PSEUDO-RANGE & PHASE DATA COMBINATIONS FOR AMBIGUITY RESOLUTION |
The combination of eqns (6.4-14) and (6.4-15) leads to the following "geometry-free"
relation (neglecting noise terms):
 |
(6.4-24) |
Eqn (6.4-17) can be modified to include the P(L6) narrow-lane component (eqn (6.4-21)):
 |
(6.4-25) |
where the wide-lane ambiguity can be isolated (Note, small noise on P(L6)):
 |
(6.4-26a) |
Using a similar approach leads to an ionosphere-free expression for the narrow-lane ambiguity (note, unlikely to be useful because of high noise on P(L5)):
 |
(6.4-26b) |
A combination of eqns (6.4-24) and (6.4-25) leads to the following "four observable" linear combination from which the L1 and L2 ambiguities have been isolated:
 |
(6.4-27) |
This relation has a role to play both in aiding ambiguity resolution and for cycle slip detection and repair.
Under Anti-Spoofing it may not be possible to have P code pseudo-ranges
from some dual-frequency instruments (some instruments are capable of outputting
P(L4) directly but not its components P(L1)
and P(L2)). Often there will only be three observables
: P(L1) (usually just the C/A code pseudo-range
measurement), 
(L1) and (L2). A linear
combination of these (after eliminating the geometric range and ionospheric
term from the relevant observation equations) is:
 |
(6.4-28) |
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© Chris Rizos, SNAP-UNSW, 1999