controller pactor software order now who we are

Who we are

Today SCS is one of the world leading manufactures of high end HF radio modems. Still working on new technologies to fullfill our customers needs. development team consists of four guys that share all work and responsibilities to create the world's best modem technology.
The picture shows us at our booth at the HAM Radio exhibition in 1999.
From left to right we are:

1. Dr. Thomas Rink (DL2FAK)
used to work as a physician, a specialist for nuclear medicine. As SCS' managing director, he is responsible for contracts, cost analysis and general accounting.
Leading the company with a great deal of personal engagement, he makes sure every single customer is satisfied. This has made him very popular among our clientele. Without his selfless efforts, SCS would not be as successful and not function as seamlessly as it does today.

2. Martin Clas' (DL1ZAM)
background is development engineer for military electronics and specialist for EMC (Electro Magnetic Compatibility).
At SCS he performs the CAD, EMC as well as Analog-Design and creates the PCB-Layouts. In addition he is in charge of procurement, production management and quality engineering.
3. Hans-Peter Helfert (DL6MAA)
originally majored in physics and chemistry at the Technical University of Munich. For some years he has been intensively working on theory of communication, Signal-Theory and implementing the newest results in algorithms for DSP use.
His main profession is system and software development for SCS. As the main inventor of PACTOR®, PACTOR-II and PACTOR-III he programmed the software for all PTC's.

4. Peter Mack (DL3FCJ)
working as an engineer for electronics designs the PTC's microprocessor sections. Besides being in charge of SCS' tech support hot line and the web site, his responsibilities encompass the german manuals and programming the PTC-II BIOS.
Pictures from the HAM Radio exhibition.
SCS weather stations

Contact us

Address: SCS
Special Communications Systems GmbH & Co. KG
Roentgenstr. 36
63454 Hanau
Tel: +49-6181-85 00 00
9:00 - 12:00 and 14:00 - 18:00 German time (CET)
Current time in Germany:
Fax: +49-6181-99 02 38
VAT ID No.: DE 218002556
Bank: Postbank Frankfurt
Account No.: 555 836 600
Banking Code: 500 100 60
IBAN: DE25 5001 0060 0555 8366 00

PACTOR® is a registered trademark of SCS, Germany.

Note: To get rid of all the trash sent to us via e-mail we use a very effective spam filter! To make sure your mail gets through please consider the following points when sending your e-mail:

  • Please use a descriptive subject.
  • Use plain text instead of HTML in your message. Never use pure HTML messages without alternative text.
  • Do not enclose any attachments (specially .exe files) with your mail.

The next paragraph is for the German bureaucracy. :-(
So please ignore it if don't read German!


Spezielle Communications Systeme GmbH & Co. KG
Röntgenstr. 36
63454 Hanau

Telefon: 06181 / 85 00 00
Telefax: 06181 / 99 02 38

Persönlich haftende Gesellschafterin: SCS Beteiligung u. Verwaltung GmbH
Vertretungsberechtigter Geschäftsführer: Dr. Thomas Rink

Registergericht: Amtsgericht Hanau
Registernummer: HRA 5579

Umsatzsteuer-Identifikationsnummer gemäß §27a Umsatzsteuergesetz: DE 218002556

Haftungshinweis: Trotz sorgfältiger inhaltlicher Kontrolle übernehmen wir keine Haftung für die Inhalte externer Links. Für den Inhalt der verlinkten Seiten sind ausschließlich deren Betreiber verantwortlich.

The history of SCS

Two German radio amateurs (Ulrich DF4KV and Hans-Peter DL6MAA) initiated the PACTOR® project. As early as 1986, experiments with modified AMTOR/SITOR protocols began. In tedious tests, the noise conditions on the HF-Bands were investigated, and the best transmission parameters were determined. Additionally, a lot of mathematical calculations and simulations were performed, the PACTOR® protocol deduced from these results.

The first PTC's were wire-wrapped on bread-boards. Hans-Peter built his PTC based on a SMD Z80 single-chip processor, while Ulrich wire-wrapped his PTC in conventional Z80 technology. The third station that got on the air using PACTOR® was Tom (DL2FAK). His PTC was based on DL6MAA's SMD Z80 version. Tom and Hans-Peter ran a lot of tests that resulted in considerable improvements over PACTOR®. In the fall of 1989 Tom developed a PT-link system that facilitated access to Packet-Radio nets from PACTOR®. Tom also took on the difficult task of a project manager to coordinate the various proposals, comments, and critiques that came pouring in, Hans-Peter's version was too difficult for home construction, and Ulrich's version contained too many parts. Thus, the decision was made to develop a completely new hardware design.

Peter (DL3FCJ) developed the digital section of this hardware, Hans-Peter developed the modem and carried out software adjustments. The software was rounded off with inclusion of an RTTY and AMTOR routine developed by Ulrich. Martin (DL1ZAM) revised the circuit diagram and produced the printed-circuit-board layout. Thus the first well known PTC was created and quickly sold all over the world.

At that time, SCS was founded.

In 1993 the production of the Z80-STI peripheral chip, used in the Z80 PTC, ended. This created the opportunity to develop the PTCplus. Based on an MC68000 processor, the PTCplus is the springboard to a totally new dimension in modern HF communications.

Together with the PTCplus, the development of the PTC-II was also undertaken. The PTC-II project required a thorough knowledge of signal processing technology and it's associated programming. Much research work was necessary to develop the present PACTOR-II modulation process. Despite all this, it was possible to astonish visitors with the first prototype PTC-II at the 1994 HAM-Radio convention.


In summer of 1999 the "small brother" of the PTC-II, the PTC-IIex was ready for sale. Being less expensive at excellent performance and the increasing need of email via HF made the PTC-IIex to be THE standard modem for HF-email within a short time.

Summer 2001 is the time of the PTC-IIpro. Being the successor of the PTC-II, the first PACTOR-II modem, the PTC-IIpro now establishes the new top of SCS' s goal to provide the best modem-technology for data transmission via HF at all.

At the first of May 2002 SCS introduced the new developed high speed data mode PACTOR-III. PACTOR-III is a third generation HF protocol building on latest developments in 2-dimensional orthogonal pulse shaping, advanced error control coding, and efficient source coding. Due to the advanced signal processing methods applied, PACTOR-III provides outstanding performance under poor and moderate signal conditions. As PACTOR-III also achieves very high throughput rates under good signal conditions, it is well-suited to HF channels with good SNR and low signal distortion as well. During the development of PACTOR-III, high importance was attached to compatibility with ordinary SSB transceivers (using standard 2.2-2.4 kHz wide IF-filters). Therefore, PACTOR-III can achieve its maximum speed with using unmodified, common SSB transceivers. The occupied bandwidth is around 2200 Hz.

Thus PACTOR-III is the ideal means of fast and reliable data communication over (the sometimes difficult medium) HF-radio. The new protocol is fully backwards compatible to existing PACTOR-I/II networks.

In summer 2003 the PTC-IIex suceeded the PTC-IIe. Although both models nearly not differ from their outer appearance, in the inside the PTC-IIex has been deeply reworked. The PTC-IIex comes with a more powerful DSP section, a TXCO stabilized oscillator, a better power supply and with 2 MB of static RAM.