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DIGEST
DIGITAL MODES ON HF
Rivet and a New Decoder
Mike Chace
mikechace@monitoringtimes.com
www.chace-ortiz.org/umc
Last month I detailed the venerable
CCIR493-4 or “Australian” 4 or 6 digit
selcall system. This is a versatile mode
supported by many different radio manufacturers
to set up HF radio links, send text messages, GPS
fixes, and a number of other useful functions for
today’s busy world.
❖ The Rivet Decoder
Ian Wraith, based in the UK, has been
steadily adding new modes to his free software
decoder called “Rivet.” Choosing a number of
lesser-known Russian systems and working
largely from first principles, Rivet now supports
the following modes:
• CIS 36-50 aka BEE, a common Russian Naval
FSK system (see Digital Digest, March 2009)
• CROWD-36, the Russian multitone system
used by Diplomatic and Intelligence stations
• FSK200/500, a Baudot-based system used by
Russian Intelligence
• XPA and XPA2, a slow, multitone, 10 or 20bd
mode used by Russian Intelligence stations
to send five figure group off-line encrypted
traffic to agents in the field
Rivet has the capability to read and decode
audio from a standard soundcard input in
real-time or from an 8bit, WAV off-line file or
recorded audio. Received traffic can be saved
to a text file and settings saved to computer,
too.
One of the more unusual and pleasing
aspects of Rivet is that, rather than demand
the user to precisely tune a given signal, Ian
lets the computer do the hard work and has
the software automatically detect the tones,
synchronization and other key parameters that
the user might otherwise have to enter. Bravo!
Also unusual, is that Ian chose to write his
software in the Java programming language.
The advantage of Java is that it is available on
hundreds of operating systems from simple
“embedded computers” in TVs, set-top boxes
and automobiles, to the usual Windows, Linux
and OS X operating systems. One version
of the “run time” or executable code can be
distributed to users who then simply need
to install Java for their operating system of
choice and can immediately run the program.
Bravo again.
Since releasing the first version in 2011,
Rivet has grown steadily and Ian has received
plenty of input from fellow listeners on the
Utility DX Forum (UDXF) internet mailing
list. He’s also been extremely responsive to
that feedback, releasing fixes and new features
often within hours of the original request.
❖ Rivet and CCIR493-4?
Around the time that I was writing the
July edition of this column, I saw a growing
number of UDXF listeners report channels with
CCIR493-4 selcall activity but with no way to
decode it. Like other selcall or ALE (Automatic
Link Establishment) systems, they support radio
networks across multiple channels, so the more
users you have with the capability to decode the
identifiers, the more chances you have of being
able to piece together the network structure in
addition to the basics of how many channels are
in use.
To my knowledge, the CCIR493-4 mode is
only supported by the original radios themselves
or by high-end decoders like WaveCom and
Hoka, despite it being a relatively simple system.
Having used Rivet for a while, I wondered if Ian
might be up to the challenge of adding CCIR493-
4 to his software to open up this interesting
system to more users. I contacted Ian, asked if
he would be interested in building a decoder, and
sent him a link to the detailed specifications.
To my delight, I got a reply from Ian in
very short order saying that he’d give it a go. I
think it was within a week of my sending that
email that the first version was in my hands
and running under Windows XP and Mac OS X
Lion. Unfortunately, the initial versions proved
to have a bug that prevented proper decoding,
which Ian spotted and corrected. Within another
week or so I was decoding the selcall activity
on the Colombian Navy channel of 12230kHz
USB.
You can see a saved text file of Rivet decoding
CCIR493-4 activity below:
Rivet (Build 24) by Ian Wraith
6:10:56 PM CCIR493-4 Individual Selective Call
Station 9201 Calling 9213 (Routine)
6:34:30 PM CCIR493-4 Individual Selective Call
Station 9218 Calling 9201 (Routine)
7:10:38 PM CCIR493-4 Individual Selective Call
Station 9201 Calling 9214 (Routine)
7:24:19 PM CCIR493-4 Individual Selective Call
Station 9218 Calling 9201 (Routine)
8:06:06 PM CCIR493-4 Individual Selective Call
Station 9207 Calling 9201 (Routine)
8:17:41 PM CCIR493-4 Individual Selective Call
Station 9207 Calling 9201 (Routine)
8:24:56 PM CCIR493-4 Individual Selective Call
Station 9201 Calling 9213 (Routine)
8:31:34 PM CCIR493-4 Individual Selective Call
Station 9201 Calling 9203 (Routine)
Check out the Resources section for details
of where to download Ian’s software, and happy
CCIR493-4 hunting! We can certainly do with
more testers, since most of the networks I can
hear are only using the selcall feature, and not
other functions like GPS fix, telephone call, fax,
etc. The more testers and feedback, the better the
software will be!
❖ Algerian Army Update
As I mentioned in the May 2012 edition of
this column, the Algerian Army ALE networks
have changed identifiers every so often over
the past years. Unsurprisingly, no sooner was
the May column published, than I began to see
reports of different identifiers in use. The new
series of the letter-letter-number-number identifiers
appears to include:
BD10
FN20, 40
JE42
MX40, 43, 47, 48, 50, 52, 53, 54, 56, 57,
60, 61, 62
PT01, 40
WA01
XA01
XL13, 15, 18, 21, 22
XT01
XV01
ZB20
ZT02
❖ Taiwanese Navy Update
The Taiwanese Navy appears to have reactivated
its MIL-188-141A ALE network using
some amusing six letter identifiers familiar to
many a Scrabble® addict. How Apple2 got in
there, is something I’d love to know. Nevertheless,
here they are:
ABACUS, ABDUCT, ABJECT, ABLAZE, ABOARD, ABOUND, ABROAD,
ABSEGC, ABSURD, ACACIA, ACCEDE, ACCENT, ACCESS, AC-
TUAL, ADJUST, ADMIRE, ADROIT, AFFORD, AGHAST, AIRGUN,
AIRPLE, AJRENN, AMBUSH, AMOUNT, ANSWER, ANTENN,
ANYHOW, ANYWAY, APHALE, APPCEF, APPEAL, APPEAR,
APPLE2, ARIGHT, ASLANT, ASSAIL, ASSORT, ASSURE, ASTYRE,
ATTEND, AWHILE, AWNING and AZALEA
Frequencies in use include:
5123, 5433, 6066, 6659, 6747, 7137, 7216, 7508, 7642, 7841,
8051L, 8171, 8173, 8251, 8777, 9169, 9202U/L, 9330,
9392U/L, 9881, 10109, 10180U/L, 10410, 10660U/L,
10755U/L, 11218, 11261, 12184, 13410, 14350L, 14360,
14919L, 16000, 16180, 17420, 17460, 18035U/L, 19160,
19180, 20190, 21860kHz USB (unless denoted by L for LSB
or U/L for both)
Data is sent using the MIL-188-110A HF
serial tone modem.
That’s all for this month. The best of digital
DX to you!
RESOURCES
Rivet Decoder: github.com/IanWraith/Rivet/
downloads
August 2012 MONITORING TIMES 27