雷达测距.pdf

文档介绍：雷达测距、测速、测角和跟踪
¾雷达测距、测速、测角和跟踪
¾ Range Measurement
¾MTI与脉冲多普勒雷达
¾ Velocity Measurement
¾ Radar Measurement Uncertainty
(Certainty of the Uncertainty Principle)
¾ Angle Measurement
¾ Radar Tracking
X. Xu: Theory of Modern Radar Systems, Class-09 1 X. Xu: Theory of Modern Radar Systems, Class-09 2
Range Measurement The Maximum unambiguous range
1
R = ct
2 R
X. Xu: Theory of Modern Radar Systems, Class-09 3 X. Xu: Theory of Modern Radar Systems, Class-09 4
1 c
Rmax = ct P =
2 2 f P
1 c
Rmax = ct P =
2 2 f P
X. Xu: Theory of Modern Radar Systems, Class-09 5 X. Xu: Theory of Modern Radar Systems, Class-09 6
门限与脉冲前沿相交处的噪声电压
Range Measurement Accuracy: S = n(t) / ∆T
ln R 时延测量误差
c
δR = δt
2 R
Sl0 = A/ trise
X. Xu: Theory of Modern Radar Systems, Class-09 7 X. Xu: Theory of Modern Radar Systems, Class-09 8
假定无噪声的脉冲和有噪
声的脉冲之间的上升斜率相等, 如果脉冲的上升沿受到矩形中频滤波器的带宽限制,近似为
则
A n(t)
= trise ≈ 1/ B
trise ∆TR
令 S = E /τ
t
所以, ∆T = rise
R A
n(t) N = N 0 B
trise
δTR = var()∆TR =
2 2 则有τ
A / n 脉冲宽度
δTR =
2BE / N 0
或表示为信噪比关系:
精确的时延测量要求发噪声功率谱密度
t 射脉冲具有陡峭的上升沿和
rise 矩形滤波器的频带宽度信号能量
δTR =
2S / N 高的脉冲峰值。
X. Xu: Theory of Modern Radar Systems, Class-09 9 X. Xu: Theory of Modern Radar Systems, Class-09 10
时延精度与有效带宽
当同时用脉冲前沿和后沿进行时延测量,且脉冲前后沿的噪声是不相 1
关的,则通过求平均,上述均方根误差可以减小2 倍,即时延精度: δTR =
β 2E / N 0
τ∞
2
δTR = (2πf ) 2 S( f ) df
∫∞
4BE / N 1 2
0 有效带宽: β 2 = −∞= (2πf ) 2 S( f ) df
∞ E ∫
∫ S( f ) 2 df −∞
−∞
S( f ) 2 的归一化二阶中心矩;
S( f ) 的频谱能量越朝两端汇聚,则有效带宽就越大,时延(距离)
的测量精度越高.
X. Xu: Theory of Modern Radar Systems, Class-09 11 X. Xu: Theory of Modern Radar Systems, Class-09 12
Velocity Measurement
高分辨力成像中的“测距”:
连续波(CW)多普勒雷达:
1
可采用短脉冲、LFM、SFW等波形。 V = λf
2 d
X. Xu: Theory of Modern Radar Systems, Class-09 13 X. Xu: Theory of Modern Radar Systems, Class-09 14
脉冲多普勒(Pulsed Doppler)雷达:
X. Xu: Theory of Modern Radar Systems, Class-09 15 X. Xu: Theory of Modern Radar Systems