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86 TELE-audiovision International — The World‘s Leading Digital TV Industry Publication — 01-02/2015 —
dozen shortwave bands to
choose from. If you are inter-
ested in listening to interna-
tional shortwave broadcasts
begin with the 31m band
covering frequencies 9.400 –
9.900 MHz. The 31m band is
one of the more heavily occu-
pied bands where you’ll find
plenty of interesting listening
24/7 due to favorable iono-
spheric conditions affecting
this slice of spectrum. Sadly,
many old-time shortwave
broadcasters such as Swiss
Radio International, Radio
Austria, and Radio Moscow
have “gone dark” (ceased
broadcasting) on shortwave
due the advent of satellite
and Internet radio, but plenty
of entertainment from around
the world still exists on short-
wave, so tune in and listen.
In addition to international
broadcasters, the HF spec-
trum is occupied by military,
government, aeronauti-
cal, amateur radio, marine,
weather, and other utility
(“ute”) communications using
voice (Upper or Lower Side
Band) and non-voice digital
modes such as CW, RTTY,
FAX, ALE, Sitor B, NAVTEX,
HFDL, JT65, PSK31, and
SELCAL to name a few. In-
teresting transmissions such
as synoptic marine weather
reports to mariners, QSOs
(conversations) between ham
operators using Morse code,
PSK31, and teletype, fac-
simile weather maps of dif-
ferent regions of the world,
infrared satellite images, and
emergency/welfare mes-
sages from ships at sea are
being transmitted around the
clock. The good news is that
the SDR dongle is sensitive,
selective, and stable enough
to allow decoding of many of
these non-voice digital trans-
missions. This aspect of the
radio listening hobby is re-
ferred to as HF Utility (“UTE”)
monitoring. If you are inter-
ested in these types of trans-
missions an excellent source
of information is The Spec-
trum Monitor Magazine (www.
thespectrummonitor.com ),
a monthly on-line magazine
staffed by columnists with a
wealth of experience in the
radio listening hobby.
Use of digital mode decod-
ing software will significantly
enhance the overall experi-
ence with your SDR dongle as
there are many exiting and in-
formative transmissions being
sent by commercial, military,
and amateur radio entities.
Two excellent programs wor-
thy of consideration are fldigi
) and MultiP-
SK
which feature decoding of
many common digital modes
including RTTY, FAX, CW, PSK
31, NAVTEX, Sitor B, etc. Two
other digital modes used by
commercial interests include
SELCAL (Selective Calling)
and ALE (Automatic Link Es-
tablishment). One word of
advice though: before ventur-
ing into digital mode decoding
software become thoroughly
comfortable with using your
SDR dongle. Take your time
and remember that the learn-
ing curve will be very steep
the first few weeks. If you be-
long to a radio club perhaps a
member already has experi-
ence with an SDR dongle so
tap into their knowledge and
experience. If you are on the
fast track then I suggest you
check out YouTube as it con-
tains a prodigious number of
user videos by those already
experienced in the hobby. Fi-
nally, remember that at a cost
of $16.00 USD a dongle SDR
will not perform on par with
commercially available SDRs
costing several hundred dol-
lars. However, for its minimal
cost you’ll get a lot of “bang
for your buck” as we Ameri-
cans say.
13. RTTY (RadioTeleType) transmission from German station DDK 9 broadcasts marine weather
for locations such as Western Europe. You’ll need a good decoding program such as MultiPSK to
decipher RTTY transmissions. SDR# is running in the foreground with MultiPSK in the background.
The audio stream from SDR# is fed directly to MultiPSK.
14. Facsimile broadcast from US Coast Guard Station NMG, New Orleans, LA, with map of coastal US
and Caribbean. Many stations service the marine community with facsimiles containing important
meteorological information in the form of weather maps and satellite images. SDR# is running in the
foreground with fldigi (decoding software) in the background.