ASK Demodulator Switching to Reject Ringing Oscillation Errors
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Solution Overview
Problem
Amplitude-modulated signal demodulation is hindered by ringing oscillations in receiving circuits, leading to errors in symbol detection due to amplitude envelope distortion, particularly when the carrier is off, causing bit errors and waveform distortion.
Innovation Solution
A demodulator system comprising a matching network, an amplitude detector, and a phase/frequency detector, which detects phase and frequency shifts to differentiate between actual signal changes and ringing oscillations, adjusting the demodulated output accordingly to mitigate errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If amplitude modulation is used to transmit signals, then signal transmission efficiency is improved, but ringing oscillations cause amplitude envelope distortion leading to symbol detection errors
Solution Approach 1:
The patent segments the demodulation process into multiple detection paths: a primary amplitude detection path and a secondary phase/frequency detection path. The phase/frequency detector segments the detection function to specifically identify ringing oscillations, allowing the system to differentiate between legitimate signal changes and distortion artifacts, thereby resolving the contradiction between transmission efficiency and detection accuracy.
Solution Approach 2:
The patent introduces phase and frequency detection as intermediary measurement mechanisms. These intermediaries provide additional information about the signal state that helps distinguish between actual symbol changes and ringing-induced distortions. By adding these intermediary detection layers, the system maintains reliable symbol detection despite the presence of amplitude envelope distortion.
2Use of energy by moving object
If the carrier is turned off to transmit logic zero, then power consumption is reduced, but ringing oscillations occur causing bit errors
Solution Approach 1:
The patent implements feedback through the phase/frequency detector that continuously monitors the signal characteristics. When the carrier is off and ringing occurs, the phase/frequency detector provides feedback information that helps the system recognize the ringing state and differentiate it from intentional carrier-off signaling. This feedback mechanism allows reliable bit detection while maintaining the energy-efficient carrier-off representation for logic zero.
Solution Approach 2:
The patent employs dynamic detection that adapts to the signal state by combining amplitude detection with phase/frequency detection. The system dynamically adjusts its interpretation of signal levels based on phase/frequency information, allowing it to correctly identify carrier-off states for logic zero transmission while rejecting false indications caused by ringing oscillations, thus maintaining low power consumption without increasing bit errors.
3Measurement precision
If matching network is used to receive amplitude-modulated signals, then signal reception sensitivity is improved, but ringing oscillations are amplified causing waveform distortion
Solution Approach 1:
The patent introduces phase and frequency detection as intermediary measurement mechanisms that provide additional information about the signal state. These intermediaries help distinguish between legitimate signal changes and ringing-induced distortions, allowing the system to maintain high reception sensitivity while compensating for the waveform distortion generated by the matching network's ringing oscillations.
Solution Approach 2:
The patent changes the detection parameters by adding phase and frequency detection capabilities alongside amplitude detection. This multi-parameter detection approach allows the system to maintain the matching network's high sensitivity while using phase/frequency information to identify and reject distorted signal portions caused by ringing, thus preserving signal reception quality despite the harmful waveform distortion.
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 system effectively reduces bit errors by accurately distinguishing between signal changes and ringing oscillations, ensuring reliable demodulation of amplitude-modulated signals by damping oscillations and setting appropriate thresholds based on resonant frequency offsets.
Implementation Method 1
receiving a detection signal generated with a matching network coupled to the antenna, based on the amplitude-modulated input signal
Implementation Method 2
A demodulator system comprising a matching network, an amplitude detector, and a phase/frequency detector, which detects phase and frequency shifts
Implementation Method 3
A demodulator system comprising a matching network, an amplitude detector, and a phase/frequency detector, which detects phase and frequency shifts
Implementation Method 4
ensuring reliable demodulation of amplitude-modulated signals by damping oscillations
Data Source
AI summary
A circuit for demodulating an input signal is described. The circuit may be configured to demodulate signals modulated with amplitude-based modulation schemes, such as amplitude shift keying (ASK), such that information is encoded in the amplitude of the signals. The circuit may comprise an amplitude detector for extracting the envelope of a received amplitude-modulated signal, a phase/frequency detector for detecting phase and/or frequency shifts, and a selector configured to select one between the output of the amplitude detector and the output of the phase/frequency detector. The selector may be controlled by a control circuit including a delay unit.