5.2 Accuracy of Radar Location and Radio Navigation Systems
99
Fig. 5.12 Clarification to
accuracy of object position
finding through dead
reckoning method
W x = W
x cos 0 − W
y sin 0 ,
W y = W
x sin 0 − W
y cos 0 .
(5.53)
Herewith, equations of Doppler dead reckoning (5.52) become a form:
x(t) = x 0 +
t
t 0
W
x cos 0 − W
y sin 0
dt,
y(t) = y 0 +
t
t
W
x sin 0 − W
y cos 0
cos
x
R
dt.
(5.54)
Accuracy of Doppler dead reckoning is usually characterized by mean-square
value σ r of radial error of object position finding, which at independent values x(t)
and y(t) equals:
σ r (t) =
σ 2
x (t) + σ 2
y (t),
(5.55)
where σ
2
x (t) and σ
2
y (t) are the dispersions of object coordinates finding errors in axes
OX and OY.
In each time moment (point) t, instantaneous values of coordinates calculation
errors of an object are determined by equations:
x(t) = x m (t) − x(t), ,y(t) = y m (t) − y(t),
(5.56)