QUIZ 1 QUESTION 1 In a Sidelooking Radar

QUIZ 1

QUESTION 1 • In a Side-looking Radar (SLR) system in Figure 1, what will happen if; – the slant-range distance between the building is less than – the slant-range distance between the building is greater than 10 marks

• The slant-range distance between the buildings is less than PL/2. • The pulse had time to travel to B and have its echo return to A, while the end of the pulse A continues to be reflected. • The 2 signals are overlapped and will be imaged as one large object extending from building A to B.

• If the slant range distance between A and B is greater than PL/2, the 2 signal will be receive separately resulting 2 separate image response. • Thus, the slant range resolution of and SLR system is – independent of the distance from the aircraft – Equal to half the transmitted pulse length

QUESTION 2 • With the help of a diagram, explain the basic operating procedure of a side looking radar (SLR) ? 40 marks

Side-looking Radar (SLR) • Microwave energy transmitted from an antenna in very short bursts or pulses. • The high energy pulses emitted over a time period on the order of microseconds (10 -6 sec). • The propagation of one pulse is shown by indicating the wavefront locations at successive increments of time. • Beginning with the solid lines (labeled 1 – 10), the transmitted pulse moves radially outward from the aircraft in a constrained (narrow) beam.

Cont… • After time 6, the pulse reach the house • A reflected wave (dashed line) is shown beginning at time 7. • At time 12 the return signal reaches the antenna and is registered at that time on the antenna response graph. • At time 9, transmitted wavefront is reflected of the tree and reached antenna at time 17. • Because the tree is less reflective of radar waves, a weaker response is recorded.

Side-looking Radar (SLR) Basic operating principle Return from house Pulse strength High energy output pulse Return from tree 0 2 4 6 Time 8 10 Figure 5. 2 12 14 16 18

Cont… • By electronically measuring the return time of signal echoes, the range or distance between the transmitter and reflecting object may be determined. • The slant range to any given object is: SR = slant range (direct distance between transmitter and object) c = speed of light (3 x 108 m/sec) t = time between pulse transmission and echo reception