1. Explain the code observation and phase measurement pseudo-range observation equations. What are their observations and unknowns? (Mind mapping method, make corresponding text description)
2. The form and function of linear combination?
In the form of a linear combination of universal application: single difference, the difference between double and triple difference
single difference (the SD): the different stations, the same difference between the simultaneous observation satellite observations of the resulting (differencing between receivers)
bis difference (DD): the different stations , Simultaneously observing the difference of single difference (difference between satellites) and
triple difference (TD): Observation of the same set of satellites in different epochs, the difference of observation double difference (difference between epochs)
:
1. It can eliminate or weaken the influence of some systematic errors, such as satellite orbit error, clock error and atmospheric refraction error;
2. It can reduce the number of unknowns in the adjustment calculation;
3. The original independent observation, caused by the difference The correlation between the difference components can not be ignored.
4. After the difference, the data of the observation equation will be significantly reduced.
5. During the difference, if it is in a certain epoch, the observation of the reference station or reference satellite cannot be used. , Makes the difference of observation difficult, and the more receivers participating in the observation, the more complicated the situation.
