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Digital Digest
Mike Chace
mikechace@monitoringtimes.com
Synoptically Speaking
This month we focus on some of the remaining
weather transmissions that are
audible on the HF bands using simple
RTTY equipment and answer a reader’s question
about software.
First, let’s take in a little background concerning
the coded messages that the majority of weather (WX
for short) stations send.
❖ Weather Codes
The World Meteorological Organization (see
Resources) was responsible for defining the set of
coded messages (the synoptic codes), used by weather
observing stations throughout the world for decades
to communicate their local readings. There are a large
number of these standard codes, each tuned to both
the kinds of observations being made and the type
of observing station. The code names for the most
commonly seen types of reports are as follows:
SYNOP
SHIP
METAR
BUOY
PILOT
TAF
for reporting surface observations from
fixed land stations
for reporting surface observations from
stations at sea
for reporting routine aviation weather
for reporting observations from buoys at
sea
for reporting upper wind conditions
for reporting conditions at an airfield
Each of these codes has been developed to
transmit essential weather information quickly and
succinctly with a well-defined, compact message.
Indeed, it’s very likely that any of the weather reports
you see nicely decoded into “human readable form”
on weather sites like IPS Meteostar, The Weather
Channel and others, were originally compiled by
reporting stations in synoptic form.
Here’s what an actual report looks like, in this
case taken directly off-air from the German Weather
Service’s station DDH7:
zczc 70 fo
sivx48 edzw 225:00
bbxx
elzl3 22211 99293 70186 46/// /0310 10248 2018/
40175 52011
22216 0426-.
elwt7 22211 99536 70159 41/9/ /3609 10228 20156
40191
53005 7//// 22254 04253=
nnnn
As you can see, to the untrained eye, this is little
different from the off-line encrypted messages from
Havana, Moscow, and other places!
One can decode the message by hand (a very
tedious job indeed) or one can engage the “synoptic
decoder” function found on many digital decoder
software packages. In the case of the Hoka decoders,
once we have correctly determined the speed, shift and
transmission system in use, and are correctly receiving
the coded traffic, pressing the “W” key starts the
synoptic decoder.
After receiving the correct start codes for the
particular messages (AAXX for SYNOP type report
or BBXX for a SHIP type report), the decoder reads
the complete message, turns it into readable form and
displays it on the screen. These reports can even be
saved to disk automatically: just think, your very own
worldwide weather receiving system!
❖ Synop Stations
If we were writing this article a decade or two
ago, a listing of active HF weather stations sending
synoptic messages would probably have taken at least
a page and a half of Monitoring Times. Sadly, as with
the press stations, many WX stations have gone silent.
But some live on, so here are a couple to try listening
out for:
German Weather Service (DWD)
The DWD (Deutscher Wetter Dienst) station,
transmitting from Pinneberg in northern Germany,
is probably the most well-known of the remaining
WX stations. Widely audible, Hamburg Meteo, as it
is commonly (though incorrectly) known, transmits
a variety of reports for shipping in the Baltic, Atlantic,
Mediterranean and North Seas on a number of
frequencies throughout the shortwave spectrum on a
24hr schedule (see Resources).
You can hear the station on the following
frequencies. In each case, standard Baudot RTTY is
used.
147.3 kHz DDH 47 50bd/85Hz Baudot
4583 kHz DDK 2 50bd/450Hz Baudot
7646 kHz DDH 7 50bd/450Hz Baudot
10100.3 kHz DDK 9 50bd/450Hz Baudot
11039 kHz DDH 9 50bd/450Hz Baudot
14467.3 kHz DDH 8 50bd/450Hz Baudot
The station has also been heard on 15988 kHz
on occasions. Unlike most stations, the DWD sends
a frequency list as part of its call-up, like this:
cq cq cq de ddh47 ddh9 ddh8
frequencies 147.3 khz 11039 khz 14467.3 khz
ryryryryryryryryryryryryryryryryryryryryryryryryr
and on alternate frequencies, like this:
cq cq cq de ddk2 ddh2 ddk9
frequencies 4583 khz 7646 khz 10102.8 khz
ryryryryryryryryryryryryryryryryryryryryryryryryryr
Nairobi Meteo
Another easy catch with a Baudot decoder is the
Kenyan Meteorological Department’s weather station
5YE. Once operating on several HF frequencies, this
has since been reduced to three frequencies (which,
by the way, also carry facsimile weather maps at other
times):
7462kHz 100bd/850Hz Baudot
9041kHz 100bd/850Hz Baudot
17441.6kHz 100bd/850Hz Baudot
The call-up marker for this station looks like:
ryryryryryryryryryryryryryryryryryryryryryryryryr
cq cq cq de 5ye 5ye 5ye
ryryryryryryryryryryryryryryryryryryryryryryryryryr
❖ What Decoder Software?
Reader Bill B wrote in with the following question:
Hi there Mike. I hope you can help me out; I am
truly interested in tuning in RTTY, FAX, NAVTEX as
well as FEC and ARQ. But I have searched online to
no avail trying to find software. I have MMTTY, but
it’s a ham radio rtty program. I hope you can point me
in the right direction where I can locate software.
Fortunately, with Mike Agner’s recent updates
to Utility Monitoring Central, this is an easy question
to answer. Point your browser at UMC and follow the
links to “Software”, “Hardware” and “WWW Links”
and peruse Mike’s work which catalogs just about every
known free, shareware and commercial hardware
and software for decoding the kinds of signals that we
discuss here in Digital Digest. Mike has thoughtfully
organized the sections for the software decoders by
type:
- those using some kind of interface hardware (you
may need to make or buy your own)
- programs that combine decoding with a radio
control function
- those that talk directly to soundcards or need
some interface hardware
- and finally, programs for manipulating the audio
from your radio.
Check out this very useful resource next time
you have a question about which software or hardware
is right for you.
Resources
German Weather Service
http://www.dwd.de
DWD HF Weather Schedule
http://www.dwd.de/de/wir/Geschaeftsfelder/Seeschifffahrt/Sendeplaene/e_telexpln.htm
World Meteorological Organization
http://www.wmo.int
Kenya Meteorological Department
http://www.meteo.go.ke
Utility Monitoring Central
http://www.chace-ortiz.org/umc
January 2005 MONITORING TIMES 31