A new multipath channel estimation and mitigation using annihilation filter combined tracking loop implementation in software GPS receivers

2021 ◽  
Author(s):  
ARUL ELANGO ◽  
René Jr Landry
Keyword(s):  
Phase Error ◽  
Sampling Rate ◽  
Frequency Component ◽  
Gps Tracking ◽  
Gps Receiver ◽  
Tracking Loop ◽  
Positioning Accuracy ◽  
Gps Receivers ◽  
The Mean ◽  
Carrier Phase Error

Abstract Abstract: The multipath effect causes severe degradation in the positioning of commercial GPS receivers. Due to multipath error, the positioning accuracy could reach a few 10 meters. If the cumulative Multipath delay is less than 0.1-0.35 chips, then it is difficult to mitigate in GPS receivers. This causes severe degradation in GPS signals and can cause a measurement bias. To alleviate this problem, the estimation of multipath parameters using annihilating filter and its mitigation in the GPS tracking loop is proposed in this work. The estimation of randomly generated multipath signals can be performed in the receiver with a lower sampling rate when compared to the larger bandwidth of the GPS baseband signal. Here, the frequency components of the Multipath signal in superimposed complex exponentials have been transformed from the time delay and the amplitude of the path observables. The Rayleigh fading model in the urban scenario has been simulated in which the amplitude and the phase of the number of paths (i.e., the frequency component of superimposed complex exponentials) are set and this fading signal is convolved with GPS signal that forms the multipath faded signal. In the GPS receiver post-processing stage, with the help of the annihilation filter, the multipath components are estimated, then an inverse/adaptive filter and compensation technique are further applied to mitigate the multipath component. The mean square error with the different number of paths with noisy environments is analyzed utilizing the cadzaw denoising algorithm. The simulation results of the proposed technique employed in the tracking module of the software GPS receiver under severe multipath conditions indicate a substantial enhancement in the performance of the GPS receiver with minimal code and carrier phase error when compared to the least squares and adaptive blind equalization channel techniques. Moreover, the positioning accuracy is also calculated with the inclusion of multipath components in two satellites out of six satellites used in the simulation, the results showed that the annihilation filter improved the mean position accuracy up to 9.3023 meters.

scholarly journals GPS Swept Anti-Jamming Technique Based on Fast Orthogonal Search (FOS)

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3706
Author(s):  
Mohamed Tamazin ◽  
Michael J. Korenberg ◽  
Haidy Elghamrawy ◽  
Aboelmagd Noureldin
Keyword(s):  
Spectral Analysis ◽  
Spectral Estimation ◽  
Simulation System ◽  
Controlled Environment ◽  
Gps Receiver ◽  
Positioning Accuracy ◽  
Gps Receivers ◽  
Noise Floor ◽  
Fast Orthogonal Search ◽  
New Applications

Recently, there has been growing demand for GPS-based reliable positioning, with the broadening of a range of new applications that mainly rely on GPS. GPS receivers have, recently, been attractive targets for jamming. GPS signals are received below the noise floor. Thus, they are vulnerable to interference and jamming. A jamming signal can potentially decrease the SNR, which results in disruption of GPS-based services. This paper aims to propose a reliable and accurate, swept anti-jamming technique based on high-resolution spectral analysis, utilizing the FOS method to provide an accurate spectral estimation of the GPS swept jamming signal. resulting in suppressing the jamming signal efficiently at the signal processing stages in the GPS receiver. Experiments in this research are conducted using the SpirentTM GSS6700 simulation system to create a fully controlled environment to test and validate the developed method’s performance. The results demonstrated the proposed method’s capabilities to detect, estimate, and adequately suppress the GPS swept jamming signals. After the proposed anti-jamming module was employed, the software receiver was able to provide a continuous positioning solution during the presence of jamming within a 10 m positioning accuracy.

Combating GNSS Interference with Advanced Inertial Integration

2005 ◽  
Vol 58 (3) ◽  
pp. 419-432 ◽  
Author(s):  
Paul D. Groves ◽  
Daniel C. Long
Keyword(s):  
Low Cost ◽  
Gps Tracking ◽  
Low Grade ◽  
Gps Receiver ◽  
Tracking Loop ◽  
Integration Technique ◽  
Integration Architecture ◽  
Integration Techniques ◽  
Tightly Coupled ◽  
Signal Environment

There are many scenarios where an integrated INS/GNSS navigation system may be required to operate in a high interference or weak signal environment. The GPS receiver may exploit the inertial aiding by operating with narrow tracking loop bandwidths in order to increase interference resistance. However, where a low grade INS is used, wider bandwidths are desirable to calibrate the INS errors effectively. This is important for GPS tracking loop aiding and sole-means inertial navigation during jamming. To obtain both effective INS calibration and jamming resistance, an adaptive tightly-coupled (ATC) INS/GPS integration architecture has been developed. The ATC technique has been assessed by simulation, showing that it provides a significant anti-jam margin over an INS/GPS with fixed tracking bandwidths selected for INS calibration. Compared to the deep (or ultra-tightly-coupled) integration techniques currently under development, ATC is a low cost anti-jam integration technique as it does not require a complete re-design of the navigation architecture. When there is too much interference for any GNSS signals to be tracked, the INS provides sole-means navigation. Thus, it is important to optimise the calibration of the INS when GNSS signals are available. To this end, the effects of estimating higher order inertial instrument errors and satellite range biases within the INS/GPS integration filter have been assessed.

scholarly journals Cerebral CT Perfusion in Acute Stroke: The Effect of Lowering the Tube Load and Sampling Rate on the Reproducibility of Parametric Maps

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1121
Author(s):  
Georgios S. Ioannidis ◽  
Søren Christensen ◽  
Katerina Nikiforaki ◽  
Eleftherios Trivizakis ◽  
Kostas Perisinakis ◽  
...  
Keyword(s):  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Sampling Rate ◽  
Volumetric Analysis ◽  
Sampling Interval ◽  
Diagnostic Efficiency ◽  
Temporal Sampling ◽  
Sampling Intervals ◽  
The Mean ◽  
Parametric Maps

The aim of this study was to define lower dose parameters (tube load and temporal sampling) for CT perfusion that still preserve the diagnostic efficiency of the derived parametric maps. Ninety stroke CT examinations from four clinical sites with 1 s temporal sampling and a range of tube loads (mAs) (100–180) were studied. Realistic CT noise was retrospectively added to simulate a CT perfusion protocol, with a maximum reduction of 40% tube load (mAs) combined with increased sampling intervals (up to 3 s). Perfusion maps from the original and simulated protocols were compared by: (a) similarity using a voxel-wise Pearson’s correlation coefficient r with in-house software; (b) volumetric analysis of the infarcted and hypoperfused volumes using commercial software. Pearson’s r values varied for the different perfusion metrics from 0.1 to 0.85. The mean slope of increase and cerebral blood volume present the highest r values, remaining consistently above 0.7 for all protocol versions with 2 s sampling interval. Reduction of the sampling rate from 2 s to 1 s had only modest impacts on a TMAX volume of 0.4 mL (IQR −1–3) (p = 0.04) and core volume of −1.1 mL (IQR −4–0) (p < 0.001), indicating dose savings of 50%, with no practical loss of diagnostic accuracy. The lowest possible dose protocol was 2 s temporal sampling and a tube load of 100 mAs.

Implementation and Performance Assessment of a Vector Tracking Method Based on a Software GPS Receiver

2011 ◽  
Vol 64 (S1) ◽  
pp. S151-S161 ◽  
Author(s):  
Sihao Zhao ◽  
Mingquan Lu ◽  
Zhenming Feng
Keyword(s):  
Global Positioning System ◽  
Carrier Frequency ◽  
Gps Receiver ◽  
Tracking Loop ◽  
Frequency Tracking ◽  
Tracking Method ◽  
Global Positioning ◽  
Vector Tracking ◽  
Tracking Loops ◽  
And Performance

A number of methods have been developed to enhance the robustness of Global Positioning System (GPS) receivers when there are a limited number of visible satellites. Vector tracking is one of them. It utilizes information from all channels to aid the processing of individual channels to generate receiver positions and velocities. This paper analyzes relationships among code phase, carrier frequency, and receiver position and velocity, and presents a vector loop-tracking algorithm using an Extended Kalman filter implemented in a Matlab-based GPS software receiver. Simulated GPS signals are generated to test the proposed vector tracking method. The results show that when some of the satellites are blocked, the vector tracking loop provides better carrier frequency tracking results for the blocked signals and produces more accurate navigation solutions compared with traditional scalar tracking loops.

scholarly journals A Dual Frequency Carrier Phase Error Difference Checking Algorithm for the GNSS Compass

Sensors ◽  
2016 ◽  
Vol 16 (12) ◽  
pp. 1988 ◽  
Author(s):  
Shuo Liu ◽  
Lei Zhang ◽  
Jian Li
Keyword(s):  
Carrier Phase ◽  
Phase Error ◽  
Dual Frequency ◽  
Carrier Phase Error

scholarly journals Flight Tracks of Homing Pigeons Measured with GPS

2001 ◽  
Vol 54 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Karen von Hünerbein ◽  
Wolfgang Wiltschko ◽  
Eckhard Rüter
Keyword(s):  
Power Supply ◽  
Sampling Rate ◽  
Operating Time ◽  
Release Site ◽  
Gps Receiver ◽  
Homing Pigeons ◽  
Flight Duration ◽  
Ground Speed ◽  
Animal Navigation ◽  
The Village

This and the following paper were first presented at the RIN01 Conference held in Oxford under the auspices of the Animal Navigation Special Interest Group, April 2001.Flight paths of homing pigeons were measured with a newly developed recorder based on GPS. The device consists of a GPS receiver board, a logging facility, an antenna, a power supply, a DC-DC converter and a casing. It has a weight of 33 grams and works reliably with a sampling rate of 1 Hz for an operating time of about three hours, providing time-indexed data on geographic positions, ground speed and altitude. The devices are fixed to the birds with a harness, and the data are downloaded when the bird is re-captured. The measured flight paths show many details : for example, initial loops flown immediately after release and large detours flown by some pigeons. Three examples of flight paths are presented from a release site 17·3 km northeast of the home loft in Frankfurt. Mean speed in flight, duration of breaks and total length of the flight path were calculated. The pigeons chose different routes and have different individual tendencies to fly loops over the village close to the release site.

Are the initial frequency-modulated components of the mustached bat's biosonar pulses important for ranging?

1991 ◽  
Vol 66 (6) ◽  
pp. 1951-1964 ◽  
Author(s):  
D. C. Fitzpatrick ◽  
N. Suga ◽  
H. Misawa
Keyword(s):  
Maximum Amplitude ◽  
Signal Amplitude ◽  
Frequency Component ◽  
Target Range ◽  
Constant Frequency ◽  
Range Resolution ◽  
Mustached Bat ◽  
Pteronotus Parnellii ◽  
Target Ranging ◽  
The Mean

1. FM-FM neurons in the auditory cortex of the mustached bat, Pteronotus parnellii, are specialized to process target range. They respond when the terminal frequency-modulated component (TFM) of a biosonar pulse is paired with the TFM of the echo at a particular echo delay. Recently, it has been suggested that the initial FM components (IFMs) of biosonar signals may also be important for target ranging. To examine the possible role of IFMs in target ranging, we characterized the properties of IFMs and TFMs in biosonar pulses emitted by bats swung on a pendulum. We then studied responses of FM-FM neurons to synthesized biosonar signals containing IFMs and TFMs. 2. The mustached bat's biosonar signal consists of four harmonics, of which the second (H2) is the most intense. Each harmonic has an IFM in addition to a constant-frequency component (CF) and a TFM. Therefore each pulse potentially consists of 12 components, IFM1-4, CF1-4, and TFM1-4. The IFM sweeps up while the TFM sweeps down. 3. The IFM2 and TFM2 depths (i.e., bandwidths) were measured in 217 pulses from four animals. The mean IFM2 depth was much smaller than the mean TFM2 depth, 2.87 +/- 1.52 (SD) kHz compared with 16.27 +/- 1.08 kHz, respectively. The amplitude of the IFM2 continuously increased throughout its duration and was always less than the CF2 amplitude, whereas the TFM2 was relatively constant in amplitude over approximately three-quarters of its duration and was often the most intense part of the pulse. The maximum amplitude of the IFM2 was, on average, 11 dB smaller than that of the TFM2. Because range resolution increases with depth and the maximum detectable range increases with signal amplitude, the IFMs are poorly suited for ranging compared with the TFMs. 4. FM-FM neurons (n = 77) did not respond or responded very poorly to IFMs with depths and intensities similar to those emitted on the pendulum. The mean IFM2 depth at which a just-noticeable response appeared was 4.48 +/- 1.98 kHz. Only 14% of the pulses emitted on the pendulum had IFM2 depths that exceeded the mean IFM2 depth threshold of FM-FM neurons. 5. Most FM-FM neurons responded to IFMs that had depths comparable with those of TFMs. However, when all parameters were adjusted to optimize the response to TFMs and then readjusted to maximize the response to IFMs, 52% of 27 neurons tested responded significantly better to the optimal TFMs than to the optimal IFMs (P less than 0.05, t test).(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Investigating the Benefits of Vector-Based GNSS Receivers for Autonomous Vehicles under Challenging Navigation Environments

Signals ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 121-137
Author(s):  
Haidy Y. F. Elghamrawy ◽  
Mohamed Tamazin ◽  
Aboelmagd Noureldin
Keyword(s):  
Autonomous Vehicles ◽  
Tracking System ◽  
Satellite System ◽  
Velocity Estimation ◽  
Estimation Accuracy ◽  
Positioning Accuracy ◽  
Gps Receivers ◽  
Car Industry ◽  
Vector Tracking ◽  
Global Navigation Satellite

There is a growing demand for robust and accurate positioning information for various applications, including the self-driving car industry. Such applications rely mainly on the Global Navigation Satellite System (GNSS), including the Global Positioning System (GPS). However, GPS positioning accuracy relies on several factors, such as satellite geometry, receiver architecture, and navigation environment, to name a few. In urban canyons in which there is a significant probability of signal blockage of one or more satellites and/or interference, the positioning accuracy of scalar-based GPS receivers drastically deteriorates. On the other hand, vector-based GPS receivers exhibit some immunity to momentary outages and interference. Therefore, it is becoming necessary to consider vector-based GPS receivers for several applications, especially safety-critical applications, including next-generation navigation technologies for autonomous vehicles. This paper investigates a vector-based receiver’s performance and compares it to its scalar counterpart in signal degraded conditions. The realistic simulation experiments in this paper are conducted on GPS L1 C/A signals generated using the SpirentTM simulation system to create a fully controlled environment to examine and validate the performance. The results show that the vector tracking system outperforms the scalar tracking in terms of position and velocity estimation accuracy in signal-degraded environments.

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