Office of Military Government for Germany (U.S.)
Office of the Director of Intelligence
3 October 1945
By
J.A. Parott
Technical Industrial Intelligence Committee
For better understanding what this system is about, we consider this brief schematic first
The Germans, maybe also in Switzerland, this postal serve was known as 'Drahtfunk'.
I still can remember having seen and listen to this wire-broadcasting servie; a black box with a selector Drahtfunk or wire antenna.
During the course of the war, this service was becoming rather relevant, as it also worked when mains power failed.
Although, originally meant as a commercial service, later these long wave signals being distributed in such a manner, that a small wire nearby a telephone connectionwas enough for picking up the three distributed long wave channels. Generally distributed at: 155 kHz, 210 kHz and 260 kHz (wartime situation, maybe also valid for the pre-war situation)
Keywords: All program equipment seen was in good condition, very few documents available; Three voice frequency programs were usually modulated at a toll office, mixed and distributed via broad band amplifiers and cable pairs, inclucing the regular subscriber loops, without interferring with their low frequency use for telephone purposes;
Shortly before the war the Reichspost is reported to have initiated a ten-year program to extend their wired broadcast service "to all potential listeners. the reasons given are:
1 The lack of adequate radio broadcasting frequencies to satisfactorily serve many areas evem taking into account frequency modulation.
2 The likelyhood of jamming from abroad
It was known that a considerable number of installations had been made before the war. However, during the war the scope of this service increased greatly as it was also used for air raid warnings and to some extent for messages during the raids, ...For example, Hamburg was stated to have served about 30,000 stations, whereas the areas in and around Nürnbergand Munich had under 200. It was observed in the offices visited in the south that few facilities were provided for this service
Thre modulators with carriers of about 155, 210 and 260 kHz are located in a toll office program room, ...
The broad band amplifier output is given as 8 volts into 150 ohms for the three carriers (presumably unmodulated).
The allowable loss from a broad band amplifier transmitting programs, to a station is given as about 6.7 N to provide a receiving level of 10 mV across 150 ohms ...
The amplifier equipment is capable of transmitting 30 to 10,000 cycles (Hz), but the received progra, material was not more than 30 to 8,000 cycles and usually less.
During the war, several experients? were adopted to furnish the service to a greater number of people. The basic plan was to impress an adequately high level on all the cable pairs to ground ...
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