RF Signal Modulation to Lower Peak Spectral Density
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Solution Overview
Problem
RF ID and memory spot devices face challenges in reducing peak power spectral density during power and data transmission, leading to potential interference with other devices, while maintaining low cost and simplicity in receiver design.
Innovation Solution
Implementing phase or frequency modulation on amplitude modulated signals to spread the spectrum, reducing peak power spectral density without altering the existing simple amplitude modulation receivers in passive devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If amplitude modulation is used for power and data transmission, then power delivery and data communication are achieved, but peak power spectral density increases causing interference with other devices
Solution Approach 1:
The patent applies phase modulation to the amplitude modulated signal, changing the signal parameters to spread the spectrum. This phase modulation spreads the power spectral density across a wider frequency range, reducing the peak PSD while maintaining the power delivery capability through the AM component.
Solution Approach 2:
The patent separates the power transmission and data transmission functions by using amplitude modulation for power delivery and phase modulation for data encoding. This segmentation allows the power delivery function to be maintained while the phase modulation component spreads the spectrum to reduce peak PSD.
2Object-generated harmful factors
If phase or frequency modulation is applied to spread the spectrum, then peak power spectral density is reduced, but signal complexity increases
Solution Approach 1:
The patent merges amplitude modulation for power delivery with phase modulation for spectrum spreading into a single transmission signal. This combination allows the receiver to extract power from the AM component while the phase modulation provides the spectrum spreading benefit, achieving both goals without requiring separate transmission systems.
3Ease of manufacture
If simple amplitude modulation receivers are used in passive devices, then device cost is reduced, but peak power spectral density causes interference
Solution Approach 1:
The patent introduces phase modulation as an intermediary technique that modifies the transmitted signal to reduce peak PSD without requiring changes to the simple AM receiver architecture in passive devices. The phase modulation acts as a mediator that resolves the conflict between maintaining simple receivers and reducing interference.
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
The proposed solution effectively reduces peak power spectral density by approximately 13 dB, minimizing interference with other devices without requiring modifications to the passive device receivers, thus maintaining performance and cost-effectiveness.
Implementation Method 1
phase or frequency modulating the signal
Implementation Method 2
phase or frequency modulating the signal
Implementation Method 3
a first device for storing data and adapted to transmit it to a reader when energised by an electromagnetic energy field transmitted by the reader
Data Source
AI summary
A method for modulating a signal transmitted by a first device to a second device which is energised by the signal, wherein the first device is further arranged to amplitude modulate the signal so as to transmit data thereon, the method further comprising phase modulating the signal.