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ETM-1810/M
HF radio modem with FEC

ETM-1810/M is a high-end HF radio modem with error-correcting features like Forward Error Correction (FEC) and echo-cancelling, developed around 1985 by Telefunken 1 in Ulm (Germany). The device was mainly intended for use by the German Armed Forces and by its NATO allies.

The device supports multiple waveforms and allows additional modes to be added later by updating the firmware or by soft-loading them.

The ETM-180/M was commonly used in the fully adaptive (modified) STANAG 4285 mode with QPSK in the upper sideband and suppressed carrier (J2D). Data transmissions generally took place in 3.2 sec frames at a speed of 2400 baud. The German Army (Bundeswehr) generally used it in combination with the ARCOTEL ACT-1810 data transmission processor, for controlling its adaptive ARQ and automatic frequency selection.
  
Echotel Modem ETM-1810

The device was also used in FARCOS and MAHRS systems, and as part of the HF-7000 special forces radio system. During the Cold War it was also used as part of the base station of the pan-European HARPOON stay-behing radio system. It is fully compatible with the ETM-1820/M that offers some additional features and has an extended control panel with Liquid Crystal Display. At the time of its use, the ETM-1810 was available from Telefunken 1 for EUR 47,550 per unit.

  1. Due to name changes, the ETM-1810 was also sold under the names Telefunken System Technik (TST), DASA, EADS, Racoms, EADS Racoms, and Telefunken Racoms.

Echotel Modem ETM-1810 Front panel
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Echotel Modem ETM-1810
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Front panel

Controls
As the ETM-1810 was usually controlled by the ARCOTEL ACT-1810 controller, or by an external computer system, its front panel does not have any controls apart from the power (ON) and TEST buttons. There are four LEDs that show the current status (go/nogo) and mode (receive/transmit). All further user-interaction is via the CONTROL interface (i.e. the external computer system).



Interior
The ETM-1810 is housed in a 19" 1U rackmount enclosure. Its interior can be accessed from the top, by removing 9 recessed screws from the top panel and lifting the top panel upwards. Note that the top panel is held in place at the sides by two rows of RF-shielding contact 'fingers'.

Inside the enclosure are two PCBs (printed circuit boards): a larger one at the bottom that contains the interfaces (interface board), and a smaller at the top, that holds the firmware and the Digital Signal Processors or DSPs (the DSP board). The image on the right shows one of the two Motorola DSP56001 DSPs.   
Motorola DSP

Top panel removed DSP board Firmware in two sockets Two Motorola 65000-series DSPs Interface Firmware Motorola DSP Interface
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Top panel removed
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DSP board
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Firmware in two sockets
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Two Motorola 65000-series DSPs
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Interface
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Firmware
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Motorola DSP
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Interface

Features
  • High data rates up to 19,200 bps
  • Suitable for MAHRS
  • Suitable for FARCOS
  • Suitable for STANAG 5066 systems [3]
  • Suitable for STANAG 4538 systems
  • Suitable for fax and data transmissions
  • Suitable for burst transmissions
  • Suitable for duplex, half-duplex and simplex transmissions
  • Decision feedback equalizer
  • Compatible with existing cipher equipment
  • Synchrone data interface
  • Remote control (option)
  • Mains or battery power supply (option)
  • Stationary or mobile applications
  • 19" 1U rackmount module
Transmission modes
  • MAHRS/FTA including Frequency Hopping (FH)
  • MIL-STD-188-110A/B
  • MIL-STD-188-110B Appendix F Idependent Side Band (ISB)
  • STANAG 4538
  • STANAG 4539 Annex B, High Data Rate (HDR), inclusive Autobaud
  • STANAG 4415 75 bps (NATO robust waveform)
  • STANAG 4481 FSK
  • STANAG 4285, including Annex E
  • STANAG 4529 (Narrow-Band)
  • STANAG 5065 (MSKLF mode)
  • FSK mode
Single-tone waveforms
  • STANAG 4538
  • STANAG 4539
  • STANAG 4285
  • STANAG 4529
  • MIL-STD-188-110B including Appendex F (ISB)
Interfaces
  • Data
    EIA RS-232C, DIN 66020, CCITT V.24.V.28
  • Control
    EIA RS-232C, DIN 66020, CCITT V.24.V.28 (internal connector)
  • Speed
    75, 150, 300, 600, 1200, 2400, 4800, 9600, 19200 baud asynchonous
Compatible equipment
The following equipment is known to be compatible with ECHOTEL:

References
  1. Telefunken Racoms, ECHOTEL ETM 1810/M
    Website. Retrieved May 2013.

  2. Roland Prösch, Technical Handbook for Radio Monitoring
    2003. Retrieved February 2018.

  3. Wikipedia, STANAG 5066
    Retrieved March 2018.
Further information
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Crypto Museum. Created: Tuesday 20 March 2018. Last changed: Monday, 26 March 2018 - 15:02 CET.
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