Spy sets
Burst encoders
Logo (click for homepage)
Voice encryption handset

ORTHROS was a small leight-weight handset with built-in encryption and decryption, developed by Philips Usfa in Eindhoven (Netherlands) around 1987. Being half-duplex, it was intended for use in combination with mobile VHF radios. Unfortunately, it was never taken into production.
ORTHROS was an attempt by Philips Usfa to produce equipment for civil applications, based on their extensive experience in the military market and an earlier design. Using advanced in-house developed cryptographic algorithms, ORTHROS would have posed a real threat to eavesdroppers on mobile radio channels [2].

The device measured 75 x 100 x 300 mm, which is roughly the size of a telephone handset with a large 'blob' at the bottom. It weighted 600 g and was available in either black or white. It could be powered by the radio or by internal batteries.

Speech was processed by a digitally controlled delta modulator (DCDN) before it was encrypted at 9,600 to 64,000 bits per second by the military-grade crypto unit, making it suitable for VHF/FM radio with 25 kHz channel spacing [2].
All photographs on this page courtesy Philips Usfa [1]

The unit has 4 control buttons at the bottom and a push-to-talk (PTT) button at its side. Above the 4 control buttons are 5 indicator lights. The first three lights show which encryption key is selected. The upper left button is used to select the required key. The upper right button is used to turn the unit off. The device can be turned on by pressing either volume-up or volume-down.

ORTHROS could hold up to 3 encryption keys, but at present it is unclear how the keys were loaded into the device. Whenever security was compromized, the keys could be destroyed by pressing 3 buttons simultaneously (PTT, KEYSEL and volume-up). This is called: ZEROIZING. The keys were also destroyed automatically, whenever the unit was opened (tamper-proof).

It was the aim of Philips Usfa to develop a family of secure voice devices of which the radio version (ORTHROS) was planned to be released first. The complete product was developed and a full-colour leaflet was released, but the unit was never taken into production. This was partly due to the fact that the Dutch government didn't want advanced cryptography to be available to the general public at the time [3]. As far as we know, there are no surviving ORTHROS units.
White ORTHROS unit with a curly cord The black and the white version of ORTHROS shown side-by-side The black and the white version of ORTHROS shown side-by-side Key panel of the ORTHROS unit Rear view of the ORTHROS' key panel

In Greek mythology, ORTHROS was the two-headed guard dog, brother of the three-headed Cerberus. Orthros was charged by the giant Eurution with guarding his purple herd. As far as we know, there are no ORTHOS units left. The only item that has surfaced in 2011, is the keyboard of this unit. It is a plug-in unit with 4 PCB-mounted switches and 5 LEDs, made by Fela Switch Panel in Switzerland. If you know a surviving ORTHOS unit, please contact us.
Military handset
The design of ORTHROS was based on the development of a military encryption handset that was developed by Philips a year earlier [4]. Based on past experiencies with mobile voice encryption devices like the Spendex 10, Philips wanted to build the entire crypto device into the handset.
The old Spendex 10 was designed as a separate encryption unit that was intended for the RT-3600 radio, built by PTI in Hilversum. Being the same size as the RT-3600 and being integrated with the complete concept of the RT-3600, it was not very practical on other types of radio.

By integrating the electronics into the handset, the encryption unit could be used with virtually any type of (military) radio, simply by connecting it to the 5-pin U-229 socket that is present on nearly all radios. The image on the right shows an artist impression of such a military handset.
Artist impression of the military encryption handset (1986)

This military handset was designed around 1986 and was initially intended for use with the successor of the RT-3600, the RT-4600, that was also being developed by PTI in Hilversum. Unfortunately however, the design wasn't finished when the radio was ready for release, and a competing product was chosen instead. As a result the project was cancelled and the product never saw the light of day. Two attempts to release the handset as a commercial product, the half-duplex ORTHOS (above) and the full-duplex UP-2081 (below) also failed.
The UP-2081 was another attempt to use the technology developed for the Military Handset and the ORTHOS handset above. The UP-2081 was developed in 1989 for full-duplex applications, such as ordinary (domestic) telephone sets and the first generations of (analogue) car phones.
The UP-2081 was much smaller than the earlier ORTHROS and had a far more elegant design, resembling a simple standard telephone handset of the era. Most of the controls were located on the inside of the handset, together with a 2-digit 7-segment LCD display. Two versions of the UP-2081 were planned: one with 3 sets of up/down buttons and one with a standard phone keypad.

The image on the right shows the version with the up/down buttons. The display was probably intended for selection of the appropriate crypto key. A picture of the other version is available below. Apart from these case mock-ups, no actual hardware was ever released.
One of the case designs for the UP-2081

Artist impression of the military encryption handset (1986) Artist impression of the military encryption handset (1986) Artist impression of the military encryption handset (1986) One of the case designs for the UP-2081 Alternative design of the UP-2081 with standard keypad

  1. Philips Usfa stock photographs
    Crypto Museum Photo Archive.

  2. Philips Usfa BV, ORTHROS mobile secure radio voice system
    ORTHROS leaflet. 1987. Document number 9922/154/13041.

  3. Interview with a former Philips Usfa employee
    Eindhoven, June 2011.

  4. Former Philips Usfa/Crypto employee, Military handset and UP-2081
    Personal correspondence, February 2013.

Further information

Any links shown in red are currently unavailable. If you like this website, why not make a donation?
Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Sunday, 24 February 2013 - 23:16 CET
Click for homepage