Fast fine acquisition algorithm of GPS receiver aided by INS information

Acquisition time of global position system （GPS） receiver, which is the main factor contributes to time to first fix （TTFF）, can be shortened by estimating the Doppler frequency shift through external inertial navigation system （INS） information and almanac data and reducing the searching area. The traditional fast acquisition is analyzed, the fast acquisition of the GPS receiver aided is presented by INS information, and the signal is fine captured by spectrum zooming. Then the algorithm is simulated by sampled GPS intermediate frequency （IF） signal and the result verifies that this acquisition can dramatically improve the capability of GPS receiver and reduce its acquisition time.

Calibration of GPS receivers based on IGS and CORS techniques

Concerning the traditional methods,more technical details and more strict conditions are required for global positioning system(GPS)receiver’s calibration especially for mid and long baseline which influenced by the environment around easily,and more investigations have to be done.In this paper,a new method on how to calibrate GPS receivers is suggested,which is based on the convenient condition that Kunming has one international GPS service station and its own continuously operating reference stations,and the method is confirmed by a test using six different types of GPS receivers.Compared with the traditional methods,the new method is more efficient by decreasing routine calibration works up to 50%.

Design of a low power GPS receiver in 0.18 μm CMOS technology with a ΣΔ fractional-N synthesizer

A 19 mW highly integrated GPS receiver with a ΣΔ fractional-N synthesizer is presented in this paper.Fractional-N frequency synthesizer architecture was adopted in this work, to provide more degrees of freedom in the synthesizer design.A high linearity low noise amplifier(LNA) is integrated into the chip.The radio receiver chip was fabricated in a 0.18 μm complementary metal oxide semiconductor(CMOS) process and packaged in a 48-pin 2 mm×2 mm land grid array chip scale package.The chip consumes 19 mW(LNA1 excluded) and the LNA1 6.3 mW.Measured performances are:noise figure<2 dB, channel gain=108 dB(LNA1 included), image rejection>36 dB, and-108 dBc/Hz @ 1 MHz phase noise offset from the carrier.The carrier noise ratio(C/N) can reach 41 dB at an input power of-130 dBm.The chip operates over a temperature range of-40, 120 °C and ±5% tolerance over the CMOS technology process.

Analysis of unmanned aerial vehicle navigation and height control system based on GPS

According to the characteristic of global positioning system（GPS） reflection signals,a GPS delay mapping receiver system scheme is put forward,which not only satisfies the unmanned aerial vehicle（UAV） guidance localization but also realizes height measurement.A code delay algorithm is put forward,which processes the direct and land reflected signal and outputs the navigation data and specular point.The GPS terrain reflected echo signal mathematical equation is inferred.The reflecting signal area,when the GPS signal passes the land,is analyzed.The height survey model reflected land surface characteristic is established.A simulation system which carries guidance localization of the UAV and the height measuring control through the GPS direct signal and the land reflected signal is designed,taken the GPS satellite as the illumination source,the receiver is put on the UAV.Then the UAV guidance signal,the GPS reflection signal and receiver＇s parallel processing are realized.The parallel processing reduces UAV＇s payload and raises system＇s operating efficiency.The simulation results confirms the validity of the model and also provides the basis for the UAV＇s optimization design.

Portable device to assess dynamic accuracy of global positioning system(GPS)receivers used in agricultural aircraft

A device was designed to test the dynamic accuracy of Global Positioning System(GPS)receivers used in agricultural aircraft and other aerial vehicles.The system works by directing a sun-reflected light beam from the ground to the aircraft using mirrors.A photo detector points downward from the aircraft to detect the light beam,and photo detection circuitry triggers an event in the guidance system data file at the aircraft’s location corresponding to the precisely georeferenced position on the ground.Construction details are presented on the mirror-based light reflection system and photo-electronic circuitry designed to trigger an event in the guidance system’s log file.An example application evaluated the horizontal accuracy of a stand-alone GPS receiver by matching dynamic data with data from the aircraft’s guidance system.Results indicated a 2.16 s lead in position registered by the stand-alone receiver over that registered by the aircraft’s guidance system GPS receiver,which had been previously evaluated to be within 0.13 s of Real-Time Kinematic(RTK)-referenced time and position.

An RF frontend circuit design of a Compass and GPS dual-mode dual-channel image rejection radio receiver

This paper introduces a fully integrated low power consumption radio receiver frontend circuit for a Compass（Beidou） and GPS dual mode dual channel system with 2.5 dB NF,1.02 mm^2 areas,and 8 mA of current in 0.18μm TSMC CMOS process.Except for a few passive components for input matching,other components such as an off-chip low noise amplifier or a balun are not required.With a non-tunable passive image rejection filter,the receiver frontend can achieve around 60 dB gain and 34 dB image rejection.

A single-to-differential low-noise amplifier with low differential output imbalance

This paper presents a single-ended input differential output low-noise amplifier intended for GPS applications. We propose a method to reduce the gain/amplitude and phase imbalance of a differential output exploiting the inductive coupling of a transformer or center-tapped differential inductor.A detailed analysis of the theory of imbalance reduction,as well as a discussion on the principle of choosing the dimensions of a transformer,are given.An LNA has been implemented using TSMC 0.18μm technology with ESD-protected.Measurement on board shows a voltage gain of 24.6 dB at 1.575 GHz and a noise figure of 3.2 dB.The gain imbalance is below 0.2 dB and phase imbalance is less than 2 degrees.The LNA consumes 5.2 mA from a 1.8 V supply.