PSEUDO-RANGE & PHASE DATA COMBINATIONS FOR MULTIPATH STUDIES |
The interesting characteristic about eqn (6.4-28)
is that it is both "geometry-free" (as in the case of eqn (6.4-14)) and "ionosphere-free" (as
in the case of eqn (6.4-7)). Furthermore,
what is missing in the above expression are the components of pseudo-range
and carrier phase noise, and the corresponding multipath components.
Under the assumption that multipath and noise in the carrier phase measurements
is negligible in comparison to the P(L1) multipath and noise,
this linear combination of code and phase essentially gives the C/A or P1
multipath mp(P1) and noise 
(P1) -- offset by a constant
component due to the carrier phase ambiguities:
a3.P(L1) + b3. (L1)
+ c3.(L2) = mp(p1) + (p1)
+ n1 – d3.n2 |
(6.4-29a) |
or, K1 = (n1 - d3.n2)/a3
:
| P(L1) – 4.0915.(L1) + 3.0915.(L2)
= mp(p1) + (p1) + K1 |
(6.4-29b) |
A similar expression for multipath on the L2 pseudo-range is:
| P(L2) – 5.0915.(L1) + 4.0915.(L2)
= mp(p2) + (p2) + K2 |
(6.4-30) |
Values of ( mp(p1) + (p1) ) can be computed
and plotted to evaluate the mutipath disturbance environment on pseudo-range
data (a good indicator that it is also present in the carrier phase data,
but at a substantially lower level).
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© Chris Rizos, SNAP-UNSW, 1999