FLL and subcarrier loop united frequency discrimination tracking loop

Abstract

The invention provides an FLL and subcarrier ring united frequency discrimination tracking loop which comprises a carrier tracking loop, a subcarrier tracking loop and a spreading code tracking loop. The carrier tracking loop comprises a carrier numerically-controlled oscillator, a mutual correlation processing unit, integral zero clearing units, a carrier loop frequency discriminator and an FLL loop filter. The subcarrier tracking loop comprises a subcarrier numerically-controlled oscillator, a mutual correlation processing unit, integral zero clearing units, a subcarrier loop phase discriminator and an SLL loop filter. The spreading code tracking loop comprises a numerically-controlled oscillator, a mutual correlation processing unit, integral zero clearing units, a code loop phase discriminator and a DLL loop filter. According to the structural characteristics of BOC signals, the FLL and subcarrier ring united frequency discrimination tracking loop can achieve independent tracking of the carrier frequency, the subcarrier phase and the spreading code phase, the tracking stability performance of weak signals is improved, the dynamic range of the loop is increased, and the problem of tracking ambiguity of the BOC signals under the low signal to noise ratio can be effectively solved.

Description

technical field [0001] The invention relates to the technical field of satellite navigation and tracking, in particular to a combined frequency discrimination and tracking loop of a frequency-locked loop and a subcarrier loop for BOC modulation signals. Background technique [0002] With the continuous development of satellite navigation technology, the satellite navigation systems of various countries have made great progress. Advances in the Global Navigation Satellite System (GNSS) are first and foremost advances in GPS modernization. On the basis of the existing satellite signals, the new generation of GPS satellite signals has been improved in many aspects such as modulation mechanism, pseudo code sequence form and carrier frequency band. Binary Offset Carrier Modulation (BOC) is a modulation method commonly used in future military GPS signals. The unique power spectrum splitting characteristic of the BOC modulation method can achieve frequency band sharing and spectr...

AI Technical Summary

Problems solved by technology

[0006] In 2010, Beihang University applied for a patent called a binary offset carrier signal tracking loop, which introduced a subcarrier tracking loop to eliminate the problem of BOC signal ambiguity. However, the two-quadrant arctangent phase detector used in it does not consider the influence of noise on the phase detection error

If the signal-to-noise ratio is low, the phase detection error will be submerged in the noise, which will bring high ambiguity to the phase detection result

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