Direct Access Arrangement Distortion Cancellation
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Solution Overview
Problem
Conventional Direct Access Arrangement (DAA) devices introduce high signal distortion, limiting their use in security alarm systems that require higher bandwidth communication, as they are costly and not designed to handle signal distortion effectively at higher baud rates.
Innovation Solution
A DAA device with a receive optical isolator module and two transmit optical isolator modules, where the transmit modules are connected in parallel to cancel distortion and include impedance matching, ensuring low signal distortion and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional DAA devices use optical isolators to isolate the phone network, then cost is reduced compared to transformers, but signal distortion increases significantly
Solution Approach 1:
The patent applies distortion cancellation by using the optical isolator's inherent non-linearity in a controlled manner. Two optical isolators are configured where one introduces distortion and the other cancels it, converting the harmful non-linear effect into a beneficial distortion-cancellation mechanism. This allows the use of cost-effective optical isolators while achieving low signal distortion.
Solution Approach 2:
The patent changes the operating parameters of the optical isolators, specifically biasing them at different current levels (one at higher current, one at lower current) to exploit their non-linear characteristics. By adjusting these parameters, the system achieves distortion cancellation while maintaining cost-effectiveness.
2Productivity
If security alarm systems use higher bandwidth communication channels, then communication capability is improved, but signal distortion becomes more problematic
Solution Approach 1:
The distortion cancellation technique converts the harmful effect of optical isolator non-linearity into a beneficial feature. By carefully configuring two optical isolators with opposite distortion characteristics, the system enables high-bandwidth communication while actively canceling signal distortion, making high bandwidth achievable without suffering from the usual distortion problems.
3Object-generated harmful factors
If DAA devices use transformers to isolate the phone network, then signal distortion is reduced, but cost increases significantly
Solution Approach 1:
The patent replaces expensive transformers with cheaper optical isolators. While optical isolators individually introduce distortion, the patent's distortion cancellation technique using two optical isolators achieves transformer-level performance at a fraction of the cost, making this a successful application of using cheaper components to achieve premium performance.
Solution Approach 2:
The patent creates a composite isolation system using two optical isolators with different operating characteristics. By combining these two components in a specific configuration, the system achieves the low distortion performance traditionally associated with transformers while maintaining the cost advantages of optical technology.
4Speed
If conventional DAA devices operate at higher baud rates, then communication speed is improved, but signal distortion and jitter increase
Solution Approach 1:
The distortion cancellation technique enables high-speed data transmission by converting the harmful non-linear distortion into a beneficial feature. The two optical isolators are configured to cancel distortion across the bandwidth required for high baud rate operation, allowing fast communication without the usual penalty of increased jitter and 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 solution reduces signal distortion, enhancing signal integrity and reliability for security alarm systems, allowing higher bandwidth communication without increasing costs, and maintaining low signal distortion even at low receive signal levels.
Implementation Method 1
One purpose of the optical isolator is to transfer electrical signals across an optical path in order to isolate from one another both sides of the electrical device. Optical isolator blocks common mode electrical signals, thereby leaving differential mode electrical signals that are coupled through an optical path.
Data Source
AI summary
A direct access arrangement (DAA) device configured to interface a security alarm modem with a phone network. The DAA device comprises a receive optical isolator (OI) module and first and second transmit OI modules. The transmit OI modules are joined in parallel with one another to receive signals from the security alarm modem and convey the signals to the phone network. The receive IO and first and second transmit OI modules may each be interconnected to at least partially cancel distortion generated by the first and second transmit IO modules.