A power line carrier communication modem wherein even when the signal attenuation characteristic in the transmission path largely differs depending on the frequency band, the varying transmission path characteristic can be dynamically followed. A power line carrier communication modem (100), which includes a coupler (10), a receiver circuit (20), a driver circuit (40) and a modem circuit (30), uses a power line (1) as a transmission path. The power line carrier communication modem (100) further includes an equalizer circuit (50) comprising a series connection of a pre-amplifier (52) the signal gain of which is variable and a filter circuit (51) the frequency characteristic of which is variable. The modem circuit (30) has a transmission path estimating means (32) that monitors a known signal in a communication band included in a signal received from the power line (1) and estimates the gain and frequency characteristic of the received signal as the transmission path characteristics; and an equalizer control means (33) that varies the signal gain of the pre-amplifier (52) and also varies the frequency characteristic of the filter circuit (51) in such a manner that compensates for the transmission path characteristic estimated by the transmission path estimating means.
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