InterceptRadio.com Forums

Yea, like I don't have enough to do already...

I recently obtained a simple software application to decode two-tone sequential pages. It's made by a company called Comm Tekk, and so far it seems to work ok. I got it so I could decode the two tone sequential frequencies (Tone out) used by local fire departments. So far, I've been concentrating on Whidbey Island - however, I have been listening to Skagit, Snohomish, and North King County, and have decoded some of those tones.

Is anyone interested in this information? It's slow going, as you have to figure out what dispatched unit is related to what tone. More difficult during large tone-outs.

As this information becomes more useful (for the people with the newer Unidens), perhaps it can be included along with the frequency information on their respective County pages.

Brad/N7JGX
Whidbey Island, WA

_________________
Whatever.....

Here's an example, as heard off the 154.400 in East King County:

Bothell Station 42
2688 hz
1287hz

Bothell/Shoreline M47
1082 hz
1287 hz

Shoreline M65
1082 hz
1598 hz

Shoreline M63
1082 hz
2688 hz

Kenmore Sta 51
643 hz
1985 hz

Kirkland Sta 22
2575 hz
1130 hz

Kind of fun to figure this stuff out....

Brad/N7JGX
Whidbey Island, WA

_________________
Whatever.....

Here is Snohomish Ccounty Fire District # 7 154.235

AF Tone (All Calls)

2575 hz
1403 hz

Batt. 71

2575 hz
1180 hz

I have always found 2-tone and other tone signaling schemes fascinating. Wierd, I know, but in a fun kind of way.

I guess you have to be there...

If you are sick like me, go to http://www.midians.com and click on the "downloads" then "tone signaling charts".

Midian Electronics offers a very cool .pdf file from that page, or they offer an e-mail address where you may request a free wall chart version of the pdf.

Looking at these charts you will find that there are many 2 tone as well as 5/6 tone signaling schemes available, and which schemes may be employed in any given system may depend on a wide variety of factors, most often revolving around the type of console(s) employed and / or which radio sets are deployed in the field. I found in supporting users across the US that, sometimes, the format in use now is actually dependent upon what equipment was first deployed years, even decades ago.

Note that one tone, (in an example above it would be the the first or "A" tone) might be the same in a common group of stations. Often this is used to allow a simple form of "group" calling, by sending a long burst of the single tone.

If you look at the Midian chart you will see that the tones used here for Bothell and Shoreline appear to come from the Plectron tone sets.

5/6 tone can be even more interesting, as each tone refers to a single digit or HEX character. 5 or 6 digit long codes can be sent using 5/6 tone signaling. In "the old days" this was used for digital paging as well as unit ID features. Nowadays ICOM and Vertex offer a comprehensive set of features including unit ID, EMER ID, radio kill, listen in, and even remote channel change control of radios via 5/6 tone signaling.

73,
Nick
N7QOR

Yep, I have been referring to that Midan's chart quite a bit the last few weeks. It's a wealth of information about tone sets. It has been especially useful in decoding the South Whidbey toning scheme. I finally figured out that they had a logical, sequential usage of tones in a particular tone group. Just by figuring out a few of the more frequent tones, the rest of the stations just kind of fell in place.

Once I have this figured out, I'll start listening to the other local frequencies more regularly (well, at least those that will continue using two-tone sequential for the foreseeable future). Kind of fun to work on...a twisted radio puzzle, if you will....

Brad/N7JGX
Whidbey Island, WA

_________________
Whatever.....