What is Packet Radio?

by Andy Nemec, KB9ALN

Packet Radio is a Ham Radio Operator's way of connecting a computer to a radio for the pupose of communication and information exchange, simply put.

Why is it called "Packet Radio"?

Information that a computer process and sends out via radio is assembled into data groups called "Packets". And as radio is involved..... well, you get the idea.

How does it work?

A radio operator first has to connect his computer to a device called a Terminal Node Controller, a TNC for short. This device is similar in function to a telephone modem that people use to connect their computers to a telephone line, or perhaps to a cable modem, eventually connecting them to the Internet. The computer plugs into the TNC and the TNC connects to a radio instead of a telephone line or a cable connection.

Can anyone do it?

Any Ham Radio Operator (legally known as an Amateur Radio Operator) can use the Amateur Packet Radio system, as long as he or she obeys the appropropriate laws governing the Amateur Radio Service. In order to use the Amateur Packet Radio System, one has to be a licensed Amateur Radio Operator.

Are Amateur Radio Operators the only people with Packet Radio?

No. Wireless Ethernet cards actually use the same basic principles as Amateur Packet Radio uses, although they are incompatible with the current Amateur Packet Radio Network. Some Hams use these wireless ethernet cards for Amateur Radio use, however. Some are specially adapted to be more powerful and operate on radio channels designated for Amateur Radio Only use.

How far can a Ham Radio Operator "talk" with Packet Radio?

That depends on a number of variables.

1)   What kind of radio is used and what radio channels are used

2)    Whether the operator chooses to communicate in "Real Time" (similar to a chat room) or by "Packet Mail".

Let's elaborate:

Some radios are intended to operate on the "Shortwave Radio Bands". These radios are capable of allowing the operator to communicate world-wide. If you've ever had a shortwave radio and listened to the BBC, you can understand that Ham radio operators have a similar capability.

However, there are also radios that Amateurs use for more local communications, like two-way radios that Police and Fire departments use. This is the most common way that Amateurs use Packet Radio. They rely on a network to "relay" their communications to more distant areas, sometimes utilizing the services of shortwave packet radio stations, or the Internet to complete "long-haul" communications.

Amateur packet radio also has a number of operational modes. Operators can contact each other and have a keyboard-to-keyboard chat in real time. They can also send mail to each other, similar to E-Mail that most people are familiar with. Using amateur packet radio for mail also relies on a network of Bulletin Board Systems (BBSs) to relay that mail to the intended destination. Very many locations world-wide are accesable via packet radio mail.

Can this replace the Internet?

Not really. Amateur Radio is a volunteer system - therefore, we can't match the speed and completeness of the internet. In spite of this, packet radio is capable of providing emergency communications in times of disaster, in addition to the routine use that it normally sees.

The Internet is well-funded, has a lot of people hired to expand it's network and is commercially supported. Amateurs are a much smaller, and more independent group of people.

How many people use packet radio?

No one can say for sure. Surely thousands, perhaps tens of thousands in the U.S. World-Wide, surely more than tens of thousands.

How do I get involved?

First, you need an Amateur Radio Operator's License. If you haven't already got one, look here for more details and information.

If you already a ham, here's a good place to look for good basic information: The Tuscon Amateur Packet Radio Association. In addition, you can consult the "Packet Primer" section on this site.

Once you learn a little more, your best bet is to look for a local ham to help you out. He or she will know about local operating frequencies and conventions. 

What would I need to get started?

Most packet operations take place on VHF, so you'll need a VHF Radio to start with. Most hams have one of these. You don't often need a very powerful one, either, unless you happen to be distant to other operators or packet relay stations. Even a hand-held portable radio can work well for this, along with some kind of small-sized (less than 2 feet in length) remote antenna.

You'll need a Terminal Node Controller. New, most cost in the range of $100-$200 U.S. There are cheaper alternatives, however.  Used units are fairly cheap, and a local ham radio operator who dabbles in packet radio may well know of a cheaper unit to buy, or perhaps one you can borrow to see if you like packet radio. Some operators are even able to use the sound card in their computer instead of a TNC.

You will also need a computer, of course. And it does not need to be one with great capabilities. There are many people who use an older computer dedicated to packet radio, such as an old 8088, 286, 386 or 486 based computer. Of course you can use your "family P.C." or MacIntosh computer to try out packet. You don't need a dedicated computer. Some Hams just find that to be a more convenient arrangement.

The computer must have a free serial communications port, and you'll need a serial cable to connect the TNC to the computer. There's another cable you will need to connect the TNC to the radio. Preassembled cables are available for the more popular TNC and radio combinations. Most hams elect to fabricate one themselves with parts obtained from a local electronics store, like Radio Shack.

There is a wide range of software available for use on packet radio. It ranges from software that you may already have, such as a standard "terminal program" like Windows "Terminal", "Hyperterminal" or  "Procomm" (DOS or Windows versions) to complex programs designed to run on a dedicated computer. The good news is that software cost is seldom an issue as you may already have it, or can get "freeware" software written specially for the purpose. It is not necessary to run Windows to use packet, Apple and DOS users aren't discriminated against.

I don't run Windows or a Mac, I use Linux. Will that work?

Certainly! The author of this piece uses it exclusively. You can try out packet radio with a simple terminal program like minicom or seyon. Alternatively, you can use the built-in networking capabilities of Linux to run more elaborate packet radio programs, or operate a packet radio Bulletin Board System, if you get deeply involved in packet radio.

Who makes Packet Radio work?

A varied assemblage of individual Amateur Packet Radio operators, and those who choose to affiliate themselves with local, state (such as the Wisconsin Amateur Packet Radio Association) and national organizations. In short, Hams  - individually and collectively - make packet radio work!

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