Tones?

[ILbandit]

I am a newby to this, so this might be a dumb question.

When there are PL tones listed with freqs., Do I have to do anything special to hear the freq.?

I have a BCT8, if I just save the freq. to my private list will that do the job?
Or is there something else I need to do?

 

[safetyobc]

not entering the pl tone does not affect you being able to hear the freq.

 

[ILbandit]

Thanks for the quick response!
That I what I thought, but I wanted to make sure.
Are the tones used to seperate the transmissions to certian recievers or something like that?

 

[safetyobc]

i'm not certain on the tones but I think that if tones are used on a freq, different agencies can use the same freq but have different tones. That way they don't interfere with each other. I think this is how it works, but I could be wrong. Maybe someone with more knowledge will know

 

[INDY72]

Very good for a basic explanation.

CTCSS/CDCSS tones are used on pro equipment to eliminate users from hearing interference from other users on the same freq. Creative usage of tones on a scanner designed for them can allow you to put many users of one freq in and not have to hear them "walk on" each other. Usage of tones on a scanner also will let you confirm who uses what freqs, and also if different tones are usedfor say "talk around". Also on statewide conventional analog systems, usually each repeater on the system uses a different tone. With a tone capable scanner you can selectively program what repeaters you want to hear. Same with different agencies on different tones.... HH Scanners with tones can be psuedo set up like a HT when it comes to recieving selectively.

Radio Shack HH's with tone functions: PRO-92 series, PRO-96, PRO-99, and the upcomming PRO-97.
Mobiles: PRO-2067, PRO-2096, upcomming PRO-2051.

 

[ILbandit]

Thanks for the info,

I think I got it now. It's basicaly a way for several different groups to use the same freq., only their radios are set up to only recieve the transmissions preceded by their individual tone.

So by just putting in the freq. only. I will hear ALL transmissions, but without a scanner that can do PL Codes (like my BCT8 ) Sometimes I might hear several people walking on top of each other?

Forgive me if I sound like an idiot, I'm starting to really get hooked on scanning, so I'm trying to learn as much as possible right from the start.
God help me when I start trying to play with the trunk programming!

 

[INDY72]

LOL welcome to the hobby!


Yes if you enter a freq and you have a scanner with no tone system.. you will hear everyone that uses it, and during skip/ducting.. you can get a lot of "walking over" which will cause a PITA till you learn who uses the freqs in a certian range of you.

And there are a lot of us willing ready and able to assist when you jump into the "Trunkin'" universe!

By the way, once your bitten by the scanning bug.... your infected for life!

 

[ILbandit]

I am definately already "bitten" by it!! :lol:

I am recovering from back surgery for the next month,So I have alot of spare time on my hands. So I am going to start on the trunk stuff soon, and try to get it figured out before I go back to work.

This is a great forum, I am glad I found it.

And I will definately take you up on the "trunking universe" help. I'm sure I will need it!

I'm already realizing that I'm missing out on alot of stuff by not having some local trunk freqs. programmed into the BCT8.

I also realize that this is going to be just as expensive than my CB/DXing hobbie that I already have. Always looking for bigger and better!!

 

[INDY72]

It will cost more than CB'ing will ever be.

If your in an area using digital.. your cheapest scanner will cost $500.00.

Most expensive CB is $150.00

Antenna gear minus towers for iether ar under $100.00

Scanner preamps are under $100.00 which is a good thing for rural areas.. or if your running a longer than 50 ft cable run.

 

[nmfire10]

PL does NOT allow more than one user to transmit at a time. It only makes it so group A doesn't have to listen to group B on the same frequency. You can not have multiple transmitters going at the same time.

 

[INDY72]

Umm dude-
You can have users on one repeater talking at the same time as users on another repeater.
Both same freq.
Different tones.

The usage of tones allows you to not hear interference from the other users....

Example:

MS Department of Forestry & Agriculture-
SW District repeaters use 151.4150 MHz
Unit Copiah 6, talks to district HQ in Brookhaven on the Copiah Repeater using tone of 203.5 PL.... At the exact same time Franklin 3 is talking to Jefferson 5 on the Jefferson Repeater using tone of 173.8 PL... they do not interfere with one another and are on the same freq at the same time...

If multiple radios could not talk at the same time.... then the entire Laws of Physics need rewritten.

 

[nmfire10]

Oh here we go again.

Why don't you state how far awy from eachother these repeaters are. Of course genious, if you put enough disatance between the transmitters and receivers, you can both talk at the same time. But it needs to be a lot of distance and at that point, it no longer has anything to do with the PL. It is simply a significantly closer and/or stronger signal capturing over the significantly weaker signal. This would happen without PL.

CTCSS is NOT a filter. It is a mute switch. Once the RF leaves your transmitter, it will mix with whatever else on the same frequency within range. The receiver will hear that mix. The result of having the two PL's from two transmitters just means that both group's radios will unmute for the useless garbage. It does not take two seperate and simultaneously received signals and fitler out the unwanted one. Period.

 

[INDY72]

30 miles tops

More like 25 to 30

 

[nmfire10]

Well Gee. That's a LONG way. As I suspected, that has nothing to do with PL whatsoever. That is two geographicly isolated repeaters. If you put yourself in location where they both were received very strong and they both keyed up simultaneously, all you'll get is garbage. You will not filter out one from the other with PL. It is not going to happen.

 

[INDY72]

The coverage zone of all the repeaters overlap.... each has a seperate input PL, and seperate output PL

And to really make you go gaga...

Lincoln County EOC has two repeaters on same freqs for input and output.

One is north, the other south.... and they are less than 25 miles apart...

Each repeater has a seperate PL for input, and for output.. I have monitored BOTH on at the SAME TIME... nada interference!

The only time there have been issues have been when you have multiple agencies on multiple incidents and they get crowded.. thats when the chiefs will have one or more go to the Statewide Tac nets.

 

[n4voxgill]

CTCSS tones are really misunderstood. When a receiver is programed with a "tone" it will not open or in effect hear until the subaudible tone is heard. Once the correct tone is detected, the receiver opens and hears everything on the frequency. If more than one station is transmitting then all of the transmissions are received, even ones with a different "tone". what keeps interference is called capture effect. In FM the strong signal will be captured and you will not hear the others. Hopefully the strong signal is the one close to you, but with ducting that is not always possible. If the signals are almost equal then you will get a mix of the two and garble.

30 miles with equal power will normally result in capture. There is no way to have multiple transmitters on the same frequency, but with different "tones" in the same area. If there was , the shortage of frequencies would not be common in most areas. I would love to hear 30 100 watt transmitters in the same town but with different CTCSS tones, well actually I wouldn't hear as all would be unintelligble.

gill

 

[nmfire10]

THANK YOU!

 

[loumaag]

Lincoln County EOC has two repeaters on same freqs for input and output.

One is north, the other south.... and they are less than 25 miles apart...

Each repeater has a seperate PL for input, and for output.. I have monitored BOTH on at the SAME TIME... nada interference!

Not from the same location using a similar or same antenna you didn't. The only way this will work is if each is using a directional antenna and pointed in the correct direction.

Another thing which I have not seen brought up, but should be mentioned. In reference to your overlapping repeater footprints you were mentioning earlier; they will interfer with each other in the overlap area, both on input and output. The outpu is self-explanatory, but the input works this way. A unit from Agency A using tone A and Repeater A starts talking and only Repeter A is up and that individual is heard. But if a Unit from Agency B, using Tone B, and aiming for Repeater B, is closer to Repeater A, then he will interfer with the first user on the input and his transmission will likely go out on Repeater A, becasue the squelch is already open and most controllers, once the squelch is open operate COR as opposed to CTCSS. He will also be transmitting on Repeater B.

 

[INDY72]

2 92 B's on seperate ants... one with North Tower set up.. the other on South Tower

Units on North Tower were talking to Dispatch en route to a grassfire...
Units on South Tower were talking to each other working car wreck...

Same time.

When A second wreck happened in another FPD.. the ones working the grassfire went to the State Tacs to let the repeater be free for the wreck response.

But the whole point of this thread was about scanners againnnnn

And I stated factually that on a scanner.. certian things can be done tonewise.. and without a tone ability.. you hear everything on that freq, no matter if you do or not.

 

[nmfire10]

That's not what you were saying at all. Your getting into the habit of that aren't you? Your better off admitting you're wrong rather than pretending you didn't say something and acting like we are somehow changing the subject. Not sure where you get the idea this topic swayed away from scanning in any way.

You are saying that a PL can filter out two users that are both coming in at the same time. That is not humanly possible with PL and a scanner, period. No two ways about it. As has been said over and over, you are describing capture which has nothing to do with PL. It will happen with or without PL. If you are experiencing capture and think it is because of your PL, turn off the PL decoder and watch as nothing changes. ALL CTCSS DOES IS CAUSE THE SPEAKER TO UNMUTE OR REMAIN MUTED.