dewey

Anybody know anything about police scanners? Wouldn't it be cool if they sold one that fit in the 3rd generation's "expansion bay"?

UCSBgeek

yeah it'd be cool to have those or to be able to hear what truckers are saying... lol

JJB

Be sure that you bother to check your local laws about the use of scanners in your car. Some states have some pretty hefty rules about having a scanner in the car that can listen to police bands.

I was always under the impression that it was perfectly legal until we started to talk to a state trooper (NY) friend of mine. Apparently, in NY state the scanne can be confiscated on the and a fine will follow. It does not even have to be on!

If you want to hear what the trucks are saying a CB unit is a pretty inexpensive piece of gear.

shackmgr6073

"Trunking" is the feature Protege Menace is talking about. Trunking is a feature that is used in larger Urban areas. What happens is bands used by law enforcement do not have enough frequencies. When this happens they have to share them or "Trunk." You need a scanner that can follow that or you will only here 1/2 of most of the calls. And yes, it is illegal to have a scanner in your car in most states. As for one that fits in the expansion bay, I will check to see if we offer one that skinny. Otherwise you can go for a handheld (cheaper and easier to transport from house to car.) And if you guys can figure out if your area uses Motorola, Ericcson, or any other type of carrier, let me know and I will put together an info sheet with specs if you guys show some interest. Also, I can get them below cost. Depending on the numbers, I would also pay shipping. Let me know, I will check this thread if you guys are interested.

shackmgr6073

When you check your scanner look to see what ranges it covers. Trunking frequencies are locally assigned and are above the 800 MHz range. And different areas use different ranges. For example Motorola systems use a small slice of the 800MHz range. I don't remember the exact numbers but it doesn't amount to much. I should have made myself more clear. Trunking is defined by a scanner that is able to follow conversations that are automatically tuned by a computer. So what happens is when the "base" keys their microphone it is on one frequency. When they unkey that mic, the computer system they are using (Motorola, Ericcson, etc...) automatically skips to a different frequency. That's why on some scanners you can only hear one side of the transmission. When you use a trunking scanner they have the ability to follow the complete conversation. And yes, a lot of people think that they do that so you can't hear them. That is not true because there is technology (perfectly legal) that will let you listen to them. That is what trunking is for. When local law enforcement agencies update to new computer systems, a lot of the scanners in use in that area are not capable of scanning above the 800 MHz range.

Dave Cameron

I am not quite as versed as shackmgr6073, so thanks for your wisdom. I do know that the the big two way communications manufactures such as Motorola and and Ericson pitch trunked systems heavy at states and cities now rather than older and perhaps less expensive systems. This type of hardware simply cost more to do right, so there is more money to be made from thier sale.
They do provide some compelling savings and features if implamented right. For Example, Fire, Rescue, Ambulance, and Police, traffic control and public works can all communicate with each other in emergency or disaster instances. By getting rid of two or three seperate systems and standardizing on a single type of system for repair and maintenace there are manpower and cost savings for towns, cities and states. In some instances they can link cities, suburbs, and smaller towns that could never link up before. States like them for the same reason, more efficient use of air space, a single sysem, and the ability of multifunction between agencies and departments.
Here it is in limited use so for, but the city is purchasing a new Motorola sytsem for millions of dollars. Our area will be a true test of planning and deployment, there are over 20 localities surrounding and inside the city that they would like to link, but who it to pay for the hardware or agree on how it is to be used? Also some surburbs have already purchased similar systems, how will they be intergrated.
From a scanning point of view, it should be a interesting few years here locally. By the way, my town has it's own ords about scanning, don't get caught with it in the car, or it is confiscated and you are fined!

JFanaselle

Allow me to elaborate on this subject a little as well. Warning...novel approaching:

For starters, a trunked system is very complex. There is a single frequency dedicated strictly for the transmition of data - both for the radios themselves, and for the mobile data transmiters (or MDT's) in most police vehicles. The system is nice for the agency to use, however very complicated to be part of without the exact same system on your own radio. Every radio in a trunked system has an identifier assigned to it (the depuity or representive usually logs into the radio when they get in the vehicle). The dispatchers can tell exactly who is transmitting whenever a transmision is occuring. Everytime you key up, the system finds one of the few (usually 6 or 7) frequencies assigned to the network which is free for you to talk. As soon as that transmission has ended, another random frequency is selected for the other end of the conversation to speak and so on and so on. The system involves a box in the trunk of the vehicle to encode and decode all of the data so it knows which frequency to switch to every time (hence the term TRUNKED). Contrary to what Dave Cameron said, it is very difficult for multiple agencies to operate on a single trunked system. You are very lucky to have the agencies in your area co-operating with other. Every single agency would have to operate on the same frequencies with a common dispatching facility. Agencies are very hesitant to upgrade systems so that they can work with surrounding agencies. It is cheaper and more practical to designate special communications units and deploy them to incidents where multiple agencies are working together. I personally am part of the communications team for the Riverside County Fire Department here in Southern California. We have a special vehicle (a large motor-home) with 30 or so different radios at 2 seperate consoles just so that everyone can talk to each other. Most police agencies that have more than 50 or so patrol vehicles will invest in a trunked system, and this is STRICTLY to deter people from listening to them on a scanner.

However, all software and encoding can eventually be cracked and de-coded by people trying to hear it. The major trunking systems used today are Motorolla, Ericson, and GE. Both Uniden and Radio Shack have scanners available today that use the same technology as the police radio itself to decode the data and jump to the proper fruquency and follow the conversation. The scanner will jump from channel to channel, but you will hear it like you're listening to a straight conversation. As for the frequencies to use, There are several resources available both online and in print ("Police Call" to name just one) where you can find the frequencies. In most cases states themselves do not have laws against the use of scanners (alot of volunteer fire and rescue agencies depend on having them in their vehicles in order to get to calls as they happen), however alot of counties and cities can place ordinances agains the use of a scanner in a vehicle. To be absolutely certain if it's ok to do it in your area, get a copy of your state vehicle code, and of your local ordinances from the DMV and from your local City Hall.

JJB

Are you saying that the term "trunked" comes from the location of the equipment. If that is the case, then the assumption is wrong. Trunking has been in use long before it was applied to wireless systems.

JFanaselle

that is very true, but it wasn't referred to as a trunked system until it was made for vehicle applications. It was a slang term that hung around until it became a standard word.

JJB

We'll have to agree to disagree on this one.

The term trunking is really a telco term. It comes from the "trunk" long distance lines that ran from city to city. Whenever you place a long distance call, you get the first available trunk line. The next time you call the exact same number you may, or may not, get the same line. You will get the first available line for that call as well.

In the case of trunked radio systems, you get the first available RF channel (ie: repeater pair) for each radio call.

Dave Cameron

I have to toss back in on this one, I think earlier I was quoted for what I posted. I think I described the "ideal" situation for trunked systems. I would say I have seen at least two pointed failures of systems like this to deliver what they claimed to purchurses.
Here locally the system mercfully has hit the rocks prior to implamentation and is still on hold. Most of the 20 plus smaller municipalities here have refused to invest, which is hurting the dollar arrangements of the larger deal to the city. I will be surprised to see the system go any further at this point. As a technology attourney, I can tell you that now have a client in the matter....
There is often a great belief in our country that technology can be used to overcome problems. In this instance, crowded airwaves, and heavy traffic. At best a system like trunked is more complex, hence more to go wrong.
But you can scan it!!

fallintoshadow

Sounds like we have some city radio shop guys in here. I'm glad I came across this thread. I'm a 911 dispatcher and we are issued Police radios, ours happen to be Motorola. The explainations of the trunking system have all been pretty good. You guys know what your doing.

JFanaselle

I've been trying to get on as a dispatcher for our county Fire Dept. for some time now. I have a test scheduled in the next couple of months. I've been on the communications team for the past 2 years, and I know more about the department's system, policies and procedures than most of the dispatchers that are employed there now! wish me luck.

ZZOOOMM

I have one that will fit in that spot I will give you if you pay the shipping. It is one a trucker buddy gave me a few years ago. Let me know e mail me at zzooomm@msn.com