4. Satellite Geometry and Measurement Time 5. Multipath and Length of Baseline Satellite Geometry: The number of satellites tracked at ultipath is station dependent, it may be significant for any instant translates into a better dilution of precision nort baselines. As in the case of atmospheric and orbital alue. Thus if a receiver tracks seven or eight satellites. it Tors for long baselines, multipath has the effect of both is preferable since redundant satellites aid in the efficiency ontaminating the station coordinates and ambiguities and reliability of ambiguity resolution Multipath is also a critical factor for ambiquity resolution. Length of measurement Time: The information content of the carrier phase is a function of time which is directly 6. Major Steps of Ambiguity Resolution correlated to the movement of the satellite The Main First Step is the generation of potential integer The time is a critical component of ambiguity resolution mbiguity combinations that should be considered by the even under good geometric conditions. Example: every 15 seconds for one hour, every second for A combination is comprised of an integer ambiquity for. four minutes, a total of 240 measurements per satellite. egeach of the domble-difiference satellite nairs. Search Space is the volume of uncertainty which surrounds the approximate coordinates of the unknown The Second Major Step is the identification of the antenna location correct integer ambiguity combination. Static positioning: it can be realized from the so- called float ambiguity solution, The Third Major Step is the a validation(verification) Kinematic positioning: it is realized from a code of the ambiguities ange solution ize of the Search Space will affect the efficiency, i.e Integer ambiguity combinations to assess, which in tum ncreases the computational burden. This is typically important for kinematic applications. It is necessary to balance computational load with a conservative search space sIze 2.2 Basic Approaches Characteristics of Single-Frequency: 1. With Single Frequency Phase Data For only one frequency(Ll or L2)available, the most direct 1. The unmodeled errors affect all estimated parameters Therefore the integer nature of the ambiguities is lost and 1. Establishing model by Eq(9.14), hey are estimated as real values. teger values, a sequential adjustment could be performed ordinates, clock parameters, etc. )is estimated along with N in a common adjustment. 3. After an initial adjustment, the ambiguity with a computed value closest to an integer and with minimum standard When using double-differences over short baselines, this approach is sually successful. The critical factor is the ionospheric refraction bias is then fixed, and the adjustment is repeated(with one which must be modeled and which may prevent a correct resolution less unknown) to fix another ambiguity and so on.3 Satellite Geometry: The number of satellites tracked at any instant translates into a better dilution of precision value. Thus, if a receiver tracks seven or eight satellites, it is preferable since redundant satellites aid in the efficiency and reliability of ambiguity resolution. Length of Measurement Time: The information content of the carrier phase is a function of time which is directly correlated to the movement of the satellite. 4. Satellite Geometry and Measurement Time The time is a critical component of ambiguity resolution even under good geometric conditions. Example: every 15 seconds for one hour; every second for four minutes, a total of 240 measurements per satellite. Since multipath is station dependent, it may be significant for short baselines. As in the case of atmospheric and orbital errors for long baselines, multipath has the effect of both contaminating the station coordinates and ambiguities 6. Major Steps of Ambiguity Resolution Multipath is also a critical factor for ambiguity resolution. 5. Multipath and Length of Baseline The Main First Step is the generation of potential integer ambiguity combinations that should be considered by the algorithm. A combination is comprised of an integer ambiguity for, e.g., each of the double-difference satellite pairs. Search Space is the volume of uncertainty which surrounds the approximate coordinates of the unknown antenna location. • Static positioning: it can be realized from the so￾called float ambiguity solution, • Kinematic positioning: it is realized from a code range solution. Size of the Search Space will affect the efficiency, i.e., computational speed. • A larger search space gives a higher number of potential integer ambiguity combinations to assess, which in turn increases the computational burden. This is typically important for kinematic applications. It is necessary to balance computational load with a conservative search space size. The Second Major Step is the identification of the correct integer ambiguity combination. The Third Major Step is the a validation (verification) of the ambiguities. 2.2 Basic Approaches 1. With Single Frequency Phase Data For only one frequency (L1 or L2) available, the most direct approach is. 1. Establishing model by Eq. (9.14), 2. Linearizing the model, 3. Solving the model, a number of unknowns (e.g., point coordinates, clock parameters, etc.) is estimated along with N in a common adjustment. When using double-differences over short baselines, this approach is usually successful. The critical factor is the ionospheric refraction which must be modeled and which may prevent a correct resolution of all ambiguities. 1. The unmodeled errors affect all estimated parameters. Therefore, the integer nature of the ambiguities is lost and they are estimated as real values. 2. To fix ambiguities to integer values, a sequential adjustment could be performed. 3. After an initial adjustment, the ambiguity with a computed value closest to an integer and with minimum standard error is considered to be determined most reliably. This bias is then fixed, and the adjustment is repeated (with one less unknown) to fix another ambiguity and so on. Characteristics of Single-Frequency: