Specifications

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