K band ghosting?

[bigalinwv]

Can a V1 ghost on K band? Just wondering, I ran across 2 troopers today about 1/2 mile apart, and my V1 showed 3 bogeys. Even if a front and rear antenna is possible, I don't think I have ever seen that set up around here. My V1.8 is a Pop1 unit.

[snoopyc4]

Yes V1 can ghost. LEOs change their tactics all the time so don't rule the possibility of a rear antenna.

[John_in_NC]

NO, RD's do NOT ghost.

Radar signals can multipath.
V1's can pick up and display both paths and increment the counter

[Bridge Cables]

Hey John, so I can wrap my head around this, not the most technically astute at this end. This multipath (reflections?) will keep the original frequency and also change a portion of the beam to a different frequency from one LEO’s antenna and cause the V1 to increase the bogey count to two or three?

I'm guessing here but I would imagine that if the V1 saw the exact same frequency from several directions, i.e., reflections, it would assume it to be the same radar gun and a bogey count of one, am I correct?

I guess I have been fortunate compared to some others, but I have yet to see this ghosting (?) out of my V1.

BC

[djrams80]

NO, RD's do NOT ghost.

Radar signals can multipath.
V1's can pick up and display both paths and increment the counter

LOL! A V1 showing three contacts when there are only one or two is ghosting, period. As far as I know, we around here developed the term and that's how we define it. That certainly is how we use it around here.

Edit: Same radar source, different bogey counter readouts. One bogey counter works, the other does not. Trying to blame this on the radar signal is totally incorrect.

[ame]http://www.youtube.com/watch?v=ml3irX-EF0s[/ame]

[ame]http://www.youtube.com/watch?v=VVvJ5X4Xd3Y[/ame]

[Freebird]

The two V1 3.864's I owned ghosted very badly, but the 3.872 is a major improvement.FYI

[bigalinwv]

That's good to know, I had heard of Ka band ghosting, but wasn't sure of the K band ghosting. I have NEVER seen a two antenna K band setup around here, and since were 49th out of 50 (thank God for Mississippi) states in being poorest, I doubt there's money available for more equipment.

[Red Turbo Tegg]

I guess I've been pretty lucky. My 3.819 hasn't ghosted at all, at least that I've noticed. Is the newist revision fixed?

[MEM-TEK]

NO, RD's do NOT ghost.

Radar signals can multipath.
V1's can pick up and display both paths and increment the counter

Yes, some RD models can and do ghost, depending on the design of their mixer and down conversion circuitry. The V1 can and does ghost. Technically, the Whistler rev C design ghosts, but you don't see the ghost since it is designed to only show the alert for the strongest signal. Yet this is why a Pro78 for example may suddenly switch its display to X band when in actuality a K band signal is being detected.

[John_in_NC]

Believe me, I see the numbers jump on my v1 as well but it is called MULTIPATH. It is okay to use slang and call it ghosting once you understand what it is. Again it is a phenomena of the reflected RF signal, not necessarily the detector.

Radar detectors do not ghost, there is no such thing

It is RF signals that ghost,

First lets determine what ghosting really is

http://en.wikipedia.org/wiki/Ghosting_(television)



Ok, now imagine this.


If part of a single oscillated transmission is received via a reflection off a fixed object and the other part of it is received off a moving object. Would the signals from both path be on the same exact frequency?

Hint: radar uses Doppler to determine speed

So would the detector see the same frequency signal or would it see two signals one slightly higher in frequency than the other?

Of course if you only could receive the strongest signal there would be no ghost because you would only get one signal at a time.

This is one of the reasons why radar is not 100% accurate when read by the police officers vehicle.

So, why does it happen more with the Valentine One than other RD's?
Because the V1 can determine that slight variance in frequency and call it a second bogey.

Still don't get it? ok, let's try it in reverse.

You are a cop and shooting radar from an overpass onto the highway.

Closest to you in a truck and behind him is a sports car obviously speeding.

You click your radar on and get the speed of the truck. Then you switch the radar to "Fastest" and get the speed of the car.

If there was just one signal coming back to your radar how could you do this, would you now agree that one signal can come back as various frequencies?

SO, if I am wrong can someone please tell me how a receiver GHOSTS?