Interference-Compensated Optical Signal Measurement Device
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Solution Overview
Problem
Existing optical signal transmission path measurement devices face challenges in reducing energy consumption while maintaining sensitivity, particularly in mobile applications where limited energy resources are available, and are often disrupted by interference radiation such as fluorescent tubes.
Innovation Solution
The device incorporates a power-saving mode that switches off non-essential components during measurement intervals, uses a variable internal resistance interference radiation compensation unit to minimize energy consumption, and alternates between low and high resistance states to optimize signal reception, allowing for efficient interference compensation and reduced energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the device operates continuously with all components active to maintain high sensitivity and interference compensation, then measurement precision and reliability are improved, but energy consumption increases
Solution Approach 1:
The device implements periodic measurement intervals with active measurement phases followed by sleep modes. The controlling unit switches the measuring transmitter and receiver between active and inactive states based on whether a measurement interval is currently active, enabling the system to maintain measurement capability while significantly reducing energy consumption during non-measurement periods.
Solution Approach 2:
The device dynamically adjusts its operational state based on measurement requirements. The measuring transmitter and receiver can be switched between active and inactive states by the controlling unit, allowing the system to adapt its energy consumption to the actual measurement needs while maintaining measurement precision when required.
2Device complexity
If a gyrator is used to set the operating point of the photodiode, then the circuit is simplified, but the low input resistance of the gyrator loads and dampens the photodiode output signal, reducing sensitivity
Solution Approach 1:
The patent removes the gyrator component from the circuit entirely. Instead of using a gyrator to set the operating point, the invention uses a voltage-controlled current source that directly compensates for interference radiation photocurrent without loading the photodiode output signal, thereby maintaining high sensitivity while achieving circuit simplification.
3Measurement precision
If the sensitivity for the measurement signal is increased, then measurement precision is improved, but interference sensitivity also increases, making the system more susceptible to disruption by fluorescent tubes and other interference radiation
Solution Approach 1:
The patent converts the harmful effect of interference radiation into a beneficial compensation mechanism. The voltage-controlled current source generates a compensation current that is equal in magnitude but opposite in direction to the interference-induced photocurrent. By adding this compensation current to the photodiode output, the system eliminates interference effects while maintaining high sensitivity to measurement signals.
Solution Approach 2:
The system implements feedback through the voltage-controlled current source that continuously compensates for interference radiation effects. The controller adjusts the compensation current based on the detected interference level, creating a feedback loop that actively cancels out interference signals while preserving the measurement signal integrity.
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 enables reliable optical signal transmission path measurements with reduced energy consumption, improved sensitivity, and robustness against interference, making it suitable for mobile devices with limited energy resources.
Implementation Method 1
a photodiode is typically operated in the reverse direction... to compensate for a photocurrent resulting from (e.g. ambient) interference radiation
Implementation Method 2
processing an electrical signal which is present at a first circuit node which is electrically coupled to the at least one receiver and is amplified by means of a measurement amplifier
Data Source
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AI summary
The interference-compensated device for measuring an optical signal transmission link is equipped with at least one measuring transmitter (H1, H2, H3) and at least one receiver (D), which is exposed to interference radiation, e.g., from the environment. Furthermore, the device has a control and evaluation unit (17) for controlling the at least one transmitter (H1, H2, H3) and the at least one receiver (D) for transmitting or receiving an optical signal during a measurement phase (C) of a measurement interval and for evaluating the received optical measurement signal by processing an electrical signal that is present at a first circuit node (61, 62) electrically coupled to the at least one receiver (D).The at least one first circuit node (61, 62) is coupled to a first interference radiation compensation unit (26, 27, 28, 29) having a variable internal resistance for the electrical biasing of the at least one receiver (D) by providing a first compensation current with a value that is essentially equal to the magnitude of an interference signal generated by the at least one receiver (D) as a result of the interference radiation. Furthermore, the interference radiation-compensated device has a functional unit (14) for switching the at least one measuring transmitter (H1, H2, H3) and the at least one first interference radiation compensation unit (26, 27, 28, 29) into a power-saving mode in which the at least one measuring transmitter (H1, H2, H3) and the at least one first interference radiation compensation unit (26, 27, 28, 29) are switched off.