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Power line communications (PLC) is a term describing different systems for using electric power lines to carry information. All power line communications systems operate by impressing a modulated carrier signal on the power wires. Different types of power line communications may use different frequency bands, depending on regulations and the system characteristics. Since the power wiring system was originally intended for transmission of AC (or DC) power, it has limited ability to propagate higher frequencies. Data rates over a PLC system vary widely. Higher data rates generally imply shorter ranges, such that a local area network operating at megabits per second may only cover several meters.

Narrowband PLC (NB PLC) is a generic term for PLC that typically operates in frequencies below 500KHz. Specifically, frequencies below 148.5KHz have been authorized by Europe's CENELEC for broadly deployable PLC systems. Within this range high-voltage transmission lines may carry data to distances ranging from hundreds of meters to a few kilometers. The resulting data rates are modest, ranging from 1Kbps to 200Kbps. These rates are appropriate for telemetry, data gathering and control applications.

The most broadly deployed Narrowband PLC solutions employ relatively simple, but extremely cost effective FSK and B-PSK modulation techniques. Several interoperable standards have been developed based on these techniques. With the advancement of communication technology, more advanced modulation techniques have developed and are being deployed. Most notably Orthogonal Frequency Division Multiplexing (OFDM) has proven to be particularly effective due to its inherent ability to adjust to the noise environment, resulting in a more robust more capable communication network.

Semitech has placed itself at the forefront of Narrowband PLC with products ranging from the most integrated FSK/S-FSK/B-PSK solution (SM6401) to one of the first market deployed OFDM solutions (SM2200), specifically developed to support applications on the Low and Medium Voltage power distribution networks. Semitech is committed to stay at the forefront of the Narrowband PLC by expanding its product portfolio to take advantage of newly emerging technologies and standards.