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public saftey repeater pl tones

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klown

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I recently was given a vx-800 uhf transceiver. Iam able to program all my work freq's and through process of elimination I have found the encode/decode pl tones for each individual freq. But, I do have a couple of questions.

-When in field test mode I try to find PL tones by selecting each one and listen for it to break squelch. The tones are listed in code (0-54) I have know idea which number corresponds to which tone until I run through and find the tone. Then go home and find the tone I have entered using dos software ARGGH! Can someone provide a link to a table which shows which numbers relate to each individual tone?

- Also I am tring the same process of elimination to find out the local emergency operations frequency. I have been through all 54 including 0 which brings a total of 55. And still have not found the tone that opens the repeater. I know that they must use different tones because sherrif's dept. and city police cannot hear one another unless the dispatcher relays their transmission. UNDETRSTAND THAT I AM NOT TRING TO TRANSMIT ON THOSE FREQUENCIES. I just would like the ability to discriminate between the endless city police chatter and the more interesting sherrif office frequency. And would also like to have it as a backup for emergecy calls, since I despise cell phones. I asked another ham and he told me that they may use a pl tone not covered under the pl tone list. How often is DCS used? I have not tried to eliminate those tones. Is it possible that they are using this instead of ctcss.

-Third and final question, is there any software out there I can used with my scanner and sound card to decode ctcss tones. I have tried several with no avail. i've even tried using a dos based software ARRGH agian and it came up some error pertaining to the software.

Any help would be appreciated, and if there is another vx-800 user out there, contact me and we can compare notes. I have learned a few tricks with these awsome little radios.


Thanks in advance for any help given.
 

nexus

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Crayon beat me too it. This information is SOOOOO readily available if one just simply types in CTCSS or PL tones in google. Remember google is your friend, it'll find almost anything.

It sounds like they are using DCS if you've gone through all of the PL codes and nothing opens the receiver. There are several agencies who use DCS because PL is so heavily used that they never have enough codes. Your radio does support DCS. Have you tried scanning DCS for them?
 

klown

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No, I haven't tried dcs. Is there any truth that a public saftey repeater may use pl tones not listed in the rr database (private)?
 

Grog

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They can use whichever tones that will not interfere with anyone else (the main reason to use them anyway). The datebase here is only composed of what users have summitted.

Some systems can use multiple input tones, and they can also use split tones (179.9 input PL, and a 156.7 output).
 

2112

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Grog said:
They can use whichever tones that will not interfere with anyone else (the main reason to use them anyway). The datebase here is only composed of what users have summitted.

Some systems can use multiple input tones, and they can also use split tones (179.9 input PL, and a 156.7 output).
And, they don't even have to use "standard" tones... how about 108.5 Hz?
 

crayon

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klown said:
Is there any truth that a public saftey repeater may use pl tones not listed in the rr database (private)?
Some of the information in the RRBD is after-the-fact.

Scannerists everywhere discover what is being used and then submit that information so that others will not need to work so hard to find it. That is part of the fun of scanning ..

:)
 

ReceiverBeaver

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Knowing a repeaters PL tone is not necessary for LISTENING. Only for transmitting. So I'm not sure what the fuss is about.

If you want to the listen to the sheriff's dispatch, then just put in their frequency and you've got it. No pl tone is necessary.

Public saftey repeater offsets also differ greatly. The ham UHF standard is a 5mhz offset while ham 2 meter (VHF) is 600khz. But with public saftey you'll see all sorts of variations and there is not standard. You just have to find out what is used department to department. This info is usually available in the FCC database.
 

n4voxgill

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As a general rule, public safety repeaters are not required to use any form of PL. Occasionally the FCC will require that a ctcss other than one that is named when they know the systems will likely interfere with each other. Public safety licensees may use any any PL or DPL, this is why ctcss information is not in the FCC files and is not on the license.
 

klown

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I am pretty sure that our public saftey repeater uses different pl tones for tx and rx. I was listening in tonight and heard a deputy ask the dispatcher to relay directions to the ems service. As I said before I do not intend to transmit on these frequencies i would just like to discriminate agianst different agencies. I care nothing about the ems chatter or the local police only the sherriff's transmissions. I also tried the software suggested by ve3snv and as the web site suggest this program is very much alpha with a lot of bugs. Most of the time when a transmission comes over the scanner it doesn't display anything. When it does display the tones jump around so much you can't level it down to just one. I put the tone in that looked more constant than the others but, still had no luck. Also the offset between rx and tx is 5mhz. The rx is 453.3625 and tx is 458.3625, I monitored both freq's and the tx was very faint and noisy. Can someone else suggest some better software or give advice on how to run wintone on xp. Thanks for the help guys.
 

ReceiverBeaver

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Hey Klown,

To discriminate amongst services, all you need is to learn thier unit numbers.

In a Single Frequency County-Wide Dispatch System, say in a county with a county-wide Sheriff's office, 4 cities and the EMS

They do something like this:

Sheriff's is the 100 units

city 1 is the 200's, city 2 is the 300's, city 3 is the 400's and so forth.

So if dispatch calls out to 403, it is the designated #3 officer on duty in city number 3

If this information helps you and appears to be the way your locale works, then you should be able to find someone in your area to help you determine which department uses which set of call numbers. You can post to the State Forum where you live, or you could stop and ask one of your local police officers or firefighters sometime. This is not secret information and they probably will not at all mind telling you.

Also, you can probably determine who is who just by listening.

Hope this helps
 

16b

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ReceiverBeaver said:
Hey Klown,

To discriminate amongst services, all you need is to learn thier unit numbers.

(snip)
I don't think that he has a problem telling who is who. His problem is having to listen to stuff that he doesn't want to. I'm not sure about you, but I can completely identify with that.

Klown,

Unfortunately, I don't think that there is any easy way to decode DCS with a computer. If you send me a digital recording of a (short) piece of the audio, I can probably tell you whether they are using DCS or CTCSS. If they are using CTCSS I might be able to figure out what tone they are using. Just send me a Private Message and I can give you my email address.
 

klown

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Kentucky, Auburn
Both receiverbeaver and 16b are correct. 700's are sheriff, 800's are city police, 400's are fire and so forth. But, 16b hit the nail on the head. That's exactly what I want to do.
 
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