Monday 23 July 2012

Receiving weather information using Shortwave radio

One of the things that I've been thinking about that was prompted by our friends trip across the Atlantic and then Pacific to New Zealand:

http://ishtaryacht.blogspot.co.uk/2012/05/brians-heading-south.html

is the issue of communication with the outside world. I'll post more on 2 way communication soon, but earlier this year I became interested in receiving weather information using a short wave radio and a laptop computer. Clearly, when close to land, it's easy enough to pick up weather information using a mobile phone, or by listening to the coastguard broadcasts every three hours on VHF. Further out, though, these methods are unavailable, and the mariner is left to the short wave radio for information.

There is plenty of information out there on how to do this, and there are some links to useful reading sites at the end of this post, but the basic requirements are shown below.


A Laptop computer, running relevant software. I used Jvcomm32, which can be used for fax and teletext transmissions.

A shortwave radio. Pictured is a Degen DE1103, which I bought for about £50 from ebay. I've also used a Sony ICF-SW7600, a better radio, but 2-3 times the price. The radio needs to cover (typically) from around 2MHz-15MHz (check links for full range of frequencies), and, importantly, must have SSB (Single side band) or USB (Upper side band) capability.

A short lead to connect the radio headphone socket to the microphone input socket on the laptop, for sound transfer.

(Not pictured) Both radios come with a ~10m long external antenna, which I run down the garden to a pole - without this additional aerial, I received nothing.

I picked up the transmission in the following picture using 10100.8MHz, from Offenbacch in Germany, but there are many transmitters, and many frequecies.


You may just be able to make out some weather information on specific dates for the North and South Aegean sea, wind directions and speeds and so on. at the top of the picture is the spectrum window. I found that by using the fine tuning button on the radio, I was able to change the sound (which screeches like a fax machine) until a wide block of mainly noise shows up as distinct peaks of information. The text will also become clear. When not tuned correctly, odd characters appear, and the text becomes more and more unreadable as you drift away from the correct frequency.

It took me around three days of playing about to get this, and it's very much a question of teach yourself, and sticking at it through the frustrations. When I eventually got the text, I was elated! After a bit of fiddling, I also managed to receive some weatherfaxes, again from Germany, on 7878Mhz:




I'm just begiining to understand how all this works, but I'm convinced that, as my understanding and experience grows, I'll soon be able to get accurate text and fax weather information as easily as I currently do using my phone and VHF radio.
Links


http://weather.mailasail.com/Franks-Weather/Radiofax-Schedules-Northwood-And-Offenbach - Frank's weather.

http://www.thiecom.de/ftp/informationen/seefunk/ - Offenbach broadcast shedules

http://www.jvcomm.de/index_e.html - JVcomm software