LDI DIGISONDE 4D - Figure 1-11: Natural Timing Limitations for Monostatic Vertical Incidence Sounding

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DIGISONDE-4D
SYSTEM MANUAL
VERSION 1.2.11
SECTION 1 - GENERAL SYSTEM DESCRIPTION 1-19
Figure 1-11: Natural Timing Limitations for Monostatic Vertical Incidence Sounding
1:36. The autocorrelation function as applied to code compression in the DPS is defined as:

+=
n
knpnpkR )()()(
1-6
Therefore the ideal as described above is R(k) = (k).
1:37. For ionospheric applications, the received spread-spectrum coded signal, r(t), may be a superposition of
several multipath echoes (i.e., echoes which have traveled over various propagation paths between the transmit-
ter and receiver) reflected at various ranges from various irregular features in the ionosphere. The algorithm
used to perform the code compression operates on this received multipath signal, r(t), which is an attenuated
and time delayed (possibly multiple time delays) replica of the transmitted signal s(t) (from Equation 1-5),
which can be represented as:
( )

=
−=
P
i
ii
tsatr
1
)(

or
( )
 
ii
P
i
i
tfjtpatr  −−=

=
0
1
2exp)(
1-7
where  shows that the P multipath signals sum linearly at the receive antenna, a
i
is the amplitude of the ith
multipath component of the signal, and 
i
is the propagation delay associated with multipath i. The carrier
phase 
i
of each multipath could be expressed in terms of the carrier frequency and the time delay 
i
; however,
F2
525 km
E
90 km
Tx
Rx
Tg = 0 s
Te = 600 s
Tf = 3.5 ms
VIS1-5
Not to scale