Tag: fldigi

Receiving HF Weather Fax

If you have spent time listening to HF you may have noticed the distinctive sound of HF Fax, something I thought had disappeared 20 years ago.

FAX seems like a very old technology now, although before the days of email the FAX machine was the only way to send near real-time images between people. HF Fax uses the same principle, but instead of squirting the tones down a phone line we modulate them onto an HF carrier.

It’s still very slow, but if you are on a yacht in the middle of the Atlantic its a very low-cost alternative to using a Sat phone and data. The charts are still transmitted from a number of locations around the world, using very high power 5 to 20 KW HF stations, so reception is easy even with a modest antenna.

How to identify Wefax on the HF bands 

The history of Radiofax

Worldwide Marine Radio facsimile broadcast Schedules

You can use one of the online KiwiSDR to display the maps, this allows you to select the FAX overlay option in the top right-hand box, then region and download the image.

FLdigi can also be used to display the images on your screen. Using the schedule of transmissions tune your HF radio to 4608.1 KHz USB and set up FLdigi to your sound card. You will need to set the OP Mode to WEFAX then WEFAX-IOC576,

If you miss the start of a transmission don’t worry, just leave the receiver and program running and it will sync and start decoding on the next image. The transmission schedule is quite extensive, so you never have to wait long to resolve an image.

Here is an example from 4608 KHz decoded at 12:58 Hrs on 1/1/18

The transmitted images change based on a schedule, one typical example is included below.


TIME   Chart                                  Valid   I.O.C.
03:41  MSLP ANALYSIS FOR 00:00                00:00    288
04:31  500 HPA CONTOUR/TT (1000/500HPA) 
       ANALYSIS FOR 00:00                     00:00    288
04:40  MSLP 24-HOUR FORECAST (VT 00:00)       00:00    288
08:06  MSLP 48-HOUR FORECAST (DT 00:00)       00:00    288
08:12  MSLP 72-HOUR FORECAST (DT 00:00)       00:00    576
09:29  SEA/SWELL ANALYSIS FOR 00:00           00:00    288
09:35  SEA/SWELL 24-HOUR FORECAST             00:00    288
09:41  MSLP ANALYSIS FOR  06:00               06:00    288
10:00  500 HPA CONTOUR/TT (1000/500HPA)
       T+24 FORECAST                          00:00    288
10:10  SEA/SWELL 48-HOUR FORECAST             00:00    288
10:31  NORTH ATLANTIC INFERENCE               00:00    576
10:42  MSLP 24-HOUR FORECAST (VT 06:00)       06:00    288
14:12  UK SEA TEMPERATURE ANALYSIS            00:00    288
15:41  MSLP ANALYSIS FOR  12:00               12:00    288
16:02  NORTH ATLANTIC SEA ICE CHART           00:00    576
16:22  SCHEDULE: MARINE PRODUCTS              05:00    576
16:30  GENERAL NOTICES (if any)                        576
16:41  MSLP 24-HOUR FORECAST T+24 (VT 12:00)  12:00    288
17:08  500 HPA CONTOUR/TT (1000/500HPA)
       ANALYSIS FOR 12:00                     12:00    288
20:12  SEA/SWELL  ANALYSIS FOR 12:00          12:00    288
20:18  SEA/SWELL 24-HOUR FORECAST             12:00    288
21:41  MSLP ANALYSIS FOR  18:00               18:00    288
21:52  SEA/SWELL 48-HOUR FORECAST             12:00    288
22:22  MSLP 48-HOUR FORECAST (DT 12:00)       12:00    288
22:30  MSLP 72-HOUR FORECAST (DT 12:00)       12:00    288
22:41  MSLP 24-HOUR FORECAST (VT 18:00)       18:00    288
23:33  MSLP 96-HOUR FORECAST (DT 12:00)       12:00    288
23:40  MSLP 120-HOUR FORECAST(DT 12:00)       12:00    288

High Altitude Balloon (HAB) tracking

Amateurs often launch HAB containing telemetry and sometimes SSTV of the ability to take and store pictures. The launch schedule is usually published online, its worth starting with this online resource. Tracking is based on an adapted version of FLdigi, this program once configured with your callsign and location will manage the upload to a central server.

UKHAS have published a beginner’s guide to HAB in the UK

You select the balloon you wish to receive and the program will configure the mode and frequency (requires CAT)

Here is an example of the data sent, the packet includes Launch name, packet number,time,location,altitude,satellites and a checksum.


Its quite incredible to think you can often receive these balloons at 800 miles or more when they transmit as little as 10mW. I guess it helps if your antenna is 30 Km about the earth.

baloon2You will notice on this decode the frequency is drifting a little, probably due to the extreme temperature experienced by the transmitter. Your data will be combined with other stations, and the location of the HAB will be displayed on a map.

This is ROTIO, you can see it has some issues with GPS lock….


Frequency stability can sometime be an issue.


Unfortunately things dont always go to plan, sometimes the conditions are just too harsh or something fails and the telemetry stops.


Electronic log books

In the days when computers filled the size of your front room most people used paper to log their QSO, but today electronic QSO logging has a number of advantages. I was first licensed in 2003, and I took the decision to electronically log from the start. I mainly operated digital modes, so electronic logging was the only way to add calls and so this became the usual way I log.

The choice of electronic logbooks will depend on your preference, band and operating modes. Some electronic logs are free, others are integrated with the digital modes software like HRD.

Electronic logging can be split into two parts, what do you use to record the QSO while on air and subsequently how do you save this and gain any DXCC or other awards.

So lets look at the QSO stage first.

minosMinos for VHF and UHF – The program is free and open source written by Mike G0GJV and you can read the history of its development on his site. Its the best VHF contest software, so thank you Mike for this sterling effort.




hrd2HRD – Ham Radio Deluxe is a paid suite of programs that logs and decodes digital modes.




fldigiFLDIGI – is a free and open source, the program decodes and logs digital modes. The Wiki page makes interesting reading.




pztPZT log – is a free program developed by Charlie M0PZT. You also have the option of a more advanced version PZT Pro for just a few pounds.




n1mmN1MM – is a free program designed for contesting. Developed by N1MM Thomas Wagner it has the reputation of being the most popular logging program in the world. The program can be used as a stand alone logger, but it can be integrated with RTTY to be used in contesting.



Doing something useful with your electronic log.

Once you have logged all this data you have a choice to keep it safe on your drive, or upload so the world can see how many people you have worked. Electronic QSL cards or electronic QSO confirmation is the main benefit but keeping track of your WAS or DXCC has never been easier.

lotwARRL LOTW – Log Of The World  is the defacto standard in electronic QSO conformation. Its the only electronic confirmation system that is recognised and secure enough to allow you to claim DXCC awards. It can also track and credit you for numerous other awards. Yes its a “pain” you have to prove who you are and sign the log before uploading, but its very security is what makes it the trusted authority on electronic QSL. Its not for the paper collectors, you don’t get any pretty pictures but it does what it says on the tin. Oh the best bit is its free.



EQSL.cc –  Electronic QSL cards, with pretty pictures. Its great if you like to collect cards and wanted to save on postage, but their is little or no validation on who the uses the system and so the awards are worthless towards DXCC.





Clublog – Electronic award tracking and confirmation of QSO. Developed by Michael G7VJG.




qrzQRZ – They have jumped on the electronic QSL band wagon, sometimes less is more.




hrdHRDlog.net – Another electronic awards and QSL tracking system





I tend to upload to all of these logs, but only take any interest in the LOTW awards. The other systems help to keep the paper QSL count down, although I reply to any cards received via the RSGB bureau.


© 2015 Dave, M0TAZ