Modular base station for FS-5000
- Wanted item
BS-5000 was the name of the base stations of the SY-5000 secure
communication systems. It was capable of receiving and processing encrypted
messages to and from FS-5000 field stations. It was used by stay-behind
organisations, Special Forces (SF) and intelligence agencies.
As the base station consists of a number of products, it comes in many
variations under various names.
The FS-5000 field station was capable of sending digital data at very high
speed (2000 baud) over a narrow-band HF radio channel, using a sophisticated
technique called Vestigial Side Band modulation (VSB). This was done to
minimise the risk of Radio Direction Finding
(RDF or DF). It takes the FS-5000 transmitter
just 0.8 sec. to send a typical 55-character message.
Creating a VSB-signal is relatively straight-forward, but it requires a
very complex and sophisticated decoder at the receiving end. For this reason
the receiver uses 'ordinary' single-channel
SSB-modulated Frequency Shift Keying (FSK) at a speed of just 75 baud.
As a result, direct communication between two FS-5000 field stations
is not possible. An FS-5000 field station can only communicate
with a BS-5000 (or the later BS-7010) field station.
The image above shows the block diagram of a typical BS-5000 base station.
At the heart of the base station is a PR-5000 Central Processing Unit (CPU)
and a KG-5000 Crypto Unit, that allows incoming and outgoing data to be
decrypted and encrypted in real-time.
The teleprinter is used to control the CPU, whilst a separate terminal
(Televideo 955) is used for entering messages, cryptographic keys and
Note that the RX and TX antennas have to be 150 metres or more apart
in order to avoid interference.
Please note that the above block diagram shows internal model numbers
that were issued especially for the FS-5000 project. The block diagram
is based on the information given in the user manual and is used for a
technical and functional explanation only. It does not represent the
actual configuration of the base station, which was largely built from
In reality, the base station consisted of separate transmitters,
receivers, modems and other equipment from various manufacturers.
The block digram above shows an example of a practical implementation
of the BS-5000 base station, built from standard off-the-shelf products.
For reception, the highly acclaimed Telefunken E-1800/A receiver
was used. This receiver was also sold under the AEG, TST and DASA brands.
At the time it was the only receiver with a Digital Signal
Processor (DSP) that was capable of demodulating VSB signals.
A Telefunken Echotel modem was used for modulation and demodulation
of the digital signals, as well as for encryption and decryption of
the data. All components were controlled by a single PC that could
also be used as a data-entry terminal.
For transmission, a standard Rohde & Schwarz XK852 transceiver
is used. This is a heavy duty transmitter with a configurable output
power of up to 100 W.
The image on the right shows the interior of a mobile base station
as it was shown in the 2006 Telefunken brochure . The various
parts are mounted in the 19" rack at the center.
At the top is the transmitter and, immediately below it,
a Telefunken E-1800 receiver. The middle part of the rack contains
the ECHOTEL and ARCOTEL modems. In the bottom section are further transceivers
and power supply units. The controlling PC is at the far left.
This semi-permanent (mobile) station was also used with the
HF-7000 radio set.
The image above was taken from the old HF-7000 brochure .
Funnily, the image in the brochure was erroneously mirrored.
As the behaviour of the HF radio bands changes continuously (propagation),
the suitability of a certain frequency for long distance communication
depends on a number of circumstances, such as time of the day (or night),
time of the year, temperature, distance, etc. This requires a complex
table of usable radio channels that changes continuously.
For this reason, the BS-5000 station was often equipped with multiple
E-1800/A receivers, all controlled from a central PC.
The E-1800/A receivers were later replaced by the fully digital
PC-based E-2000LH-5 receivers that were also manufactured by Telefunken.
At some point, Telefunken even introduced the EKASUS, a PC-based
frequency management system with built-in propagation prediction.
A similar system was later used with the
HF-7000 radio set and
became known as EKS-7000 .
At present we have no photographic image of a complete BS-5000 or BS-7010
It is possible that some countries used different base stations than the
one described here. It is also possible that it was known by a different
name or number.
If you have any additional material, documentation, information,
or - better - a complete base station, please contact us.
For our demonstration setup, we are also looking for an E-1800/A receiver.
- Feldstation FS-5000M, Technisches Handbuch, Teil 1, Beschreibung
Field Station FS-5000, Technical Manual, Part 1, Description (German).
- Feldstation FS-5000M, Technisches Handbuch, Teil 2, Bedienungsanleiting
Field Station FS-5000, Technical Manual, Part 2, User Manual (German).
- Telefunken Racoms, HF Gerätefamilie 7000
12-page full-colour brochure (German). April 2009. Retrieved August 2010.
- Telefunken Racoms, HF Gerätefamilie 7000
12-page full-colour brochure (German). April 2006. Retrieved May 2013.
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