Phase Tracking Loop Research Articles

Performance analysis of cross-frequency Doppler-assisted carrier phase tracking

Using the Doppler frequency obtained from tracking a GNSS pilot signal to aid in tracking another signal modulated with higher rate navigation messages in a different frequency band can improve tacking robustness and lower the message demodulation threshold. Based on an analysis of received signal frequency coherence, a linearized mathematical model of the cross-frequency Doppler-assisted carrier phase tracking loop is built, a thermal noise jitter calculation equation for the assisted tracking loop is derived, and its dynamic stress response characteristics are examined. The loop design requirements for eliminating the influence of inter-frequency frequency bias are clarified, as are the cross-frequency assist signal selection criteria. Monte Carlo simulations and preliminary field tests validate the theoretical results using the B1C pilot signal-aided tracking B2b signal of the MEO satellite in the BeiDou satellite navigation system (BDS). Experimental results show that the carrier phase tracking threshold of the B2b signal can be reduced by about 4 dB.

A Fractional-N Synthesizable PLL Using DTC-Based Multistage Injection With Dithering-Assisted Local Skew Calibration

A standard-cell-based fractional-N synthesizable phase-locked loop (PLL) [or multiplying-delay-locked loop (MDLL)] is proposed, where the multiple phases of the three-stage ring digitally controlled oscillator (DCO) are utilized for injection. The required digital-to-time converter (DTC) range is reduced to one third of the DCO’s period, resulting in higher linearity, less jitter, lower power consumption, and smaller area. The issue of the mismatches among DCO’s stages is solved by the proposed dithering-assisted local skew calibration, which removes the skews in the injection path and smears out the periodic pattern at the PLL side to reduce spurs. Most of the dithering noise is suppressed by the injection locking and the phase tracking loop. Measured at 1.0095-GHz output frequency with 24-MHz reference frequency, with the proposed solution, the integrated root-mean-square (rms) jitter can be reduced from 6.40 to 2.55 ps, and the power consumption is 3.36 mW. This translates to −226.6-dB figure of merit (FoM) and −232.8-dB FoM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ref</sub> . The measured fundamental fractional spurs range from −56 to −45 dBc.

ПОДДЕРЖКА ПЕТЕЛЬ СЛЕЖЕНИЯ ЗА ФАЗОЙ В ПРИЕМНИКЕ СПУТНИКОВОЙ НАВИГАЦИИ С ПОМОЩЬЮ ИЗМЕРЕНИЙ ИНЕРЦИАЛЬНОЙ НАВИГАЦИОННОЙ СИСТЕМЫ

Satellite radio navigation systems make it possible to evaluate the user's state vector, usecoordinates, user speed and time relative to the system scale. The requirements for the characteristicsof these systems constantly depend on the fact that they have application features in theiralgorithms for processing radio navigation signals. One of the main characteristics of satelliteradio navigation systems is the accuracy of estimating the user's state vector. This characteristiccan be improved by the presence of estimates of the phase of the received radio navigation signals.In a satellite radio navigation system, phase estimation errors in the tracking loop have two components:dynamic and noise. To compensate for the noise error, it is necessary to reduce theequivalent noise band of the anti-aliasing filter of the phase tracking loop. However, the minimumpossible bandwidth of the smoothing filter is limited by the presence of consumer dynamics and thequality of the reference oscillator. As a result, in the presence of consumer dynamics, the sensitivityand reliability of phase tracking deteriorates. To compensate for the dynamic error in the phasetracking loop, information from an inertial navigation system can be used. The satellite radio navigationsystem and the inertial navigation system have complementary characteristics. The use ofsupport for phase tracking loops from an inertial navigation system makes it possible to increasethe sensitivity and reliability of its operation in the presence of consumer dynamics. It is assumedthat with such an implementation, the sensitivity of the phase tracking loops will be limited only bythe instability of the reference oscillator and the error of inertial measurements. To improve thecharacteristics of accuracy, sensitivity and reliability of the coherent mode of operation of the enddevice, an algorithm was developed to support phase tracking loops with measurements from aninertial navigation system. A study of the developed algorithm was carried out on a model thatuses real measurements of satellite and inertial navigation systems as input data. The developedalgorithm is implemented in the software of the NV216C-IMU inertial satellite navigation systemprototype. Experimental studies were carried out in the conditions of automobile dynamics in openareas. The research results are presented in the work.

Examining the Tolerance of GNSS Receiver Phase Tracking Loop Under the Effects of Severe Ionospheric Scintillation Conditions Based on Its Bandwidth

AbstractThis study aims to evaluate the performance of phase‐locked loop (PLL) under the presence of distinct scintillation patterns in the signal. Scintillation is very common in low‐latitude regions due to the ionospheric dynamics. Under strong scintillation scenario the occurrence of deep fading events is usually registered and may cause severe degradation in the communication. The investigation conducted in this study uses the amplitude scintillation index S4, the decorrelation time, and the bandwidthas main parameters. The study evaluates 54 different combinations of these parameters. The results indicate that in order to minimize the occurrence of cycle slips in the output phase of the PLL, the most appropriate tracking loop bandwidthdepends on the values of both S4and, which characterize the scintillation fading pattern. Simulations showed that as the S4index increases, the automatic increment in the PLL bandwidth may not be the best choice as the performance depends on the temporal characteristics of the scintillating signal. The analysis showed that, among the configurations tested, the equivalent noise bandwidth of 10 Hz achieved the best performance overall. The investigation also showed that choosing the wrong parameter regarding the PLL bandwidth may increase the probability of cycle slip by up to 10 times during fading events.

A 0.7-V Sub-mW Type-II Phase-Tracking Bluetooth Low Energy Receiver in 28-nm CMOS

We present an architecture of a Bluetooth low energy (BLE)-compliant receiver which, for the first time ever, breaks the 1mW barrier of power consumption. It is based on a type-II phase-tracking loop and addresses the mutual magnetic coupling between on-chip inductors of a digitally controller oscillator (DCO) and low-noise transconductance amplifier (LNTA), which causes RX performance degradation in the prior-art implementations. An inverter-based inductor-free LNTA is employed instead. The resulting adjacent channel rejection (ACR) improves by 1.5/2.5dB at 2/3MHz offset. By further leveraging current-reuse and switched-capacitor circuitry, this RX achieves the best-in-class FoM of 183.2dB with sensitivity of -93.2dBm. Thanks to the single-channel topology, the proposed RX occupies tiny area of 0.48mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in 28-nm CMOS.

Two-way laser regeneration pseudocode rangefinder of intersatellite optical crosslink

The millimeter-level bidirectional long-distance asynchronous ranging has long been a huge challenge in the field of measurement and instrumentation. Correspondingly, a laser pseudocode ranging algorithm based on regenerative synchronization mechanism is proposed to address the problems obstructing precise distance measurement between asynchronous satellites. First, the synchronization strategy of a double-ended asynchronous terminal based on the regenerative pseudocode is discussed. Subsequently, we look at the algorithm of the generation, transmission, detection, and the code phase tracking loop, which forms the base of obtaining high precision of pseudocode ranging. On this basis, the error of laser pseudocode ranging link is analyzed, which mainly incorporates receiver noise and clock error. In terms of receiver noise, the influence of the photodetector carrier-to-noise ratio on random noise distribution is evaluated, and the design of receiver parameters is guided as such. As for the clock error, we look at the constraint relationship between the range and the precision under the action of the clock error, which provides the basis for the selection of the clock. Finally, the optimized system is tested when a double-ended laser link is set up in the laboratory. As a result, the comprehensive accuracy results of 3.47 mm systematic error and ±1.73 mm random error is obtained, and the long-scale measurement performance has been tested by the temperature-compensated crystal oscillator pulse frequency experiment. In conclusion, the experiment is consistent with the theory proposed in this study, which provides a theoretical and experimental basis for long-distance high-precision intersatellite ranging.

Referenceless single‐loop CDR with a half‐rate linear PD and frequency acquisition technique

A referenceless single-loop clock and data recovery (CDR) circuit with a half-rate linear phase detector (PD) and an inherent frequency acquisition technique are introduced. Cycle-slip in the half-rate linear PD and its relationship with the frequency acquisition are described in detail. The single-loop CDR consists of a conventional phase-tracking loop and a frequency-tracking unit, referred to as the cycle-slip detector. The proposed CDR is fabricated in a 28 nm CMOS process and achieves a wide capture range of 2.6 Gb/s for a PRBS31 pattern. The RMS and peak-to-peak jitter of the recovered clock are and , respectively, at 8 Gb/s. The high frequency jitter tolerance is measured as . The CDR occupies and consumes 26 mW at 8 Gb/s from a 1.0 V supply.

A Semi-Open Loop GNSS Carrier Tracking Algorithm for Monitoring Strong Equatorial Scintillation

Strong equatorial ionospheric scintillation of radio signals is often associated with simultaneous deep amplitude fading and rapid random carrier phase fluctuations. It poses a challenge for satellite navigation receiver carrier phase tracking loop operation. This paper presents a semi-open loop algorithm that utilizes the known position of a stationary receiver and satellite orbit information to estimate carrier phase variations during deep signal fading. Strong GPS scintillation data collected on Ascension Island in March 2013 are processed to reveal fast phase changes of half and full cycles over tens of milliseconds on all three GPS frequencies. Simulated signals are used to validate the algorithm and confirm that the fast phase changes are true scintillation effects rather than receiver processing artifacts. The algorithm performance is demonstrated through comparison with several closed-loop implementations. Potential errors associated with receiver clock bias and other environmental factors are also analyzed. A statistical summary of the concurrent fast phase changes and deep fades based on the processing results of the Ascension Island data is presented.

Tracking time varying multipath phase at very low signal to noise ratios

Diverse acoustic environments support multipath propagation. Estimating the arrival gains allows receiver structures to coherently combine acoustic energy for improved reception. In the case of mobile acoustic sources and receivers or dynamic boundaries, the amplitudes and phases of those arrivals are time varying such that estimation is made more difficult and typically entails some kind of phase tracking loop. This can be challenging as trackers are often formed as recursions in time employing previous observations to predict the phase at present, updating each phase estimate with the most recent observation. At extremely low SNR, recursive tracking can suffer loss of lock. Since a great deal of information about the instantaneous phase is contained in observations before and after it is judicious to seek estimators that exploit all of the observations in the signalling interval to infer the time varying response phase. Presented here is a scheme for simultaneous time varying phase estimation from the reception of a long duration, high time-bandwidth product transmission. In this approach, the phase process is derived from a minimum mean square error estimate of the sparse acoustic time varying response under an assumed sparse mixture model prior over Doppler and frequency. Demonstrations in shallow water at less than −12 dB received signal to noise ratio are presented.

Effect and mitigation of oscillator vibration-induced phase noise on carrier phase tracking

The influence of vibration-induced oscillator phase noise on carrier phase tracking of a GNSS receiver is analyzed. We show that when the oscillator is vibrating, the vibration-induced oscillator noise is increased and the carrier phase tracking is affected. In order to mitigate the influence of the vibration-induced oscillator phase noise on carrier phase tracking, a vector tracking structure based on an extended Kalman filter called vector phase tracking loop (VPLL) is proposed. In this method, an individual phase lock loop (PLL) for each channel is used to track the satellite-dependent parameters such as atmospheric delay, and a common vector loop is integrated for common parameters tracking such as the receiver clock. The performance of the conventional PLL and the proposed VPLL under oscillator vibration is compared using data collected from a simulator and from a field test. Different PLL bandwidths are tested in order to consider different operating conditions. The test results show that when similar thermal noise error is present, the proposed method can improve the carrier phase tracking compared to conventional PLL.

Improvement of Carrier Phase Tracking Based on a Joint Vector Architecture

Carrier phase measurements are essential to high precision positioning. Usually, the carrier phase measurements are generated from the phase lock loop in a conventional Global Navigation Satellite System (GNSS) receiver. However there is a dilemma problem to the design of the loop parameters in a conventional tracking loop. To address this problem and improve the carrier phase tracking sensitivity, a carrier phase tracking method based on a joint vector architecture is proposed. The joint vector architecture contains a common loop based on extended Kalman filter to track the common dynamics of the different channels and the individual loops for each channel to track the satellite specific dynamics. The transfer function model of the proposed architecture is derived. The proposed method and the conventional scalar carrier phase tracking are tested with a high quality simulator. The test results indicate that carrier phase measurements of satellites start to show cycle slips using the proposed method when carrier noise ratio is equal to and below 15 dB-Hz instead of 21 dB-Hz with using the conventional phase tracking loop. Since the joint vector based tracking loops jointly process the signals of all available satellites, the potential interchannel influence between different satellites is also investigated.

Phase tracking for pulsar navigation with Doppler frequency

Doppler frequency in pulsar navigation is an effect caused by spacecraft and pulsar motion, which would worsen the pulsar navigation accuracy. To describe this influence, we establish the Doppler frequency measurement model based on pulsar timing. With this model, we describe the relationship between the phase estimation performance and the observation time when Doppler frequency exists. To reduce the pulsar navigation error due to the Doppler frequency, we designed the phase tracking loop for the pulsar navigation. The pulsar frequency can be modified before the phase estimation. As a result, the impact of the Doppler frequency could be lessened, and the observation interval lengths can be lengthened to improve the phase estimation performance.

Performance analysis and design of the optimal frequency-assisted phase tracking loop

The frequency-assisted phase tracking (FAPT) is investigated extensively in comparison with the phase tracking (PT) in a Kalman filter (KF) frame to explore the role the augmented frequency measure...

Effect of GNSS receiver carrier phase tracking loops on earthquake monitoring performance

This research focuses on the performance of GNSS receiver carrier phase tracking loops for early earthquake monitoring systems. An earthquake was simulated using a hardware simulator and position, velocity and acceleration displacements were obtained to recreate the dynamics of the 2011 Tohoku earthquake. Using a software defined receiver, GSNRx, tracking bandwidths of 5, 10, 15, 20, 30, 40 and 50Hz along with integration times of 1, 5 and 10ms were tested. Using the phase lock indicator, an adaptive tracking loop was designed and tested to maximize performance for this application.

Performance analysis of a Kalman filter carrier phase tracking loop

The equivalent bandwidth of a Kalman filter (KF) tracking loop for a Global Navigation Satellite System receiver is widely used to compare the performance of the KF with that of the traditional phase lock loop (PLL), but the existing literature does not adequately describe why they are comparable in terms of the equivalent bandwidth. The literature does neither address how the factors, including the line-of-sight (LOS) jerk, the local oscillator error, and the measurement noise, impact on the performance of the KF. Furthermore, there is no the rule-of-thumb threshold for the KF up to now. We prove that the steady KF is equivalent to a 3rd-order PLL in the sense of the minimum covariance in the continuous KF form, which makes it possible to compare the KF and the PLL loops in terms of the equivalent bandwidth. The factors that impact the performance of the KF are further investigated by error budgeting and suboptimal analysis. The analysis results show that the oscillator error, the LOS jerk, and the measurement error affect the steady KF error significantly while the initial state covariance has little effect on the convergence of the KF. A rule-of-thumb threshold for the KF, which is determined by the root mean squares of the loop thermal noise and the dynamic stress noise, is presented by analyzing the counterpart for the PLL. Four KF tracking loops are designed upon the proposed rule-of-thumb analysis, which are further validated by the Monte Carlo simulations.

A 0.8-to-6.5 Gb/s Continuous-Rate Reference-Less Digital CDR With Half-Rate Common-Mode Clock-Embedded Signaling

This paper presents a continuous-rate reference-less clock and data recovery (CDR) circuit that utilizes common-mode clock-embedded signaling (CM-CES) and injection locking techniques to reduce design complexity for the half-rate data recovery. In the proposed receiver, the use of wideband injection-locked oscillator (ILO) greatly suppresses its phase noise while the narrowband digital phase tracking loop (DPTL) tunes retiming phase. For wide-range and continuous-rate operation, four circuit techniques have been adopted: a VCO with active inductance load for low VCO gain at high frequency, a wide-range digitally-controlled delay line (DCDL) with adaptive band selection, a linearized delay control unit with CM-to-delay conversion technique, and a coarse frequency detection scheme to drive the free-running oscillator frequency toward injection locking. The prototype CDR, fabricated in low power CMOS 65 nm technology, successfully detects 0.8–6.5 Gb/s data rates over 5 $^{\prime\prime}$ FR4 trace with $2^{31}-1$ PRBS pattern satisfying ${\text{BER}} . The power efficiency was 2.4 mW/Gb/s at 6.5 Gb/s.

Design and Performance Evaluation of a Dual Antenna Joint Carrier Tracking Loop.

In order to track the carrier phases of Global Navigation Satellite Systems (GNSS) signals in signal degraded environments, a dual antenna joint carrier tracking loop is proposed and evaluated. This proposed tracking loop processes inputs from two antennas, namely the master antenna and the slave antenna. The master antenna captures signals in open-sky environments, while the slave antenna capture signals in degraded environments. In this architecture, a Phase Lock Loop (PLL) is adopted as a master loop to track the carrier phase of the open-sky signals. The Doppler frequency estimated by this master loop is utilized to assist weak carrier tracking in the slave loop. As both antennas experience similar signal dynamics due to satellite motion and clock frequency variations, a much narrower loop bandwidth and possibly a longer coherent integration can be adopted to track the weak signals in slave channels, by utilizing the Doppler aid from master channels. PLL tracking performance is affected by the satellite/user dynamics, clock instability, and thermal noise. In this paper, their impacts on the proposed phase tracking loop are analyzed and verified by both simulation and field data. Theoretical analysis and experimental results show that the proposed loop structure can track degraded signals (i.e., 18 dB-Hz) with a very narrow loop bandwidth (i.e., 0.5 Hz) and a TCXO clock.

A 1.248 Gb/s - 2.918 Gb/s Low-Power Receiver for MIPI-DigRF M-PHY with a Fast Settling Fully Digital Frequency Detection Loop in 0.11 ㎛ CMOS

This paper presents a 1.248 Gb/s ? 2.918 Gb/s low-power receiver MIPI-DigRF M-PHY with a fully digital frequency detection loop. MIPI-DigRF M-PHY should be operated in a very short training time which is 0.01 μs the for HS-G2B mode. Because of this short SYNC pattern, clock and data recovery (CDR) should have extremely fast locking time. Thus, the quarter rate CDR with a fully digital frequency detection loop is proposed to implement a fast phase tracking loop. Also, a low power CDR architecture, deserializer and voltage controlled oscillator (VCO) are proposed to meet the low power requirement of MIPI-DigRF M-PHY. This chip is fabricated using a 0.11 μm CMOS process, and the die area is 600 μm x 250 μm. The power consumption of the receiver is 16 mW from the supply voltage of 1.1 V. The measured lock time of the CDR is less than 20 ns. The measured rms and peak jitter are 35.24 PsSUBp-p/SUB and 4.25 PsSUBrms/SUB respectively for HS-G2 mode.

Synthesis of a two-discriminator phase-locked loop circuit

A new phase-locked loop circuit that is a system of two discriminators is described. One of the discriminators is used in the phase-tracking loop, and the other is used in the loop of the cycle-slip detector. It is shown that the use of coprocessing of the data received from both discriminators makes it possible to detect the cycle-slipping moments and introduce corrections for the slipping.

A New Inertial Aid Method for High Dynamic Compass Signal Tracking Based on a Nonlinear Tracking Differentiator

In Compass/INS integrated navigation systems, feedback inertial navigation solutions to baseband tracking loops may eliminate receiver dynamic effects, and effectively improve the tracking accuracy and sensitivity. In the conventional inertially-aided tracking loop, the satellite-receiver line-of-sight velocity is used directly to adjust local carrier frequency. However, if the inertial solution drifts, the phase tracking error will be enlarged. By using Kalman filter based carrier phase tracking loop, this paper introduces a new inertial aid method, in which the line-of-sight jerk obtained from inertial acceleration by a nonlinear tracking differentiator is used to adjust relevant parameters of the Kalman filter's process noise matrix. Validation is achieved through high dynamic Compass B3 signal with line-of-sight jerk of 10 g/s collected by a GNSS simulator. Experimental results indicate that the new inertial aid method proposed in this paper is free of the impact of the receiver dynamic and inertial errors. Therefore, when the integrated navigation system is starting or re-tracking after losing lock, the inertial error is absent from the navigation solution correction that induces large drift, and the new aid method proposed in this paper can track highly dynamic signals.