Deteksi Radar Terhadap Multi-Object Bergerak Dengan Pemrosesan Doppler

In general, Radar or Radio Detection and Ranging is an electromagnetic wave system that is useful to measure distance and answer and make maps of surrounding objects. Radar has an advantage compared to other navigation tools, which is that radar does not require a transmitter station as a transmitter. Radar has an electronic wave emission principle that emits short radio wave pulses emitted in a narrow beam by a directional antenna. In this study, a multi-object radar detection simulation was carried out using Dopler processing both MTI and PDP, which later on the radar will detect related objects. Multi-object here is a condition that is achieved when a navigation radar detects more than one object. The result of this research is a multi-object detection process using the MTI and PDP methods and the matched-filter obtained from the predetermined data. So Doppler processing aims to mitigate the clutter signal to improve the detection performance of moving targets even though there is a dominance of signals originating from stationary clutter.

46. The structure of the solar chromosphere from centimetre-wave radio observations

The atmosphere of the sun is transparent to visible radiation, is nearly transparent to millimetre and centimetre radio radiation, and becomes opaque to the metre and longer wave radiation. Information about the chromosphere can then be given by observing the radiation from the sun at short radio wave-lengths. In its outer part, the atmosphere of the sun is highly ionized. Absorption in any region is directly proportional to the square of the density and the wave-length squared and inversely to the temperature to the three-halves power This is the familiar equation for the absorption of radio waves in an ionized medium. By consequence of this, the longer wave radiation is absorbed in the outer layers of the sun's atmosphere and can escape only from these outer regions. The shorter wave-length radiation is absorbed very little in the outer part of the solar atmosphere where the density is quite low, and hence radiation from the chromosphere escapes as centimetre and millimetre radio waves. In fact, the principal radiation from the sun in the centimetre and millimetre region comes from the chromosphere.