Portable Packets

Turn a Tiny "Palmtop" Computer Into a Dynamite Packet Station!

By Phillip Nichols, KC8DQF ( QST - March 1997 )

I have been interested in computers since the "old days" when I dabbled with a Commodore Vic-20 and my parentís Atari 400. Back when the Macintosh was still an Apple IIe! I kept pace with the changing technology while I upgraded my computer skills. In recent years Iíve relied on my notebook PC and a Hewlett-Packard HP-200LX "palmtop" computer.

Actually, my notebook PC has taken a few trips to the computer doctor. At one point it was absent for two months! It was during this time that I became more interested in exploring the capabilities of my HP-200LX. I also learned of a fascinating hobby: Amateur Radio.

After four weeks of study and the inevitable exam, I was rewarded with my Technician Plus ticket. A few months later I earned my Advanced. I was eager to see what I could do with this new hobby. Before long, I discovered packet.


Whatís Packet?

In case youíre a stranger to the term as hams use it, packet is a method of connecting computer systems and networks by radio - typically using FM transceivers. Many hams use packet to connect to bulletin board systems (BBSs) where they download files and exchange electronic mail (e-mail). Others use packet to help them hunt DX and gather contest points (DX PacketCluster networks), while some enjoy tracking moving objects on computer-generated maps (APRS - the Automatic Packet Reporting System).

Besides the radio and the computer, all you need to get started is a terminal node controller (TNC). Think of a TNC as a radio modem and youíll understand how it works. A TNC takes data from your computer and turns it into audio tones that the radio can transmit. A TNC also takes audio tones from the radio and converts them to data for the computer. In addition to the conversion task, TNCs assemble data into the proper packet formats, check for errors in received packets (and request replacements if necessary) and perform many other functions.

TNCís can be stand-alone devices - little boxes that sit next to your radio and computer. But TNCs can also be created in software with just a tiny external modem to convert tones to data and vice versa. Software TNCs have the advantage of requiring little external hardware. That makes them ideal for portable packet operating!

Creating a Palmtop Portable Station

Portability is important to me. I live with the most restrictive antenna requirements you can imagine: no outdoor antennas allowed! Like many "indoor hams", I hang antennas in my living room (Iím blessed to be married to a forgiving wife!).

I started to wonder if I could use my palmtop for packet. With a palmtop and an FM rig, I could log on from anywhere - even from inside a shopping mall or at work.

The key ingredient turned out to be the BP-2 by Tigertronics. It comes with Baycom 1.4 software and a modem (a small 2-inch-square custom analog/digital modem based on the old Bell-202 standard). The BayCom software makes a computer behave like a TNC. In computerese we say it "emulates" a TNC. BayCom is available free on various landline BBSs, Compuserve, and on the World Wide Web.

I connected my BP-2 modem to my Radio Shack HTX-202 handheld according to the BP-2 instructions, keeping the cables as short as possible. It worked like a charm!

The Future

Iím planning to operate a land-mobile packet station while Iím taking vacation trips this summer. Iíd also like to try aeronautical mobile packet from a private airplane just to see how it would work. Of course, a portable packet station like mine is ideal for public service work. You could, for example, assist disaster relief by relaying emergency traffic. The possibilities are endless!

If youíre living in a restricted environment, or if you are intrigued by the idea of portable packet operating, get your hands on a palmtop and give it a try!

Palmtop Packet Resources:

PO Box 5210
Grants Pass, OR 97527
tel 800-8BAYPAC, or 541-474-6700
fax 541-474-6703
World Wide Web http://www.tigertronics.com

The Palmtop Paper
(a newsletter devoted to palmtop computing)
Thaddeus Computing
57 E Broadway
Fairfield, IA 52556
tel 800-373-6114

Other palmtop software on the Web at: ftp://eddie.mit.edu/pub/hp951x/NEW/ includes:

REAL95.ZIP - A satellite-tracking program.  Slow, but effective.

GRID.ZIP - A grid-square locator

ARS-LOG.ZIP - A logging program database for the HP-200.

GEO44CGA.ZIP - Graphical display of day/night illumination of the earth as well as the twilight "gray line".  Can also plot 
contacts by latitude and longitude.

Phillip Nichols
e-mail brasheth@gatecom.com
packet kc8dgf@kb8rmx.amps.org