[Elecraft] OT: HF weather fax

[Fred Jensen]

Ummm ... NAVTEX is transmitted on a rotating schedule covering several 
dozen "regions" world-wide from a variety of stations, all on 518 KHz. 
Each station has a time slot -- 5 mins or so -- and the traffic varies 
and is highly repetitive.  There is some WX, but it's mainly Notice to 
Mariners about various conditions and situations such as hazards, 
objects falling from the sky without warning [aka military exercises], 
lights and buoy's out of service, and the like.

With the new synthesizer, I can copy NAVTEX [or at least could, haven't 
tried since we moved to N. NV] very well on my K3.  If I recall right, 
connect the antenna to the auxiliary  RX ANT jack.  There are a number 
of decoders, I use YAND [Yet Another NAVTEX Decoder] which is free and 
findable using the usual methods.

The transmission is SITOR-B, using the CCIR-476 character code and I 
think is unreadable using a normal 5-unit RTTY decoder, although I've 
never tried it.  I think AMTOR FEC mode will decode it, although I've 
never tried that either.

Any vessel sailing in the open ocean should have NAVTEX receive, but for 
general weather, it is probably not adequate.  The WEFAX transmissions 
include visible and IR satellite photography, what appear to be 
hand-drawn forecast summaries [those of the Bering Sea will have the 
edge of the ice pack marked], wave height charts, schedules, and 
synopses.  They are way bigger than what our printers will handle, you 
need to wait until it gets to the area you're interested in before 
starting to save the image to a file for printing.

On 4/11/2016 5:07 AM, a45wg wrote:
> Clint, Your brother will find it easier to revise the 518 Khz NavText
> messages - which are transmitted every 6 hours (if memory serves me
> correct). They are a simply RTTY format. I tried for long time to get
> HF WeFAX to work - but the number of stations transmitting it are
> extremely few and far between. They are more local +/- 1500 kms (more
> than enough for coastal use). There are some small black boxes
> available which do this - for < $200 - which may be worth looking
> at.