'Splain to me the concept of "trunked" scanner frequencies???

[<SantinoCorleone>]

Here in my new market, one law enforcement agency uses a "trunked" system--the rest use regular frequencies.

To hear the trunked channels, do I have to press the TRUNK button on my hand-held scanner? If I do, does this then not allow me to hear the non-trunked channels?

Thanks for the info--as you can tell, I'm a "newbie" who's coming from a very simplistic market scanner-wise.

 

[ewink]

Whether or not you have to press the trunked button on your scanner and whether or not you can hear non trunked frequencies depend on your scanner.

On my scanner I have one bank that is trunked but I can still listen to non trunked frequencies. Yet my last scanner I could only listen to either or. I assume if it's a newer model you should be able to listen to both. You should check the manual or the scanners website for more information about that.

As for trunking, here is a basic simple explanation. Trunking uses a base number of frequencies (we'll use my local PD as an example for this case) like eight. Of those eight one is the control channel. The control channel transmits data from the base station to the mobile units.

When the dispatcher keys his mic, the control channel assigns his traffic one of the available seven frequencies. It then tells all the units on the same talk group (ie PD Channel 1) to listen to the frequency it assigned the dispatcher.

The same is when a mobile keys his mic. The control channel tells the dispatch station to listen to the frequency it assigned the mobile unit.

So of those seven available frequencies, one conversation can jump around on four different frequencies.

Trunking is good for cities and other government bodies for multiple reasons. First, it saves money. Instead of having to lease three frequencies for police, four for fire, two for ems, two for public works, and one for every other government agency they only need to lease eight or so.

Using my city as an example, before trunking they had about 30 different frequencies. Trunking allows all the agencies to share those eight frequencies.

It also cuts down on equipment costs. In Milwaukee County most municipalities and the Sheriff's office use the trunking system. Instead of having to buy and program radios for each department they all can use the same type of radio. For cities that work with each other (like small suburbs that back each other up) it's cost effective because they don't need to equip their officers with one radio with each cities frequency in it. One cities officer can simply switch to another cities talk group if he needs to communicate with their officers or dispatcher. Trunked radios are easy to program as well, so equipment can be shared.

And though this isn't an issue now, trunking radios when they first came out were a bit more secure since most people didn't have trunking scanners. That made it hard for a person to follow a single conversation.

If you have any more question about this, let me know. I am sure I can direct you to a website with more technical explanations.

[ December 19, 2004, 07:40 AM: Message edited by: ewink ]

 

[Terry E. Toller]

that was an excellent way of putting it. When you scan with a trunk tracker, you are not scanning frequencies, you are scanning the 'user ID".

Back in 1985 I learned that another stringer in Sacramento was listening to my RCC mobile phone that was on UHF. I went to motorola and they sold me on a trunked radio system that also had a phone connection, no operator. It worked on 800 mhz and at that time there was only one 800 scanner on the market. It cost about $1500! Sure enough, he went out and bought one. BUT, our conversations jumpped around and he never really could listen in...

 

[RichVid]

What a weirdo....why was he trying to listen in? Was he skimming stories off your conversations or was/is he a perve'? - As far as the first trunking question and whether or not if you scan trunked freqs will you not be able to listen to the non-trunked ones, it all depends on which scanner you're using...there are several out that will allow both and several that will allow only trunking or conventional banks at one time...

Rich

Rich

 

[Just Wondering]

The ONLY reason for "trunked" Freqs is to keep people from listening.

Media can buy recievers but all the channels (useres) jump around. It won't be long before all the different agencies have them (trunked freqs.)

 

[Terry E. Toller]

they guy was my competition and actually a friend. He was OK but rather unsure of himself. He was actually the best competition I have ever had. He just wanted to keep track of what I was doing.

Before we went trunked, I called my audio tech at home from my car. I told her that I got a secret tip that part of the courthouse in Woodland had caved in and there were several people trapped.

Sure enough, about ten minutes later we got a call from a TV station asking us about the 'call'. I just told everyone to think about it, if it did happen, there would be lots of scanner traffic. the other stringer sort of let the cat out of the bag and hurt his credibility at the same time...

 

[ewink]

Chuck,

Trunked scanners are widely available on the market for the general population. If the police didn't want people listening they would switch to digital encryption, which is illegal to listen to.

Maybe that's what you're thinking of because media wouldn't need to buy a special receiver for that.

Trunking really is simply a cost saving measure, not a security measure.

 

[stargazer]

Digital encription is not illegal to listen too, as long as it is a public safety radio system. There are several new scanners on the market that will decode the encription.
Cell phone conversations, mostly digital now, are covered under the privacy laws, but if a government agency uses a digital encripted radio system they are suseptable to being scanned. And, a side note, if that agency uses their system to make "private calls" from their radios, that is also legal to listen to.
The illegal act is to use the information gained by listening to the scanner for commercial gain. In other words, you can't report the information you may get from the scanner as fact. Journalism ethics also dictate that you not report information gained directly from the police radios, without confirming the information first.
Also, several videographers record scanner audio for use in thier stories. According to the law, this is illegal. If you are standing next to a cop and record his radio audio with your mic, this is legal to use; but using your scanner to record the same audio is illegal because you are intercepting their signal and using it for commercial gain.
Our staff has discussed this issue on several occasions, and actually had a stringer detained by a federal agent on one scene. The charges against the stringer were dropped after the officer read the specific law. We had our lawyers research the issue and the above information is what they came up with.

 

[ewink]

No...

The law (The Electronic Communications Privacy Act of 1986 and the Communications Act of 1934 as amended) says it's legal to intercept traffic "readily accessible to the general public", and as defined it states that to be "readily accessible to the general public" means that the traffic cannot be scrambled or encrypted.

Digital is NOT illegal. Encrypted digital is.

There is a HUGE difference. If you have a scanner that can pick it up, it's not encrypted. All scanners made for sale in the US have to be made so that they cannot be easily modified to recieve such transmissions.

Cell phones have been grouped into the 'common carrier' part of the CA and the ECPA.

your lawyers are obviously talking about simple digital ENCODING. If they are actually telling you it's legal to listen to encrypted communications - well you all need new lawyers.