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vor 116 Jahren fing es an.... (Netzwerktechnik)
Hallo,
in Englisch, aber da ist zu lesen:
"On 15th of March, 1901 the patent office in Berlin granted the patent No. 118717 to the
French inventor C. Loubery [Loub_01]. It was the first notable description of a remotely con-
trolled load management system. This is why the IEEE standardization group P1901
[IEEE_09] selected this number for their name. Loubery used a multiple carrier signal, with
one frequency carrier to control one target device. The client implemented a dedicated fixed
filter to detect ‘his’ frequency. The bit rate was not very high, but it was clearly a powerline
communication. "
und etwas weiter:
"The Carrier Frequency Transmission of voice over high voltage transmission networks be-
gan in the 1920’s. The network provided a bidirectional communication channel which was
important for management and monitoring purposes, because at the beginning of electrifica-
tion, just a telephone network could not cover the communication between transformer stations
and power plants. Due to favorable transmission characteristics, low noise and relatively high
carrier frequencies (15-500 kHz), distances of up to 900 km were reached with a transmission
power of 10 W. Initially, only voice was transmitted and amplitude modulation was used.
Later, telemetering and controlling functions were also implemented."
Quelle: http://www.ets.uni-duisburg-essen.de/download/public/Schwager_Andreas_Diss.pdf
interessant, 900km Reichweite mit 10W über Hochspannungsleitungen....(heute wohl nicht mehr)
Grüsse
Hartwig
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