• 360° Protection against all types of Laser
• X, K, Ka, and Super Wideband Ka Detection
• VG-2 Undetectable
• Spectre I Undetectable
• Instant-On (Pulse) Detection
• Cordless Option
• Alpha Numeric Display With Backlight
• 8 Level Signal Strength Indicator
• Low Battery Indicator
• Auto Power Off
• Retains Memory After Power Off
• Teach/Tutorial Mode
• Muting
• 3 Filter Modes: FILTER-NORMAL, FILTER-HIGH, and FILTER-OFF
• Volume Control
• Self Test

• Windshield Bracket (2 styles)
• Visor Bracket
• Dashboard Hook and Loop Fasteners
• 10 Retaining Clips
• Coiled Power Cord
• Straight Power Cord
• Two AA Batteries

Mai multe despre radare

Radarul este practic un dispozitiv de masurare a vitezei. Este format dintr-un transmitator, un receptor, o antena si un sistem electronic pentru a procesa si inregistra datele. Transmitatorul genereaza pulsuri scurte si succesive ( sau pulsuri de microunde (A) la intervale regulare care sunt concentrate de antena intr-un singur fascicul (B). Fasciculul radar lumineaza suprafata oblica la un unghi potrivit fata de sensul de miscare a platformei. Antena primeste o parte din energia reflectata de la diverse obiecte (C). Prin masurarea timpului petrecut de unda de la transmitere pana la receptionare radarul masoara intarzierea cu care acesta se intoarce si determina viteaza masinii. Pe masura ce automobilul se indeparteaza radarul primeste semnale, le inregistreaza si le proceseaza construind o imgine bidimensionala a suprafetei.

In timp ce am caracterizat radiatia electromanetica in portiuni visibile si infrarosii a spectrului in principal prin lungimea udei, portiunile in microunde ale spectrului sunt deseori referite in cele doua moduri lungime de unda si frecventa. Regiunea in microunde a spectrului este destul de larga, in comparatie cu infrarosu si exista cateva lungimi de unda sau benzi folosite denumite dupa niste litere in al doilea razboi mondial si care au ramas pana azi.

      Benzile Ka, K, si Ku: lungimi de unda foarte scurte folosite la primele sisteme radar aeropurtate.
      Banda X: folosita intensiv pe aparatele aeropurtate pentru recunoastere militare si cartografierea terenului.
      Banda C: foarte folosita pe multe sisteme de cercetare aeropurtate(CCSR Convair si NASA AirSAR) si pe sistemele spatiale (incluzand satelitii)
      Banda S: Folosita pe satelitii facuti in Rusia ALMAZ
      Banda L: Folosita pe satelitii Americani SEASAT si cei Japonezi JERS-1 si totodata pe sistemele aeropurtate de la NASA.
      Banda P: Cea mai lunga lungime de unda, folosita pe sistemele experimentale de cercetare de la NASA.

2 imagini radar ale aceluiasi teren agricol

Mai sus sunt 2 imagini radar ale aceluiasi teren agricol, fiecare imagine fiind colectata folosind o banda radar diferita. Prima imagine s-a realizat folosind banda C si cea de jos a fost realizata folosind banda L. Se poate vedea clar semnificantele diferente dintre diferitele campuri. Aceasta se intampla datorita faptului ca energia benzii radar interactioneaza in mod diferit in functie de lungimea undei radar.

Antunci cand se vorbeste despre ergia microundelor, polizarea radiatiei este la fel foarte importanta. Polarizarea se refera la orientarea campului electric. Cele mai multe radare sunt construite sa transmita radiatie prin microunde fie polarizata orizontal (H) fie polarizata vertical (V). Similar antena primeste fie energie polarizata orizontal fie energie polarizata vertical. Unele radare pot le pot primii pe amandoua. Aceste doua polarizari sunt redate de literele H pentru orizontal si V pentru vertical. Totusi aici pot fii 4 combinatii pentru amandoua sa transmita si sa primeasca polarizari dupa cum urmeaza:

     HH – pentru transmitere orizontala si receptionare orizontala.
     VV – pentru transmitere verticala si receptare verticala.
     HV – pentru transmitere orizontala si receptionare verticala.
     VH – pentru transmitere verticala si pentru receptionare orizontala.

Primele doua combinatii de polarizare se refera la polarizare egala deoarece polarizarile trimitere si receptare sunt la fel. Ultimele doua combinari se refera la polarizare incrucisata deoarece felul polarizarii transmise este opusul polarizarii receptate. Aceste imagini in banda C ale campurilor agricole demonstreaza variatia in raspunsurile radarului in urma schimbarii polarizarii. Cele doua imagini de jos sunt egal polarizate (HH, respectiv VV) si imaginea din coltul de sus dreapta este polarizata incrucisat (HV). Imaginea din coltul de sus stanga este rezultatul afisarii polarizarilor combinate impreuna, fiecare printr-o culoare primara (rosu, verde si albastru). Similar variatiilor in lungimea de unda, depinzand de polarizarea transmisa si primita, radiatia o sa interactioneze cu  aceasta si va fii reflectata diferit de la suprafata. Ambele, adica lungimea de unda si polarizarea afecteaza modul cum un radar vede suprafata. Asadar se colecteaza mai multe imagini folosinduse diferite combinatii intre polarizare si lungimea de unda pentru a obtine informatie complementara despre tintele de la suprafata.

Microwave remote sensing
Radar Basics

As noted in the previous section, a radar is essentially a ranging or distance measuring device. It consists fundamentally of a transmitter, a receiver, an antenna, and an electronics system to process and record the data. The transmitter generates successive short bursts (or pulses of microwave (A) at regular intervals which are focused by the antenna into a beam (B). The radar beam illuminates the surface obliquely at a right angle to the motion of the platform. The antenna receives a portion of the transmitted energy reflected (or backscattered) from various objects within the illuminated beam (C). By measuring the time delay between the transmission of a pulse and the reception of the backscattered "echo" from different targets, their distance from the radar and thus their location can be determined. As the sensor platform moves forward, recording and processing of the backscattered signals builds up a two-dimensional image of the surface.

While we have characterized electromagnetic radiation in the visible and infrared portions of the spectrum primarily by wavelength, microwave portions of the spectrum are often referenced according to both wavelength and frequency. The microwave region of the spectrum is quite large, relative to the visible and infrared, and there are several wavelength ranges or bands commonly used which given code letters during World War II, and remain to this day.

• Ka, K, and Ku bands: very short wavelengths used in early airborne radar systems but uncommon today.
• X-band: used extensively on airborne systems for military reconnaissance and terrain mapping.
• C-band: common on many airborne research systems (CCRS Convair-580 and NASA AirSAR) and spaceborne systems (including
• ERS-1 and 2 and RADARSAT).
• S-band: used on board the Russian ALMAZ satellite.
• L-band: used onboard American SEASAT and Japanese JERS-1 satellites and NASA airborne system.
• P-band: longest radar wavelengths, used on NASA experimental airborne research system.

Two radar images of the same agricultural fields
Here are two radar images of the same agricultural fields, each image having been collected using a different radar band. The one on the top was acquired by a C-band radar and the one below was acquired by an L-band radar. You can clearly see that there are significant differences between the way the various fields and crops appear in each of the two images. This is due to the different ways in which the radar energy interacts with the fields and crops depending on the radar wavelength. We will learn more about this in later sections.
When discussing microwave energy, the polarization of the radiation is also important. Polarization refers to the orientation of the electric field (recall the definition of electromagnetic radiation from Chapter 1). Most radars are designed to transmit microwave radiation either horizontally polarized (H) or vertically polarized (V). Similarly, the antenna receives either the horizontally or vertically polarized backscattered energy, and some radars can receive both. These two polarization states are designated by the letters H for horizontal, and V, for vertical. Thus, there can be four combinations of both transmit and receive polarizations as follows:

• HH - for horizontal transmit and horizontal receive,
• VV - for vertical transmit and vertical receive,
• HV - for horizontal transmit and vertical receive, and
• VH - for vertical transmit and horizontal receive.

The first two polarization combinations are referred to as like-polarized because the transmit and receive polarizations are the same. The last two combinations are referred to as cross-polarized because the transmit and receive polarizations are opposite of one another. These C-band images of agricultural fields demonstrate the variations in radar response due to changes in polarization. The bottom two images are like-polarized (HH and VV, respectively), and the upper right image is cross-polarized (HV). The upper left image is the result of displaying each of the three different polarizations together, one through each of the primary colours (red, green, and blue). Similar to variations in wavelength, depending on the transmit and receive polarizations, the radiation will interact with and be backscattered differently from the surface. Both wavelength and polarization affect how a radar "sees" the surface. Therefore, radar imagery collected using different polarization and wavelength combinations may provide different and complementary information about the targets on the surface.