scottlirwin
Posts: 21
Joined: Mon Dec 30, 2019 10:19 pm

Weather Fax - need hardware advice

Mon Dec 30, 2019 10:23 pm

Please excuse me if I'm asking a question that has already been answered. I have looked around and found related items but nothing exactly like what I am trying to accomplish.

​I use my sdruno rsp1a radio to receive weather fax documents while camping in Baja California, Mexico. I currently use a Lenovo Windows machine running Sdruno and SeaTTY (pc based wefax decoding software). It works great except for two problems. First of all, the windows machine is power hungry and I am running everything off of a 12 volt deep cycle battery and small solar panel which can't handle the load too long. I'm camping for a couple of weeks at a time far from civilization so plugging into the wall isn't an option The second problem has to do with my inverter which adds a lot of RF interference into the signal. the interference is so bad, most of the time the received images are unusable. I'd rather bypass the interver all together and plug straight into an existing 2 amp USB charging port wired to my camper electrical system.

​I am looking into purchasing a raspberry pi for receiving weather fax documents. I like to tinker but have no experience with raspberry pi. My "google research tells me":

​- I should download and use the SDRplay_RPi_V0.6.img.xz image from the sdruno website. The software on this image will control my rsp1a radio.
​- I can install fldigi for use with decoding the weather fax image and saving it to the sd card
​- I can use port audio to move the received signal to fldigi
​- I can save precious battery power by not running a mouse, keyboard, monitor, etc.....
​- I can use some sort of terminal software so I can connect to the pi using an android table through bluetooth to control the radio and view my weather fax images. I'm not sure what software will allow me to do this.
​- I heard the pi can get hot so I should purchase a metal case with fan and heat sinks.

​QUESTIONS:
​- Am I heading in the right direction with my thinking?
​- Should I purchase a Raspberry Pi 4 or 3B? If a 4, should I purchase 1, 2, or 4 gigs of ram? Please remember I don't plan to use the pi for anything other than what is listed above and saving power is very important to me.


​Thanks for any help you can provide.

jbudd
Posts: 1942
Joined: Mon Dec 16, 2013 10:23 am

Re: Weather Fax - need hardware advice

Tue Dec 31, 2019 1:01 am

Should I purchase a Raspberry Pi 4 or 3B? If a 4, should I purchase 1, 2, or 4 gigs of ram? Please remember I don't plan to use the pi for anything other than what is listed above and saving power is very important to me.
I can't comment about downloading or converting your weather fax images, I have no idea if the Pi can substitute for a PC there.

But since low power consumption is more important than processing power, you should consider a Raspberry Pi Zero W or A+. Should be no problem powering either of them from a USB battery pack or from a USB plugin adapter to the camper's 12V socket.
And I doubt if overheating will be a problem on those models even in Mexico, though some sort of case makes accidental short circuits less likely.

As for accessing the Pi headless, take a look at https://www.raspberrypi.org/documentati ... ccess/vnc/

You will need some sort of network, and the Pi can be set up to provide it through WiFi.

But if your project includes an android tablet, is it possible to process the data on that and not use a Pi at all?
If you do take a Pi, I recommend adding a Blinkt! from Pimoroni https://shop.pimoroni.com/products/blinkt as a backup camping light.

scottlirwin
Posts: 21
Joined: Mon Dec 30, 2019 10:19 pm

Re: Weather Fax - need hardware advice

Sun Jan 12, 2020 4:45 pm

I thought I would follow up on this thread. I was able to create an automated weather fax receiving station using the raspberry pi and a sdrplay software defined radio. It works on a pi4 with 4 gigs of ram and a cooling fan. I run headless which isn't too complicated especially if you have a mac laying around to turn VNC on when you first start the pi. Decoding radio takes horsepower and glitches cause problems with decoding so purchase the fastest pi you can!

I use an image that I downloaded from SDRPlay's website. You can get it here: https://www.sdrplay.com/sdrplay-downloa ... 3-model-b/

It has everything minus fldigi - a free software that decodes weather faxes. I use CubicSDR (free software defined radio software that comes pre-installed and configured on the image from SDRPlay) and the audio is ported to Fldigi to be decoded using pulse audio (which again I know nothing about configuring but it was pre-configured on the image). NOTE: The cheap power supply that came with my pi kit caused all kinds of RF interference - which then results in severe image distortion.

My pi4 runs an adhoc network which means when I'm out in the field I can connect to the pi through my laptop using wifi (when there is no router or network in the area). These directions worked for me: https://www.raspberrypi.org/documentati ... s-point.md

So my setup is:
- put up the antenna and plug the rsp1a into the pi usb port (doesn't matter which port)
- plug the pi into my camper battery (solves interference problem described above)
- boot the pi
- turn on the laptop - use the VNC client to set up the radio receiving and decoding software to listen and record
- disconnect from VNC and go surfing
- wait until the radio broadcasts are complete - see here for schedule: https://www.nws.noaa.gov/om/marine/rfax.pdf
- turn on laptop, connect to pi through VNC, download the saved images to the laptop and disconnect from the pi
- pi stays on and waits until the next cycle of images to record

I can look at the images and keep what I want :)

The pi is running 24 hours a day and using a minimal amount of power compared to the laptop. A fun solution that took some tinkering :)

jbudd
Posts: 1942
Joined: Mon Dec 16, 2013 10:23 am

Re: Weather Fax - need hardware advice

Sun Jan 12, 2020 5:56 pm

I'm glad you got it working, it sounds like a really interesting use for a Pi.

Over in England we have the Meteorological Office and BBC to forecast the weather for us but it's dumbed down so far. When I feel the need for proper weather maps I look to the USAF!
Last edited by jbudd on Sun Jan 12, 2020 7:15 pm, edited 1 time in total.

stevend
Posts: 441
Joined: Fri Oct 11, 2013 12:28 pm

Re: Weather Fax - need hardware advice

Sun Jan 12, 2020 6:14 pm

jbudd wrote:
Sun Jan 12, 2020 5:56 pm
Over in England we have the Metrological Office and BBC to forecast the weather for us but it's dumbed down so far. When I feel the need for proper weather maps I look to the USAF!
Have you found http://www.metbrief.com/charts.html - they do synoptic charts .

User avatar
DougieLawson
Posts: 41892
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: Weather Fax - need hardware advice

Sun Jan 12, 2020 6:33 pm

jbudd wrote:
Sun Jan 12, 2020 5:56 pm
I'm glad you got it working, it sounds like a really interesting use for a Pi.

Over in England we have the Metrological Office and BBC to forecast the weather for us but it's dumbed down so far. When I feel the need for proper weather maps I look to the USAF!
The UK Meteorological may have a dumbed down website but their data is there if you look hard enough.
https://www.metoffice.gov.uk/weather/ma ... e-pressure

A good source of data is the Air Traffic Information Service (ATIS) at your nearest airport.
https://www.aviationweather.gov/metar/d ... s=0&taf=on (for Heathrow for example)
Languages using left-hand whitespace for syntax are ridiculous

DMs sent on Twitter/LinkedIn will be answered next month.
Fake doctors - are all on my foes list.

The use of crystal balls and mind reading is prohibited.

User avatar
scruss
Posts: 4478
Joined: Sat Jun 09, 2012 12:25 pm
Location: Toronto, ON
Contact: Website

Re: Weather Fax - need hardware advice

Sun Jan 12, 2020 6:43 pm

Nice writeup! Glad to hear that weather fax is still working well. It's a very simple system that works well where there's no network.
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.
Pronouns: he/him

jbudd
Posts: 1942
Joined: Mon Dec 16, 2013 10:23 am

Re: Weather Fax - need hardware advice

Sun Jan 12, 2020 7:17 pm

Thanks for the links Dougie & Steven :)

Return to “General discussion”