A paper onRADAR ANTENNA COMMUNICATIONTo TECHNOBRAIN-2009ATST.JOHNS COLLEGE OF ENGINEERING & TECHNOLOGYBY P.UJVALAV.HARITHA 064!A04"" 064!A04A III B.TECHIII B.TECH#$%$#&'$.()*&+&,-.&$+./0. 1&2$'1&.*332+&,-.&$+./0.92483597629703921024FROMGUDLAVALLERU ENGINEERINCOLLEGEGUDLAVALLERUAbstract : This paper deals with Terminal DopplerWeather Radar (TDWR) installed in airportsto provide wind shear detection services andprecipitationreflectivitydatatocontrollersand supervisors. The TDWRs narrow beamand aggressive ground clutter suppressionalgorithms provide excellent data onboundary layer reflectivity and winds inparticular the locations of thunderstormoutflow boundaries. These data are nown tobe essential for providing high resolutionconvective weather forecasts out to twohours. !imilarly" itsnarrowbeamcouldbeuseful for detection of severe weathersignatures (e.g." tornado vortices) with smalla#imuth extent. Relative to the Weather!ervice Radar $$%D(&'(R)D) it scansrapidly (e.g." surface updates once perminute)" facilitating monitoring of rapidlyevolving low altitude wind shear ha#ards. *tis typically located near to population centersand congested airspace" sothat it is wellsituatedforsupportingweatherservicesforoperationally important areas. )s the name suggests" the Terminal DopplerWeather Radar (TDWR) was purposely builtto serve the terminal area of the airport. *tsmission is to detect wind shear and so as toenhance the safetyof aircraft landingandtaeoff. *t is locatednear the airport at adistance of +, m so that it has a clear viewof the runways" airport approach anddeparture #ones. TheTDWRisspeciallydesignedtooperate in a high clutter environmentnormally present in the vicinity of airports. *tmaes use of a variety of methods tominimi#e clutter and to eliminate theinfluence of suchmovingtargets as birds"aircrafts.TDWR ARCHITECTUREThe TDWR system was designed and built inthelate+-$.s" andis encounteringissuesrelated to parts obsolescence. To ensure thatthe system continues to be maintainable" the/)) has commenced a !ervice. 0ife'xtension 1rogram (!0'1) to improvesupportability and" where appropriate"introduce improved capability. ) simplified bloc diagram of theTDWR is shown in /igure. The R12subsystem" shown in green on the upper left"has recentlybeenre%hostedfroma 3arris&ighthaw 4&*( system to one based on a pair of redundant !2* 5rigin computers. Thenext ma6or digital subsystem to be addressed"and the focus of this paper is the RD)"which includes the receiver and D!1subsystems. The existing TDWR D!1subsystem hardware consists of a mixture of75T! and custom cards" installed in a single+-8 9ultibus systemchassis. The 75T!boards include a :$.,.%based single%board F$-(23 2.A$2 T2&44$/ C05'20+ A5&+6%$%computer (!;7) and a !7!* and serialcontroller. Thecustomcomponents includefive boards to handle the )/Rinclude an airspeed indicator"altimeter" andmagnetic directionindicator.9inimum flying conditions in radar%controlled airspace in transition areas specifya cloud ceiling about ,+? m (@.. ft) above ground level and +.: m(+ mi)visibility. 5ther >/R re=uirements forvisibilityanddistancefromclouds dependon altitude and whether operation is incontrolled or uncontrolled airspace. >/Rflight isnot permittedinall airspaces" andterminal control areas sometimes re=uirepositive (radar) air traffic control. )irporttraffic areas typically encompass a radius of$ m (? mi) and are extended laterally for thecontrol of instrument%dependent departuresand landings. 7ontrol #ones around airportsextend upwards with no limit.UP!A"AT#$% $& !A"A!'WEATHER SERVICE RETIRES LAST OF OLD RADARThe new radars are more sensitive" which means they can detect more weather details than the old ones could. also means they can detect wind speeds and directions" giving a much betterpicture of bad weather. The new radars mae extensive use of computers" which means they can be programmed to sound an alarm when weather patterns are beginning to appear dangerous. With the old radars" someone had to watch the screen constantly when storms were possible to mae sure nothing important was missed. A*t too considerable sill todetermine storm intensities from greenblotches on the radar scope"A said !teveRich" meteorologist%in%charge of the7harleston office. A*t too even greater sillto tell if a storm had tornado characteristics.A0ie the user%friendliness built into much oftodayBstechnology" thenewDopplerradarsproduce highly accurate stormsignatures.A/or the first time in history" we are now abletobroadcast atornadowarningforagivenarea before a tornado is formed"A Rich said.AThis is a remarable technologicalachievement and has already saved manylives.8THE DOPPLER EFFECT"The obsere! cha"#e $" the%re&'e"c( o% so'"! or e)ectro*a#"et$c+aes!'etothere)at$e*ot$o"so% theso'rce a"! obserer,"The Doppler 'ffect is best describedby the change in pitch of a trains whistle asthe train passes by your position. The pitchof the trains whistle changes because thefre=uency