<h3>Abstract</h3> Precise point positioning (PPP) service is of great significance for BDS. The design and implementation the are presented. PPP-B2b signal constructed, which efficient multiplexed with other components, achieves compatibility between two phases. A customized message format that can augment all visible satellites four core constellations in mainland China proposed. high-gain, 64-ary, low-density parity check (LDPC) coding used, facilitates integrated receivers. quality test...

Inter-satellite links (ISLs) can be employed in global navigation satellite systems (GNSSs) for space-based telemetry, telecommand and ranging, which reduces the requirement a large number of ground stations (GSs). However, polling time division duplex (PTDD) ranging hierarchy ISLs raises topology design problem networks. To optimize communication performance with constraint precise orbit determination GNSSs, we model network finite state automation (FSA) solve optimization integer linear...

The problem of wide bandwidth management in ultra-high resolution SAR systems can be solved by adopting stepped chirps and applying synthetic approach.However, high image formation is a non-separable 2-D impulse compression processing, so the procedure should modified correspondingly with algorithm adopted.This paper demonstrates application approach Polar Format Algorithm (PFA) using deramp technique.The motion compensation between sub-pulses within burst discussed, signal processing flows...

Traditional polar format algorithm (PFA) is widely used in high-resolution and highly-squinted (HRHS) synthetic aperture radar (SAR) systems, because of its unique decoupling ability for any squint angle. However, the image size limit traditional PFA, affected by wavefront curvature, too small to meet modern wide-scene requirements. To break limit, a new two-step PFA proposed this letter. It uses twice. The first obtain coarse focused big image, from which number subimages can be filtered...

A new approach to process stepped chirps in spotlight synthetic aperture radar is presented this letter, which based on exploiting the principle of chirp scaling (PCS). In particular, PCS integrated into polar format algorithm (PFA), obtaining a more efficient solution compared with existing interpolation technique. The main contribution letter implementation azimuth scaling, bandwidth synthesis embedded. developed dedicatedly for dealing chirps. signal processing flow investigated detail,...

A novel coherent integration method for the wideband radar is proposed in this paper based on two-dimensional frequency correction. The realizes motion compensation by data re-alignment fast time frequency-Doppler domain and can be implemented quickly efficiently chirp-Z transform. validated simulation measured data. work provides a new effective way radar.

The problem of wide bandwidth management in current ultra-high resolution spotlight SAR systems could be solved by adopting stepped chirps and utilizing synthetic approach. High image formation is a non-separable 2-D impulse compression processing, so the procedure should modified correspondingly with algorithm adopted. This paper demonstrates application frequency-domain approach Polar Format Algorithm (PFA). motion compensation between subpulses within burst discussed, signal processing...

In high squint and resolution SAR, one key technique is the large Range Cell Migration (RCM) correction method. As gets higher angle larger, RCM of point target might extend 10,000 range bins in whole aperture. An appropriate algorithm fit for mode acquired with very precision to accurately correct severe migration. this paper, a new digital spotlighting preprocessing based 2-step PFA method proposed. The performs beam segmentation via firstly generate multiple full-resolution phase...

In this work, a 2-D subaperture polar format algorithm (PFA) based on steppedchirp signal is proposed. Instead of traditional pulse synthesis preprocessing, the presented method integrates process into range processing. Meanwhile, due to multi-resolution property processing, able compensate space-variant phase error caused by radar motion during period cluster. Point target simulation has validated algorithm.

The approximation of planar wavefront in traditional Polar Format Algorithm(PFA) limits the effective scene size PFA for high-resolution squinted Synthetic Aperture Radar (SAR). In this paper, a new wide-field based on quadtree sub-image segmentation is proposed. original phase history full-beam filtered recursively to generate multiple sub-beams by recursive segmentation. As long as each sub-beam narrow enough, standard could be implemented produce number fully focused sub-image. Finally,...

Gaofen-3 (GF-3) is China' first C-band multi-polarization synthetic aperture radar (SAR) satellite, which also provides the sliding spotlight mode for time. Sliding-spotlight a novel to realize imaging with not only high resolution, but wide swath. Several key technologies in spaceborne SAR resolution are investigated this paper, mainly including parameters, methods of velocity estimation and ambiguity elimination, algorithms. Based on chosen Convolution BackProjection (CBP) PFA (Polar...

The Polar Format Algorithm (PFA) is the most suitable imaging algorithm for high-resolution and highly-squinted spotlight Synthetic Aperture Radar (SAR), but approximation of planar wavefront in this limits effective scene size PFA. To meet wide-swath requirement modern SAR system, a quadtree beam-segmenting based PFA proposed paper. original full-beam echo signal filtered recursively as quadtree, generating multiple sub-beams. Each sub-beam only illuminates small part total swath. As long...

Based on the study of existed least-squares and weighted phase unwrapping methods, an improved algorithm based error compensation is proposed. First, conventional method used to get initial result unwrapping. Then optimised by iterative error. In addition, for reasonable selection times iteration, mechanism designed avoid redundant or insufficient caused too many few. Compared with traditional least-square method, using proposed global influence noise constrained processing, meanwhile,...

For Synthetic Aperture Radar (SAR) images, there are moving targets in the ground stationary scene. Since motion parameters unknown, target shows azimuthal deviation and defocus SAR image. Under condition of high resolution, is more likely to have cross-Range Cell Migration (RCM) phenomenon so as affect focus image target. This paper studied multichannel SAR-GMTI technology proposed a focusing imaging based on Clutter Suppression Interferometry (CSI) Map Drift (MD). method combines...

A new approach for processing stepped chirps in spotlight SAR is presented this manuscript, which based on exploiting the principle of chirp scaling (PCS). In particular PCS integrated a polar format algorithm (PFA), obtaining more efficient solution compared with existing interpolation technique. The main contribution implementation azimuth bandwidth synthesis embedded in, and it developed dedicatedly dealing chirps. signal flow investigated detail, no interpolations but only FFT's complex...

This paper proposes two modified space time adaptive processing (STAP) methods based on piecewise sub-apertures and data constraints for non-stationary interference cancellation in synthetic aperture radar (SAR) applications. In these methods, the entire is divided into several so that can be considered as stationary each sub-aperture. At same time, consistency of echo phase slow domain preserved by constraint to ensure null depth antenna pattern performance azimuth focusing SAR. The...

Abstract Although the multi-channel SAR-GMTI technology can be used in ground moving target detection, but only get trace point of target, tracking and track reconstruction can’t achieved. This article presents a new method detection which is based on sequence SAR images. Firstly, velocity estimation realized using processing. Secondly, location estimated accurately high accuracy knowledge-aid. The uses matching technique sequential images to realize target. Next, image reference locking...

This paper introduces an absolute calibration algorithm of RDSS (radio determination satellite service) channel. The signal is used as the test signal. input and output for are sampled in synchronization. Digital processing based on SDR (Software Defined Receiver) has been made with sampling data channel output. high rate stream converted into several low streams. start point PRN (Pseudo Random Noise) code can be gotten parallel phase search acquisition each Calculating delay between data,...

In-orbit long-term performance of GNSS (Global Navigation Satellite System) clocks is being estimated with respect to the monitoring information phase comparisons between main clock and redundancy. In satellite generator, time-difference against each other for onboard redundancy sampled continuously as information. The transmitted down ground. receiver on sensor station demodulated monitor Data processing operated on-board property can be estimated. proposed technique considered simple, fast...