Weatherfax — sourcepool

WEFAX ("weather fax") is a radio fax transmission service intended for use by ships and

boats. Transmissions usually include various sea maps (currents, forcasts, etc) and

sattelite photos.

Dedicated and professional reception equipment of course exist, but a simple PC with a sound

card can also be used. Ideally the radio audio output should be wired directly to the PC

sound input, but using a microphone next to the radio also works, however surrounding

sounds will add noise to the final image.

For the technical details of how WEFAX works, I recommend

the Radiofax Wikipedia page.

Weather fax services are likely to eventually completely disappear, many countries have

in fact already ceased broadcasting. That's too bad, I just missed (two years!) the end of

the New Zealand ZKLF service (ended in 2023). With luck I could have managed to receive images...

Now is a good time to try receiving everything I can before stations forever disappear!

Reception and frequencies

The weatherfax.com website is an excellent guide

to the stations available in different corners of the world and their respective schedules.

To receive a station, the receiver must be in SSB-USB mode (upper side band) and tuned to a frequency

1.9 kHz below the published center frequency.

JMH (Weather fax - Japan)

Being located in Japan, receiving the Japanese JMH station frequencies was the obvious first step.

JMH: 3622.5 kHz (USB 3620.6 kHz)

JMH2: 7795 kHz (USB 7793.1 kHz)

JMH4: 13988.5 kHz (USB 13986.6 kHz)

Origin: I'm not certain. Is it Tokyo? Kagoshima?

Here are some images I received on Demcember 8, 2025 on 13988.5 kHz: (JMH)

Kyodo News still broadcasts a newspaper in japanese (and reportedly, english too) on shortwave for ships at sea! This

might very well be the last service of the type in the world! I find this extremely fascinating!

Transmission is done at 60 lines per minute instead of the usual 120 for weather charts. This is most likely

to increase legibility of the compact japanese characters.

Frequency: 16971 kHz (USB 16969.1 kHz)

Origin: Tokyo?

Excerpt from a newspaper received on 2025-12-11

HLL2 (Weather charts - Seoul)

Frequency 1: 7433.5 kHz (USB 7431.6 kHz)

Frequency 2: 9165 kHz (USB 9163.1 kHz)

Frequency 3: 13570 kHz (USB 13568.1 kHz)

Origin: Seoul (South Korea)

The station also transmits on 5857.5, but I have not been able to hear it so far. I seem to get

best results on 13570 kHz.

The signal was very weak, but I recognize the shape of Autralia and its north-west surroundings.

Image received on 2025-12-30

Decoding using a PC

I use Fldigi which can (among many other things)

decode WEFAX transmissions and automatically create PNG files. I can just leave this software running

and come back later with a bunch of files in the target folder.

Reception in progress with Fldigi

Conditions where very good while receiving the above, but this is not always the case. When there are

interferences or noise due to a weak signal, the image quality quickly drops:

Noisy reception

Depending on the day (or the time) conditions can change, leading bad reception. Switching frequency

can help in some cases. With my setup during the day, I tend to get better results with high frequencies. Here

is an example where I switched frequency when an image was being received from HLL2:

Receiving different frequencies from a given station

One should make sure the audio signal does not get distorted. The input volume should be as high as possible,

but without clipping. Fldigi has a level indicator which should be green (occasinally yellow is fine) but

never red!

Decoding using an iPhone

There are also apps such as "HF FAX" which can decode fax transmissions but I find that Fldigi on a PC is easier to use.

Other pages

This page is part of Radio. Other pages in this section:

WEFAX Reception : WEFAX is a system to transmit imags (such as weather charts) over the radio without using much bandwidth. A PC with a simple USB sound card can decode and display those tranmissions. : From Japan, I was of course able to receive images from Japan, but also from Korea, China, Hawaii and even as far as Australia.

BroadCast Listening (BCL) : The pleasure of attempting to hear a great number of stations and collect QSL cards.