Analysises and comparisons on noise performances of PLL, DLL and data demodulator in GNSS receiver

PLL, DLL and data demodulator are key components in a GNSS receiver. Basing on the parameters of widely-used hardware, this paper calculates the noise performance of data demodulator and input SNRs of PLL and DLL. The phase models of GNSS receiver´s carrier-tracking loop and code-tracking loop with thermal noise are also established. Then the loop SNRs(Signal to Noise Ratio)of carrier-tracking loop and code-tracking loop with additive noise are calculated. The results indicate that navigate data demodulator has the worst immunity from thermal noise and the code-tracking loop has the best immunity of the three.