The reason for EXTREMELY short alerts on Ka? Is this Why?

[Freebird]

Long time California resident and radar detector user, I have always noticed a huge difference in distance of alert and strength of the alert from CHP units. Sometimes only 500 feet on flat ground, but when they are shooting .5 mile on hilly conditions and sometimes over 4 miles on flats. I WAS CONVINCED THEY HAD A LOW POWER SETTING. I think I found the answer to the short 500 feet alerts that NEVER go to full alert when passing the LEO. I found this from a site explaining how police analog vrs digital radar works. What I believe causes the short alert is the part of the radar system that keeps track of the patrol cars speed.

Shadowing, as any state trooper knows, occurs when moving radar's low Doppler locks on to a large moving object-like an 18-wheeler-instead of the road surface in front of his or her patrol car to compute patrol speed. This incorrectly adds to the actual speed of an approaching target vehicle in the opposite lane, and many an officer has lost in court when knowledgeable defense council discovers shadowing.

Two-piece digital radar guns-like Kustom Signals Inc.'s Golden Eagle and Applied Concept Inc.'s DSR-offer speedometer interfaces to eliminate shadowing. The VSS (vehicle speed sensor) signal of the patrol car is fed into the radar gun providing accurate patrol speed not dependent on the radar's low Doppler. Goodbye shadowing.

Shadowing, as any state trooper knows, occurs when moving radar's low Doppler locks on to a large moving object-like an 18-wheeler-instead of the road surface in front of his or her patrol car to compute patrol speed.
I believe the the LOW DOPPLER is what we are picking up in 500ft alerts that never go to full alert.

[KaPro]

Could be, but I'll betcha it's because the antennas are intentionaly off axis.

[jimbonzzz]

There are NO Ka radar units that transmit a separate, low-power signal to acquire the patrol car speed. There was only one radar unit in history which used a second low-power signal to get the patrol car speed: the Kustom KR-11 (circa 1978), and these were K-Band only.

Police radar (other than the vintage KR-11) only transmits ONE signal, and determines patrol and target speeds via the multiple reflected signals. The "Low Doppler" is referring to one of the reflected signals. In moving mode (traditional oncoming moving mode) the signal that is reflected off of the road/terrain that the patrol car passes is the lower frequency signal, hence the term "low doppler". The signal reflected off the target vehicle is the higher frequency signal, hence the term "High Doppler", and it represents the sum of the patrol car speed and the target vehicle speed. Some radar units do have spedometer assist, which helps the unit select the right "low doppler" signal.

[KnightHawk]

I believe the the LOW DOPPLER is what we are picking up in 500ft alerts that never go to full alert.

On top of jimbonzz explanation, you can be in standby mode and the radar unit will display your patrol speed in moving mode and your radar detector is dead silent even if you touch each others antenna together.

[amoney]

Just to add to the almighty answer above, not much mind you, it is known that Ka has the most narrow (shorter wave length) radar "beam" whihch makes it more difficult to detect over longer distances.

Thus if your not in the direct path of the beam such as an officer passes on the opposite side of a median (concrete divider), or if the radar signal is obstructed such in the case when an officer has pulled over a vehicle and is directly behind so that the radar signal is obstructed by the vehicle. This really does occur and is normal. Besides on these two situations, you are not drectly targeted and thus are not at risk.

[djrams80]

I personally feel that every time I have been targeted by CHP, my detection distance has been excellent. Just Saturday, I got well over a mile in fairly heavy traffic from a CHP sitting on the right shoulder. My best guess is that the CHP sometimes turn off the rear antenna during a traffic stop for some reason.

[Freebird]

I agree, I normally get alert well in advance . I thought about all the short alerts I recall and the patrol car is pulled directly behind the victims car (victims car blocking radar source) and is normally on the other side of the median(off axcess). Or the patrol car is pointed away from me with victims car blocking and only patrol cars front antenna on. Thanks for your responses, makes sense to me.