What does Base Reflectivity mean in regards to Doppler Radar images?
453853
An NWS Doppler radar emits beams of radiation which particles such as precipitation reflect back to the radar (thus called echoes - similar with how your voice echoes off objects and back to you). Scans can be done at elevation angles (angles above the horizontal plane) between .5° and 19.5°. Being the lowest scan - closest to ground - the .5° scan tends to best represent the intensity of precipitation reaching ground and is called the "base reflectivity" (analogous to how an object's base is at its bottom). Higher scans can avoid ground interference and clutter at some locations, but also detect more of the large droplets/crystals in the clouds which won't reach the ground.
887961
Use the general equation for Doppler effect from here( http://en.wikipedia.org/wiki/Doppler_effect ). f'/f = .86 and v0 =0 for you since the observer isn't moving. Note that since the frequency is lower that it must be moving away from you.
505284
Sure, I have a scanner and the website I use to find frequencys is http://www.radioreference.com/modules.php?name=RR&stid=17 . \n\nHope that Helps :)
51986
Are you referring to millimeter wave radar? I'm not familiar with any system that includes lasers.\n\nMillimeter wave radar is just radar of a particular band (somewhere between 30 GHz and 300 GHz). Some applications include cloud radar to detect the tops and bottoms of clouds; using doppler techniques to detect vertical movement within a cloud; and adaptive cruise control in cars to maintain a pre-set distance.
1105659
D'un point de vue mathématique, calculer la vitesse de la balle revient à résoudre un système de n équations différentielles avec conditions initiales. C'est un peu laborieux, donc dans la pratique on utilise effectivement un radar à effet Doppler, le plus souvent sous forme de canon.\n\n Ce radar est pourvu d'un émetteur à radio-fréquences (dans la gamme des micro-ondes) dont les ondes sont réfléchies par la balle en déplacement. Le délai de retour de l'onde est proportionnel à la vitesse de la balle. Ce délai est amplifié, filtré et analysé par une puce DSP qui pratique une correction d'erreurs et envoie les données analogiques à l'afficheur. \n\nA noter que les joueurs amateurs peuvent eux aussi chronométrer leur coup droit, grâce à un module de type Speed Trac qui s'accroche sur le filet. Ludique et pas trop cher.
388065
This is due to the doppler radar effect.  The wavelength of the reflected sound waves from an object travelling toward you is short (blueshift) whereas the wavelength from a receding object is long (redshift)
161236
WHAT ARE YOU LOOKIN FOR? IS IT THE HARDWARE TOWER ANTENNA, TRANSMITTER/ RECEIVER , DISPLAY??????\n\nWhat specification\n\nWhat are they looking for is it a weather radar or is it a navigation radar.  IS is used for landing aircraft aboard the rig?  Is the rig on the land or is it in the water.  Is the rig in the Gulf of Mexico or is it in the North Atlantic. If it is in some body of water what body.  If it is land bound where?  Is it within 150 miles of an airport?\n\nWhere is the rig located and what does the radar need to see?  Is it for the Weather or Aircraft?\n\nWHAT IS THE FUNCTION OF THE RADAR ON THE RIG IF IT IS AN OIL DRILLING RIG???\n\nWHAT DOES TEXACO NEED RADAR FOR ???\n\nBe glad to help \n\nAPS
607361
Actually NOAA has quite a handful of planes with high-quality radar, and they do use them in such projects.  I direct you to http://www.stormresearch.com/vortex/ for one such project, and http://www.ucar.edu/communications/newsreleases/2002/ihop.html for a more recent project on rain.\nI am currently related to a project looking at some high resolution Dopplar data from a hurricane a few years back while it was over the ocean.\n\nRegular WSR-88D Dopplar (the network the NWS uses) is decently effective at general alerting to possible tornadic storms... and it would be extremely expensive to send planes out all the time just for warning purposes (though there is a new test-project to setup a larger network of low cost radars to improve warnings a lot (http://www.casa.umass.edu/)).\n\nBut there are some things regular 88Ds can't give us, including:\n- better time and spatial resolution of features (we want to be near a tornado to get a more precise view of what it looks like, and WSR88Ds only update something like every 5 minutes because they scan the entire 360 degree sky)\n- the vertical wind fields.  You need at least two properly located radars to get the full 3-dimensional structure of winds... and this is crucial to understanding what's actually happening in a storm.\n\nSo, yes, portable Dopplars are very useful.  They also help us look at weather in places where we don't/can't have any fixed radars (like at sea or in mountain ranges).\nGenerally, portable radars on trucks will get us the same information, are much cheaper (and safer) to transport, you don't have to worry about removing the motion of the radar (planes are moving, trucks can be stopped), and you don't have as much trouble with beams hitting the ground... and thus most of our tornado information comes from truck-mounted radars like the famous Dopplar on Wheels (http://aaron.ou.edu/dow/dow.htm).  However, there are some reasons to use planes even in such experiments, including better upper-level resolution, the ability to reposition quicker, and the fact that trucks can only hold and power radars that are a cerain size.\n\nPlanes are indeed useful, and hopefully we'll continue to get better ones for research... as they really can provide quite a great suite of information (dropsondes (weather sensors that are dropped from airplanes) are also great because they give a rather quick profile of the atmosphere)!\n\nAwesome question!\n\nHope I helped answer things,\nGod bless,\nShane
26442
Radar guns get two signals returned; one is the reflection from the target car, and the other is the reflection from everything around it (particularly from the road).  If the police car is not moving, then only the target car's reflection is Doppler shifted.  But if the police car is moving, then both the road reflection and the target car's reflection are Doppler shifted.  \n\nSome radar guns (called moving mode radar) can measure the difference in Doppler shift between these two signals, and thus measure the speed of the target car relative to the roadway.  Other radar guns (stationary mode) just pick the target car signal and will not work at all from a moving police car. If the police car were moving, a stationary mode radar will interpret the ground reflection as a target car reflection and will only report the police car's speed, regardless of what the target car is doing.  In otherwords, a policeman never just "adds his speedometer reading to the radar gun speed" as the previous answer said.\n\nThe important trick is that the target car must be moving either away form or towards the radar gun (whether stationary mode or moving mode), within about +/- 12 degrees, otherwise the radar gun will report a lower speed than the actual target car speed.
241465
No. Wave dispersion separates frequencies. The Doppler effect is caused by motion towards or away from a source, altering the perceived frequency.
28138
Infrared. Radar. Sonar. does that help?
397942
Air and Spaceborne Radar Systems - An Introduction \nBy: Lacomme, P.; Hardange, J-P.; Marchais, J-C.; Normant, E. © 2001 William Andrew Publishing/Noyes; This book focuses on the history, main principles, functions, modes, properties, and specific nature of modern airborne radar.\nhttp://www.knovel.com/knovel2/Toc.jsp?BookID=262\n\n\nRADAR SYSTEMS\nENGINEERING HANDBOOK\nhttps://ewhdbks.mugu.navy.mil/
1041802
Could not find a word to fit the gaps however found this website which might help.\n\nhttp://www.engr.mun.ca/~ggeorge/astron/blackholes.html\n\nP.S. The Doppler effect actually affects frequency so can be observed in sound, LIGHT and electromagnetic radiation.
214158
Well in some cases yes, in others, no. In the USA the three main Ka frequencies are 33.8(MPH industries) 34.7(Stalker Radar) and 35.5(Talon and Dectuar radar). And some of these guns are used in some other countries as well. In some europe countries they use Ku-band(13.400 GHz ± 25 MHz) radar guns which some american radar detectors detect\n\nIn many areas besides the US there are fixed cameras used which use 34.3 MHz which is extremely hard to detecto unless a radar detector is tuned into that frequencies. That is why you might not be able to use an american bought radar detector in another country. However there are some that that you can purchase to use every where, like the BEL 990 internation, BEL v995 international, BEL rx65 (in international mode), BEL 975r, or Valentine 1\n\nI found one website that might help you understand the different frequencies used for radar.\nhttp://copradar.com/preview/xappA/xappA.html
37112
A pamphlet of scanner frequencies is usually available at the track, or you can check out this link:\n\nhttp://www.jayski.com/links/scanners.htm
211329
ABOVE IS A TRAITOR,SCUM (TO YAHOO!)\n\nIF I LIVED IN  PEORIA ILLINOIS, UNITED STATES OF AMERICA NA , MY TRUE LOYALTIES WOULD LEAD ONE TO THE TRUE DOPPLER RADAR PLACE AND THAT IS  >>>>>>> Y A H O O  ! <<<<<<< WEATHER.  ALAS YAHOO! WEATHER, CAN ANSWER THIS QUESTION.\n\nWHY SEARCH FURTHER WHEN THE ANSWER IS UNDERNEATH YOUR NOSE!  \n\nOF COURSE YOU CAN GO TO THE FAA .GOV  AND THOSE OTHER UNNECESSARY SITES ---- GO TO YOUR AIRPORT SITE  AND SEE.\n\nHAVE FUN AND A GOOD DAY!\n\nYAHOO! IS ALL YOU NEED !\n\n\nAPS
24203
The 'Doppler Shift' indicates the color or wavelength of light.  Light traveling toward you would be more in the red end of the spectrum, while light traveling away would be more in the blue end.