RFID Carrier Wave Shaping for Overshoot and Undershoot Control
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Solution Overview
Problem
RFID communication systems face issues with amplitude modulated data signal transmission due to nearby objects causing overshoots, undershoots, and distortions in the RF Field, leading to non-compliance with standards and potential communication failures.
Innovation Solution
A transmitter with a shape stage that dynamically selects waveforms with varying energy content based on the data signal to prevent overshoots and undershoots, using waveforms like sawtooth or triangular waves to adjust the energy content of the carrier signal, thereby stabilizing the RF Field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic voltage changes are used to prevent overshoot, then communication compliance is improved, but device complexity increases due to multiple supplies required
Solution Approach 1:
The patent changes the waveform parameter of the carrier signal dynamically based on the modulation stage requirements. The wave generator switches between different waveform types (sine, square, triangular, sawtooth) to optimize the RF field characteristics during different phases of modulation, preventing overshoot without requiring multiple voltage supplies
Solution Approach 2:
The wave generator is designed to dynamically adjust the waveform shape in real-time based on control signals from the modulation stage. This dynamic adaptation allows the system to respond to changing modulation requirements and prevent overshoot conditions while maintaining a single supply architecture
2Reliability
If antenna de-tuning is used to prevent overshoot, then communication compliance is improved, but communication range is reduced
Solution Approach 1:
Instead of changing the antenna's resonant frequency through de-tuning, the patent changes the waveform parameter of the transmitted carrier signal. This approach modifies the RF field characteristics to prevent overshoot while maintaining the antenna's optimal resonant frequency and communication range
Solution Approach 2:
The patent replaces the mechanical/electrical approach of antenna de-tuning (changing L or C values) with a signal processing approach (changing waveform shape). This substitution allows compliance optimization without affecting the antenna's fundamental resonant properties and communication range
3Power
If waveform energy is increased to overcome distortion, then signal strength is improved, but overshoot and undershoot increase
Solution Approach 1:
The patent applies different waveform characteristics locally at different times during the modulation cycle. By selecting specific waveform types (square, triangular, sawtooth) at specific moments, the system optimizes signal strength when needed while preventing distortion artifacts like overshoot and undershoot during critical transition phases
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 maintains communication stability and compliance with standards even in the presence of disturbing objects, ensuring reliable data transmission over a wide range without requiring multiple supply voltages or significant antenna tuning.
Implementation Method 1
a wave generator (6) to generate a carrier signal (7) with a particular frequency and waveform
Implementation Method 2
an antenna (11) connected to the modulation stage (15) or wave generator (6) via an amplifier (9) and a matching circuit (10) to transmit the amplitude modulated data signal (2) in the RF-Field (3) over the air
Data Source
AI summary
A transmitter (1; 21) to transmit an amplitude modulated data signal (2) in an RF-Field (3) over the air to a receiver (4) of an RFID communication system (5; 22) which transmitter (1; 21) comprises:a wave generator (6) to generate a carrier signal (7) with a particular frequency and waveform;a modulation stage (15) to modulate the carrier signal (7) in relation to a data signal to be transmitted;an antenna (11) connected to the modulation stage (15) or wave generator (6) via an amplifier (9) and a matching circuit (10) to transmit the amplitude modulated data signal (2) in the RF-Field (3) over the air,characterized in that the transmitter (1; 21) furthermore comprises:a shape stage (16) connected to the wave generator (6) to select the waveform of the carrier signal (7) depending directly or indirectly on the data signal.