Friday, May 7, 2010

NWR SAME software decoder?

Server weather season is upon us.

I have often thought it would be nice if there was an open source (soundcard/ FOB based) SAME decoder solution.

One could dedicate a cheap USB sound FOB to a receiver parked on their NOAA weather radio frequency that would sit and decode any SAME data bursts.

I am thinking for interfacing to repeaters to provide custom weather alert signaling.

It does appear that software to decode SAME data exists, just not open source.

http://www.dxsoft.com/en/products/seatty/

A SAME software decoder would benefit projects like thelinkbox, and asterisk app_rpt as well as other projects.

{Update 6/11}
Greg Hewgill, has updated the source to his NWR tools, now at:

https://github.com/ghewgill/nwr


"Drew" Kirkman, W4KMC writes:
"TECHNICAL INFORMATION:
NOAA’s Specific Area Message Encoding (or SAME) protocol is used to further streamline the Emergency Alert System. Information about an emergency message (such as locations affected, type of message, where it’s coming from, and how long it will be considered effective) is transmitted in the form of digital bursts at the beginning and end of said message. These bursts are AFSK-modulated data with a throughput of 520.83 bits per second. Mark tone (binary 1) is 2083.3 Hz and space tone (binary 0) is 1562.5 Hz, with each tone lasting about 1920 microseconds. Bytes are transmitted in reverse order (LSB -> MSB), that is, 00010111 would be transmitted as 11101000. There are other technical specifications regarding its use in the real world, but it’s irrelevant here. Essentially, if you handed the right text to it, I have a SAME encoder. It outputs true SAME-encoded data."

See his NOAA SAME web based audio encoder/decoder at:
http://www.drewkirhttp://www.blogger.com/img/blank.gifkman.com/projects/noaa-same/

I also stumbled into:

"Using an Arduino Uno and a few other external components, I've been able to reliably decode the SAME messages."

http://www.raydees.com/Weather_Radio.html


{Update 2012}
Someone updated multimon, and it now has EAS / SAME decoding support!
https://github.com/EliasOenal/multimonNG/blob/master/README

And this PHP-based SAME AFSK encoder: http://www.whence.com/minimodem/

7 comments:

ws4e said...

I still don't know why Icom,Yaseu,Alinco,Kenwood, etc..can put SAME decoding in their radios/HT's when its can be put into every $29 scanner.

I would by a HT over another JUST because it had SAME decoding ability.

Bill Chellis said...

Here is a link to the NOAA SAME spec...
http://www.weather.gov/directives/010/pd01017012c.pdf

Seems to me that someone with coding experience and the will, should be able to distill this spec into a FOSS offering.

I am not sure that I could code my way out of a paper bag, but I am sure that plenty of hams out there can.

Bill, KB1ROP

Dave K said...

Any idea if anyone has done any FOSS work on this?

I'm considering doing a soundcard based software project to decode SAME messages, but I don't want to reinvent it if it's already been done.

Also, if I do such a project I'm curious what sort of output options I should provide for integration into other software.

AC0KG

kb9mwr said...

Dave, there is no FOSS work that I aware of on this.

I have bounced the idea past a few groups/people, none of them were aware of anything like that, but also equally surprised there wasn't.

Bill Chellis said...
This comment has been removed by a blog administrator.
Bill Chellis said...

Hi all,

I keep revisiting this post....
Found this tonight.

http://hewgill.com/nwr/

Might be a good place to start tinkering.

Bill Chellis said...

Hi all,

This post is still alive....
I wrote Greg last July, and he sent me an email, copied below, regarding the source code for his SAME decoder software. It's available for download and tinkering. Not sure what license, if any it under, but Greg is open for questions. Drop a note if anyone else is going to play.

-Bill, KB1ROP

Greg Hewgill to r, KB1ROP

show details 7:41 AM (2 hours ago)

On Fri, Jul 02, 2010 at 11:44:07PM -0400, KB1ROP wrote:
> What are your plans for the SAME capture program?
> Are you developing it more? Is it portable to other platforms?
> Are you making it available to others?
> Is it open sourced?

You will be pleased to hear that I have (finally!) uploaded the source
to my NWR tools at https://github.com/ghewgill/nwr

I don't use this code right now because I no longer live in the US, but
feel free to ask if you have any questions.

Greg Hewgill
http://hewgill.com