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

Chapter 3 / Sensors / Radar
_ _
Figure 3-42 and Figure 3-43 show the non-dimensional glint error and the
normalised RCS for a target rotating at 1 Hz with respect to the target sightline
with the radar operated at 20 Hz.
3.8.8 Sensor Limitations
Provision of radar range, range-rate, bearing and elevation measurements of
the target and missile at the sensor interface depends on:
• User target measurement selection ( MS_MSAV1 bits 17 to 20 cleared )
• User missile measurement selection ( MS_MSAV1 bits 21 to 24 cleared )
• Range limiting ( GB_TR_ER bit 20 is set )
• Squint threshold limiting ( GB_TR_ER bit 21 is set )
• Out-of-beam limitations ( GB_TR_ER bit 22 is set )
• Fade ( GB_TR_ER bit 23 is set )
When active, if any of these limitations are violated, bits 1-4 in the
measurement ready flag MS_MSRY1 are cleared. Failure to provide
measurements at the user request is indicated by setting bits 1-4 of
GB_TR_VF depending those measurements affected.
Measurements are provided if the target (or missile) range is within
[RMIN,RMAX], defaulting to [1,60] km. Failure to provide target
measurements due to minimum or maximum range limiting is indicated by
setting bits 5-6 of GB_TR_VF respectively, and bits 7-8 of GB_TR_VF for
the missile measurements.
The beam angle with respect to the detector boresight is usually restricted to
prevent excessive squint losses. Trunk [T.2] determined that the optimum
number of phased array faces was 3, a maximum squint angle (ξSQ) of 60°.
Target and missile measurements are only provided when the off-boresight
beam angle is less than the maximum squint angle,
⎛
⎜
⎜
⎜
⎝
ξ
ξ
T
M
T A M A
( T , T ) : = ( T ⋅ T , T ⋅ T )
T
TD
L
M
TD
TD
⎞
⎟
⎟
⎟
⎠
TD
3.8-16
A
TD
T
T
( cosΘ
⋅ cos Ψ )
⎛ −1
cos
⎞
⎜
TD TD ⎟
: = ⎜
L
⎟ ≤ RDξ
⎜ −1
M
M ⎟
⎝
cos ( cosΘ
TD ⋅ cos ΨTD
) ⎠
A
TD
Equation 3.8-58
SQ
Equation 3.8-59
Failure to provide measurements due to excessive squint is indicated by the
setting of bits 9-10 in GB_TR_VF for the target and missile respectively.
Measurements are also suspended if the target (or missile) lies outside a
beam angle (RDξBW) of ± 2°,