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Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

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Chapter 3 / Sensors / Radar<br />

_ _<br />

3.8 Radar<br />

3.8.1 Description<br />

The radar model in Figure 3-38 comprises an electro-mechanical gimbal<br />

arrangement pointing an electro-optical detector; a decomposition shown in<br />

Figure 3-39. For simplicity, the radar tracks the missile and a single target<br />

"simultaneously" forming separate beams along the predicted LOS to each<br />

object, whereas in reality the beams would be multiplexed.<br />

5<br />

GUI<br />

F_E_AT<br />

GIMBAL DEMAND<br />

1533 I/F<br />

1<br />

2<br />

3<br />

4<br />

PX_TOT<br />

VX_TOT<br />

THT_AT<br />

PSI_AT<br />

D_THT_AT<br />

D_PSI_AT<br />

3.8-1<br />

M_PX_TOT<br />

M_VX_TOT<br />

M_THT_AT<br />

M_PSI_AT<br />

GROUND<br />

BASED RADAR<br />

TARGET RANGE<br />

1553 I/F<br />

M_PX_TOT I_PX_TOT<br />

TARGET RANGE<br />

RATE 1533 I/F<br />

M_VX_TOT I_VX_TOT<br />

TARGET ELEVATION<br />

1553 I/F<br />

M_THT_AT I_THT_AT<br />

TARGET BEARING<br />

1533 I/F<br />

M_PSI_AT I_PSI_AT<br />

Figure 3-38 : Radar Model<br />

The model has been characterised as a static phased array radar operating in<br />

the North Atlantic Treaty Organisation (NATO) F band. Surveillance prior<br />

to dedicated target tracking is ignored, however, the expected beam pointing<br />

error when switching modes is approximately 1/12 of the beam-width. For<br />

convenience, the detector reference point is located at point (o) the origin of<br />

the Alignment frame. It is with respect to this frame that the radar provides<br />

target and missile range, range rate, bearing and elevation measurements.<br />

3.8.2 Gimbal Demands<br />

The detector boresight initially points north and is elevated to 45° the<br />

missile and target beams formed with locked gimbals remaining within the<br />

maximum squint angle for the trajectories described in §2. If the gimbals<br />

are free, the radar uses low frequency (LF) gimbal demands at its output<br />

interface rate (RDfO) of 10 Hz (clock 18), from one of the following sources<br />

depending on the value of GB_TR_DS:<br />

1 Reference angles<br />

2 Radar detector outputs<br />

1<br />

2<br />

3<br />

4

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