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Spendex 30/35   UA-8237
Secure telephone - wanted item

Spendex 30 was a low-cost narrow-band secure telephone, developed between 1974 and 1982 by Philips Usfa in Eindhoven (Netherlands). It is built around a Formant Vocoder, developed at the prestigious Philips Nat Lab. 1 It was never taken into large-scale production, but a small quantity was manufactured by Philips-daughter MBLE in Belgium for use by the Belgian Police (Rijkswacht).

At the initiative of Philips Usfa, Philips Research (i.e. Nat Lab) developed a narrow-band vocoder based on the formants present in human speech. After the first functional prototype, the device was redeveloped a number of times, but the results with respect to the speech quality were disappointing [3]. The price was low however.

The image on the right shows a prototype of a Spendex-30 unit. It consists of a small metal case with all controls at the front. Also at the front is a standard telephone handset, that is connected to the unit by means of a DIN-plug.
  
Spendex-30 prototype

The cryptographic strength of the Spendex-30 was good enough for military and governmental applications. For civil use, the Spendex-35 variant was available. Development of the device was postponed several times due to problems with MUCOLEX which was developed at the same time. By the time the device was finished however, its design had become obsolete as better vocoders had meanwhile become available, such as Linear Progressive Coding (LPC), and variants like LPC-10, CELP and RELP. The LPC-10 vocoder was later used used with the Philips Spendex 40 phone.

A small quantity of civil Spendex-35 units was built by Philips-daughter MBLE in Belgium for use by the Belgian Police (Rijkswacht). Although MBLE assembled most of the set, the crypto-heart was provided by Philips Usfa. The exact number of supplied units is unknown, but from surviving internal documents it is known that Philips Usfa built no more than 45 PCB sets for it [3].

  1. Philips Nat Lab (Philips Physics Laboratory), later: Philips Research.

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Documentation
  1. Spendex 30, Brochure (English)
    Philips Usfa, Preliminary, February 1980.

  2. Spendex 30, Operating Instructions (Dutch)
    Philips Usfa, Preliminary, February 1980.
References
  1. AIVD website, Photograph of Spendex 30
    Retrieved July 2011.

  2. Philips Usfa/Crypto, Spendex 30 stock photographs
    Crypto Museum Photo Archive.

  3. Philips Usfa, Internal Memo L/5636/AvdP/JG
    23 August 1982, page 5.
Further information
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Crypto Museum. Created: Friday 08 July 2011. Last changed: Tuesday, 24 September 2019 - 07:59 CET.
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