CTCSS/DCS search?

[dispatcher812]

When changing the audio type in my SDS 100 from all to analog, it selects CTCSS/DCS search as a default. will this slow down the scanning rate? I am hoping that by doing this i can eliminate those annoying birdies I get when i enter a city.

 

[trentbob]

When changing the audio type in my SDS 100 from all to analog, it selects CTCSS/DCS search as a default. will this slow down the scanning rate? I am hoping that by doing this i can eliminate those annoying birdies I get when i enter a city.

Doesn't slow you down when you're searching, you will however pick up any agency or radio interference within range The whole idea of the search is to pick up something you are interested in that's local and what you're looking for, notice the CTCSS or DCS and then permanently enter it, that will eliminate the inner city interference that you're getting.

Technically, they are not birdies, birdies are generated within the radio itself, not so much now, as opposed to the old days, by using the tone squelch you are going to eliminate that external noise you get from everything in the city. More referred to as front end overload LOL.

You will only pick up the agency you chose the right number for that will open the squelch. The radio interference won't open the squelch. When you're on search, you get it all. HTH.

 

[dispatcher812]

Doesn't slow you down when you're searching, you will however pick up any agency or radio interference within range The whole idea of the search is to pick up something you are interested in that's local and what you're looking for, notice the CTCSS or DCS and then permanently enter it, that will eliminate the inner city interference that you're getting.

Technically, they are not birdies, birdies are generated within the radio itself, not so much now, as opposed to the old days, by using the tone squelch you are going to eliminate that external noise you get from everything in the city. More referred to as front end overload LOL.

You will only pick up the agency you chose the right number for that will open the squelch. The radio interference won't open the squelch. When you're on search, you get it all. HTH.

Hmmm. Ok. I usually get the interference on certain Marine and Railroad channels when I enter, in my case Boston. I had always thought those birders were caused by digital interference from say security systems and the like. That is why I changed the audio type from ALL to analog to try to eliminate that interference. That's when is asked about a certain CTCSS or search. I f the search slowed things down i would have just left the audio to all.

 

[trentbob]

Hmmm. Ok. I usually get the interference on certain Marine and Railroad channels when I enter, in my case Boston. I had always thought those birders were caused by digital interference from say security systems and the like. That is why I changed the audio type from ALL to analog to try to eliminate that interference. That's when is asked about a certain CTCSS or search. I f the search slowed things down i would have just left the audio to all.

You are comparing apples to bowling balls. Let's clear up what a birdie is, that is interference, perhaps an open carrier on a specific frequency that is generated from within the radio itself by its own circuitry. You are referring to what might sound like a birdie but it's external interference from external sources, radio interference from various sources in a busy RF environment.

Marine frequencies and railroad frequencies that are not protected by a tone squelch assigned to it are vulnerable to that outside interference.

If a certain analog frequency, police, fire or otherwise is assigned a pl tone in the listings you attach it to the frequency when you program it. Maybe you have various agencies in your state who use that frequency but you won't hear them you will only hear the agency assigned that PL tone. They will be the only ones that open the squelch. The RF interference in the area won't open the squelch and things will be quiet unless the frequency is used. If you don't know what that PL tone is and you put it on search and all of the agencies that use that frequency with their own PL tone will be heard except each one will have its own PL tone visible to you. If you recognize the agency that you want to hear you would write down that PL tone on a piece of paper because you know that's the agency you want to hear and then you would program that PL tone to that frequency permanently and that is the only agency you will hear again on that channel assignment.

 

[dispatcher812]

Ok, so I have yet another question about CTCSS. I thought I understood how this works but now not sure. So before going into work I was listening to Amtrak. I saw that the dispatch road frequency was putting out a CTCSS of 103 5hz. The MBTA commuter rail uses that same frequency with a different CTCSS. However the trains themselves are not using any CTCSS. So how does the dispatcher here the trains if no CTCSS is coming from them? And vise versa? I did not think railroad radios would use a tone like this since the locomotives can be used anywhere by any railroad, on any railroad.

 

[trentbob]

Ok, so I have yet another question about CTCSS. I thought I understood how this works but now not sure. So before going into work I was listening to Amtrak. I saw that the dispatch road frequency was putting out a CTCSS of 103 5hz. The MBTA commuter rail uses that same frequency with a different CTCSS. However the trains themselves are not using any CTCSS. So how does the dispatcher here the trains if no CTCSS is coming from them? And vise versa? I did not think railroad radios would use a tone like this since the locomotives can be used anywhere by any railroad, on any railroad.

That's a very good question and you are from Connecticut. I am not familiar with Railroad frequency operations north of New York. I regularly listen from Philadelphia to Trenton.

When I'm listening to 160.92 Amtrak Road between Philadelphia and Grundy interlocking south of Trenton there is no PL tone, Trenton operations to New York is a road channel of 161.01, it changes over right near me and in this area there are no Pl tones.

So you are theoretically right, all the trains and train dispatchers and towers should be able to hear each other. Same with the marine frequencies in my area.

I'm just not familiar with North of New York or Connecticut but they're very well might be someone who understands exactly what's being done, there are various options. Some rail sections use repeaters. That may be what's going on in your area but as far as ctcss search it basically works the way we discussed.

Maybe there is somebody out there that is more familiar with the New York Connecticut area that can explain Amtrak Road channels and MBTA frequencies. I know our local commuter line SEPTA uses repeaters, sounds like they are too.

 

[pb_lonny]

Not related to your area but here, we have some users who use a CTCSS tone on the base but not the mobile units, it allows base to talk to the units but not the units to talk to each other directly.

If you have a frequency + the CTCSS programmed, you will only hear transmissions that match both, I have used this in the past when I have had my scanners lock up on specific frequencies. You just need to know the CTCSS tone to program it in.

 

[trentbob]

Okay I got curious and checked out the MTBA radio system and that they are on an EDACS trunked system. There is probably some kind of link with Amtrak Road frequencies. 

 

[trentbob]

By the way it seems that you do understand CTCSS search on the SDS 100 now.. try going to Connecticut state forum and see what you can find on MBTA radio system and there might be posts there that explain the interaction between the commuter system and Amtrak. Just Google your questions every which way.

 

[INDY72]

Railroad dispatch radios, as well as some non mainline operations use a tone, whereas the trains and most other operations use CSQ. Amtrak police have repeaters, and some PBX systems are on repeaters that use tones.

 

[trentbob]

Railroad dispatch radios, as well as some non mainline operations use a tone, whereas the trains and most other operations use CSQ. Amtrak police have repeaters, and some PBX systems are on repeaters that use tones.

Yes I monitor Amtrak police on the same National frequency but we have many different PL tones which is very convenient. I live near Philly but my PL tone is from the Trenton repeater and only have to listen to two cars that cover my part of the Northeast Corridor. They use Philly dispatch.