A. A. Povalyaev - Dr. Sci (Eng.), associate professor, Moscow Aviation Institute (National Research University), JSC «Russian Space Systems » (RSS). E-mail: povalyaev_aa@rniikp.ru
A. N. Podkorytov - graduate student, Moscow Aviation Institute (National Research University). E-mail: thepompous@gmail.com

Currently precise point positioning (PPP) technique has become a widely spread approach in global navigation satellite systems (GNSS). In the approach absolute coordinates of one receiver are estimated in a global scale on a high-precision level. During the filtration process a number of systematic biases are compensated in measurements, and the most precise available ephemerides are used. Equipment satellite and receiver delays are lumped together with integer carrier phase ambiguities as nuisance parameters. As a result, phase ambiguities lose their integer nature, and they are estimated as float values. For this reason, such kind of processing is called as Float PPP. Main disadvantage of Float PPP mode is long convergence time. To get receiver coordinates with 1-3 cm accuracy it is necessary to process measurements up to 6-12 hours. Not so long ago new PPP approach has appeared in GNSS, for which ambiguity resolution procedure for carrier phase measurements is used to reduce convergence time. This technique has name Integer PPP. General theory of the technique is currently still under deep investigation. Some examples of Integer PPP realization are described in literature. The most clear and forward-looking approach, as authors think, is one based on decoupled clock model. In current study the authors consider approach for positioning in Integer PPP mode, for which uncombined measurements on initial frequencies and decoupled clock model concept are used.