Can scanners be detected?

[chaz0426]

I heard radar detectors can be detected through radio by the police. Can police scanners be detected in the same way? I wouldn't think so since scanners aren't transmitting anything but I also thought radar detectors didn't transmit anything either.

 

[unixfreak0037]

Do you mean like this?

Active receiver detection and ranging - Patent 7676205

 

[chaz0426]

Yeah I guess, but are these technologies used by police.

Sometimes right when I start scanning, it seems like a lot of the police and other utilities ect. ask to be called on their cell phone ect.

It gives me the feeling that they know they are being listened in on somehow. Perhaps it's just me.

 

[ibagli]

The short answer is no. The long answer is no, with a long-winded explanation of how receivers can be detected but still with no practical police application.

Sometimes right when I start scanning, it seems like a lot of the police and other utilities ect. ask to be called on their cell phone ect.

So they could be asking beforehand, and you wouldn't know because you weren't scanning before that.

 

[reedeb]

Yeah I guess, but are these technologies used by police.

Sometimes right when I start scanning, it seems like a lot of the police and other utilities ect. ask to be called on their cell phone ect.

It gives me the feeling that they know they are being listened in on somehow. Perhaps it's just me.

I think i's just your timing. A lot of traffic is done by phone nowdays as a lot of it is confidental. Back before cell phones were around we would have to ask the officer to call us [if close to a phone or stop into the station to pass on info we didn't want broadcast over the air.

 

[chaz0426]

I think i's just your timing. A lot of traffic is done by phone nowdays as a lot of it is confidental. Back before cell phones were around we would have to ask the officer to call us [if close to a phone or stop into the station to pass on info we didn't want broadcast over the air.

Yeah that's what I was thought. I'm still new at this so I was just making sure.

 

[mdulrich]

In most places if they had to call everytime a scanner was detected they never would get anything done as they would be constantly on the phone.

Mike

 

[Gator596]

This ability goes way back....

Do you mean like this?

Active receiver detection and ranging - Patent 7676205

I'm no techie, so I don't know if it was done the same way, but British Mi5 could do the same thing as far back as late 1940's. They called it "Rafter". Peter Wright's book Spycatcher had details on it.

It was used to find receivers listening to clandestine transmissions from Russia. Today, no LE agency I know has the time or need to worry about finding someone's scanner...

 

[GTO_04]

Scanners have local oscillators in them, so they do have very low power transmitters in them, so theoretically they can be detected. As a practical matter, it is probably not real common.

GTO_04

 

[apd3190]

Paranoia.. Truth is..Who knows whats going to happen with the way things are going..Will we all become outlaws?? The police are not searching for Scanner listeners. Relax and enjoy

 

[HillWalker]

If you're within a couple of metres of the person transmitting then often they will get an echo on their radio, like when you hold two walkie talkies near each other. It's happened to me once when trying to get a security frequency using Close Call in a shopping centre and the guard enters the bathroom, transmits, gets a strange echo and he walked off. I had what I wanted and left as well.

I've never known anyone to have been caught by this though, in one story I heard, the police presumed that there must have been plainclothes officers operating nearby and left it at that! Not sure how believable it is though.

For important communications, mobile phones are used over here as well. Each patrol unit has one, paid for by the tax payer, as an interim measure while the roll out of encrypted TETRA hand sets continues. All you can hear on the few remaining areas using VHF are vehicle checks and the odd dispatch to a fight, car accident, road traffic offences, etc.

 

[kb2vxa]

To elaborate briefly on GTO's post, the technical answer is yes, the local oscillator(s) in a superheterodyne receiver radiate enough signal to be detected by highly sensitive receivers. A good example of this is how in the UK the Ofcom "snoop vans" detect unlicensed TV sets.

On the practical side again it's Ofcom, out of 24 vans in greater London only 2 are so equipped and at any given time one is in the shop for service. The rest are dummies intended to scare the public making the whole thing a joke. Weighing all things considered in the balance the answer to the question becomes a resounding no when the weight of "I really don't care" on the part of authority is overwhelming.

Then there have always been passive receivers but that's the subject of another discussion altogether.

"If you're within a couple of metres of the person transmitting then often they will get an echo on their radio, like when you hold two walkie talkies near each other."
While completely off topic an interesting point none the less. "Often" happens when the unit is transmitting through a repeater and the digital delay in the controller audio processing chain spits out what was said usually a quarter second behind real time.
"It's happened to me once when trying to get a security frequency using Close Call in a shopping centre and the guard enters the bathroom, transmits, gets a strange echo and he walked off."
In a case like that your Close Call falsed on you with an on site repeater when it should have locked on the unit transmitting and you would have heard the squeal of ordinary feedback.

Bathroom echo? Sounds familiar, RCA Victor did it the cheap and dirty way by placing a monitor speaker and microphone in the bathroom during the recording of Heartbreak Hotel by Elvis Presley. Betcha didn't know that now didja? (;->)
YouTube - Elvis - Heartbreak Hotel

 

[N_Jay]

Very good Warren, except (There is always an EXCEPT with a Warren explanation) with digital radios (and even with some analog radios that use digital signal processing) there is sufficient delay ion even a simplex path to break the typical analog feedback howl and provided varying degrees of "echo" like feedback.

 

[Gezelle007]

In most places if they had to call everytime a scanner was detected they never would get anything done as they would be constantly on the phone.

Mike

I agree, even if its the not average joe scanner listening, theres always news crews listening to the action. Most police vehicles come with scanners now as well so they can monitor other agencies.. and besides, most places dont mind scanners. now if your commiting a crime and listening, then thats another story..

So basically, they cant do everything without someone noticing..

 

[kb2vxa]

Oh N_Jay what would we ever do without you? You're such a talented fellow, I'll bet you get really busy in tick season. (;->)

 

[N_Jay]

Oh N_Jay what would we ever do without you?

My guess is you would increase the breadth and depth of your misinformation.

Correcting each other is the way for both of us to fine tune our knowledge. (unless you are one of those dreaded "know-it-alls")

 

[gmclam]

I wouldn't think so since scanners aren't transmitting anything but I also thought radar detectors didn't transmit anything either.

This is the basic flaw in your thinking. Both RADAR detectors and scanners ARE "transmitting" something. They all have local oscillators, and there is some signal there which can be detected.

Most RADAR detectors are sitting in someone's windshield and built in a plastic case. They are, by comparison "easy" to detect. Modern scanners have more than one local oscillator, and usually not sitting in your window, which creates some challenges to detect them.

The answer to your original question is yes. But, it is not something that can be done in a practical manner. To add to the complexities, different brands and models of scanners have different local oscillator frequencies. A device could JUST detect these frequencies, but then it would be an even larger step to try and figure out if those signals were coming from an iPod, iPad, other radio or a long list of other devices.

We had a long thread on this topic a couple of years ago. It was called RADAR detector detector or scanner detector or something like that.

 

[Thayne]

My guess is you would increase the breadth and depth of your misinformation.

Correcting each other is the way for both of us to fine tune our knowledge. (unless you are one of those dreaded "know-it-alls")

Fine tuning is good, a panoramic adapter is more fun than an "S" meter, but for you 2 guys neither one of those tools would work--

The main thing is that you both keep this site interesting and safe from the encroaching "know it alls."

 

[13riverking]

The am/fm radio in you're vehicle has a local oscillator, along with ham radios, telivisions, marine radios all the radios in the police vehicles, not to mentions all the enterference from microwave transmissions, so i think, even if L E agencies could detect these "signals" they would have no clue what they were looking at

 

[apd3190]

Intresting topic..Along those lines How do the radio shows(Basic am-fm) rate the amount of listeners?