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UA-8244 / Mucolex II - Wanted item

BVO-M was a Trunk Encryption Device (Dutch: Bundel Vercijfer- Ontcijferapparaat), developed by Philips Usfa in Eindhoven (Netherlands) around 1981 for the Dutch Army. It was part of ZODIAC, the integrated communications network, and was installed in the automated telephone switch. BVO-M allows transfer speeds of up to 2Mb/s and is also known as Mucolex II and UA-8244.

BVO-M allowed voice and text data to be bundled, encrypted and sent over a line-of-sight radio link. A number of BVO units were generally installed as part of the ZODIAC automated switch, designed by Philips daughter HSA. Many of such switches were implemented as mobile installations, allowing the fast creation of a flexible networks in the field.

Two versions of the BVO were available: BVO-M and BVO-T. The image on the right shows a typical BVO-M which was backwards compatible with the earlier MUCOLEX trunk encryption devices installed in the Army's communication vehicles.
Typical BVO-M unit. Photo courtesy Philips Usfa [1]

BVO was generally installed as part of a terminating subsystem on the DELTACS (ZODIAC) switch. Each unit was housed in 3U 19" drawer, together with a Line Terminating Unit (LTU) and a Universal Junctor (UJ). It allowed multiplexed data (subscriber and trunk channels) to be exchanged at 1 Mb/s with existing MUCOLEX units in the field. An alternative to BVO-M, called BVO-T, was used for compatibility with the standard Trunk Encryption Device (TED) KG-81.

The image on the right shows a complete terminating subsystem in a 19" rackmount. Each subsystem consists of a Line Terminating Unit (LTU) at the left, a BVO Link Encryptor (LE) at the center, and a Universal Junctor (UJ) at the right.

The LTU is marked as LA (Dutch: Lijn Aanpassing). It regenerates a multiplexed data stream at an aggregate bitrate of 256, 512 or 1024 kb/s. It also ensures equalisation for cable lengths up to 2.4 km. The LTU/LA connects either to a standard phone line or to a line-of-sight radio link, such as the FM-200 transmitter [3].
Complete terminating subsystem. Photo courtesy Philips Usfa [1]

The Universal Junctor (UJ) is marked as UO (Dutch: Universele Omzetter. It handles the coupling of the matrix subsystem, the control subsystem and the LTUs. The UJ also handles all possible signalling protocols supported by ZODIAC. It converts the different types of signalling to a uniform protocol for the information exchange wih the control subsystem [3].

BVO-M Trunk Encryption Device Complete BVO unit Variant of the BVO-M called DACOLEX Eearly prototype of DELTACS (ZODIAC). Note that the key fill connectors are missing) Complete ZODIAC switch in the Royal Dutch Signals Museum Close-up of a BVO unit

ZODIAC was an integrated tactical communication system, used by the Dutch Armed Forces from 1979 until the early 2000s. It consisted of a series of (mobile) switches that could be linked together in various ways, e.g. via cables or via line-of-sight radio links. Each mobile ZODIAC switch is generally equipped with a series of BVO units.

The image on the right shows a typical ZODIAC automated switch, with many BVO units installed. The image was taken at the Royal Dutch Signals Museum [2] in July 2008. It shows a completely functional installation, that was installed in the museum after ZODIAC was decomissioned in the early 2000s.

Another image of a nearly identical installation is shown below. It shows the switch at an early stage, when it was still called DELTACS [3]. Note that the key-fill sockets are missing from the BVO units in that image.
Complete ZIODIAC switch in the Royal Dutch Signals Museum

BVO was compatible with a number of international data-standards, including EUROCOM. This allowed the ZODIAC network to communicate with similar systems from other countries. ZODIAC was phased out in the early 2000s, when it was replaced by TITAAN (see below).

When the new TITAAN system was introduced in the early 2000s, the existing ZODIAC equipment was phased out. The BVO-M remained in use however, and was given a new lease of life by TNO, who designed a new UJ (UO) for it. By allowing the BVO to communicate with a modern matrix, existing FM200-based line-of-sight radio links could be integrated with the new system. TNO called the new interface TC-FEC (Turbo Code Forward Error Correction).

In 2005, some BVO-M units were still in use [4]. The last BVO-M units were eventually phased out in 2007, after nearly 30 years of service! More information on the ZODIAC page.

  1. Philips Usfa, BVO-M stock photographs
    Crypto Museum Photo Archive #300633.

  2. Royal Dutch Signals Museum

  3. AJW van Daal & P van der Vlist, DELTACS - a versatile tactical communication system
    Philips Telecommunicatie Industrie BV (PTI), Hilversum (Netherlands), 1984.
    Reprint from Philips Telecommunication Review, Vol. 42, No. 2, pages 74-89.

  4. Th. Sierksma & A. Bijlsma, Transmissie binnen TITAAN
    Intercom, 2005, Volume 1, p. 41-45. Dutch.
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Crypto Museum. Created: Friday 14 December 2012. Last changed: Saturday, 24 February 2018 - 15:27 CET.
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