Can someone explain digital to me?

[StoliRaz]

This may sound stupid, but I haven't used my scanner on a regular basis in quite a while up until now. I listened to it a lot through the 90's and until maybe 2003. I'm getting back into it now. Now that I'm back into it, I was greeted with trunking, making it more difficult to listen (at least I think so). Now, I learn about digital. I stumbled across an article from 2005 from Gene Hughes, the guy who wrote the "Police Call" books for Radio Shack which I loved, and he stated one reason he was giving up writing them because of digital scanning. It was making it impossible to listen like in the past because a lot of the information was now encrypted. I guess my questions are-

1- I get trunking, but why digital? How is it different than analog (in layman's terms, please)

2- Is digital really going to kill scanning? (say it ain't so!) I see Radio Shack has some pricey scanners with Digital in the title. Are these the answer? (btw when I say kill scanning I'm talking years from now, assuming that most cities and places will eventually shift to digital. Sign of the times I guess)I live in a large metro area, and love listing to police, fire, utilities and the like. It'll really be a downer if this is true.

 

[gmclam]

Analog vs digital

1- I get trunking, but why digital? How is it different than analog (in layman's terms, please)

You understand that trunking is where there are a "pool" of frequencies being shared by many users or groups of users. In the old days when 10 groups (think 10 police channels) each wanted their own channel it required 10 frequencies (more if repeaters are involved, etc). Now you can basically multiplex those channels (called talkgroups) onto fewer frequencies. It just takes a computer to keep things co-ordinated, which constantly transmits on a "control channel".

Analog vs digital - there are a lot of technologies I can use to compare. Think audio cassette vs CD. Think old cell phones vs new cells. Think the new TV system (ATSC) vs the old analog NTSC. In other words; audio is digitized and sent as "data". There are lots of pros and cons to this. For example; even when the sound quality is poor, we can often make out a poor analog signal. But when digital is poor, if bad enough it becomes total garbage.

2- Is digital really going to kill scanning? (say it ain't so!)

Digital itself, NO. But now that audio is just digital data it can easily be encrypted. If all communications are encrypted, that would essentially kill this hobby for many people. But there is an awful lot out there to hear. I do not expect everything to go to digital and be encrypted in my lifetime.

I see Radio Shack has some pricey scanners with Digital in the title. Are these the answer?

LOL. All of the scanners listed below in my tagline are "digital" because they use computers to scan. But they can only receive analog audio. Be aware of what they are really saying. But the PRO-96 (and it's base equivalent) can receive digital communications, at least most of it. It can not receive digital cell phones or encrypted public service communications for example.

 

[bradjg25]

hypothetical question

Heres a hypothetical question! Say that most departments do switch to APCO 25 and decide that they want to go with encrypted signals as well. I know that the rules state that you are not supposed to be listening to those signals, but heres the hypothetical:

Disregarding whether such equipment is even possible to make or not, Say for instance that a scanner was made that if you knew the key used for encryption you could plug it in and listen. Would that signal then be legal to listen to? I am curious because if such a scanner could be created, then even with APCO 25 with encryption the hobby would still be alive.

I know getting the keys would be difficult, but there are people who work in public safety that are also scanner enthusiasts, who would have access to the information. Maybe there would have to be another column here on radioreference for these keys?

With such a scanner would the signal be legal to listen to?

 

[UPMan]

Unless you were specifically authorized by the agency to listen to such signals, listening would be illegal.

 

[hoser147]

"I know getting the keys would be difficult, but there are people who work in public safety that are also scanner enthusiasts, who would have access to the information. Maybe there would have to be another column here on radioreference for these keys?"

That will never be an issue on Radio Reference. Why would Lindsay get involved in any kind of Criminal activity? If someone were to post something that had a key, the Mods would pull it immediately. This is already covered in the rules of the forum. Good Scannin Hoser

 

[REDave]

Don't get your hopes up to much guys. The Keys are held by the System Administrator or someone with a security clearance of some sort, a snowball in hell stands better chance of getting out, than a Key released to the public. Also if a Key were to be compromised they would just issue a new Key rendering the old one useless.

 

[Raccon]

I know getting the keys would be difficult, but there are people who work in public safety that are also scanner enthusiasts, who would have access to the information.

But maybe they like to keep their jobs and hence won't give them out.

 

[snikliw87]

I heard somewhere it might be too expensive to do something like that.

 

[n2mdk]

But maybe they like to keep their jobs and hence won't give them out.

Plus I'm sure prison time is a deterrent as well.

 

[bradjg25]

Oops, my bad!

Hey Guys,

My bad. I guess I never realized getting the keys and giving them out were something that was illegal. My original thinking was they were like finding frequencies, some aren't given out, but if you found them you could use them.

 

[AZScanner]

The theory is sound. Forgetting the legal aspects of it, technically it could be done if the scanner supports it (and despite official claims to the contrary I think the Unidens do - and no I won't elaborate further). But if you somehow miraculously did it you'd best keep it to yourself. As others have said, unless you get permission from the agency you're monitoring, it's illegal as hell.

-AZ

 

[bownasterm]

encryption would suck for companies such as IPN and INA.....and of course the media. I would imagine the media would make a big stink about it though.

 

[mcooke]

Just to play devil's advocate I'll ask the question... what law makes it illegal to decode an encrypted transmission?

 

[UPMan]

The Electronic Communications Privacy Act (as amended), for one makes it illegal to receive most communications that are not readily accessible by the general public. One of the definitions of "not readily accessible" is signals that are scrambled or encrypted.

 

[mcooke]

Thanks UPMan... I was contemplating the definition of "encrypted" and was thinking that a person could make the argument that we are already decoding encrypted communications by using scanners that can receive digital signals. Carrying that logic forward couldn't an enterprising person build a scanner that decodes the encryption and make the argument that it's no different than decoding the digital signal?

 

[NorthCOVideo]

Be glad you don't live in Colorado, here about 90% of the state is digital and becoming somewhat of a monoarchy.

 

[UPMan]

There is a distinction between encoding (i.e. making it digital) and encrypting. Decoding P25 is not the same as decrypting P25 DES.

 

[wlmr]

There is a distinction between encoding (i.e. making it digital) and encrypting. Decoding P25 is not the same as decrypting P25 DES.

Just to elaborate on UPMan's excellent statement, the P25 signal structure can be read about in open documents by just finding the right web sites.

Encryption techniques can be read about but need the additional step of determining the correct "key" to decode the info, and another step of creating the means of using the key to decode the data.

(And then the people in charge of the key will change it.)

 

[standers420]

in terms of legality, one must be caught in order to be punished. monitoring radio waves is a one- way street, similar to pirating satellite tv. compare this to closed- system communications like cable tv. unless you do something stupid like publicize the fact that you are engaging in illegal activities, the chances of actually getting caught are slim.

encryption is not perfect. it is based on mathematical algorithms and therefore can be "cracked." moore's law guarantees an exponential increase in computing power over time, so the encryption game could be quite cat-and-mouse.

the ethics of the dilemma: the public has a right to monitor law enforcement and public safety directly, instead of relying on the media or the PD pub rel spokesperson to filter it for us. sure some morons might attempt to race to a crime scene to apprehend a criminal, but do you really think someone that dumb could figure out "trunking" in the first place? the benefits to society of open public safety communication far outweigh the potential pitfalls, regardless of analog/digital or encrypted/open.

 

[gldavis]

the ethics of the dilemma: the public has a right to monitor law enforcement and public safety directly, instead of relying on the media or the PD pub rel spokesperson to filter it for us..

Which brings up a question that I have been wondering for awhile now. Where is this "right" spelled out. I'm know it isn't in the Constitution, nor the Bill of Rights. So where, and when, was this "right" given to us. Since Sept 11th, I've seen many changes in the listening arena, and the "Rights" of the Government are ALWAYS held above that the citizen. Do we really have a "right" to listen? Or is it mearly a"privilege"?