| |
Digital Modes in EMCOMM
Today's amateur radio operator has several modes to chose from
when operating. These modes include voice, i.e. SSB, AM or FM, and digital
modes, i.e. CW, PACKET, PACTOR, PSK, MFSK, RTTY, SSTV and more. With the
exception of CW, all digital modes require a control apparatus or interface
between your radio and your computer. The most used digital modes used by EMCOMM
are PACKET and PACTOR.
There are also several software programs to chose from that allow you to operate
in these modes. Some of the more popular ones that are in use are Airmail for
PACKET and PACTOR and Mix-W for modes that make use of your computer's sound
card.
There is a system that is available to all amateurs that makes use of two of
these digital modes. This is the Winlink 2000 system. (For more information go
to www.winlink.org.) This system allows you
to send and receive messages via standard email addressing and allowing you
access to the Internet to forward these messages.
The Winlink 2000 system takes advantage of two of the more tried-and-tested
digital modes, PACKET and PACTOR. THERE IS NO WINLINK DIGITAL MODE.
Winlink 2000 requires access to the Internet for the forwarding or storage of
all messages.
Stations that use the Winlink 2000 system normally use the client side software
Airmail for preparing and sending messages. The stations that are Sysops (system
operators) – these stations are known as a RMS (Remote Message Station) Node,
use proprietary software developed by the Winlink Development Team. Most of this
software is in beta release, meaning that it may still have some problems that
have yet to be resolved. This software allows them to hook their stations
(PACTOR or PACKET at this time) to the Internet for the exchange of
messages/email. They do not store messages without specific software that is
still under development for use at a later date.
The essential parts of a digital station are the radio, the control/interface
device and a computer capable of running the associated software. Most of the
software for these digital modes is written for computers running Windows 98 or
later. There is some software written for Linux-based computers, and there may
be a few programs for Mac computers, but they are few and far between.
Digital modes used for formal messages, those that require a printed (hard)
copy, are PACKET and PACTOR. These modes allow for store-forwarding of messages
between stations. Other sound-card modes don't have this capability. This is
almost a requirement for EMCOMM digital operations.
PACKET and PACTOR modes require a Terminal Node Controller (TNC). There
are some "Packet Engines" that can be used with your computer's sound card such
as AGW, but they, in my opinion, leave something to be desired. PACTOR requires
a TNC to transmit but some software like Mix-W has a PACTOR receive mode via
your computer's sound card. This allows for the reception of PACTOR 1 signals.
PACTOR today has 3 different speeds/modes referred to as PACTOR 1 (the original
PACTOR mode), PACTOR 2 and PACTOR 3. PACTOR 2 and 3 require a SCS TNC/Modem and
a proprietary license to use these modes. PACTOR 1 is available with the use of
the AEA/Timewave PK-232 and several of the Kamtronics TNCs.
There are several TNC/Modems available for PACKET. Although PACKET is generally
thought of as a VHF/UHF mode, although it may also be used on HF. The most
common of the PACKET TNCs in use are the PK-88 by Timewave, the Kamtronics
KPC-3+ and MFJ- 1278 (discontinued).
Digital operation can be lots of fun and a great asset to emergency
communications when you are aware of its limitations. What it's NOT is the ONLY
mode for EMCOMM. Digital is great for sending messages over long distances,
depending on your station's capabilities, but it will not deliver the message
the last mile; this has to be done by a human operator.
The best way to learn digital, like any other mode, is through practice. Join
local digital nets and participate in digital exercises to become proficient at
operating in these modes, and you will be ready when called on.
Your Washington State ARES teams make use of PACKET and PACTOR modes when called
upon. If you are thinking about operating these modes W7EMD is available on via
PACKET on 145.630 MHz and on PATOR on 3595 kHz. (center frequency). If you'd
like to know which station close to you may be operating a digital connection,
check the map here.
|
