A semi-stupid question on CTCSS

[nyquiljunkie]

I never gave this one much thought since my dinky scanner has no ability to input these while programing, so of course I did the normal thing.

I ignored the subject and just listened to the scanner.

Now in the radio shack thread I am in a pickle on which scanner to upgrade to and I was reading the various owners manuals and see, one I was looking at you actually program in a tone # for each frequency.

So I had to comb the wiki and the forums to learn something I didnt realize.

Ok correct me if I am wrong but..... a new scanner that I can input a CTCSS or (I guess?) a PL #, this will isolate that listed frequencies user (in my area) and I wont hear everyone else for 100 miles around on that freq too?

Did I understand this one right?

like the chart tells me, my local sheriff is on 155.01000, and the tone is 110.9 PL.

SO with a nifty new scaner that I can punch in "110.9", I wont hear all those other people using THAT frequency???

I have to them assume a GOOD scanner can store multiple channels with 155.01000 and DIFFERENT pl/ctcss # and they will in effect act as totally different channels and I will for instance hear the sheriff on copy 1 (with his tone#) and someone else on copy2, with their unique tone #?

Forgive my stupid questions but I tend to learn things the hard way and backwards.
lol

Do I have this right?

if NOT....

Someone explain it to me please.

thanks!

oh I have a pro-2018 toy and I was looking to buy a pro433 or a 2055...... maybe.
those better ones can input ctcss #s....

which I have a half clue what they are.
sorta.

 

[nexus]

You understood correctly...

The sole purpose of the CTCSS tones (Mototola trademarked name "PL" for privateline) is to silence the receiver of a radio until a user with the same PL tone transmits.

You could have Podunk PD on 155.6400 and 40 miles away have Gooberville PD on 155.6400. During certain atmospheric conditions both departments would interfere with one another. There are 38 selectable CTCSS tones that a radio technician can program in. None of these require any sort of licensing. The frequency is licensed and really complicated to get changed. So instead of changing the frequency, each department selects their own unique tone from the 38 available tones.

So Podunk PD is on 155.6400 with PL 127.3 hz, and Gooberville PD on 155.6400 with PL 107.5 hz. Now neither agency will hear each other unless someone turns off their PL button on their radio.

Having PL tones enabled also eliminates annoying interference from other devices causing radio interference like computers, etc. They'll generate radio frequency interference but won't be able to open up a radio's receiver which has a PL tone enabled.

A lot of scanner owners started demanding (requesting) that the makers start providing a way to program PL tones so they too could block out unwanted interference or traffic from a different agency on the same frequency. And that basically sums up the usage of PL tones. IMHO its a minimal featrure (to me) I don't bother using the PL tones on any of my scanners or ham radios unless its absolutely necessary.

 

[gmclam]

Your new knowledge of CT/DC tones is accurate. Note that CT is the generic name, PL is Motorola's trademarked name. DC is the generic term for digital codes whereas DPL is Motorola's trademarked name.

Adding to the prior post; yes you can enter several agencies with the same frequency but different tones so that the ALPHA text displays correctly.

For example, I have:
154.4150 94.8 PLACER FIRE EAST
154.4150 123.0 BUTTE COUNTY FIRE
154.4150 131.8 NAPA COUNTY FIRE

In the case where one agency has no tone (or CSQ), then I just put them last. It is not foolproof, but usually works ok. Such as:
151.4750 100.0 ORANGEVALE PARKS
151.4750 151.4 DON PEDRO REC
151.4750 search CAL FIRE TAC 13

BTW, you don't have to put all the frequencies adjacent to each other. Since I usually program everything in frequency order they do get programmed in order. However, in the last case where there is an agency with no tone (CSQ), that situation really only works when the freqs are all programmed adjacent to each other with the CSQ last.

Good luck

 

[nyquiljunkie]

oh jeeze.
if I had known that yrs ago i woulda invested in a better scanner by now.

live and learn I guess!

this is great, now I will be able to isolate just the locals even better.

I love this place!

why didnt someone come tell me yrs before now you guys were here?

lol

Thanks!!

 

[SkipSanders]

Besides CTCSS tones, there are also DCS 'tones', standing for Digital Coded Squelch. Same deal, but using a digital signal at very low level, instead of a simple tone. More codes, though different.

A user will probably only use one or the other, though some may use both at once for certain things.

Also, CTCSS/DCS is often used to 'select' which of several repeaters on different high places you wish to repeat your transmissions, all using the same input and output frequencies. In that case, you probably don't want to use CTCSS yourself, since you'd only hear one site and not all of them, but there might come a time you wanted to specify. You could program the same channel several times with different CTCSS to 'see' which mountain is transmitting, for instance.

A devious user might transmit on a repeater input without the tones, to use the input as a 'secret' simplex channel, since few program in and listen to the input of a repeater.

 

[nyquiljunkie]

and if the chart says "CSQ " or its blank, then its just an open line?

Ok now I am stoked to go get a new scanner.

cool!!

 

[nexus]

Correct...

CSQ = Carrier Squelch
DCS = Digital Coded Squelch (Motorola trademarked name DLP "Digital PrivateLine")
CTCSS = Continuous Tone Coded Squelch System (Motorola trademarked name PL "privateline")

In CSQ, the only thing that is keeping the radio silent is turning down the squelch and a carrier signal will open the squelch.

 

[gmclam]

and if the chart says "CSQ " or its blank, then its just an open line?

In "chart", I think you mean what is posted here in the RR database. When it is blank, it usually means no one has reported a (specific) tone. Note that in some cases the tone freq will vary within the same agency.

Your term "open line" I guess has something to do with the scanner. That depends on the specific scanner model. The PRO-97, for example, will not display a tone freq when the channel is set to FM. The user must specify whether the tone is CT or DC for a tone to be decoded. If the tone freq is left blank, that is called search mode and any decoded tone will be displayed. To make the scanner only open the squelch with a tone, a specific frequency must be specified.

I understand some scanners do not have to be told whether to search for a CT or DC tone. That might affect what specific scanner you want (kinda depends on the agencies you plan to listen to as well).

 

[jparks29]

So Podunk PD is on 155.6400 with PL 127.3 hz, and Gooberville PD on 155.6400 with PL 107.5 hz. Now neither agency will hear each other unless someone turns off their PL button on their radio

But Gooberville uses a tone of 156.7 ....

 

[nexus]

jparks, that's Gooberville, SC. I was talking about Gooberville, KY

 

[DiGiTaLD]

A devious user might transmit on a repeater input without the tones, to use the input as a 'secret' simplex channel, since few program in and listen to the input of a repeater.

A department I used to work for had just such a setup on VHF high band for their "TAC" channel. "TAC" was the repeater input frequency with no CTCSS tone. That way, users of "TAC" could talk unit-to-unit simplex and not go through the repeater, but would, in most cases, still hear other units talking in to the repeater, so that way they'd know if they were being called. It was an interesting use of spectrum resources, but it could prove problematic is if users were talking on the "TAC" channel, and another user was trying to talk through the repeater, not knowing the "TAC" users were there, and getting their signal interfered with.

 

[nyquiljunkie]

>Your term "open line" I guess has something to do with the scanner.

oh thaats my noobie speak for "no pl#"
lol

sorry bout that.

good info.... now I know more than the dude at the radio shack store did.

I want his job.

LOL

 

[loumaag]

A devious user might transmit on a repeater input without the tones, to use the input as a 'secret' simplex channel, since few program in and listen to the input of a repeater.

And

A department I used to work for had just such a setup on VHF high band for their "TAC" channel. "TAC" was the repeater input frequency with no CTCSS tone. That way, users of "TAC" could talk unit-to-unit simplex and not go through the repeater, but would, in most cases, still hear other units talking in to the repeater, so that way they'd know if they were being called. It was an interesting use of spectrum resources, but it could prove problematic is if users were talking on the "TAC" channel, and another user was trying to talk through the repeater, not knowing the "TAC" users were there, and getting their signal interfered with.

A very dangerous practice. Any radio shop that sets this up needs to rethink their career choices. I addressed this a couple of times in the past, using the input of the repeater for anything other than the repeater input puts officer's lives at jeopardy.

I think I last explained this here:
http://www.radioreference.com/forums/showthread.php?p=331168

 

[nexus]

>Your term "open line" I guess has something to do with the scanner.

oh thaats my noobie speak for "no pl#"
lol

sorry bout that.

good info.... now I know more than the dude at the radio shack store did.

I want his job.

LOL

LOL!!!!
nyquil, you're gonna fit in here just nicely. And I'm pretty sure you're correct about now knowing more than the dude at radio shack... Thanks for the chuckle.

 

[bassmkenk2508]

... PD on 155.6400

Loving the old Biloxi PD freq you picked there, Nexus!! Ah, the fun days

 

[nexus]

Yeah, instead of just pulling something outta my a$$ I picked the old Biloxi PD freq. And you're right.... ahhh the fun days. It still irks me that we're on EDACS provoice. I miss scanning the pd.

 

[Don_Burke]

Many of the scanners with tone capability can search for the tone for you. The tone search speeds vary widely.

My BC-796D is so slow at this that it is painful to watch.

The Pro-97s are really fast. They can search for either CTCSS or DCS, but not both at once. My answer is to use two 97s, one searching CTCSS and one searching DCS.

Once I have found the tone I can either program a channel with it or just leave that channel in tone search and identify the transmitter from the displayed tone.

 

[kb2vxa]

Lou made a good point, a signal on a repeater input having an incorrect PL or DCS code or none, stronger than one with the correct one will block it out of the receiver and nobody will hear the stronger one or recognize the interference. The receiver simply remains squelched, the call is missed. That will happen to a scanner too so if you program memory slots having the same carrier frequency and different tone or digital codes you'll experience erratic operation. It can be useful but you'll have to get used to the strange behavior and missed calls. A simpler and less frustrating way to do it is program one memory slot with the carrier frequency and no code. Use carrier squelch only and hear everything, your ears know who you're listening to.

"Any radio shop that sets this up needs to rethink their career choices."

Like... presidential advisers?

 

[nyquiljunkie]

>>A simpler and less frustrating way to do it is program one memory slot with the carrier frequency and no code. <<

Thats just what I ended up doing.

several banks with the same lists, one set to the sspacific PL#s and one set to search for them, and one just set to FM not CT/DL

I take turns carefully watching each bank and what channels are coming in, or I turn on all 3 banks when the air is busy, and see (often) the same freq in each bank is actually totally different conversations.
using that I'm figuring out who to ignore or block out.
I'm not real interested in a slip and fall 70 miles away but in my own twp and adjoining ones, yes.

No one told me there was more to this than tap in a number and bada bingo you have one line....

lol

 

[kb2vxa]

Then leave well enough alone and use those other banks/slots for something else. To borrow a slogan from the 82nd Airborne, listen to them all and let your brain sort them out.

BTW the phrase is "budda bing", some New Yawkah you are! (;->)