List of top GNSS / GPS Questions asked in GATE GE

According to the first order ionospheric delay term, the time delay experienced by the GNSS signal is directly proportional to the Total Electron Content (TEC) in the ionosphere, and inversely proportional to the square of the frequency of the carrier wave. Based on this, the GPS L2 (1227.60 MHz) carrier is slower than the GPS L1 (1575.42 MHz) carrier by a factor of ________ for a given TEC (Rounded off to the nearest integer).

Satellites A and B are in circular orbits at a height of 900 km and 300 km, respectively, above the Earth's surface. The velocity of satellite B will be ________ times the velocity of satellite A (Rounded off to three decimal places).

Assume radius of Earth to be 6378 km, acceleration due to gravity to be 9.81 \(m\,s^{-2}\), the product of universal gravitational constant and mass of Earth is \(3.98601\times10^{14}\ m^3\,s^{-2}\).

Hint: For a satellite to remain in circular orbit around the Earth, the Earth's gravitational force must be balanced by the centrifugal force of the orbiting satellite.

In the context of GNSS positioning, which of the following statements is/are INCORRECT?

In GNSS positioning, the cycle slips are the most detrimental for estimating ________.

Which one of the coordinate pairs represents the satellite orbit in the skyplot of the GNSS constellations?

In GNSS positioning, the dilution of precision is a good indicator of ________.

The carrier phase observation model in GNSS is given as
\[ \phi_A^i = f\delta^i - \frac{\rho_A^i}{\lambda} - f\delta_A + N_A^i - f\delta_{\text{iono}} + f\delta_{\text{tropo}} + \epsilon \]
where \(\phi_A^i\) is the observed carrier phase in cycles, \(f\) is the frequency of the carrier in hertz, and \(\lambda\) is the wavelength of the carrier in meters.
What is the unit of the ionospheric (\(\delta_{\text{iono}}\)) and tropospheric (\(\delta_{\text{tropo}}\)) delay terms in the given equation?