Abstract: A system for testing PLC equipment, network conditions, and protocol performance is provided. Noise measurements can be made at a single point, and protocol traffic, signal levels, and upper-layer parameters of any transmissions by other equipment on the same network are logged. Alternatively, a plurality of units located at different points in the PLC network are at least part of a distributed test system. As a result, coordinated tests can be conducted by multiple nodes, such as point-to-point network transfer function measurement and analysis, estimation of the location of noise sources and system null and resonances, receiver operating curve (ROC) measurements with actual protocol modulation, or any other suitable tests. Preferably, the test devices are able to test using a plurality of PLC protocols. In some devices, PLC protocol-specific modules can be added or removed as desired to increase, decrease or change the test device's protocol abilities.

Abstract: An underground monitoring system includes one or more sensors configured to monitor an underground electrical system, a processor configured to monitor the one or more sensors and an alarm device configured to send an alarm when a condition is detected by the processor.

Abstract: A portable unit, preferably adapted for plugging into a common wall outlet, has circuitry for monitoring the voltage and/or current provided through an electrical outlet. In addition to the monitoring circuitry, the unit preferably includes a microprocessor for digitally processing the power waveform as well as analytical quantities related to the waveform. Further, the unit preferably has a storage area for storing samples of the input waveform as well as a log of related analytical quantities for downloading to a computer, local area network, or other destination, for collection and analysis. Preferably, the unit is provided with a local visual display and an alarm indicator.

Abstract: An apparatus to establish bi-directional digital communication over a power line network includes a signal launching circuit to impose a digital communication signal onto a power signal carried by a power line network and thereby form a digital communication power signal at a first point in the power line network. The signal launching circuit is configured to position a pulse of the digital communication signal at any phase location of each half cycle of the power signal. A receiver reads the digital communication power signal at a second point in the power line network. A signal processor is connected to the receiver to recover the digital communication signal from the digital communication power signal.