Older PL Tones

[Tophtoh]

Not sure what website it was but I was reading why public service sometimes pick the PL Tones they do, and it was because most "older" Motorola equipment uses certain PL tones... if anyone knows PL Tones they are or what the website was let me know. Any help is appreciated, thanks.

 

[Voyager]

Not sure what website it was but I was reading why public service sometimes pick the PL Tones they do, and it was because most "older" Motorola equipment uses certain PL tones... if anyone knows PL Tones they are or what the website was let me know. Any help is appreciated, thanks.

Well, there are a couple factors in older equipment that no longer exist. The most likely reason is because they used reed decoders that had to physically vibrate. The decode time of the lower frequencies was much longer than the higher tones. Microprocessor decoding does not have this problem to the degree that reeds did.

Higher tones were harder to filter out than lower tones since they were closer to the cutoff point of the filter (300 Hz).

So, tones in the mid-range were preferred.

There are really no old PL frequencies that are no longer used, but there are some really non-standard tones that were (and still are) in use by some users such as 81.0 Hz.

You know, there are two tones that are not used as much as they used to be: 131.8 Hz and 136.5 Hz. Those are not used much due to the fact that the DPL turn off code is 134 Hz and will false those two tones. If you have a receiver on those tones in an area that uses DPL, you may hear a 'kerchunk' every time the DPL user unkeys.

There are also the 12 newer tones of the standard 50-tone EIA table that were not in the older standard 38-tone EIA table. Many of those tones are still not in common use. There is another recent thread that deals with PL tones that lists the tables.

Joe M.

 

[Halfpint]

Until we can get a moderator or Lindsay to `merge' this into the `original' topic/thread try this link to the "CTCSS Tones" topic.thread for more info.

http://www.radioreference.com/modules.php?name=Forums&file=viewtopic&t=25566

If it doesn't answer all of your questions you can ask the participants there and *someone* will probably be able to either answer or point you in the right direction.

BTW, thanks for the added infor, Voyager. It's going into the rest of the `file' for the BBS. (Besides whatever *I* `write' I've decided that I'd better also include a `transcript' of the thread, too. [Makes it easier for me to give credit where credit is due without having to rely on my fading memory. (Something about one's memory being being the second thing to `go' with old age and, for the love of mike, I can't remember what the first thing is?! {WAN GRIN!})])

Just an `Olde Fart's' 2¢ worth. {GRIN!}

 

[Halfpint]

loumaag,

Would it be possible to get this topic/thread `merged' with the "CTCSS Tones" topic/thread? There is no need to have a duplicate topic/thread going on, is there?

Thanks.

Just an `Olde Fart's' & BBS SysOp's 2¢ worth? {WAN GRIN!}

 

[Halfpint]

You know, there are two tones that are not used as much as they used to be: 131.8 Hz and 136.5 Hz. Those are not used much due to the fact that the DPL turn off code is 134 Hz and will false those two tones. If you have a receiver on those tones in an area that uses DPL, you may hear a 'kerchunk' every time the DPL user unkeys.

Joe M.

Thanks! You just answered one of the questions *I* had `kicking around' in the back of my mind for quite some time. There are, most likely soon to have been what with this State's headlong rush to a Statewide DTRS even though they are `holding out', a couple systems where I've been hearing that `kerchunk'. On their freqs they've chosen those two tones!? (One `tone' is for the PD and the other is for the FD radios.) Dunno just *why* whomever set up the systems chose them but I do know that the reason they went with `tones' was because the State Frequency `Coordinator?' really blew it when they assigned them their freqs because there is another system only about 50 miles `down the road' that is using the same freqs and *both* systems have been `butting heads' over this for quite a few years with neither system wanting to give up the freqs. {WAN GRIN!}

The same, or very similar, situation is happening, or has been happening, with a FD about the same distance away and another county's R&B system, too. (Seems that the so-called `coordinator(s)?' have a slight problem `coordinating?' here?) The R&B people have `had?' their freqs for at least 15 - 20 years before the FD came upon the scene and back then there were, and actually still are, enough other freqs that this situation didn't have to happen/be. 'Course it cannot be said that the `coordinators?' are all of the problem with this particular situation as *both* the FD and the R&B people are not about to `give ground', too. {FROWN!} In the first scenario one of the `participants' *is* going to the State DTRS as quickly as they can so that they and the other system won't have to put up with the interference. On top of that there wasn't as much `acrimony', even though I *did* use the term `butting their heads' to describe the situation, between the first mentioned two systems as there has been between the latter two systems. In the second scenario the R&B people are claiming that because they were `there first' they have a `right?' to the freq and the FD is claiming that because they are a FD *and* that these freqs give them `necessary coverage' *they* have a `right?' to the freq. {GRIMMACE!} (Yep! All the fuss is over *one* freq unlike the first systems which had several freqs they were having problems with! {FROWN!} Oh, and there is no `kerchunk' with either of the latter's systems as they picked `tones' well away from the 134Hz `turn off' `tone'. Getting back `on topic'. {VB GRIN!})

Just an `Olde Fart's' 2¢ worth and thanks, again. {GRIN!}