Narrowband Sinewave Modulation With Low-Sideband Carrier Stacking
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Solution Overview
Problem
Current data communication systems face challenges in increasing data throughput and addressing signal degradation, particularly due to transmission path delay, interference, and non-linearity, with existing modulation techniques like Amplitude Modulation, Frequency Modulation, QAM, QPSK, PSK, and APSK having inefficiencies in power usage, bandwidth, and error rates.
Innovation Solution
The method involves periodic waveform modulation by encoding input digital data at selected phase angles of a sinusoidal waveform to create a modulated sinusoidal waveform with data notches, using a digital-to-analog converter to generate an encoded analog waveform, and employing carrier stacking to achieve high spectral efficiency, where adjacent modulated sinusoidal waveforms are separated by less than 15 Hz with sidebands at least 50 dB below the main signal power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional modulation techniques (AM, FM, QAM, QPSK, PSK, APSK) are used to increase data throughput, then data transmission capacity is improved, but power efficiency deteriorates and bandwidth utilization becomes suboptimal
Solution Approach 1:
The patent changes the fundamental parameter of waveform selection from conventional modulated carriers to narrowband sinewave modulation. By encoding data in the presence or absence of sinewave periods rather than modulating amplitude, frequency, or phase of continuous carriers, the system achieves superior power efficiency while maintaining high data throughput capability
Solution Approach 2:
The patent segments the data stream into individual data bits that are encoded in separate sinewave periods. Each data bit is represented by the presence (logic 1) or absence (logic 0) of a sinewave period, creating a segmented transmission structure that improves both power efficiency and spectral utilization compared to continuous conventional modulation
2Productivity
If higher order QAM modulation is used to increase data rate, then data throughput is improved, but peak to average power ratio increases resulting in higher power requirements
Solution Approach 1:
The patent fundamentally changes the modulation parameter from amplitude/phase variations in QAM to temporal presence/absence of narrowband sinewaves. This parameter change eliminates the high peak-to-average power ratio problem inherent in higher-order QAM while maintaining high data rates through increased spectral efficiency
Solution Approach 2:
The patent employs periodic narrowband sinewaves as the modulation carrier, with data encoded in the periodic presence or absence of these waves. This periodic structure inherently limits peak power requirements compared to the continuous amplitude variations required by higher-order QAM, achieving high data rates with lower peak-to-average power ratios
3Loss of information
If conventional modulation schemes are used to transmit data over transmission channels, then data communication is achieved, but signal degradation occurs due to transmission path delay, interference, and non-linearity
Solution Approach 1:
The patent changes the signal parameter from broad-spectrum modulated carriers to narrowband sinewaves with controlled spectral content. This parameter change reduces susceptibility to transmission path delay and interference while simplifying the transmission requirements compared to complex conventional modulation schemes
Solution Approach 2:
The patent uses simple narrowband sinewave copies as the modulation basis, replacing complex modulated carriers. Each data bit is transmitted as a copy of a fundamental sinewave pattern (present or absent), which is inherently more robust to transmission impairments and requires simpler transmission equipment than conventional high-order modulation schemes
Data Source
AI summary
A system and method for narrowband sinewave modulation. The system includes an input buffer for storing input digital data and a sub-periodic modulator for encoding the input digital data in a periodic waveform. The sub-periodic modulator encodes one or more bit values of the input digital data within each period of the periodic waveform. One or more digital-to-analog converters generate an encoded analog waveform from a digital representation of the periodic waveform wherein the encoded analog waveform is of a frequency f and a power P. The encoding is performed by the sub-periodic modulator such that any signal of frequency f′ resulting from the encoding is of a power P′ at least 50 dB less than power P, where f′ is offset from f by more than 25 Hz.