiving apparatus including a first demodulator demodulating the plurality of the received modulated signals based on at least part of the received second signal is provided.