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17 Radio-Navigational Speed and Drift Angle Meters
Fig. 17.2 Doppler spectra of signals
frequencies in each pair of beams become diverse, i.e., f Dk = | f Dm |, f Dl = | f Dn |.
In this case, spectrums’ medium frequencies of each pair of beams are calculated
(Fig. 17.2b):
f Dkm =
1
2
( f Dk + | f Dm |),
(17.11)
f Dln =
1
2
( f Dl + | f Dn |).
(17.12)
Considering (17.7)–(17.10), we can write down the following:
f Dkm =
2
λ 0
(W x cos θ cos γ a − W z cos γ a sin θ ),
(17.13)
f D ln =
2
λ 0
(W x cos θ cos γ a + W z cos γ a sin θ ).
(17.14)
As can see, at pairwise signals processing, an information on W y is faded, and
determination algorithm of angle drift and ground speed vector is reduced to the
following expressions:
tgα =
f Dln − f Dkm
f Dln + f Dkm
ctgθ,
(17.15)
W = λ 0
f Dln + f Dkm
4 cos θ cos γ a cos α
.
(17.16)
At separate signals processing, an information is processed on each beam. In
this case, expressions for calculation of ground speed vector of (18.7)–(18.10) are
excessive and we can step to three-beam systems, for which values of ground speed
vector components are calculated in accordance with following formulas: