Marine Radio - Wefax Chart #1

This is a chart received in the Azores, from the German Weather Service. It is discussed in the article 'Weatherfax Onboard' in the Tech Articles section, or go directly via:

www.pelaginox.com/

It has been compressed as a jpeg to about 233 kb. Originally it was received, then saved, as a bitmap file (.bmp) of about 6.5 Mb, then opened in Paint Shop Pro, coloured in, then cropped and exported. When cropped it was about 1.5 Mb, which is obviously a huge file size saving just by removing the oversize canvas; then when exported to jpeg, about 480 kb, which is about half a megabyte. It was compressed further, to reduce the file size, so this page would load faster.

You can immediately see two things: firstly, even in this much smaller and compressed file size, the quality is excellent. In fact it is probably better than you could get on a fax machine on your phone line at home. Although received in mid-ocean, it's as good as you could get on the Internet; and no, I didn't cheat! The chart has NOT been 'cleaned up' IN ANY WAY.

Secondly, the German Met Office provide a useful guide to cloud cover, which I have coloured in with blue, to make it a little more obvious; it looks like I missed some over North Africa, and also coloured in some of Iceland... This is not only a useful feature, in effect it combines the synoptic chart with a satellite photo, and therefore the chart does two jobs.

The original chart, and the various stages to getting to this chart, are also given on other pages listed here; if you have a broadband connection and are interested in wefax reception, probably without your own set-up as yet (or one with problems) you will be able to see the stages and file sizes it has gone through. These charts will also point you toward the quality you should be receiving.

Note that the chart was received with a bit of old wire used as an audio cable – no demodulator cable was used. The clarity results from three factors:
   1.   The high-quality transmission from Germany.
   2.   The Lowe HF150 receiver, which is top quality.
   3.   The wefax app is pretty good too: Mscan Meteo Pro.

It's probable that most laptops would be able to produce a chart of this quality – and possibly better, since mine is getting on a bit now. But certainly not most receivers. This one cost about Ł800.

Here is a list of the chart in its various stages:

Stage 1: 6.5 Mb – the original chart as received, in bitmap (.bmp) format. Then, on this site:

Stage 2: Wefax chart 3 - 1.38 Mb   - cropped to final size, cloud areas coloured, still in bitmap format (.bmp).

Stage 3: Wefax chart 2 -   480 kb   - optimised (light compression) jpeg as exported from the graphics app Paint Shop Pro.

Stage 4: Wefax chart 1 -   233 kb    - 10 to 1 compressed jpeg – THIS CHART.

The conic projection nicely shows just how far the Azores are out in the Atlantic.

Note: unless you are on broadband, the download time for this page will be extended, due to the graphics content.