Hi all
Our sixth Navtex CLE, CLE168, will be held over Easter weekend:
Days: Thursday 28th March - Tuesday 2nd April
Times: Start and end at midday, your local time
QRG: 490kHz , 518 kHz, 424 kHz, 4209.5 kHz
(plus other HF frequencies (6314, 8416.5, 12579, 16806.5 .. . )
We are again adding an EXTRA 24 hours at the start, and at the end,
to allow us to cover the different frequencies adequately.
This is some extra early advice to help 'beginners' to get started,
or to remind us of what decoding is all about.
The usual 'Early Advice' and 'Final Details' will follow about 1 week,
and 3 days, before the start.
Below is my over-simple introduction, with advice on where to find the
fuller - and better - details.
The real home for Navtex reporting is the Navtexdx List, a sister forum
to NDB List, but we welcome occasional logs here on NDB List too.
CLE168 will be a shared event for both Lists.
Many members have 'discovered' the NAVTEX mode from our five
earlier CLEs and found it fascinating.
Hope you can join us
Brian
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From: Brian Keyte G3SIA ndbcle'at'gmail.com
Location: Surrey, SE England (CLE co-ordinator)
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NAVTEX - A SIMPLE INTRODUCTION
The worldwide NAVTEX system transmits navigational and meteorological
warnings and forecasts and urgent marine safety information to ships.
It provides a fascinating variation on our hobby, needing all the usual
skills with receivers and aerials and knowledge of different propagation
conditions, but adding some good DX reception, interesting navigational
messages and the ability to leave your receiver and PC 'listening all night'
while you are fast asleep! These short notes are just intended to GET YOU
STARTED, taking some of the initial mystery out of Navtex and Decoding,
explaining as simply as possible how to receive your first stations, how to
identify them and how to report your loggings.
To find the FULL details and advice go to our info page and select the box
to visit the DGNAV List Site
( or go direct to
http://www.ndblist.info/dgnavlist.htm )
1. TUNING TO A NAVTEX SIGNAL Set your receiver to show 516.30 kHz
on the dial for 518 kHz (or 488.3 for 490 kHz) with USB setting and
a wide filter, such as 2 kHz. You should then occasionally hear the
background noise replaced by the warbling sounds of a Navtex signal.
2. GETTING SIGNALS TO YOUR PC Make an audio connection from the
receiver to the PC sound card input. It's best to use the more professional
advice about how to do that, but I just take a length of co-ax from the two
terminals of one side of some primitive headphones direct to the PC's line
input socket. You should be able to hear the signal in the speakers by
adjusting the PC volume control settings (playback and/or recording). If
necessary you could use the microphone input socket, but it is important
to AVOID OVERLOAD which could damage the sound card.
3. INSTALLING A DECODER PROGRAM A decoder program (see the Navtex
section in the Website) is easily installed in your PC - just follow the
advice. When you have succeeded with your first decodes we recommend
using YaND, which has many features designed specially for our needs.
As a very simple 'starter' though, I recommend the Frisnit decoder - just
save the small 'navtex.exe' file, then double click on it. With a 1700 Hz
setting on the display, in no time you will see the incoming messages.
Then move on to YaND, which identifies the received Stations for you, helps
you to set up your log in the right format for REU/RNA, etc. and has many
extra features.
Alternatively, SeaTTY is also a very good decoder with some extra features.
It is quite easy to install and use (a 30 day trial period is without
charge).
4. RECOGNISING THE STATIONS You will find that most Navtex messages
start with 'ZCZC' and end with NNNN. The ZCZC is followed by two letters
and two numbers - e.g. OA12. The first letter gives you a good idea which
Station you have received and it tells you the times of day, 4 hours apart,
when that station is likely to transmit. Most of the 'O' stations transmit
starting at 02:20, then 06:20, 10:20, etc. The World is split into Navtex
areas and there is often only one Navtex station using each letter in each
area. In North West Europe (Area 01) an 'O' station heard on 518 kHz is
likely to be Portpatrick in Scotland, but it might be from Malta (Area 03)
or even St Johns, Newfoundland (in Area 04). The actual messages should
remove any doubt about which of the possible stations it is - the messages
may include the Station Name (e.g. 'MALTA RADIO'), or the Navtex Area
Number or geographical references, latitude/longitude, etc.
The second letter (A) shows what kind of message it is and the rest
provides a message number.
5. STATION IDENTS We use our own way of identifying each station in our
logs and station lists. It always starts with a '$' which means 'this is a
Navtex Station' and it allows us to include these stations in lists with the
other kinds of beacons in the Rxx database, etc. Immediately after the $
comes the two-digit Area Number (most of the eastern part of N.America is
area 04). Last comes the Station Letter - an important part which provides
the main 'key' to the station sending the message. So the 'O' station above
would be $01O if Portpatrick, $03O if Malta and $04O if St Johns. You can
find lists of the Navtex stations and the times they transmit from Alan's
World Database in the Navtex Section of the Website and in Rxx.
YaND automatically works out for you everything in 4. and 5. above!
### IMPORTANT: However, WHICHEVER decoder you use it is very important
to CHECK ALL YOUR LOG ENTRIES. Make sure that every decoded message
shows the as-transmitted Station letter and that every message
contains text that confirms the identity of the Station you are
showing.
6. OVER TO YOU! You can sit and watch the messages arriving or just leave
your receiver and decoder program running overnight, then look through the
messages afterwards to see what you have caught.
REU 
Sivu: 1
CLE 168 Navtex (Luettu 9867 kertaa)
