Abstract: An alarm switching matrix, a power distribution unit and a method of operating a power distribution unit are disclosed. In one aspect, an alarm switching matrix for use with multiple types of overcurrent protection devices is provided. In one embodiment, the alarm switching matrix includes: (1) a power circuit coupled to a power input terminal and configured to provide a supply voltage to alarm contact terminals for a circuit breaker and (2) an alarm circuit coupled to an alarm output terminal and a fuse alarm contact terminal that is one of the alarm contact terminals, wherein the alarm circuit is configured to deliver alarm signals to the alarm output terminal from both a circuit breaker connected to the alarm contact terminals and a fuse connected to the fuse alarm contact terminal.

Abstract: Test systems and methods are disclosed for determining the cause of an extended off-hook condition on a subscriber line. A test system as described herein measures a first resistance of the subscriber line based on a first current, and also measures a second resistance of the subscriber line based on a second current. The test system then determines the difference between the first and second resistance measurements. If the difference between the first and second resistance measurements is greater than a threshold value, such as 20 Ohms or more, then the test system determines that the extended off-hook condition is the result of an off-hook telephone on the subscriber line. If the difference is less than the threshold value, then the test system determines that the extended off-hook condition is the result of a short circuit on the subscriber line.

Abstract: Test systems and methods are disclosed for determining the cause of an extended off-hook condition on a subscriber line. A test system as described herein measures a first resistance of the subscriber line based on a first current, and also measures a second resistance of the subscriber line based on a second current. The test system then determines the difference between the first and second resistance measurements. If the difference between the first and second resistance measurements is greater than a threshold value, such as 20 Ohms or more, then the test system determines that the extended off-hook condition is the result of an off-hook telephone on the subscriber line. If the difference is less than the threshold value, then the test system determines that the extended off-hook condition is the result of a short circuit on the subscriber line.

Abstract: DSLAMs and associated methods of installing DSLAMs are disclosed where the components of a DSLAM are distributed in a DSL network. A distributed DSLAM as provided herein includes digital signal processing components implemented in a centralized system (e.g., a central office) on the DSL network. The distributed DSLAM also includes digital/analog conversion components (e.g., analog front end (AFE) components) implemented in a distributed node on the DSL network that is remote from the centralized system. The distributed DSLAM also includes a spanned communication link (e.g., optical fiber) between the digital signal processing components and the digital/analog conversion components. The digital signal processing components in the centralized system are considered more likely to be upgraded than the digital/analog conversion components in the distributed node. Thus, upgrades for the DSLAM can frequently be performed at the centralized system instead of at the distributed node.