Method for determining the half-cycle ambiguity of a GNSS carrier phase

A method for resolving the half-cycle ambiguity of a Global Positioning System (GPS) carrier phase, the method comprising:

• receiving a plurality of signals from a GPS satellite, the plurality of signals including:
• a first signal L1CA transmitted on a first carrier frequency fL1,
• a second signal L1P transmitted on the first carrier frequency fL1, the second signal having a known phase offset δφL1P,CA with respect to the first signal,
• a third signal L2C transmitted on a second carrier frequency fL2, and
• a fourth signal L2P transmitted on the second carrier frequency fL2, the fourth signal having a known phase offset δφL2P,C with respect to the third signal;
• tracking the first signal and the third signal and determining thereby respective estimations of carrier phases φL1CA and φL2C of said first and third signals, wherein said estimation of the carrier phase φL1CA of the first signal comprises the term AL1CA·π, wherein AL1CA is equal to 0 or 1, AL1CA being referred to hereafter as a half-cycle ambiguity of the L1CA carrier phase;
• and
• downconverting the second and fourth signals L1P and L2P to baseband by multiplication with a carrier replica of said second and fourth signals, determining a delay between the downconverted second and fourth signals, and determining a cross-correlation P between the downconverted second and fourth signals by integrating a product of the downconverted second and fourth signals over an integration time T, taking into account said delay;
• wherein a positive or negative sign of the cross-correlation P and the known phase offsets δφL2P,C and δφL1P,CA are used for determining the half-cycle ambiguity AL1CA to generate a resolved half-cycle ambiguity;
• and
• based on the resolved half-cycle ambiguity, improving a downstream application utilizing the signals from the GPS satellite.