Bernese GPS Software Version 5.0 - Bernese GNSS Software

2. Fundamentals
Table 2.10: Linear combinations (LCs) of the L1 and L2 observables used in the Bernese
GPS Software Version 5.0 .
LC Description Wavelength Noise Ionosphere
in cm rel to L1 rel to L1
L1 Basic carrier 19 1.0 1.0
L2 Basic carrier 24 1.0 1.6
L3 Ionosphere-free LC 0 3.0 0.0
L4 Geometry-free LC ∞ 1.4 0.6
L5 Wide-lane LC 86 5.7 1.3
L6 Melbourne-Wübbena LC 86 0.7 0.0
2.3.7 GLONASS Single-Difference Bias Term
Let us shortly address one important issue when dealing with GLONASS observations. As
pointed out in Section 2.1.2.2 the GLONASS system uses the FDMA technology for identifying
individual satellites. The fact that GLONASS satellites transmit on slightly different
frequencies leads to an additional term in the double-difference observation equations which
reads (neglecting additional biases):
where
n ij
kℓ
n j
kℓ
L ij
kℓ = ̺ij
kℓ + nij
kℓ λi + ∆λ ij n j
kℓ
is the double-difference ambiguity with respect to receivers kℓ and satellites ij,
is the single-difference ambiguity with respect to receivers kℓ and satellite j,
λ i is the carrier wavelength of satellite i, and
(2.53)
∆λ ij is the carrier wavelength difference between satellites j and i, where λ i = λ j + ∆λ ij .
The quantity
b ij
kℓ = ∆λij n j
kℓ
(2.54)
is called single difference bias term. This term is the main problem in cycle slip detection and
destroys the integer nature of double-difference ambiguities in Eqn. (2.53). For an extensive
discussion of GLONASS processing and GPS/GLONASS combination the reader is referred
to [Habrich, 1999].
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