Busted? Help!

[spudchucka]

Of course, if the police car is following the target vehicle very closely, this beam might report the speed of the police car relative to the followed car, rather than the road.

If a cop followed you that closely they wouldn't need a radar to know how fast you were going.

[FJRider]

furthermore, I have found all the resident officers to be good guys and helpfull, but they will take the piss at times as they are human.

AREN'T WE ALL ??? (human)

[hospitalfood]

AREN'T WE ALL ??? (human)

allegedly...........but there is no prooof it, and many posts ( including my own ) make me wonder ???

[jafar]

allegedly...........but there is no prooof it, and many posts ( including my own ) make me wonder ???

You said it :spudflip::spudflip:

[Patrick]

Handing out a ticket - thats the way it works. No problem there.

But giving a policeman the power to see the alledged offence, make a road side decision as to guilt, and roll out the punishment... hmm, thats facist allright !

No it isn't... shooting the offender then impounding and selling the bike to pay for the bullet... THAT is facism...!!!

might start to realise that they and all of us share the roads with these wankers.

Oi... who you calling wankers? Whats your QID? If not given i am taking this international... nah... global.... nah... galactic... nah... universal... nah... oh feck it.

This means that the radar cannot measure the speed of targets travelling in the same direction, they either have to be oncoming or the patrol vehicle has to be stationary.

Simply bollocks... same lane mode front antenna for a car ahead of you, same lane mode rear antenna for a car rapidly approaching from behind... all the while the patrol car is in motion....

Front and rear while stationary, moving, while eating donus even...

Of course, if the police car is following the target vehicle very closely, and..........

An example, is the radar operator is doing 80 km/hr, and is following a motorcyclist who is 50m in front (2 seconds travel time).

In the other lane, 400m away is a truck, travelling slowly, and approaching the radar operator at 55 km/hr.

The radar operator has assumed the motorcyclist is the radars target, and its the lock button.

In this situation, the radar unit may report the trucks speed not the motorcyclist. As the truck is closing on the policecar at 80+55 = 135 km/hr this is the ticket the biker would get.

By the time the biker has stopped, the truck is long forgotten by biker and policeman alike !

Part 1... is the cars speedo not going? It is called pursuit mode... speed taken from the certified speedo of the patrol car.

As for the example, if the patrol is doing 80 and the bike is only slowly pulling away, then he clearly is not doing 135. If it was leaving him in dust and pulling away at 135, then, well... same lane mode has him screwed... The "older ones" are in the museum.

[hospitalfood]

You said it :spudflip::spudflip:

your an alien if i ever met one......how you doing ? keeping those other mates of mine out of trouble ?

[jafar]

your an alien if i ever met one......how you doing ? keeping those other mates of mine out of trouble ?

Alien
Doing ok thanks mate,
Was wondering how your getting on, as the only place you can get to now is the pub down the road

[hospitalfood]

Alien
Doing ok thanks mate,
Was wondering how your getting on, as the only place you can get to now is the pub down the road

life is life is life...............between finding work, doing up the house, promoting my business and trying not to lose my licence and pay lots of fines I find time to sleep and stress.........dont manage to walk that 100 meters to the pub.

[jafar]

life is life is life...............between finding work, doing up the house, promoting my business and trying not to lose my licence and pay lots of fines I find time to sleep and stress.........dont manage to walk that 100 meters to the pub.

Oh man thats gotta suck , your so close to the pub you could almost taste it from your place
Whats the business your promoting ??

[hospitalfood]

photography, same old.
think her and I may start a branding / advertising agency as well. bit of a gap in the market up here for good company branding and adds. the stuff you see and hear in these parts makes you cry........

[Mikkel]

The reflected signal that the radar unit "hears" depends on the speed of the target vehicle. Of course, it also depends on the speed of the police car, as it actually hears the relative doppler shift.

Now, it's a few years since last time I actually used the theory of relativity in regards to an actual problem.

However, I do seem to recall that the speed of the vehicle emitting the signal has no impact whatsoever upon the doppler shift.

The doppler shift depends only upon the velocity of the surface from which it is reflected.

The problem is this: electro-magnetic (EM) radiation always travels at c/n (where c is the speed of light in vacuum and n is the refractive index of the medium effectively 1 for most gasses). It doesn't matter whether the emitter is moving or stationary - the EM radiation travels at c, this is one of the things about the theory of relativity that is hard to grasp...

Now as the EM wave travels through space from the emitter to the reflecting surface at the speed c there will be an infinitesimal displacement of the surface from the time of one wavefront being reflected 'til the next one is being reflected. Since the wave travels back towards the emitter at the speed c a change in the spacing between the wavefronts (frequency) can be observed. That frequency change is the doppler shift and that is used to determine the speed of the target.

Bearing this in mind I can not fathom the complication of a "grounding antenna"...

Edit: Oh btw. Laser guns work on the principle of range finding and calculating the speed by measuring two ranges inside a given time slot. Indeed if you used a range finding device to measure the speed of another vehicle you have to take the observers velocity into account.

[jafar]

photography, same old.
think her and I may start a branding / advertising agency as well. bit of a gap in the market up here for good company branding and adds. the stuff you see and hear in these parts makes you cry........

Sounds like a good idea , I'm sure half the slogans are dreamed up while they are stoned

[FJRider]

try an anti speeding campaign ???

[swbarnett]

Cool. Lets make speed limits subjective, then everyone can decide how fast is safe.

Well, yes, this is the idea. Then, if you get it wrong and cause an accident you get the book thrown at you.

Once upon a time a bloke got airborne in Ferndale Rd, Mt Wellington. Took out the front of a house. Told me he does that speed all the time and it is perfectly safe. Now, oif the speed limit was sibjective, how could I argue with him?

Well, the limit is subjective and obviously this guy got it wrong. That's where the cops come in. If he gets it wrong too often then he's proven he's not fit to drive and he gets his license taken away.

I guess the problem is that we all have a different idea of what is safe. Tossers in their Poorches all seem to think it's safe to do 100 in my street, while wanting us to make the plebs in the Corrollers stick to 40. Y'see, we all expect the rules to apply to everyone but us.

No, I just expect that the rules that are there make sense. In the case you describe a charge of speed not suitable for the conditions would be perfectly adequate, you don't need a hard and fast speed limit (although I do agree that a suggested maximum speed for the area would be a good idea). Also, I do accept that urban areas are somewhat different to open road areas (which is mainly what I'm talking about).

We often hear that people should be allowed to make more of their own decisions, then we hear the comments about all the idiots on the road.

We have idiots because we don't allow people to think. We get what we deserve.

[swbarnett]

As always, limits are set are a compromise to ensure the safety of ALL road users. Not all road users have the same driving / riding skills, or a vehicle capable of safe high(er) speeds. Add into this "equation" the attitude / mind set of the road users who THINK they have the ability / vehicle capable of high(er) speed, but DON'T. Do you want to be on the SAME piece of road as THEM, AT THE SAME TIME ???

If it preserves my freedom and my ability to actually enjoy life, then most definately yes. I have been in this situation and I'm still alive. I also expect the police to stop anyone they see that they consider to be driving dangerously and treat them accordingly.

And before you ask, I'd also be happy with my loved ones being in the same position. Over a life time the risk to my freedom is far greater than any risk to my physical body. I'd rather live one day as a free man than a life as a slave to other's insecurities.