Downloading Weather fax and surface pressure charts via SDR.

Jabs

Jabs

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Has anyone tried using a SDR to download data from Northwood or Offenbach?

If so, how was it and what did you use as an antenna?

Thanks

Tony
 
Unfortunately the cheap and common rtl TV usb dongles don't tune low enough, you can get upconverters to reciever lower frequencies but by that time the cost probably isn't that different from a decent ssb reciever like a Degen 1103.
http://www.rtl-sdr.com/receiving-weather-rtty-rtl-sdr/

I've played a bit with a funcube dongle pro plus on a Raspberry Pi but wasn't successful, think it can be done but I gave up easily as it isn't critical onboard with other options.

As for antenna, did a Biscay a while ago getting wfax with a Degen antenna croc clipped the chain plates in the main cabin just with an android tablet sitting next to the radio - surprisingly worked well. Also, did Atlantic W-E before knowing much about radio with the Degen plugged into an FM broadcast antenna which also worked fine, New Orleans - Boston - Northwood/DWD so a top notch antenna isn't vital.
 
I've had a play with the Android app 'HF WeatherFax' using my NASA HF3 receiver with their active antenna with surprisingly good results. It uses the audio output and so long as your phone/tablet is reasonably close to the speaker the picture quality is good enough.
 
cindersailor said:
I've had a play with the Android app 'HF WeatherFax' using my NASA HF3 receiver with their active antenna with surprisingly good results.
Click to expand...

Agreed - cheap, easy, no wires, no config.

Wasn't the OP asking about SDR - software defined radio - which needs an internet connection?
 
oldvarnish said:
Agreed - cheap, easy, no wires, no config.

Wasn't the OP asking about SDR - software defined radio - which needs an internet connection?
Click to expand...

Why would a software defined radio require an Internet connection?

An SDR samples the RF at a very high rate, then the software takes this digital representation of the RF and does things like filter, tune to a frequency and demodulate in software.
 
st599 said:
Why would a software defined radio require an Internet connection?

An SDR samples the RF at a very high rate, then the software takes this digital representation of the RF and does things like filter, tune to a frequency and demodulate in software.
Click to expand...

Ah, my mistake. thanks
 
Any updates on this subject?
I'm finding it all but impossible to discover if SDR can yet recieve well enough in the 3-3-Mhz bad required.
 
I have (not strictly true, it’s on long term loan from a friend) an SDRPlay. I use it as a quick check of band activity before powering up my transceiver (which has valves so needs time to “warm up”). It is fine for the 3.5 to 3.8MHz / 80m band.

Its spec sheet shows 1KHz to 2GHz.
 
Th trick isn' t just to receive the faxes but to receive the right one and then file it so that it is waiting for you when you wake up. Northwood for instance sends a fax every 20 minutes. Most are of no interest to sailors. They used to send the schedule as a fax twice every 24 hours but recently I have recorded every fax received and not found the schedule amongst them. What is needed is a facility to save the fax having switched the equipment on. One software that goes partly towards this by auto recording each fax and using the date and time as the fax reference is Seatty. You can leave the equipment running and then view the files at your leisure to find the one you need.

Has anyone found the Northwood schedule?

The commercial weather fax machines can be controlled by various signals incorporated in the fax which print those patterns in the header and foot of the fax in the same way as old telex machines switched the printer on and off.


Weather messages decoder - RTTY, NAVTEX, PACTOR-1 FEC, WEFAX (HF-FAX), NWR SAME software
 
Slowboat35 said:
Any updates on this subject?
I'm finding it all but impossible to discover if SDR can yet recieve well enough in the 3-3-Mhz bad required.
Click to expand...
I'm sure it can, but - I nearly replied this to your other thread yesterday - if you have no Linux experience and you've never set up a Raspberry Pi before, then I think that getting a Pi up and running and also setting up wefax SDR will be an unrealistic challenge.

I'd assume there are guides all over the web about getting the appropriate output from SDR into the wefax decoding software, but they will no doubt take it for granted that you know what it means to cat a file, what it means to "pipe" output and how to exit vim when you've finished editing your config. I doubt they'll bother to explain how to install foolib and how do identify "error: missing dependency foolib.c" amongst pages of broken output.

IMO you should buy an RTL SDR dongle and get it working on Windows. Receiving Radio 4 on a Pi with an SDR dongle would be an achievement. Don't expect to get it all right on your first try, but settle for learning something.

The amount of time this will take, you would probably be better off buying a Furuno Fax-408 or Alden WR-G33EM if you value your time at any reasonable hourly rate.
 
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Strangely I think I answered the original posters question in another thread last night. Much easier to achieve on a Windows PC than on the Pi for me (although both managed in an evening).

sdr radio and weatherfax question

RTL-SDR (and some others) can tune to below 25Mhz if they are able to do direct sampling within their hardware - usually referred to in their specifications as something like 'Direct sampling of the q-branch'.
 
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