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<strong>PK</strong>-<strong>232</strong> OPERATING MANUAL<br />
Pactor OPERATION<br />
CHAPTER 11<br />
Pactor OPERATION<br />
11.1 Overview<br />
Pactor is a relatively new Amateur data communications mode. It was<br />
developed in Germany by Hans-Peter Helfert, DL6MAA and Ulrich Strate,<br />
DF4KV. Pactor combines some of the best features of both AMTOR and packet<br />
as well as providing a few new features. Pactor operates at 100 bps or<br />
200 bps depending on radio conditions. Pactor also contains a 16 bit CRC<br />
to provide near error-free operation as does packet and can also<br />
selectively use a data compression scheme (Huffman encoding) to increase<br />
the throughput when transmitting text. Pactor uses an 8 bit word,<br />
allowing the use of the full ASCII character set.<br />
When data blocks are repeated in the case of an error, the receiving unit<br />
can often combine the information in the repeated blocks to provide a good<br />
block without the need of receiving a perfect block. This scheme is<br />
called memory ARQ.<br />
Like AMTOR and packet, Pactor has two basic modes of operation, an ARQ<br />
mode (Automatic ReQuest for reception) and a non-linked mode used for CQ<br />
calls and roundtable operation.<br />
• ARQ Pactor is a handshaking protocol that allows two stations to<br />
communicate in a near error-free fashion. When listening to an ARQ Pactor<br />
communication, you will hear a 0.96 second burst of data from the<br />
information sending station followed by a short burst from the data<br />
receiving station that is an acknowledge (ACK) or non-acknowledge (NAK).<br />
The NAK is sent by the receiving station when the CRC indicates an error<br />
in the data block. Like packet, Pactor is mark-space polarity<br />
independent. The Pactor protocol alternates the data polarity with every<br />
transmission.<br />
• The unproto(col) mode of operation is a non-linked type of operation.<br />
It is used for roundtable operation or for calling CQ. The unproto mode<br />
repeats the data blocks a selectable number of times and can use either<br />
100 or 200 bps. It also uses the CRC error check.<br />
11.2 Where to Operate Pactor<br />
Before you can operate Pactor, you must first know where the activity<br />
occurs. Most Pactor operation occurs on the 20-meter amateur band between<br />
14.065 and 14.085 MHz. Pactor activity can be found on the other HF<br />
amateur bands as well and in most often located between 65 and 90 kHz up<br />
from the bottom of the band as it is on 20 meters. On 80 meters, most<br />
Pactor will be found between 3660 and 3690 kHz. Pactor is not sensitive<br />
to the sideband used, but we recommend using LSB as in RTTY and AMTOR<br />
operating modes.<br />
2/93 11-1<br />
From The <strong>N3UJJ</strong>.COM Document Library
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