in theARRL RTTY Roundup

The popular digital mode makes its HF contest debut
January 5 – 6. Follow these instructions and give it a try!

Joe Taylor, K1JT
The annual ARRL RTTY Roundup(www.arrl.org/rtty-roundup) has
always been a multimode contest; its
rules permit digital modes, such as
ASCII, AMTOR, PSK31, and packet,
in addition to Baudot RTTY. However,
only RTTY has been widely useduntil now. In the Roundup, to be heldon January 5 – 6, 2019, users of thefree software package WSJT-X 2.0
have been encouraged to try
contesting with FT8. This article is abrief tutorial on how to do that, using
new features built into WSJT-X 2.0.
Initial caveat: The ARRL RTTY
Roundup is 30 years old and has awide and enthusiastic following. FT8users might therefore consider themselves guests of a sort, in this event.
Inevitably, there will be some crossmode interference as the available
subbands are not very wide. All
participants, using whatever mode,
should try to accommodate one
another. The RTTY Roundup may
help to determine whether an HF
contest with significant participationin more than one digital mode is agood idea.

Differences Between
FT8 and RTTY Signals
Standard amateur radioteletypesignals with Baudot encoding, keying
rates of 45.45 baud, and 170 Hz
shifts occupy bandwidths of about
250 Hz. Information is transmitted ona character-by-character basis at
about 5.7 characters per second andstart times and durations of transmis2   January 2019www.arrl.org  sions are determined by the operators. Decoding with low error rates
requires signal-to-noise ratios greaterthan about –5 dB, measured in areference bandwidth of 2,500 Hz.
In sharp contrast, FT8 transmissions
have fixed 12.6-second lengths,
always start at 0, 15, 30, or 45
seconds into a UTC minute, occupy
50 Hz bandwidths, and are reliably
decodable with signal-to-noise ratios
as low as –20 dB. The FT8 protocol
includes strong forward error correction, so decoding is an all-or-nothing
process. At the receiving end, yousee exactly the message transmitted,
or nothing at all. After a message isdecoded, the software reconstructs
its audio waveform, scales it to thereceived signal strength, andsubtracts it from the received audio
data. In this way, signals can be“peeled away,” so that several may be
decoded at the same (or nearly thesame) frequency. FT8 is optimized
for the exchange of call signs, signal
reports, and a few additional bits ofinformation, so it is potentially very
well suited to contesting. In WSJT-X
2.0 the FT8 protocol has beenenhanced to support exchanges for
the RTTY Roundup and several
other popular contests.

Setup and Operation
The following instructions assume
familiarity with everyday FT8 operating procedures; you should
consider such experience a prerequisite for using FT8 in the RTTY
Roundup. A full WSJT-X 2.0 User
Guide may not be available at thetime you are reading this, but mostprogram features are thoroughly
covered in the guide for version
1.9.1, which you will find atwww.physics.princeton.edu/pulsar/K1JT/wsjtx-doc/wsjtx-main1.9.1.html. Details about theTable 1
Common RTTY Contest Frequencies
and Suggested FT8 Contest Frequencies
Set the WSJT-X dial frequency to a multiple of 2 kHz, for example 7.082 MHz.
The RTTY contest frequencies shown for 80 and 40 meters also reflect band
plans for operations outside the Western Hemisphere.
Band(Meters)

RTTY Contest Frequencies (MHz)80

3.570 – 3.600		3.590 – 3.600

40

7.025 – 7.100		7.080 – 7.100

20

14.080 – 14.150		14.130 – 14.150

15

21.0805 – 21.150		21.130 – 21.150

1028.0805 – 28.200		28.160 – 28.200

Suggested FT8 Frequencies (MHz)program’s contesting features aredescribed in the Quick Start Guideto WSJT-X 2.0 at https://physics.
princeton.edu/pulsar/k1jt/Quick_Start_WSJT-X_2.0.pdf. Be sure toread the latter document thoroughly.
FT8 and other WSJT-X modes
require a reliable means of keeping
your computer’s clock synchronizedwith UTC. Follow instructions foryour operating system found inthe WSJT-X User Guide. Computer
aided transceiver (CAT) controlof your radio is highly recommended,and this is fully supported by
WSJT-X.
Starting with a normal FT8 setup,
configure the program for the RTTY
Roundup by navigating to FILE >SETTINGS > ADVANCED. Check thebox labeled SPECIAL OPERATINGACTIVITY, select ARRL RTTY ROUNDUP,and enter the two- or three-letter
abbreviation for your state or province, or DX if you are located outside
the United States and Canada. You
may want to select the COLORS taband check only the color-highlighting
boxes for CQ IN MESSAGE, MY CALL-IN
MESSAGE, TRANSMITTED MESSAGE,NEW CALL, and NEW CALL ON BAND.
Click OK to return to the main
window, and be sure the box AUTO
SEQ is checked.
To keep track of stations alreadyworked in the contest, it’s best tostart the contest with an empty
wsjtx_log.adi file. Select FILE > OPEN
LOG DIRECTORY, then right-click on
the file wsjtx_log.adi and rename it tosomething else, for example wsjtx_log.bak. After the contest, be sure toreverse this procedure to restore
your normal ADIF log. Before thecontest starts, execute the command
FILE > ERASE CABRILLO.LOG.
FT8 contacts in the RTTY Roundup
will typically proceed as in thefollowing example, where KF1ABC is
the “Run” station calling CQ. The
numbered items represent successive transmission intervals.

Figure 1 — Be sure to select the RTTY Roundup and enter your exchange information.

1) CQ RU KF1ABC FN422) KF1ABC WA9XYZ 579 WI3) WA9XYZ KF1ABC R 589 MA4)
KF1ABC WA9XYZ RR73
KF1ABC GM1AAA 559 00135) WA9XYZ KF1ABC 736)
KF1ABC GM1AAA 559 0013
7) GM1AAA KA1ABC R 569 MA8)
KF1ABC GM1AAA RR73
9) GM1AAA KA1ABC 73
Note that GM1AAA has called as atailender in intervals 4 and 6.
KF1ABC works WA9XYZ and
GM1AAA in quick succession, using
just two transmissions to each caller.
In this fashion, and with a continuous
string of callers, a practiced operator
can make QSOs at maximum rate
60 per hour.

Frequencies to Use
Many FT8 exchanges can fit in asingle 2 to 3 kHz window, but during
a popular contest, it will be necessary to spread out. The first twocolumns of Table 1 list conventionalfrequency ranges used on each HF
band for RTTY contesting, takenfrom the website www.aa5au.com/
rtty/rtty-sub-bands/. The thirdcolumn suggests ranges near theupper ends of these subbands where
FT8 contest activity might best beconcentrated.
Operating procedures for FT8 incontests will surely evolve over time,
as users gain experience. Initially, theWSJT-X development teamproposes that run stations should
select integral multiples of 200 Hz as
their audio transmit frequencies andcheck the TX EVEN/1ST box. Searchand-pounce (S+P) stations should
call at frequencies 0, 60, or 120 Hz
above the run frequency. The

WSJT-X user interface has tools to
make these settings easy. Tap yourF3 or F5 keyboard keys to seeconcise lists of relevant keyboard
and mouse shortcuts.
Experienced contesters may
choose to configure WSJT-X sothat it forwards contact information
to the N1MM+ contest logging
program. Setup instructions for
the N1MM+ side can be found atn1mm.hamdocs.com/tiki-index.
php?page=UDP+Broadcasts, andfor the WSJT-X side, it can be foundin Section 4.5 of the WSJT-X User
Guide. For log submission, you canuse the Cabrillo log produced by
N1MM+, which will include proper
computation of your claimed score.
Alternatively, you can invoke theWSJT-X command FILE > EXPORTCABRILLO LOG to create a valid log
for submission. Note, however, that atpresent, WSJT-X has no concept ofcontest multipliers, does not accountfor dupes, and does not compute aclaimed score. We plan to add thesefeatures in a later program release.

Dr. Joe Taylor, K1JT, is an American
astrophysicist and Nobel Prize in Physics
laureate. He is the developer of the WSJT-X
software suite, as well as many other weaksignal applications. You can contact Joe at
k1jt@arrl.net.

For updates to this article,
see the QST Feedback page at
www.arrl.org/feedback.

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January 2019   3