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Opto
Voice
Stasi
  
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Dahme 1
Opto-electronic voice transceiver - wanted item

Dahme 1 1 was a transistorised semi-portable opto-electronic device for speech communication through infrared light (German: Lichtsprechgerät), developed in the early 1960s by the Operativ Technischer Sektor (OTS) of the repressive intelligence service of the former DDR (East-Germany) — Ministerium für Staatssicherheit (MfS), also known as the Stasi. It was a three-piece unit that was designed to work in combination with a portable Dahme 2 device at the opposite side.

The device consists of three units: a base section, an optical section and an amplifier. The image on the right shows the optical section installed on the bottom section and mounted on a tripod. The battery-powered amplifier was fitted in an external grey box. It allowed two-way voice communication, using a miniature Sennheiser MM-23 microphone and an earpiece.

The device was intended as a base station, using a Dahme 2 device at the opposite end. In 1964, a Stasi agent was arrested in West-Berlin, with a Dahme 2 device in his possession. He had used it to contact a Stasi station in East-Berlin, located in a house just across the Teltow channel.
  
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The Dahme 2 device was smaller and was fitted (partly) inside a photo camera. It is believed both devices (Dahme 1 and Dahme 2) were inspired on the American XE-2 device that had been confiscated by the Stasi in 1959, when Western (CIA) agent Gisela Gebhardt was arrested. As far as we know, there are no surviving sample of a Dahme 1.

 More about Dahme 2

  1. The Dahme is a river that flows in the German states of Brandenburg and Berlin. The Stasi commonly used river names for its infra-red (IR) communication devices. As Dahme is pronounced the same as the German word Dame (lady), the name was easily transformed into Dame 1 (lady 1).

Dahme 1 device installed on a tripod, ready for use.
Dahme 1 device consisting of three parts.
Photograph taken by the German BKA of the house that was used by the Stasi to receive the IR messages.
A demonstration of the Dahme 2
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Dahme 1 device installed on a tripod, ready for use.
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Dahme 1 device consisting of three parts.
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Photograph taken by the German BKA of the house that was used by the Stasi to receive the IR messages.
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A demonstration of the Dahme 2

Specifications
  • Type
    Line-of-sight (LOS) light-based communication device
  • Purpose
    Covert cross-border agent communication
  • User
    MfS (Stasi)
  • Manufacturer
    OTS
  • Frequency
    Infrared
  • Purpose
    Speech, recorded audio
  • Usage
    Indoor (limited outdoor usage)
  • Angle (2ω)
    0.5°
  • Bandwidth
    400-2500 Hz ±6dB
  • Range
    Against Dahme 1: 3 km (at 4 km visibility)
    Against Dahme 2: 2 km (at 2 km visibility)
  • Microphone
    Sennheiser MM-23
  • Power
    Receiver: 2 x 3V
  • Transmitter: 5 x 1.5V
  • External
    5 to 8V DC
  • Lamp
    100 hours
  • Dimensions
    Upper part: 215 x 115 x 38 mm
    Lower part: 205 x 105 x 35 mm
    Amplifier: 160 x 115 x 30 mm
Documentation
  1. Dahme 1 Specification
    Original Stasi card. Mfs, Undated. 1 pages.

  2. Dahme 1 Operating Instructions
    MfS, Undated. 2 pages.
References
  1. Detlev Vreisleben, Personal correspondence
    November 2021.

  2. Bundesbeauftragte für die Stasi-Unterlagen (BStU) 1
    Federal Commissioner for the Stasi-Records.

  3. Detlev Vreisleben, Photograph of Dahme 1 (location)
    Taken at Bundeskriminalamt (BKA), Köln (Germany), 2 November 2004.

  4. Detlev Vreisleben, Photograph of Dahme 2 (device)
    Taken at Bundeskriminalamt (BKA), Köln (Germany), 2 November 2004.
  1. Full name: Bundesbeauftragte für die Unterlagen des Staatssicherheitsdienstes der ehemaligen Deutschen Demokratischen Republik (DDR) — Federal Commissioner for the Records of the State Security Service of the former German Democratic Republic (GDR) — officially abbreviated to BStU.
  2. Document obtained from BStU [2] and kindly supplied by Detlev Vreisleben [1].

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© Crypto Museum. Created: Thursday 09 December 2021. Last changed: Monday, 20 December 2021 - 09:54 CET.
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