Odd pair of pager tone frequencies...

[MLoR]

Hello, first off, I hope I posted this in the correct forum. If not, I do apologize.

Anyway, I recently came across a certain pair of tone frequencies used by a fire department near me...

Tone A: 626.0
Tone B: 1017.0

...and in all of the searching and reading I've done, I haven't yet found a paging standard that uses these particular tone frequencies. I am absolutely positive these are the ones, as I've not only seen "626.0/1017.0" printed on the back of the belt clip of a Minitor II belonging to this department, but I've seen another II belonging to this department disassembled, and saw the individual tone filters. They were Motorola filters, however, I haven't been able to find these filters again anywhere, nor have I seen these two tones listed in any code plan/table/graph.

So, my question to the community: Has anyone ever seen these two tones anywhere before, or might you know which paging standard they are a part of?

 

[N9JIG]

AFAIK these tones are not from any standard group or list. While the majority of tones are usually pulled from the list of tones commonly available in the CentraCom II consoles (due to the many of these consoles in use) or the lists of tones from the manufacturer of the equipment, custom tones can be used by departments for many reasons.

The CentraCom II had a 16 button QC-II encoder which gave a theoretical 256 different tones available and a theoretical 65,536 different combinations. In reality though there were somewhat less tones produced and less combinations due to group calls and other reasons. These lists included all the QC-II tones and many tones commonly used by Plectron, GE and other manufacturers. Some tones are so close to each other to be interchangeable, so the tables included instructions to use Tone X in place of Tone Y.

Other consoles, such as ModuCom and Zetron, as well as the newer Motorola units, produce tones individually instead of from a rigid group list. This allows any tone and combination of tones to be generated. Some consoles produce tones to the nearest 1/4 Hz., others round off to the nearest integer. Either way, as long as it is within a Hz. or two it will work fine.

This agency (or more likely the radio shop that set it up for them) probably used a console other than the CentraCom II when the tones were chosen and they selected tones that may have been chosen for a multitude of reasons. Perhaps the tech's birthday was June 26th and his anniversary was October 17th, thus using 626 and 1017 Hz. I chose some tones for one of our agencies by listening to a bunch of tones that were pleasing to my ear and did not sound similar to other agencies on our channels. Before I took over our Plectrons had several tone sets of tones that were all divisible by 200 (1200/1400, 1200/1600, 1200/1800, 1200/1000 and 1600/1000). I know of one agency that tried to figure out the Station 51 tones and use them before discovering that they were QC-I and incompatible with their radios. Boy, were they disappointed!

 

[MLoR]

Ah, makes sense then, the custom tone thing. However, what about seeing the Motorola tone filters that actually had 626.0 and 1017.0 printed on them, and not ever seeing these available anywhere? It seems I've seen just about every tone except those two. Would it be possible that the filters themselves were custom-built and ordered from Motorola?

I wish I could provide more information as to location, department, equipment, etc to provide a little bit more to go on, but I've had my rear end chewed pretty severely in the past by groups that saw what I was researching and weren't exactly pleased... =P

 

[N9JIG]

The tone filters can be ordered with any tone you want, it just takes a little longer if you needed tones that weren't kept in stock.

Most alert receivers these days are programmable and do not require reeds or filters, so this makes custom tones that much more feasible.