2. With Dual Frequency Phase Data Why Dual Frequency: because of the various possible linear combinations Wide Lane and Narrow Lane Techniques: The adjustment based on the wide lane model gives wide laI ambiguities NLl-L2 which are more easily resoled than the base Wide Lane Signal: w=du-2 Significant ase compared To compute the ambiguities for the measured phases, we can get f12=34782MHz,M=862cm 入ag=19-244cm The increased wide lane wavelength provides an increased L-2 ambiguity spacing. This is the key to easier resolution of the integer ambiguities What is b? please see p. 105, Eg.6.73 Geometry-free linear Characteristics of Dual-Frequency 3. By Combining Dual Frequency Carrier Phase and Code Data The disadvantage of this combination is The most unreliable factor of the wide lane technique is The corresponding ambiguity is no longer an the influence of the ionosphere which increases with baseline length. This drawback can be eliminated by a ombination of phase and code data. The ionosphere is a problem or the ionospheric Φ1=a1--+N influence is eliminated which destroys the integer b nature of the ambiguities carrier phases The use of other linear combinations ranging from b? please narrow lane with a 10. 7 cm wavelength to extra wide th a 172. 4 cm wavelength. 4 equations contain 4 unknowns, geometry By a series derivation, we finally get 4. By Combining Triple Frequency Carrier Phase and code data Ju-f fu+r(Ru+ This technique for ambiguity resolution based on three arriers is denoted as Three- Carries Ambiguity Resolution-TCAR This rather of the wide ty NLI-L2 for each epoch and each Similarly Du=aa-2+Nu ite. It is independent of the baseline length and of the carrier phases ionospheric ef What is a Note that even if all systematic effects cancel out, the code ranges multipath effect remains and affects phase and code differently Eq6.74 R2=a/5+ 6 equations contain 5 fus unknowns4 2. With Dual Frequency Phase Data Why Dual Frequency: because of the various possible linear combinations. fL1-L2 = 347.82 MHz, λL1-L2 = 86.2 cm λorg = 19~24.4 cm Wide Lane and Narrow Lane Techniques: Wide Lane Signal: Φ w = Φ L1 − Φ L 2 Significant increase compared to the original wavelengths • The increased wide lane wavelength provides an increased ambiguity spacing. • This is the key to easier resolution of the integer ambiguities. Φ L1− L 2 = Φ L1 − Φ L 2 L1 L 2 L1 L 2 f = f − f − NL1−L 2 = NL1 − NL 2 The adjustment based on the wide lane model gives wide lane ambiguities NL1-L2 which are more easily resoled than the base carrier ambiguities. ( ) (1 ) 2 1 1 2 1 1 2 1 1 1 1 2 1 2 L L L L L L L L L L L L L L f f f b f b f f N = Φ − Φ − N + − − − − − − To compute the ambiguities for the measured phases, we can get What is b? please see p. 105, Eq.6.73 1 2 1 2 1 2 1 1 1 1 2 1 2 ( ) L L L L L L L L L L L L L f f f f b f f N N + = Φ − Φ − + − − − After ionospheric Geometry-free linear phase combination The disadvantage of this combination is • The corresponding ambiguity is no longer an integer. • The ionosphere is a problem or the ionospheric influence is eliminated which destroys the integer nature of the ambiguities. The use of other linear combinations ranging from narrow lane with a 10.7 cm wavelength to extra wide with a 172.4 cm wavelength. Characteristics of Dual-Frequency: 3. By Combining Dual Frequency Carrier Phase and Code Data The most unreliable factor of the wide lane technique is the influence of the ionosphere which increases with baseline length. This drawback can be eliminated by a combination of phase and code data. 1 1 1 1 N b a L L L L f Φ = f − + 1 1 1 b a L L L f R = f + carrier phases code ranges 2 2 2 2 N b a L L L L f Φ = f − + 2 2 2 b a L L L f R = f + What is a, b? please see p. 105, Eq.6.74 4 equations contain 4 unknowns, geometry term, a and ionosphere term b and ( )( ) 1 2 1 2 1 2 1 2 1 2 L L L L L L L L L L R R f f f f N + + − − = Φ − − This rather elegant equation allows for the determination of the wide lane ambiguity NL1-L2 for each epoch and each site. It is independent of the baseline length and of the ionospheric effects. By a series derivation, we finally get Note that even if all systematic effects cancel out, the multipath effect remains and affects phase and code differently. 4. By Combining Triple Frequency Carrier Phase and Code Data This technique for ambiguity resolution based on three carriers is denoted as Three-Carries Ambiguity Resolution-TCAR. 1 1 1 1 N b a L L L L f Φ = f − + 1 1 1 b a L L L f R = f + carrier phases code ranges 2 2 2 2 N b a L L L L f Φ = f − + 2 2 2 b a L L L f R = f + What is a, b? please see p. 105, Eq.6.74 5 5 5 5 N b a L L L L f Φ = f − + 5 5 5 b a L L L f R = f + Similarly 6 equations contain 5 unknowns