scholarly journals Integer Ambiguity Fixation Based on SC-PAR Algorithm

2021 ◽  
Vol 2083 (4) ◽  
pp. 042093
Author(s):  
Xizi Jia ◽  
Yuanfa Ji ◽  
Wentao Fu ◽  
Weibin Liang ◽  
Bingye Pan
Keyword(s):  
Signal To Noise Ratio ◽  
Attenuation Factor ◽  
Elevation Angle ◽  
Integer Ambiguity ◽  
Single Frequency ◽  
Fixed Rate ◽  
R Ratio ◽  
Geometric Precision ◽  
Ambiguity Estimation ◽  
Satellite Signal

Abstract In terms of quality control of ambiguity estimation, the common partial ambiguity fixation algorithm is improved, and the SC-PAR (Single frequency Combined Partial Ambiguity Resolution) algorithm is proposed. After the algorithm fails to fix the full ambiguity, it filters the ambiguity subset step by step according to the number of continuous satellite lock epochs, satellite elevation angle, satellite signal-to-noise ratio, geometric precision factor, ambiguity variance and ambiguity precision attenuation factor, and searches Optimal ambiguity subset. According to the R-ratio value and the success rate index, the search results are jointly tested, and the remaining subsets are corrected with the subsets that pass the test. The results show that compared with the FAR and conventional PAR algorithms, the fixed rate of the SC-PAR algorithm is increased by 65.01% and 27.97%, respectively, and the accuracy is also significantly improved.

The Radio Probe™: A New Measurement Tool for High Speed Integrated Circuits

2005 ◽  
Author(s):  
Mark Kimball
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
High Speed ◽  
Attenuation Factor ◽  
Cost Effective ◽  
Frequency Measurement ◽  
Single Frequency ◽  
Measurement Tool ◽  
Probe Design ◽  
Differential Measurement

Abstract This article presents a novel tool designed to allow circuit node measurements in a radio frequency (RF) integrated circuit. The discussion covers RF circuit problems; provides details on the Radio Probe design, which achieves an input impedance of 50Kohms and an overall attenuation factor of 0 dB; and describes signal to noise issues in the output signal, along with their improvement techniques. This cost-effective solution incorporates features that make it well suited to the task of differential measurement of circuit nodes within an RF IC. The Radio Probe concept offers a number of advantages compared to active probes. It is a single frequency measurement tool, so it complements, rather than replaces, active probes.

Integer Ambiguity Estimation for Satellite Navigation

2012 ◽  
Vol 60 (7) ◽  
pp. 3387-3393 ◽  
Author(s):  
Christoph Gunther ◽  
Patrick Henkel
Keyword(s):  
Satellite Navigation ◽  
Integer Ambiguity ◽  
Ambiguity Estimation

scholarly journals Landsat TM image maps of the Shirase and Siple Coast ice streams, West Antarctica

1994 ◽  
Vol 20 ◽  
pp. 407-412 ◽  
Author(s):  
Jane G. Ferrigno ◽  
Jerry L. Mullins ◽  
Jo Anne Stapleton ◽  
Robert A. Bindschadler ◽  
Ted A. Scambos ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Elevation Angle ◽  
Single Band ◽  
Landsat Tm ◽  
Ice Streams ◽  
Cd Rom ◽  
Landsat Tm Image ◽  
West Antarctic ◽  
Tm Image ◽  
Convolution Algorithm

Fifteen 1: 250000 and one 1: 1000 000 scale Landsat Thematic Mapper (TM) image mosaic maps are currently being produced of the West Antarctic ice streams on the Shirase and Siple Coasts. Landsat TM images were acquired between 1984 and 1990 in an area bounded approximately by 78°-82.5°S and 120°- 160° W. Landsat TM bands 2, 3 and 4 were combined to produce a single band, thereby maximizing data content and improving the signal-to-noise ratio. The summed single band was processed with a combination of high- and low-pass filters to remove longitudinal striping and normalize solar elevation-angle effects. The images were mosaicked and transformed to a Lambert conformal conic projection using a cubic-convolution algorithm. The projection transformation was controled with ten weighted geodetic ground-control points and internal image-to-image pass points with annotation of major glaciological features. The image maps are being published in two formats: conventional printed map sheets and on a CD-ROM.

scholarly journals A SFTD Algorithm for Optimizing the Performance of the Readout Strategy of Residence Time Difference Fluxgate

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3985 ◽  
Author(s):  
Siyu Chen ◽  
Yanzhang Wang ◽  
Jun Lin
Keyword(s):  
Residence Time ◽  
Time Domain ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Transformation Method ◽  
Time Difference ◽  
Single Frequency ◽  
Time Frequency ◽  
Frequency Magnetic Field ◽  
The Time Domain

Residence time difference (RTD) fluxgate sensor is a potential device to measure the DC or low-frequency magnetic field in the time domain. Nevertheless, jitter noise and magnetic noise severely affect the detection result. A novel post-processing algorithm for jitter noise reduction of RTD fluxgate output strategy based on the single-frequency time difference (SFTD) method is proposed in this study to boost the performance of the RTD system. This algorithm extracts the signal that has a fixed frequency and preserves its time-domain information via a time–frequency transformation method. Thereby, the single-frequency signal without jitter noise, which still contains the ambient field information in its time difference, is yielded. Consequently, compared with the traditional comparator RTD method (CRTD), the stability of the RTD estimation (in other words, the signal-to-noise ratio of residence time difference) has been significantly boosted with sensitivity of 4.3 μs/nT. Furthermore, the experimental results reveal that the RTD fluxgate is comparable to harmonic fluxgate sensors, in terms of noise floor.

scholarly journals Investigation on peculiar SNR variation at TianMa radio telescope

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Qingbao He
Keyword(s):  
Signal To Noise Ratio ◽  
Elevation Angle ◽  
Main Beam ◽  
Control Software ◽  
Software Update ◽  
Astronomical Observations ◽  
Pointing Error ◽  
Long Baseline ◽  
X Band ◽  
Changing Rate

AbstractChinese lunar spacecraft Chang’E-3 (CE3) and Chang’E5-T1 (CE5T1) were launched in 2013 and 2014, respectively and very long baseline interferometry (VLBI) observations were performed. Signal to noise ratio (SNR) of the Tianma (TM) station experienced peculiar variation, whereas SNRs of other stations were rather stable. Further, it happened only when observing spacecraft, and showed no such variation when performing astronomical observations. Moreover, it was distinctive on X band signals, whereas it was not noticed on S band signals. Analysis showed that the SNR variation was closely related with changing rate of elevation angle. Further investigations discovered that there were two sets of antenna control software at TM station, and the SNR variation originated from a bug in elevation control software used for observing spacecraft, not for astronomical observations. The bug caused big pointing error (around ± 30 as) on elevation angle of TM, which resulted in the peculiar SNR variation. It was not noticed on S band signals due to its relatively wide and flat main beam comparing with ± 30 as pointing error. However, the bug was fixed in software update in July, 2016, and the SNR of TM showed no such variation in 2017 and 2018.

Improving Ambiguity Resolution Rate with an Accurate Ionospheric Differential Correction

2008 ◽  
Vol 62 (1) ◽  
pp. 151-166 ◽  
Author(s):  
Mardina Abdullah ◽  
Hal J. Strangeways ◽  
David M. A. Walsh
Keyword(s):  
Ambiguity Resolution ◽  
Elevation Angle ◽  
Reference Station ◽  
Single Frequency ◽  
Gps Measurements ◽  
Differential Correction ◽  
Resolution Rate ◽  
Differential Positioning ◽  
Range Determination

Ambiguity resolution is essential for precise range determination. As it is difficult to process, a good ionospheric model is essential to get unambiguous results or to reduce time to solve the ambiguities. In this paper, a developed model to determine the differential ionospheric error to sub-centimetre accuracy is described. As a function of elevation angle and TEC, the model is applicable at any location and only requires a single frequency receiver provided the TEC over the reference station is known. It has been evaluated using real GPS measurements at spaced stations in Glasgow (UK) and Stirling (UK), where the results showed good correlation. It was found that the variance ratio and reference variance of the ambiguity resolution rate and the quality of the differential positioning solution are improved. Significant improvements of more than 50% have also been found by correcting the differential ionospheric delay in the measurements for the estimated positions.

Single Frequency Multipath Mitigation Based On Wavelet Analysis

2007 ◽  
Vol 60 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Mohammad Aram ◽  
Ahmed El-Rabbany ◽  
Sri Krishnan ◽  
Alagan Anpalagan
Keyword(s):  
Wavelet Analysis ◽  
Elevation Angle ◽  
Least Square ◽  
Single Frequency ◽  
Multipath Mitigation ◽  
Error Sources ◽  
Data Scatter ◽  
Residual Values ◽  
Multipath Environment ◽  
The One

Multipath is still one of the major error sources that degrades the accuracy of GPS positioning. The amount of multipath is highly dependent on the antenna's environment, which makes it difficult to isolate. Usually there is at least one in-view satellite which is more susceptible to multipath, particularly the one with the lowest elevation angle. To increase the positioning the best satellites must be selected (i.e. by least square or multipath mitigation) for computing a position. In this paper we propose an algorithm which picks up the best satellites (when there are more than four satellites in view) based on wavelet analysis for calculating a position. In this experiment, code and carrier measurements were collected in 15-minute segments by exploiting a single frequency (L1), stationary, navigation-grade receiver in a high-multipath environment. The magnitudes of these pseudoranges were often inflated by multipath error. We then post-processed the received data by applying wavelet filtering to the residuals (code minus carrier) to approximate the multipath values, and compute the receiver's position based on the selected satellites. Satellites were selected based on the residual values. To compare the results with the raw measurements, statistical elements were computed. The results showed significant improvement in variance of the estimated positions and, most importantly, a normalization of the data scatter-distribution was observed.

Sign in / Sign up

Export Citation Format

Share Document