Systems, device configurations, and processes are provided for navigation and determination of navigation observables based on low Earth orbit (LEO) satellite signals. A method for navigation includes using differential carrier phase measurement of LEO signals including correction of position estimates using integer ambiguity resolution and double difference carrier phase determinations. Frameworks described herein can use a computationally efficient integer ambiguity resolution to reduce the size of the integer least squares (ILS) determination. The framework may include a joint probability density function (pdf) of the megaconstellation LEO satellites' azimuth and elevation angle to characterize a LEO system. Embodiments are also directed to correction of ambiguities of carrier phase differential (CD)-low Earth orbit (LEO) (CD-LEO) measurements that may utilize a base and a rover without requiring prior knowledge of rover position.