Discussion About Radar Detectors

[Orient_Express]

This whole thing has somehow survived the court system in some areas. The FCC states that radar signals are radio frequencies and transmitted over PUBLIC airways - in other words, the frequency spectrum belongs to the general public - not a police department. Therefore, we should be able to RECEIVE any signal transmitted - whether it be clear, encoded, laser, or encrypted in any way.

Transmission of RF or light signals requires a license, (i.e. police department, television broadcast, radio station, two way radio, cell phone company, etc.) but the reception of those signals does not require any licensing. A radar detector is a receiver - like a GPS unit - like a scanner - like a television or radio. A radar jammer is totally different than a detector simply because it transmits an interferring carrier or laser.

These "no detector" laws clearly violate the FCC mandate, but no one seems to be able to do much about the infringement.

Whether detectors are worth purchasing is another debate, but being able to receive those signals should be completely legal.

 

[ponyfool]

This whole thing has somehow survived the court system in some areas. The FCC states that radar signals are radio frequencies and transmitted over PUBLIC airways - in other words, the frequency spectrum belongs to the general public - not a police department. Therefore, we should be able to RECEIVE any signal transmitted - whether it be clear, encoded, laser, or encrypted in any way.Transmission of RF or light signals requires a license, (i.e. police department, television broadcast, radio station, two way radio, cell phone company, etc.) but the reception of those signals does not require any licensing. A radar detector is a receiver - like a GPS unit - like a scanner - like a television or radio. A radar jammer is totally different than a detector simply because it transmits an interferring carrier or laser.

These "no detector" laws clearly violate the FCC mandate, but no one seems to be able to do much about the infringement.

Whether detectors are worth purchasing is another debate, but being able to receive those signals should be completely legal.

One small problem with this theory. No radar detector worth a hill of beans is passive, or read only as you suggest. Every radar detector out there that can "see around corners" or over hills transmits a frequency as well. It sends out a signal that gets corrupted (for lack of a better word) when it encounters a radar signature and the corrupted return signal is what sets off the radar detector.

Now, as for Laser detectors, currently, they are strictly passive.

Thus, if you have a "read only" detector, I'll bet you could make your argument. And you'd have to, 'cause you sure as hell aren't going to get any advanced notice from it!!!!

 

[Orient_Express]

Theory? - Hardly. In answer to your post - they are called "detectors" because they "detect" (receive) a signal that's been transmitted. If they transmitted a signal - they would be labeled as transmitters. If they transmit & receive - transceivers.

A police radar gun operates by transmitting radio waves at certain frequencies which reflects off objects (your vehicle) and are then picked up by the radar gun's receiving section. When radar waves reflect off a moving target, a measurable frequency shift occurs. The radar unit converts this shift into miles per hour to determine the target's speed.

Two basic types of radar are used - stationary and moving. Stationary radar must be used from a static site, typically a patrol car parked along side the road.

But with a single antenna moving radar, an officer can clock approaching vehicles while driving on patrol. Moving radar with two antennae - one facing forward, the other aimed out the back of the cruiser - can also clock vehicles even after they have passed by, headed in the opposite direction. (Also known in some states as VASCAR)

A radar detector is a radio receiver tuned to specific radio frequencies used by police radar. It is extremely sensitive, whicjh accounts for it's range, often able to "hear" radar at great distances. In evaluating a detector, the two most important performance criteria are sensitivity and selectivity. Sensitivity is a measure of a units detection range. Selectivity refers to a unit's ability to reject non-police microwave signals and is an important feature because of the many sources of "electronic pollution". Note: Automatic door openers, micro-wave long distance carriers and some burglar alarms operate on X-band, which is a police radar band. A radar detector cannot tell if a store is opening a door, setting off an accidental alarm or a police officer is checking speed.

The detector can alert you of a police presence only when they are transmitting a signal. The officer may have a radar or laser gun in the car but the device may not have been turned on. No detector can alert you if no signal is transmitted!

Except for a few early units, X band (10.525 GHz) was the only frequency used for police radar until the mid 1970's. In 1976 radar guns using K band (24.150 GHz) were introduced; this led to the development of the first dual band (X/K) radar detectors. A proliferation of radar guns using Ka band frequencies began in 1987 with the introduction of photo radar (34.3 GHz) and was followed by the Stalker (34.2 - 35.2 GHz) in 1991 and the BEE 36A (33.4-34.4 GHz) in 1992.

I must also correct my earlier post and say that some frequencies are NOT in the public band - those used for used for military and startegic communications.

 

[ponyfool]

Theory? - Hardly. In answer to your post - they are called "detectors" because they "detect" (receive) a signal that's been transmitted. If they transmitted a signal - they would be labeled as transmitters. If they transmit & receive - transceivers.

I can get into a pissing contest with you if you'd like, but if you would have read ALL of the web page you copied and pasted here, you would have seen this too:

Detecting DetectorsSince they have an oscillating current, all radio receivers not only pick up radio signals, they also emit them. This means that any radar detector, whether it has a jammer or not, broadcasts a tell-tale radio wave whenever it is turned on.

In areas where radar detectors are illegal, police may be equipped with a device called VG2. The VG2 instrument is simply a high-powered radio receiver tuned to the frequency of the signals emitted by radar detectors. So while you're scanning the area for them, they might very well be scanning the area for you.

I have been using police radar for 18 years. Lidar for 11. I have been to countless classes, and have learned about the units we use as well as radar detectors. When I was an officer in Virginia, I was one of the first people to use the radar detector detector. In that class, I was specifically taught how the unit worked to detect radar detectors, and what I explained in my previous post is accurate. A radar detector transmits a signal and is NOT receive only as you and your quoted web page suggest.

 

[fjrchooser]

Tell us more Pony ! :yahoo:

 

[evil_henchman]

Radar detectors do transmit a signal of some kind, all you have to do is google search for radar detector detectors. I don't know what kind of signal they emit or how they work but they do emit something, some more than others. It's all black box voodoo to me.

 

[ponyfool]

Tell us more Pony ! :yahoo:

This one time, at band camp......

 

[fjrchooser]

<<<< I'm all ears !!!!

 

[KSFJR]

This is more of a question than a statement for I don't know the answer. I have been looking at getting a radio for communicating on my bike and it is my understanding that if they are less than so much power, 1 or so watts that they do not require a license. Wouldn't that somewhat transfer to radar detecors also?

 

[wfooshee]

Theory? - Hardly. In answer to your post - they are called "detectors" because they "detect" (receive) a signal that's been transmitted. If they transmitted a signal - they would be labeled as transmitters. If they transmit & receive - transceivers.

I can get into a pissing contest with you if you'd like, but if you would have read ALL of the web page you copied and pasted here, you would have seen this too:

Detecting DetectorsSince they have an oscillating current, all radio receivers not only pick up radio signals, they also emit them. This means that any radar detector, whether it has a jammer or not, broadcasts a tell-tale radio wave whenever it is turned on.

In areas where radar detectors are illegal, police may be equipped with a device called VG2. The VG2 instrument is simply a high-powered radio receiver tuned to the frequency of the signals emitted by radar detectors. So while you're scanning the area for them, they might very well be scanning the area for you.

I have been using police radar for 18 years. Lidar for 11. I have been to countless classes, and have learned about the units we use as well as radar detectors. When I was an officer in Virginia, I was one of the first people to use the radar detector detector. In that class, I was specifically taught how the unit worked to detect radar detectors, and what I explained in my previous post is accurate. A radar detector transmits a signal and is NOT receive only as you and your quoted web page suggest.

It's not so much that they have an oscillating circuit, you can't have radio without "oscillating circuits," but it's the use of super-heterodyne circuitry that makes them emit a detectable signal. That frequency generated by the device "leaks" out into the world.

 

[ponyfool]

<<<< I'm all ears !!!!

Here's some good reading so I don't have to type too much!

https://www.fjrforum.com/forum//index.php?showtopic=12068

 

[Orient_Express]

<<<< I'm all ears !!!!

Here's some good reading so I don't have to type too much!

https://www.fjrforum.com/forum//index.php?showtopic=12068

I stand corrected - it's much easier to say you whupped me and I'll tell everyone that you did and I won't mess with you again than to actaully fight - nobody gets hurt, out of breath and my ego can take it!!

I've been in the cable televison industry for 27 years. In the past we were mainly concerned with C and Ku band TVRO signals down coverting them to analog channels and used super-heterodyne recievers to measure and set signal levels. The device is called an SLM in the industry. With the digital format of QAM 64 and QAM 256 compression, the analog channels are being left in the dust so to speak. Cable modems, VoIP use a compressed QAM 64 or 256 forward path transmission scheme, but the return spectrum is all QPSK signals and fall under a newer measurment of average power as there is no CW carrier involved in the upstream or downsteam transmission. Testing those formats is done by comparison of MER and BER standards, along with S/N ratios and not C/N or db/uV measurment. Super heterodyne recievers that emit any signal is news to me - it sure appears that it's true in the case of radar detectors, as you have pointed out, but if that were the case in my buisness, we'd be chasing CSO, CTB and common path distortion problems being generated from our own equipment.

So, my question to you is this - Is it a shielding issue with the detectors?

 

[ponyfool]

<<<< I'm all ears !!!!

Here's some good reading so I don't have to type too much!

https://www.fjrforum.com/forum//index.php?showtopic=12068

I stand corrected - it's much easier to say you whupped me and I'll tell everyone that you did and I won't mess with you again than to actaully fight - nobody gets hurt, out of breath and my ego can take it!!

You coming to WFO? If so, I'll buy you a drink!

 

[Orient_Express]

<<<< I'm all ears !!!!

Here's some good reading so I don't have to type too much!

https://www.fjrforum.com/forum//index.php?showtopic=12068

I stand corrected - it's much easier to say you whupped me and I'll tell everyone that you did and I won't mess with you again than to actaully fight - nobody gets hurt, out of breath and my ego can take it!!

You coming to WFO? If so, I'll buy you a drink!

No - I wish I could - Citizen's arrest!!! :yahoo:

Read the above - I'm curious how these things emit any transmission - Just hard for me to get through my thick head!!

 

[evil_henchman]

So, my question to you is this - Is it a shielding issue with the detectors?

I think the short answer is yes.

I read an article on some RDD's (Radar Detector Detector's) that I found with a google search but can't find now :angry:

The tests were done in Australia where detectors are illegal. They found that most detectors were detectable from hundreds / thousands of meters but one or two were only detectable from something like 25 meters.

Late edit:

Here's a link to some RDD testing which shows that one RD appears to be undetectable.....Link

 

[ponyfool]

Well, when it comes to these things and my knowledge of them, it's just like a DVD player, VCR and TV. I honestly have no idea HOW they actually work, I only understand the principle behind them and how to hook them up to work to my advantage.

Radio waves travel in a straight line unless bounced off of something. A cop with a radar on the down side of a hill shoots the radar up the hill. The line of sight for the radar goes up the hill, but there is nothing to bounce the signal down the other side, it just keeps going up the hill, and then into the air and continues in a straight line. Thus, the cop can't read the speed of the car coming up the hill.

However, the car coming up the hill has a radar detector (an Escort or V1 -cuz if you're gonna have one, these are two of the best). With no radar signal coming down the hill towards the car, the radar detector sees the radar waves going over the hill into space and gives an advanced warning.

When radar detectors were first introduced decades ago, they were passive only, meaning they were merely radio receivers, just like a car stereo. If the radar waves hit the unit, you got a warning. I remember when Cincinnati Microwave introduced the first Escort Radar detector. My dad bought one for his weekly commute from VA to SC. They had all the drawings of how this was the first unit to "see around corners" and "see over hills". In their drawings, they showed how the detector sent a signal out, thus showing how the cop's radar waves going up the hill intersected with the detector's signal up the other side of the hill.

When I was a cop in the Norfolk Police Department, we got two radar detector detectors assigned to our traffic division. I wasn't in traffic, but I remember going to the class on the use of it because I had an interest in going to traffic. There, they explained the same thing my dad's Escort brochure explained. That every new radar detector sent out a signal and this new radar detector detector received those signals and gave an alert. We all joked about when the first radar detector detector detector would come out (don't know if one ever did).

Now, with LIDAR, the original theory you posted would be spot on. Right now, LIDAR detectors are strictly line of sight. Yes, there can be some light wave bounce, but that's typically limited to only bounce off the hood of a car, etc. It is my understanding from friends in the military that there is a similar device that the military uses that is able to identify light waves that are not in line of sight. If this ever becomes a commercial technology (if it even exists now), it will be a huge boon to the LIDAR detector companies as the LIDAR's laser will no longer have to physically touch the detector for it to give a warning.

So, like I said, I know how each technology works as an end user, but have no idea how the technology actually works. Well, I know all about Dopler, and the cosine affect, etc, but not the actual technology.

Clear as mud now?

 

[Orient_Express]

Ok - this is really interesting - what's causing any signal emmission to "leak" out. It sure doesn't do much for the driver who's speeding - and so much for "early" warning huh??

When signals "leak" out of coaxial cable, we call it a signal leak - which is a big deal with the FCC as we use bandwidth shared by police, fire and EMT sevices. The truth be known, they could care less about that, but aircraft navigation is the "biggie" when it comes to signal leakage. A pilot (and there are some on this forum) wants to get a precise altitude reading during his approach - not have CNN jamming his instruments!

Again - I stand corrected.. not trying to be a jerk, so hope I don't come off that way. I believe what you're saying and you certainly have the experience to back it up. It's just foreign to me... a reciever emmitting signals - who'd a thunk it?

Have a drink at WFO on me!!

 

[ponyfool]

I was never under the impression it was a signal leak, but more of an intentional signal sent out to intercept the radar signals.

But, I've been wrong before! Lots of times!

 

[Orient_Express]

I was never under the impression it was a signal leak, but more of an intentional signal sent out to intercept the radar signals.
But, I've been wrong before! Lots of times!

A signal transmitted intentionally - really strange - not much "stealth" here is there?

Since I've managed to hijack this thread, I have a question. Would you think that a GPS speed reading is more, or at least, AS accurate as speed measured by a radar gun that's been calibrated? The speedometer in my truck runs about 4 1/2 mph slower than what my GPS indicates.