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With so many activities available in Amateur Radio, we often hear about something new we'd like to try but find ourselves too busy with family, work or our more familiar radio pursuits.

What Is It?

The it is different for different hams. For me, it was PSK31. As many of you already know, PSK31 is one of the many so-called "sound card modes" that use a computer's sound card to process audio for receiving and/or transmitting digital communication. It's also gained a lot of currency in the low-power operating community because it doesn't require a big signal to make many QSOs--including DX.

The ease of making low-power contacts using PSK31 is possible because the computer software can dig out and interpret signals barely above the noise level--and perhaps not even audible to the human ear. These are signals that you might easily miss while listening or tuning (WB8NUT's Web page has sample sound files of many digital modes, including PSK31.)

Although this column will focus mainly on PSK31, its larger purpose is to encourage you to finally try that something new you've been meaning to try but putting it off.

Digital Modes

PSK31 is just one of many sound card modes you can try. But even if your computer doesn't have a sound card, you can still enjoy digital modes by using an earlier piece of hardware known as the multimode controller or interface or TNC (terminal node controller). Here is a brief history of digital modes for the newer hams. It can be divided into four eras:

WinWarbler is one of a large number of software programs available for PSK31. It is one of DXLab's suite of free Amateur Radio software.

HamScope is an example of another program that supports PSK31 and other digital modes.

PSK31 Deluxe is part of the excellent free Ham Radio Deluxe suite discussed in one of my previous QRP Community Columns--Software for the QRP Shack.

Several manufacturers offer radio-to-soundcard interface boxes. Here are some examples from West Mountain Radio. Visit the ARRL Advertisers Links Page for a link to the Web site of this company and several others offering similar products.

1. "Before We Called It Digital" Era: The "original" digital communication mode, CW, usually is not usually referred to as "digital." The next form of digital mode was RTTY. Hams initially used surplus mechanical teletype machines (TTY) and a simple electronic interface know as an MCU--originally built with tubes. Next came SSTV with complex self-contained interfaces, which cost more than many hams were willing to invest.

2. TNC Era: This was heralded by the introduction of "packet radio" by TAPR in 1982. TNCs allowed users to send information in a digital format using a communication protocol similar to those used in computer networks. To operate packet on VHF, a ham needed an FM radio, a dumb terminal and a TNC.

3. Multimode Controller Era: The next advance was to add more modes to TNCs, which now became known as multimode controllers. These additional modes included an easy, non-mechanical way to send and receive RTTY. Also added were HF packet, AMTOR, CW and even SSTV and FAX. For more information on a variety of digital modes, visit the ARRL's Digital Modes TIS. As with TNCs, most multimode controls could function with a simple dumb terminal interface and did not require a full-blown computer, although many amateurs ran such modes as RTTY and CW using very early Radio Shack, Texas Instruments and VIC-20 computers.

4. Sound Card Era: As computers became cheaper and more powerful and began sporting sound capability, moving signal processing the multimode control to the computer became practical. Once this happened, development of new modes blossomed, since all you needed was a piece of software. With sound card modes, you just need a very simple generic interface between the computer and radio, mainly for signal isolation, PTT function and audio control.

Sound Card Modes

Sound cards can serve a large variety of digital modes, and the list is constantly growing (remember all it takes to develop a new mode is new software). In addition to PSK31 they include: MFSK-16, RTTY, ASCII, SSTV, Feld-Hellschreiber, FAX, Q15X25, MT63, AMTOR, CW, VoIP (Voice over IP including EchoLink and IRLP), Packet, WSJT (VHF/UHF weak signal and meteor scatter), Throb and more. For information on a variety of digital modes visit the Radio Amateurs of Canada (RAC) Digital Modes page.

Setting Up a Low-Power PSK31 Station

Here's what you'll need to get started in PSK31:

1. A radio capable of receiving and transmitting SSB.

2. A computer equipped with a sound card. A minimum setup is a '486 or faster computer running at least Microsoft Windows 95 or higher with a Windows-compatible sound card (16 bit). I would recommend a Pentium 266 or higher and Windows 95 or higher. You do not need an expensive or fancy sound card; in fact inexpensive generic cards often work better. There is also software available to use with Linux computers or an Apple Macintosh computer running OS 8, 9 or OS-X.

3. Software capable of receiving and transmitting PSK31. A wide variety of programs are available--including commercial, shareware and freeware. The main difference is usually in the way that the program displays the received signals. I've compiled a list of many available programs and links to download and/or purchase them.

4. Cables to interface the computer and radio. Depending on the model of radio and the software you use, this can vary greatly and may include simple audio cables, hardware interfaces, PTT control serial cable, and/or rig control serial cable. I've compiled a list of the many available hardware interfaces and cables plus links to purchase or build them.

Operating PSK31

In Part 2 of this column I will describe how I set up my station, installed and configured the PSK31 software and adjusted sound card settings. I'll also pass along some tips for operating PSK31 with low power.

Reader Feedback and Author's Comments

My apologies for the long delay between columns. Some health problems kept me otherwise occupied, but I'm pleased to report that things are getting back to normal for me now. It was great to meet many of you in person at the "Four Days in May™" QRP symposium (FDIM) held in conjunction with Dayton Hamvention. I think I can speak for the group in saying that "a great time was had by all."

Thanks for all your e-mails. I really enjoy the feedback and welcome your comments and suggestions.

Editor's note: Anthony Luscre, K8ZT, an ARRL Life Member, lives in Stow, Ohio. He has worked in the field of medical microbiology for 18 years and is now a Technology and Computer Coordinator for a local school district. Luscre is an avid QRP operator having earned DXCC, WAS and WAC using no more that 5 W output. Readers are invited to contact the author via e-mail, k8zt@arrl.net or visit his Web site.

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