View Full Version : Does fog effect radar?
holein1
11-20-2005, 12:15 PM
Lately around where I live the fog has been getting quite thick (the kind where you can only see about 75 to 100ft in front of you)! When I turn out onto my main street there is about a mile long straight stretch and at the end of that there is a little cut out area on the side of the road where a certain sheriff's deputy likes to hide! Now when the sky's are clear and he's running his k band radar I pick him up as soon as I turn onto the main road aprox. one mile cause the dummy leave's his unit on, however the last few day's and night's when it was nice and foggy my detector didn't pick the sheriff's radar up until about the half way mark 1/2 mile! I didn't think the fog would have this much of an affect on radar, has anyone else ever experienced this?
TeamQuack
11-20-2005, 12:57 PM
yeah ive read before that fog does effect radar. but dont call the leo a dummy cause you wouldnt want him to be smart :twisted:
i know rain effects radar so fog might as well, just water in a different form.
tjbender
11-20-2005, 01:10 PM
The easiest effect I can think of would be that the fog cuts the LEO's visibility way down, and they can't see your car to aim at it past a quarter-mile or so, even on a straight road.
holein1
11-20-2005, 01:15 PM
The easiest effect I can think of would be that the fog cuts the LEO's visibility way down, and they can't see your car to aim at it past a quarter-mile or so, even on a straight road.
The sheriff's dept. has the radar unit's mounted on the inside pillars of their car's and sit in the same spot parallel to the road I'm driving on.
Carlos from Spain
11-20-2005, 01:24 PM
Humidity in the air decreases the propagation of the radar microwaves, so the signal reaching the detector is weaker under foggy conditions.
GTO_04
11-21-2005, 07:45 PM
Fog, rain or snow will probably have even more of an effect on the police radar, because it must deal with a reflected signal. It must travel to the vehicle be reflected, and travel back.
Cops don't normally run radar much in heavy rain or fog. Or at least they don't like to pull people over in those conditions.
GTO_04
RadarHell
11-21-2005, 08:11 PM
Humidity in the air decreases the propagation of the radar microwaves, so the signal reaching the detector is weaker under foggy conditions.
K band (24GHz) Radar runs near the frequency of water vapor, around 22GHz. This causes the reduction an officer has in pickup but does not affect the accuracy of the radar itself. In turn this would cause you unit not to pickup an earlier signal too since the water vapor absorbs the output signal and return.
If you also notice, you are able to receive an earlier signal on a cold night with not atmospheric moisture/clouds. In cooler/colder weather there is less moisture for the air unlike warm/hot weather.
The easiest effect I can think of would be that the fog cuts the LEO's visibility way down, and they can't see your car to aim at it past a quarter-mile or so, even on a straight road.
The sheriff's dept. has the radar unit's mounted on the inside pillars of their car's and sit in the same spot parallel to the road I'm driving on.
Which detector are you using?
stalker
11-21-2005, 11:10 PM
you will find he has the transmitting power turned down, in fog or rain the radar operators cant get a reading as far away as if it was clear weather.
Ik know for a fact in bad weather operators dont use max power and that is why you picked him up a lot later than normal.
jimbonzzz
11-21-2005, 11:17 PM
I don't know of any radar units that have variable power. Most have a "sensitivity" or "range" control, but that does not change the output power at all.
Jim
SportsFan
11-21-2005, 11:26 PM
I know the purpose of this thread was just to ask about various weather conditions and how they affect electronic equipment from a curiousity standpoint, and I can see where there would be interest about that....but I would sincerely hope that noone would be speeding in fog anyway!!! During a fog should definitely be one time when a radar detector wouldn't even need to be turned on.....
stalker
11-21-2005, 11:54 PM
well I ment Range...doesnt setting the range to a lower setting reduce the transmitting power?? I would think so??
jimbonzzz
11-22-2005, 12:10 AM
Output power is fixed. Technically they could make one with variable power, but nobody has that I know of...
Jim
stalker
11-22-2005, 12:17 AM
isnt the Kustom Silver Eagle a variable range setting radar?? I know thats what the local PD here do and they reduce the range in Fog and rain...
See the LED,s below the smaller window with 51 on it...this is the range setting, I know this as i have played with this unit before in a PD car;
http://www.pbelectronics.com/kustom24.jpg
isnt the Kustom Silver Eagle a variable range setting radar?? I know thats what the local PD here do and they reduce the range in Fog and rain... :twisted: :roll:
stalker
11-22-2005, 12:42 AM
what is that supposed to mean LS2?
Here is one for sale that shows variable range...and it is listed in the ad;
http://www.policeradar.net/special_offers.htm
"Variable audio, internal calibration test, segment test, RF hold, variable range. "
jimbonzzz
11-22-2005, 07:14 AM
Yes, variable range, but NOT variable power output.
Jim
crabman
11-22-2005, 10:20 AM
Being a commercial fisherman I use radar in that application. Our radars can adjust power, sensitivity (both near or global, and range. By lowering the range you can spread targets allowing for you to differentiate targets. Lets say I have 2 blips close together at 9 miles and the radar is set to 24. I can reduce my range to 16 which spreads the targets and this allows me to see that one is actually a tug and tow for instance. The other reason to reduce range is to simply blow up the picture. Coming into a channel thats 1 mile wide I can go to to say 3 mile range and get a much better view of my close surroundings. By adjusting sensitivity I can reduce clutter from rain mostly or fog if its thick enough. What this does is the radar does not show a return on any target that falls below the threshold of the sensitivity. What can happen real world is that a target gets lost in the return from rain. By increasing the sensitivity I can remove the return from rain clutter which will fall below the level I have set for sensitivity but the desired target such as a boat will be above the level of rejection and can still be seen. The power level of the radar does not chage, only the threshold of return sensitivity. By increasing power I can get the return of a distant target above the threshold of rejection. Here you might note that these settings are in many ways interrelated. If I increase my power the return from rain clutter increases bringing more of it above the level of rejection and an decrease in sensitivity will be called for to remove it. This in turn will affect the increase in power because now with my rejection increased my range for legitimate targets has been reduced. When I started running boats you fiddled with this constantly trying to maintain the best overall picture in any given situation. Nowdays modern radars can be set to auto for these functions (except range of course) and the computer does a pretty good job of managing it with minimal fuss. While I know this is somewhat off target on this board I think most of you here can look at this and translate how these settings might affect a LEO out on your local roads. Edit... I forgot to mention. On some radars sets increasing your sensitivity reduces rejection and the radar shows more return. On others turning the knob up increases rejection and the radar shows less. Just a lack of standardization in the business.
SmaartAasSaabr
11-22-2005, 10:33 AM
If you also notice, you are able to receive an earlier signal on a cold night with not atmospheric moisture/clouds. In cooler/colder weather there is less moisture for the air unlike warm/hot weather.
You ever been driving in the middle of nowhere at 1 or 2 in the morning, cool night, and you start picking up these AM radio stations from halfway across the continent? :)
stalker
11-22-2005, 01:24 PM
haha yeah.....I dont listen to AM tho ;)
holein1
11-22-2005, 02:07 PM
The easiest effect I can think of would be that the fog cuts the LEO's visibility way down, and they can't see your car to aim at it past a quarter-mile or so, even on a straight road.
The sheriff's dept. has the radar unit's mounted on the inside pillars of their car's and sit in the same spot parallel to the road I'm driving on.
Which detector are you using?
x50 & solo S2.
what is that supposed to mean LS2?
Here is one for sale that shows variable range...and it is listed in the ad;
http://www.policeradar.net/special_offers.htm
"Variable audio, internal calibration test, segment test, RF hold, variable range. "
I don't know??? I didn't type that response:shock: