Linjesender

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A Linjesender was a low power longwave transmitter used for broadcasting in Norway. It consisted of a PLC-system, which fed the radio programme on a frequency in the longwave broadcasting range into an overhead electric power transmission line. Because Norway is a country with many mountains, there are many large spans of power lines. Often they are quite high above the ground. In such regions, the power line served as antenna for the Linjesender.

The typical powers used by Linjesenders were between 250 watts and 2 Kw. Most systems used frequencies in the longwave band or in between the LW and MW band although some used medium wave or frequencies below the standard LW band which required special receivers.

Similar systems were used in Germany, where it was called "Drahtfunk" and in Switzerland, where it was called "Telefonrundspruch" and used telephone lines.

In the 1930s some towns in Great Britain used wire broadcasting experimentally either over dedicated cables (sometimes as baseband audio) or on power lines. However as the coverage of conventional broadcast stations improved the popularity of these "radio relay" or "rediffusion" systems waned.

Wired broadcasting had several advantages over conventional broadcasting. #

1) Less susceptible to interference
2) Potentially greater choice of stations (as overcrowding on the frequency bands was less of a problem)
3) Potentially greater audio quality as wired transmissions weren't subject to the same restrictions on bandwidth as terrestrial AM broadcasts.
4) In a mountainous country like Switzerland it was difficult to obtain satisfactory national coverage with conventional transmitters. Particularly back in the 1930's when transmissions were typically less powerful than today.

On the other hand there were practical and economic difficulties in extending such services to remote and/or thinly populated regions. Wired broadcasting could also be used by governments as a tool of censorship through promoting ownership of wire-only receivers which couldn't receive foreign stations.

The last Linjesender in Norway was shut down in 1987 although the Swiss counterpart survived another ten years.

An example of the programs carried by "Telefonrundspruch" in Switzerland: