- Speaker: Mike Walters, W8ZY
Computers and ham radio? There is more than a slight connection and Mike Walters showed us that the link is more than just electricity and cool technology, but a synergy that has grown over the years. A couple of times I was wondering where was the line between ham radio and computing. In many ways they seem to have merged. Read on and see if you agree.
Mike started with a brief review of amateur radio, which is as old as radio itself. Amateur radio operators are licensed to operate on specific frequency bands that are recognized around the world for such use. Like all communications in this country, it is regulated by the FCC. In the very early days, the term “ham” was a pejorative used by professional operators when referring to amateurs and their “ham fisted” telegraphy. Soon the “hams” adopted the term as their own. First licensed in 1977, Mike has participated in the hobby as it has evolved over many years. He is a member of the Northville Amateur Radio Association and is the Region 5 District Emergency Coordinator for the Amateur Radio Emergency Service.
Computers intersect with ham radio in four main areas:
- Logging
- Programming and Operation
- Digital Communication
- Software Defined Radio
Most hams keep a station log that records their contacts over the air. Working DX, or distant stations, is a primary activity and they’re proud of the contacts they make all over the world. Since logging is rows of similar data, it’s an activity that can be made easier with a computer. Of course logging a rare or distant contact requires proof for the bragging rights to stand up. From the early days, hams have exchanged QSL cards to verify contacts. These are typically a custom postcard printed with the ham’s call sign, location, and maybe a picture or two. A QSL card from the King of Jordan, would be a highly prized proof of contact. Rather than explain each abbreviation or “code”, I’m going to leave these to the reader as Mike did, with the reminder that your search engine and WikiPedia are your friends and most of these codes have an interesting history. Some are apparent just from the context.
As the cost of postage, especially international, rose, an electronic means to verify contacts replaced many QSL card exchanges. Two websites now allow each person in the contact to record the exchange. When matching records are entered in the database, the QSO is confirmed. While I would prefer a card mailed from the King of Jordan, these databases, run by the American Radio Relay League (ARRL.org) and a private effort based in Texas, make confirmations fast, easy, inexpensive and searchable.
The second area Mike covered is Programming and Operation. Like most technology-driven hobbies, ham radio equipment comes with features in abundance. Even the smallest hand-held transceivers have so many features that they become hard to configure due to the small screen size and obscure codes. Since many settings are rarely changed, it’s much easier to connect the device to a larger computer, like a desktop, where a Windows-based configuration program can make all the settings easier to see and set. For instance, a portable transceiver is often used with a repeater to get greater range. The repeater’s frequency never changes, so you would want the frequency setting loaded into the “speed dialer” so it can be accessed by pressing only one or two keys. The same would be true for the mode of operation (the type of FM or digital mode) and other operation parameters.
The plethora of features and options is not confined to portables. The equipment used for home stations, the traditional “ham shack”, can be just as complex to configure and operate, and it’s likely there is more equipment. I was blown away by how computers have been integrated into ham gear. Modern gear, receivers, transmitters, antenna tuning and switching, and antenna rotators can all be controlled from a computer interface. For instance, say you want to work a station in the Republic of Georgia, in which direction should you point your antenna? My guess would be just a little to “right” of the North Pole, but why guess? Plug in the latitude and longitude of Tbilisi, and let the computer figure it out and turn the rotator to the right heading. Cool!
It was inevitable that radio amateurs would incorporate Digital Radio, similar to what is used in cellular phones, into regular use on most frequency bands. The interesting part of this is that all radio started as digital. The most “primitive” form of radio signaling was to simply start and stop the radio wave. Radiotelegraphy using Morse code was the beginning of all radio communications, starting in the late 1800’s. Hams call this CW or continuous wave. As telegraph companies moved from operators with a key to put the “clicks” on the wire to various types of teletypes, radiotelegraphy made the same move using modulation techniques like PSK (phase shift keying) and FSK (frequency shift keying), and several other techniques evolved in both commercial and amateur use. All of these are a form of “digital” signaling. An important point here is that amateur radio is licensed specifically to help develop new forms of radio communications. Regulations are enforced to prevent interference with commercial radio and to maximize use of the available spectrum. Generally speaking, modern digital transmission techniques are more efficient users of spectrum, which is why cellular operators moved totally to digital over the last decade.
The latest thing is Software Defined Radio (SDR). In this technique the entire radio is created in software. In a traditional radio, like many women in the 40’s and 50’s liked to have in the kitchen, the radio station was tuned using a large variable capacitor and a coil. The combination created a tuned circuit that resonated at a desired frequency. This is what selected the desired station and rejected others. If cell phones used such tuners, backpacks would be needed to carry them. Not only is this tuning replaced by digital signal processing, but it can work over several frequency bands. Once selected, the signal is digitally “processed” and amplified. We use similar technology every day and, as you would expect, so do hams for both receivers and transmitters.
This block diagram shows the basics of how SDR can simplify a ham shack. This user interface is used to control a software defined radio. I listened intently while Mike described this, but there is no way I can reiterate that here. This device contains all the actual radio components controlled by the user interface above, once it is attached to the computer. This one device handles both reception and transmission. Notice that the only actual control is the power button!
To say I was blown away by computers in ham radio is quite an understatement. Mike Walters gave an interesting presentation that packed a lot into the time available. Mike’s slides are available on the website.