WeFax & Surf Forecasting

Using Weather Fax To Forecast Surf and Weather While Camping

I developed using a shortwave radio to receive weather information for the purpose of forecasting surf into a useful hobby. It comes in handy when I am camping where I don't have access to the internet. How?
  • Learn how to use a shortwave radio to receive weather fax images
  • Learn how to configure a computer to decode the images
  • Learn how to forecast surf based upon the data you receive in the images
To be clear, you could easily replicate what I am doing using starlink. You could subscribe to Surfline and have surf reports emailed to you on a regular basis. It would be a lot easier, more reliable, less challenging, and more costly due to data fees. It also wouldn't be a hobby......

Overview

The United States Coast Guard (USCG) broadcasts weather maps created by National Oceanic and Atmospheric Administration (NOAA) on shortwave radio using a primitive technology called radiofax. Click this link to listen to the sound of a sample transmission. The sound is similar to a fax machine.
See the bottom of this page for links to documents for learning how to interpret weather maps.

I listen to two different shortwave wefax radio stations in Baja:
Each station broadcasts the same transmission on multiple frequencies. This is done because reception quality changes from frequency to frequency depending upon the time of day and atmospheric conditions.

My First Radio Setup

At first I used a Sony ICF-SW7600GR AM/FM Shortwave Receiver and decoded the weather faxes using software on my android phone. This system had a lot of flaws. The tuner on the radio would wander which resulted in a distorted fax image. The audio cable that connected the radio to the phone was temperamental and had to be frequently repaired. The phone itself was problematic because the battery would run down quickly and plugging the phone into the charger in the camper while receiving a wefax image introduced RF noise into the system which distorted the image.

Round 2 - Dedicated digital receiver

I upgrade my system to the following:
  • SDRPlay RSP1A software defined radio. A radio that connects to my laptop computer via a USB cable. The radio came with an application called SDRUno. The software on the computer tunes the radio.
  • EFLW-1K End Fed Long Wire Antenna. - Easy to use, portable, weather resistant, durable, and has a balun to reduce RF noise. Well worth the investment. I run a long ground wire connected to the antenna body ground which I lay on the ground.
  • A Lenovo X480 Yoga laptop running VBAudio Virtual Cable and SeaTTY. SDRuno and SeaTTY expect the input/output to be an external device (i.e. speakers or physical radio). VB Cable was used to route the output of the radio software to the input of the decoding software internally within the computer itself. 
  • A USB cable with chokes to connect and limit radio interference between the radio and the laptop and a 50 ohm cable to connect the radio to the antenna. You may need a few other cables/adaptors depending upon where you have your antenna installed.

Why Is It Better?

The investment in this system is well worth it. Let me count the ways....
  • The laptop has a larger screen than the android phone which allows for easy viewing of images.
  • The RSP1A radio and EFLW-1K antenna pick up signals too weak to hear with the old setup. The radio stays on frequency (which reduces image distortion). 
  • The radio is designed to be used in conjunction with a computer and therefore it is shielded from RF noise coming from the laptop and power supply. I can leave the radio on all day and plugged into the inverter in my camper without any issues.
  • The radio picks up a wide range of frequencies - I can listen to Radio Havana, local AM/FM stations, CB stations, marine radio frequencies, weather satellites, NOAA radio frequencies, radio traffic from commercial airlines flying in and out of San Diego, weather nets from boats sailing up and down the coast of baja, etc...

Round 3 - The movement to a Raspberry Pi

There was only one flaw...the Lenovo laptop used an excessive amount of power. This isn't a problem when you are plugged into the power grid but I am using this technology while camping. I am limited to the power my solar panel can generate and running the inverter to charge the laptop required too much power. I also discovered the inverter generated radio interference.

My solution? Move to a Raspberry Pi. The Pi is a small computer that uses very little power. It lacks its own monitor and keyboard but there are other ways to interface with it. I am still using my RSP1A radio and antenna referenced above but the computer was scrapped for the following equipment:

  • Raspberry Pi 4 with a metal case and cooling fan. Even with the cooling fan running, the device uses about 1 amp of power at 5 volts. This is only a FRACTION of what the Lenovo laptop uses. The fan is necessary because decoding weather faxes uses a lot of CPU power which heats up the Pi.
  • SanDisk Extreme 32GB MicroSDHC UHS-3 Card - The Pi doesn't have a hard drive. The memory card serves as a place to store information on the Pi.
  • Apple iPad Pro - borrowed from my wife. As I mentioned, the Raspberry Pi doesn't have a monitor. The primary purpose of the ipad is to serve as a monitor. You don't have to have an ipad, just any device that runs a screen mirroring software client called VNC.  I could have used my android phone but the iPad has a larger screen.
  • Logitech Wireless Keyboard K400 - The Raspberry Pi doesn't have a keyboard either. While it is true the VNC software referenced above has a "screen keyboard", it is very limited and takes up screen real estate. The Logitech keyboard works with the pi without any additional configuration and besides.....it was laying in a box in my friend's garage so it was free. I don't use this device all the time since I can handle many viewing tasks with the VNC interface. If I am going to program or configure the Pi then I use the keyboard.
  • USB GPS - Not only does the Pi lack a monitor, keyboard, and mouse, it also doesn't have a clock that keeps track of time when it is turned off. This isn't a problem when your Pi is plugged into the network at home because the Pi knows how to search for the time on the internet. But this isn't an option while camping. I used the following tutorial to configure the GPS dongle to serve as a source for time on my PI. NOTE: having the pi know what time it is really isn't really critical for what I am doing except that I wanted the Pi to associate the date and time an image was recorded in the filename of the image itself. If you don't care about this fact then you can skip this step.
I didn't have any experience with the Linux operating system which runs on the Raspberry Pi. It took me a long time to configure the Pi and this involved a lot of trial and error....but now have a power efficient system for decoding weather faxes. I leave it on all day and it handles the task automatically.

Interested in trying? 

I recommend you do the following:

Abbreviated Steps for receiving weather faxes

  1. Identify the maps you want to receive and the time they are broadcasted. All times are listed as Universal Coordinated Time.
  2. Plug everything in and tune the radio to the appropriate single side-band station.
  3. Set the Fldigi software to record.
You will need to tinker with the process to make it work right. You will discover that not all frequencies can be received at all times. Personally I rely upon Pt. Reyes 8682 khz. The Linux learning curve is steep but the project was enjoyable and now I have a low powered radio that receives and records weather faxes automatically. The power consumption is so low, it stays on 24 hours a day without emptying my camper battery and records images without needing attention. To view the images, I connect to the pi remotely using the ipad. I delete older images as they are not needed. I can receive accurate weather data while being hundreds of miles from the nearest internet access. 

Now that you can receive weather images, what are you supposed to do with them? The next hobby you need to develop is weather forecasting and surf forecasting. The two topics are interrelated since surf is generated by weather. Read the following items below:

Useful Links

Bottom line....this project was a challenge which became an enjoyable hobby. Want a simple surf forecast but don't want to learn about shortwave radios and weather forecasting? Consider creating an account on Surfline.com and paying someone else to collect the data, forecast it, and send it to you via starlink. You will save hours of time but will miss out on an awesome learning experience.

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