SCS PTC-IIex, Manual

Page: 19 / 220

1. Introduction
5
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PACTOR-Free-Signal-Protocol, collisions-avoiding access system to HF data services.
•
More robust protocol for the PACTOR link establishment (“Robust-Connect”).
•
CCIR 491-Number-SelCalls (4- and 5 characters), as well as WRU-identifier and
Answerback for comfortable access to SITOR-coast-stations.
For permanent usage of the extended firmware features you need a license key from
SCS.
Without this key you can test the extended features for 20 connects. Refer to
LICENSE
command chapter 6.46 on page 56 . For prices and detailed information (manual) about the
Professional Firmware refer to our homepage: www.scs-ptc.com .
1.6.1 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.
The properties of the PACTOR-III protocol summarized:
•
Under virtually all signal conditions, PACTOR-III is faster than PACTOR-II. Under
average signal conditions a speed gain by a factor 3x to –4x is achieved, under very
favourable conditions the speed improvement can exceed 5x.
•
Maximum data throughput (without compression) greater than 2700 Bit/sec, around 5200
Bit/sec if PMC (online text compression) is applied.
•
PACTOR III is at least as robust as PACTOR-II under extremely poor signal conditions.
•
Maximum bandwidth only about 2200 Hz.
•
Low crestfactor (high mean output power).
•
High spectral efficiency – PACTOR-III makes very good use of the bandwidth.
•
Fully backwards compatible to existing PACTOR-I/II networks.
1.6.2 PACTOR-IP-Bridge
The PACTOR-IP-Bridge (PIB) is a new Network –Integration Protocol developed by
SCS
.
The dominant protocols of the Internet like TCP/IP, as well as the Point-to-Point Protocol
(PPP), which have become standard for establishment of links between Internet applications,
are combined with the PACTOR modes. The result of this intelligent protocol combination is a
data transparent and relatively fast Internet access via HF-radio using standardized user