Classic Computer Magazine Archive ANTIC VOL. 4, NO. 7 / NOVEMBER 1985


Ham satellites, slow scan video, repeater stations, and more...

by GIGI BISSON, Antic Assistant Editor

Listen to Jack McKirken for a while, and you wonder how amateur radio enthusiasts ever got by without personal computers.

"Why should you have to hand-turn your antenna to track a satellite transmission, when your computer can do it?," says McKirken. He's an Ohioan who formerly edited Ad Astra, the users newsletter for ham Atarians. "Anything a ham can do, a ham with a computer can do better," he says. "Using the computer to control radio hardware is another job where the Atari shines."

Hook up a short wave radio to your Atari and you could end up with a slow scan television station, a chance to eavesdrop on the space shuttle, and friends all over the world.

You could also end up with an expensive, obsessive, but fascinating hobby. "Oh gosh, ham radio is just as bad as computing," says McKirken with a laugh, "And if you combine the two..."


They work together as a team, performing feats that neither could do alone. When you combine ham radio and a computer you get (pardon the pun) a computer that likes to show off.

"There are several million hams worldwide. A vast majority of them have computer equipment." says Russell Grokett, chairman of JACE, the Jacksonville, Florida Atari users group. JACE has what is probably the largest and most active amateur radio special interest group (SIG) in Ataridom right now.

Even during simple voice transmissions, hams are increasingly reliant on computers to boost the mileage of their radios by controlling antennas and helping them home in on signals. The computer can figure the maximum or minimum frequencies and decide which is the best radio band to operate on. Hams with computers can even track a moving satellite for the clearest possible signal.

Currently, the most popular use of computerized ham radio is Radio Teletype (RTTY), the ham's equivalent of the computer telecommunications network--without phone bills. Hams with computers upload and download programs, particpate in SIGS and operate bulletin board services.

RTTY computing is only as complicated as you let it get. You could start with $100 in used equipment, or a $5,000 base station. "Your antenna can be anything from a simple piece of copper wire to massive aluminum arrays that threaten to cave in the roof of your house," McKirken says.

But hams still insist that no matter how much hardware they accumulate, RTTY is still cheaper than paying through the nose for "online time". At a peak speed of 300 baud, however, it's much slower than 1200 baud telecommunications. The other difference between "online" and "on-the-air" is privacy. Anyone with a radio can plug in and listen to ham conversations.


It probably comes as a surprise to most people that Atari computers are very popular among RTTY hams. Especially well-liked are the old Atari 800 and 400 models--which were extremely well-shielded against radio interference.

Shielding is important because computers customarily generate lots of radio "noise". This noise can totally jam the sensitive receiver of a nearby ham radio.

The metal casing inside the Atri 800 and 400 prevents interference "leakage." Though the newer XL and XE models do not have this shielding, they also work pretty well with ham radio-- a lot better than many other popular brands of computer. (Shielding an XL or XE yourself requires soldering copper sheeting to your main circuit board, or encasing the entire computer in metal. Whether or not you'd need to shield your XL/XE depends on your specific system.)


If you want to operate your own station, instead of merely listening in on other ham transmissions, you must obtain an Amateur Radio License. A Technician Class license requires greater technical knowledge than Novice, the lowest rating. But you don't need to be able to send Morse code any faster just five words per minute. And a Technician licensee gets many more privileges.

For more information on obtaining a license, contact a local ham radio store. There's also likely to be at least one ham in your local computer users group. If not, contact the American Radio Relay League. (See address at end of article.)


Disaster aid has traditionally been very big with hams. During the massive forest fires in California this summer, hams used portable stations to assist firefighters in the field, allowing communication between fire crews who couldn't see each other through the thick smoke.

When power and phone lines are knocked out during a widespread emergency, many battery-operated stations stay on the air and transmit important messages. Through it all, independent, computer-operated repeater stations would keep the communications network going.

Packet communication networks: the hams' version of LANs (Local Area Networks) exist on the east and west coast and will eventually extend across the US according to Grokett.

These packet networks are made up of "repeater stations" that receive a transmission and re-transmit it at higherpower. This can dramaticlly increase the range of less-expensive ham radios.

Repeater station are usually computer controlled. Most of them are volunteer projects of ham radio organizations. But usually any licensed amateur is allowed to use the repeater.

Grokett's JACE group and other ham organizations have subsidized seven OSCARs (Orbiting Satellites Carrying Amateur Radio) over the years. AMSAT, an amateur satellite construction group, builds them, and the space shuttle launches them. Anyone with a ham radio and a computer can use the satellites to communicate around the world.

Hams with computes can even listen in on NASA conversations on the space shuttle. The computer helps a radio antenna stay precisely focused on the shuttle as it zips through the athmosphere at 17,000 miles per hour.


The next wave in ham computing is slow scan television. This lets computers send and receive color video pictures over the airwaves. Red, blue and green separations are made of each image (as in a photo negative) and each is sent individually over the airwaves, then reassembled by the computer into a complete picture.

Slow scan lives up to its name, however, at a sluggish eight seconds per picture transmission. (Regular television transmission speed is 30 pictures per secund.) The final image has about half the resolution of regular television.

The slow scan technique was used to send the first photographs of space back from the Pioneer--in fact an amateur radio enthusiast developed the technique for NASA back in 1958.

Hams have always been involved with experimental uses of radio, and the computer is bringing new levels of sophistication to the hobbyist. For example, McKirken is currently collaborating on the development of a commercial program that, when combined with an 850 interface and an ST 980 Yaesu radio modem, will enable any Atari with 32K or more to take complete control of the radio.

The computer will turn the radio on and off, show a graphic s-meter (representation of signal strength) on the screen, and even push the mike to talk. Such programs enable the user to recieve and send messages even if they're not home, much the same way as a timer turns your lights on while you're on vacation.

And sometimes the computer is just used as a computer. When hams have contests to see how many countries and people they can reach in a given weekend, computers are used to sort out the mountains of resulting paperwork and compile statistics.

The computer is also used to set up parabolic bases that enable hams to pick up commercial satallite TV transmissions in their back yards.

About the only thing hams don't do with computers is play games--unless you consider the on-air radio chess network.

"The big thing about ham is it has always been and always will be amateur," says Crokett, who, when not operating his computer radio network works for AT&T. "It's not allowed to become a profit-making thing," he says.


If you're interested in getting started in ham computing, here are some places to consult for more information :

American Radio Relay League
This 66-year-old, 100,000-member, worldwide organization is the premier resource for anyone interested in getting involved with computer-aided amateur radio. ARRL publishes a monthly magazine, is involved with ham education and keeps an eye on FCC regulations:

225 Main Street
Newington, Conn. 06111
(203) 666-1541.

Atari Microcomputer Network
This Atari-and-radio users organization is reorganizing after a period of inactivity. They used to publish the Astra newsletter and offered a selection of public domain software. For information or advice, drop in on their international, on-the-air meeting--Sundays at 1600 Universal Coordinated Time (UTC) on frequency 14.325 MHz.

The CompuServe ham radio special interest group welcomes your questions. Just type in GO HAM II after you have logged onto CompuServe.

RTTY Today
This book is a good reference source for beginners and is available for $8.95 plus $1.75 postage from:
Universal Electronics
4555 Groves Road, Suite 13
Columbus, OH 43232
(614) 866-4605.

The Jacksonville, Florida Atari user's group is a good source of public domain ham software. Out-of-state members are invited, Call their 24-hour BBS (FOREM 300/1200 baud) at (904) 733-4515. The sysop is a ham who may be able to answer your questions. Or write: Russell Grokett, 1187 Dunbar Court. Orange Park, FL 32073

Computers and Amateur Radio
This bi-monthly newsletter about using amateur radio with personal computers costs $6 a year:
1202 E. 23rd Street
Lawrence, Kansas 66044
(913) 842-7745