Receive facsimile weather maps with an iPad [Update]

An SSB receiver for leasure boating

HF Weather Fax at Black Cat Systems is an application for decoding facsimile weather maps on an iPad, an iPhone or Android device. The analysis and forecast maps are provided by radio stations around the World. Broadcast on shortwave, they can easily be received by SSB receivers as found in catalogs for pleasure.

The facsimile maps :

The National Weather Service (NWS) publish the full list of world stations, with their frequencies, schedule for many data broadcasted in a document as a free download in PDF format updated every year. L’ouvrage RSX99 du SHOM (previously paying) also provides all station and broadcast information for the North Atlantic areas, from Europe to the Caribbean.
For Western Europe, in example, radio station in Hamburg broadcasts a surface analysis map (*) for North Atlantic from 05:25 and 18:00 UTC, and surface forecast maps(*) term H 30, +48, +84 and +108 from 5:12 and 8:17 UTC, and again from 18:30 UTC. Some maps are rebroadcast. Station Northwood U.K. also provides many forecast maps throughout the day. There are currently spoiled for choice !

The app :

HF Weather Fax is a decoder to display in full screen weather maps received by the SSB receiver and save it. A view shows the quality of tuning and so allows to adjust as finely as possible. At the first use of the application, if the received image is slightly slanted, due to slight timing variations between devices, adjustment buttons allow correct display, This initial setting is saved. It is important to note the fact that you usually need to tune about 1,9 kHz lower in frequency than the listed carrier frequency in a schedule, and then use the fine adjustment of the radio for proper reception of picture elements in black and white. Saved maps can be exported to a computer from the Documents folder of the application in iTunes.

Installation :

Careful installation is highly recommended

For best reception from a small leisure SSB receiver, it will important to take care of your installation, otherwise you may get disappointing results, especially on the high seas. An antenna dedicated to shortwave reception is desirable, the telescopic antenna of the device can not be deployed inside the boat, and not always completely, this can cause a significant loss of signal.

To avoid interference and noise in direct sounding, it is best to plug an audio cable adapter specifically designed to connect the receiver to the headphone input of Apple devices. an adapter can be used Audio line for connecting with an audio line out jack 3,5 mm (1/8") in headphone input on an iPad / iPhone. It incorporates a built-in attenuator which reduces the line level signal down to a mic-level signal suitable for input for recording. It works with cables with a mono or stereo connector (1/8")″(3,5 mm).

The advantage of this light installation weather reception is to avoid, for short sailing off, to invest in a satellite phone without which GRIB files request is impossible . There is thus, between two internet connections near the shores, weather forecast off cheaply.

(*) Also called "front charts" because they represent the warm and cold fronts for Lows.


9 Replies to “Receiving Facsimile Weather Maps with an iPad [Update]”

  1. Hello, I am confined to St. Barth and soon plan to cross. If iridium was failing, the next best is the one you mention in your blog. Flying Antenna bought in Germany for catamarans that have no backstay and I send pegged to the topping, cable audio output, and lightning adapter to headphone jack at apple, HFFAX software.
    It does not work despite trials of several hours. And at the end, we ask a lot of questions. The first : exit should it be on the seangean the headphone jack or line out?
    I try to capture the new Orleans on corrected frequency 1,9 namely 4316, 8502 LSB and 12788 SSB hours of given emission. J 'hear sporadically signal, but the iPad displays a screen with a black cloud of pixels and white.
    Do you provide me some tips?
    Thank you in advance.

  2. I did again yesterday application testing HF Fax and NAVTEX system Blackcat. For me it was working with reliable NAVTEX texts 98%. For cards that's just long but it also functioned. My test done has been for the sound output of the card to a PC with the cable indicated by Francis plugged into the headphone output. I used test signal sources available on the WEB (Navtex and HF Fax) The iPad is a 6th.
    My sea reception apparatus is a TECSUN PL680.
    Certainly for perfect reception you need a good antenna and preferably not be in port. But it is at sea in general we need this type of product. At the port we have other means.
    It is an alternative for those who do not have fixed Navtex or iridium to receive Grib off.

  3. Actually 2014 I traded for this article Jean Debèze happening to properly recover the cards with his Sangean (the model I set illustration). But I think we must have especially a very good antenna, and it is possible that the application, which is older, no longer really up. And the Sangean is not what is more powerful in HF reception.

  4. Hello,

    Francis thank you for this update that is timely; I take indeed containment Covid-19 to test these capabilities.

    My experience with HF Weather Fax :

    – auto-save functions erratic way
    – Mostly ap does not recognize neither the purpose nor the beginnings of FAX therefore registration is made until the buffer is full, vacuum and leaves the top

    the result is that unless we lose over most images

    – App does not work in the background so you have to dedicate the iPad at the reception of FAX's. My iPad is dedicated to Weather4D; no intention to buy a second for this approximate ap; rather buy an Iridium GO!

    My experience with navText in TTY mode in Blackcatsystems:

    – I never managed to recover anything. This is what I read everywhere (Hisse-et-Ho, aso.). I would love to talk to someone who manages to use

    Note that SeaTTY (on Windows 10) I finally bought a result of the frustration expressed above, (and to verify that my receiver was not involved) works like a charm with the same source – I just changes the hole jack…- FAX and TTY and does all what you expect. One can even get the signal that it is on the spectrum, and when it is above the decoder is locked and following the possible fluctuation of carrier.

    As I have no intention to put a PC on my boat I think I will do without these gadgets.


  5. Hello Francis,
    The link takes PDF documents on a page 404 !!
    The link does not seem RSX99 lead !!
    The link to the audio cable is good.

  6. Hello, in the same vein, there Navtex pad application from the same publisher….I've tried both… takes a great BLU antenna…..for the reception is clear….Other than that congratulations for your blog…Cordially

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