POP - WHY not?

€ · 04-02-2009, 04:02 AM

I know that POP can't be used as proof of speeding in US because of the law (? - correct me if I'm wrong). But WHY? What's wrong with POP?

I/O can measure object's speed within 0.4-0.5 sec (? - correct me if I'm wrong). It's no so far from POP time. So why?

All input, all facts and technical info appreciated.

**KnightHawk** · 04-02-2009, 07:15 AM

POP burst in so short at 67ms and 16ms that even the manufacturer stated in the manual that it will not support a citation based on POP mode. It is only used for estimating a potential violator's speed and minimize radar detector detection because visual speed estimate in hard specially when there is no point of reference. Most application using I/O is turned on instantly when you are in range and when the vehicle traveling gets into the point of reference in stationary mode. Once activated, they usually leave it on for a few seconds for tracking history purposes. LEO can then make his conclusions from the data he has gathered during that particular encounter.

There are 3 basic rules to follow when using radar to have good tracking history of violator. It minimizes errors when all 3 factors are bundled together and is hard to defeat in the court of law.

1. Good visual ID of target vehicle
2. Good solid audio tone
3. Radar readings

When using short burst of radar, it does not give you a solid tone. The solid tone can tell a seasoned LEO if you are going over/under PSL by just hearing the tone. If you turn radar on in half a second and turn if off, you will not have a good solid tone. This in turn can be questionable in court specially when the violator has a radar detector if you know what to ask or question LEO/Judge. He can argue that LEO did not use radar. Most radar certified operator when doing I/O will leave their radar on for a few seconds(this is what's being trained by certified radar instructors). It will also help them determine if the violator was also using a radar detector by leaving it on for a longer time because the audio tone changes when speed captured by radar changes without looking at the radar display. All LEO has to do is lock the speed shortly after it is turned on. Once it is locked, he can continue to monitor your speed based on solid audio tone and radar readings. The other importance of solid audio tone is this. If speed reading on radar does not correspond to the right audio tone, the speed reading is rejected and could also mean that radar is possibly broke and needs service. Higher tones corresponds to higher speed and lower tones correspond to lower speed. If radar reading says 75mph and audio tone is lower at the level of 60mph, radar reading is rejected.

So you can see why radar audio tones are very important when traffic radar is used.

**newkid** · 04-02-2009, 07:34 AM

Originally Posted by KnightHawk

POP burst in so short at 67ms and 16ms that even the manufacturer stated in the manual that it will not support a citation based on POP mode. It is only used for estimating a potential violator's speed and minimize radar detector detection because visual speed estimate in hard specially when there is no point of reference. Most application using I/O is turned on instantly when you are in range and when the vehicle traveling gets into the point of reference in stationary mode. Once activated, they usually leave it on for a few seconds for tracking history purposes. LEO can then make his conclusions from the data he has gathered during that particular encounter.

There are 3 basic rules to follow when using radar to have good tracking history of violator. It minimizes errors when all 3 factors are bundled together and is hard to defeat in the court of law.

1. Good visual ID of target vehicle
2. Good solid audio tone
3. Radar readings

When using short burst of radar, it does not give you a solid tone. The solid tone can tell a seasoned LEO if you are going over/under PSL by just hearing the tone. If you turn radar on in half a second and turn if off, you will not have a good solid tone. This in turn can be questionable in court specially when the violator has a radar detector if you know what to ask or question LEO/Judge. He can argue that LEO did not use radar. Most radar certified operator when doing I/O will leave their radar on for a few seconds(this is what's being trained by certified radar instructors). It will also helps them determine if the violator was also using a radar detector by leaving it on for a longer time because the audio tone changes when speed captured by radar changes without looking at the radar display. All LEO has to do is lock the speed shortly after it is turned on. Once it is locked, he can continue to monitor your speed based on solid audio tone and radar readings. The other importance of solid audio tone is this. If speed reading on radar does not correspond to the right audio tone, the speed reading is rejected and could also mean that radar is possibly broke and needs service. Higher tones corresponds to higher speed and lower tones correspond to lower speed. If radar reading says 75mph and audio tone is lower at the level of 60mph, radar reading is rejected.

So you can see why radar audio tones are very important when traffic radar is used.

Nice detailed description...

**nr2d** · 04-02-2009, 07:38 AM

Originally Posted by KnightHawk

POP burst in so short at 67ms and 16ms that even the manufacturer stated in the manual that it will not support a citation based on POP mode. It is only used for estimating a potential violator's speed and minimize radar detector detection because visual speed estimate in hard specially when there is no point of reference. Most application using I/O is turned on instantly when you are in range and when the vehicle traveling gets into the point of reference in stationary mode. Once activated, they usually leave it on for a few seconds for tracking history purposes. LEO can then make his conclusions from the data he has gathered during that particular encounter.

There are 3 basic rules to follow when using radar to have good tracking history of violator. It minimizes errors when all 3 factors are bundled together and is hard to defeat in the court of law.

1. Good visual ID of target vehicle
2. Good solid audio tone
3. Radar readings

When using short burst of radar, it does not give you a solid tone. The solid tone can tell a seasoned LEO if you are going over/under PSL by just hearing the tone. If you turn radar on in half a second and turn if off, you will not have a good solid tone. This in turn can be questionable in court specially when the violator has a radar detector if you know what to ask or question LEO/Judge. He can argue that LEO did not use radar. Most radar certified operator when doing I/O will leave their radar on for a few seconds(this is what's being trained by certified radar instructors). It will also helps them determine if the violator was also using a radar detector by leaving it on for a longer time because the audio tone changes when speed captured by radar changes without looking at the radar display. All LEO has to do is lock the speed shortly after it is turned on. Once it is locked, he can continue to monitor your speed based on solid audio tone and radar readings. The other importance of solid audio tone is this. If speed reading on radar does not correspond to the right audio tone, the speed reading is rejected and could also mean that radar is possibly broke and needs service. Higher tones corresponds to higher speed and lower tones correspond to lower speed. If radar reading says 75mph and audio tone is lower at the level of 60mph, radar reading is rejected.

So you can see why radar audio tones are very important when traffic radar is used.

What is the "warmup time" for the radar. I would think that it should take .5 to 1 sec for the radar's magnetron or TWT to stabilize. Unless speed radars are different from a normal "search" radar like on an airport. Besides being much lower in peak and average power they should work the same way, the magnetron or TWT is the oscillator.

The only other thing I can think of is that the magnetron or TWT is on continuously and they are transmitting into a dummy load and the load is switched to the antenna via something like a Pin Diode switch.

Just some thoughts.

**KnightHawk** · 04-02-2009, 08:34 AM

Originally Posted by nr2d

What is the "warmup time" for the radar. I would think that it should take .5 to 1 sec for the radar's magnetron or TWT to stabilize. Unless speed radars are different from a normal "search" radar like on an airport. Besides being much lower in peak and average power they should work the same way, the magnetron or TWT is the oscillator.

The only other thing I can think of is that the magnetron or TWT is on continuously and they are transmitting into a dummy load and the load is switched to the antenna via something like a Pin Diode switch.

Just some thoughts.

There is "no warm up" time. Radar is put on standby mode or put on hold. With instant on and when done properly, readings are instantaneous. Maybe jimbonzzz can explain it better. Just don't have much technical knowledge when it comes to this.

**jdong** · 04-02-2009, 09:30 AM

The oscillator used for police radar is not meant to be instantly ready when powered on. It takes on the order of a fraction of a second for it to be stable. During this time it can lead to blatantly wrong speed readings, and this is a problem that plagued first-generation POP units.

However, as far as I can see in tests, the Z-series 16ms K band POP guns seem quite accurate in speed measurement except for the occasional harmonic, which a seasoned cop can easily discount as a false reading.

With that said, the reason why POP isn't accepted is probably one of tracking history and the manufacturer not bother to get that mode certified.

Furthermore, let's remember what POP mode is for:

Officer sets up speed trap and turns on POP. Once every 10 seconds he flips the trigger and looks at the speed readout. If it's lower than his desired ticketing speed, he sits back. He can do this for hours with 16ms POP and the chance of any detector making a peep is nearly zero.

Once he sees a speed he likes, he just has to hold down the trigger for half a second longer and the gun sends out instant-on continuous wave radar great for issuing tickets. All the RD users see is one sudden burst of K band and think "Oh crap, that was an instant-on cop. There is no way to get advance warning on this threat except with a rabbit"

I find it hard to believe when a feature is advertised in this manner that there aren't cops with these guns and are familiar with this mode enough to use it. That's why I still feel accurate POP detection with minimal falsing, something that virtually no detector on the market does well, is STILL a valuable asset to us and something I'd like to see the RD makers work on.

€ · 04-02-2009, 10:31 AM

Thanks guys for very helpful informations.

Why tracking history is so important? Why not to trust technology? Is it after all so reliable?

The oscillator used for police radar is not meant to be instantly ready when powered on. It takes on the order of a fraction of a second for it to be stable. During this time it can lead to blatantly wrong speed readings, and this is a problem that plagued first-generation POP units.

Amazing! If you have anything more please share.

**MEM-TEK** · 04-02-2009, 11:14 AM

Originally Posted by €

Thanks guys for very helpful informations.

Why tracking history is so important? Why not to trust technology? Is it after all so reliable?...

A visual and radar tracking history allows the officer to confirm that he is getting a correct speed reading for the targeted car rather than a possibly incorrect speed reading due to another nearby vehicle, or due to a variety of other potential circumstances which could cause an inaccurate speed reading.

**jdong** · 04-02-2009, 11:30 AM

Originally Posted by €

Thanks guys for very helpful informations.

Why tracking history is so important? Why not to trust technology? Is it after all so reliable

the problem is, radar isn't "technology" at least not in the way police radar stationary antennae are designed. A broad beam gets emitted out in the general direction of traffic, signals get reflected back by various cars, signs, birds, and so on. The radar gun makes an arbitrary decision about which signal's speed to display. When you see a speed, is it plausibly the speed of what you intended to measure? That's something that a prudent officer tries to establish via a tracking history, and also the point that most people use to argue out of speeding tickets in court.

**KnightHawk** · 04-02-2009, 07:30 PM

Originally Posted by €

Why tracking history is so important?

In short, tracking history is a process of identifying a violator.

Why not to trust technology? Is it after all so reliable?

Electronics break down and you cannot depend on it 100% all the time. That is why those 3 steps mentioned are essential in increasing reliability of a speed measuring device. In the training manual, speed readings alone taken by a speed detection device cannot stand up in court or is not used as a basis for citation.