Getting tired of the "same ol' same ol'" on HF? From the father of AMTOR,
Peter Martinez, G3PLX, comes PSK31, a "live QSO" keyboard-to-keyboard mode
that occupies a sliver of bandwidth and offers terrific performance even
under weak-signal conditions.

PSK31 isn't new; it's been around for a few years, but no one really took
much notice until Martinez developed free software that works with a PC
sound card. Suddenly, PSK31 has become the latest HF fad. Unlike 'TOR modes,
PSK31 does not use a synchronized linking--or handshaking--protocol to
exchange error-checked data packets. Operationally, it's much like
traditional 45-baud RTTY. PSK31 has shown itself to be a real trouper in
weak-signal situations. Some hams experimenting with PSK31 claim that it
outperforms all other amateur modes for weak-signal work--including CW.
Indeed, PSK31 signals are easy to overlook on the bands. Most PSK31 activity
is concentrated on 14.070.15 and at 3.580.15 MHz. You'll also find it on 40
meters at 7.035.15 MHz. On 15 meters, look for activity around 21.070 MHz.

To run PSK31, you need a PC that runs Windows that's equipped with a sound
card. PSK31 software is available via the Web). Your HF SSB transceiver
should be very stable and tune in 1-Hz increments. The connections between
the radio and the sound card are very straightforward.

Several versions of PSK31 software are available as zipped files. The latest
PSK31 software includes a couple of tuning aids that make finding and tuning
signals much simpler. The "official" PSK31 Web site is, operated by Eduardo Jacob, EA2BAJ. The
site also contains lots of information and links to other PSK31 and
DSP-related sites, plus .wav files of PSK31 signals, so you'll know what to
listen for.

W1AW Station Manager Joe Carcia, NJ1Q, has experimented with the new
operating mode, PSK31, at the Maxim Memorial Station. While it took a bit of
effort to get the equipment to function properly, he says initial results
were quite good. Plans are in the works to add this mode to the complement
of modes available for W1AW visiting operators.

Some have questioned whether the FCC permits hams to use PSK31. The answer
is a definite "yes," although some confusion is understandable given the
wording of Section 97.309(a) of the rules. Responding to an ARRL inquiry,
the FCC amended the section in 1995 (Order DA 95-2106) "to clarify that
amateur stations may use any digital code that has its technical
characteristics publicly documented." PSK31 is publicly documented and
widely available, but the ARRL in late January took the additional step of
specifically documenting the technical characteristics of both PACTOR II and
PSK31 in a letter to the FCC.

02.12.1999. ...from ARRL.

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