Designing And Implementation Of Barometric Altimeter In Navigation Receivers

According to the principle of GPS positioning and timing in navigation system,the receivers can complete the user’s positioning and calculate the relative parameters through acquiring at least 4 visible satellites.When the receivers encounter the complex environment situation like the city,forests and mountains or bad weather,the number of visible satellites may less than 4.What’s more,for some navigation system,due to satellite distribution near the equatorial plane and the vertical dilution of precision is poor,the receivers can not complete the positioning and make users to inconvenience.Aiming at these problem, obtaining the height value through atmospheric pressure measurement by barometric altimeter,the receiver can reach the goal of positioning.Aiming at the situation that the barometric altimeter can play an important aided-navigation role in satellite navigation system,especially the satellites are difficult to realize three-dimensional positioning,or receiver’s positioning accuracy is not high caused by poor VDOP value,the paper designs a barometric altimeter which is getting the height information through measuring atmospheric pressure value and temperature value.Firstly,the paper introduces the application background of height measurement with atmospheric pressure and the definition of height,meanwhile,the paper describes the principle and process of height measurement with atmospheric pressure in details.The measurement way of barometric altimeter is choosing a benchmark station H0,and getting the station’s height.In fact,the barometer is determined by measuring the relative height between the station and receiver,added the station’s height and realized positioning rather than measured the receiver’s height directly.Obtaining the height value equals reducing variables which is unknown receiver’s location coordinate component in GPS positioning and timing equations.Secondly,the barometric altimeter is taking embedded chips and sensor technology to design a new generation barometric altimeter,meanwhile,the device have the advantage of low-power,small volume and high-performance.In this paper,the barometric altimeter’s development is mainly rely on STM32,therefore,the device’s design cost has been reduced,the development cycle has been shorten and the reliability and flexibility have been improved.The barometric altimeter has good practicability on the engineering,and have the effect of aid-navigation. Using digital sensor MS5534 B to obtain real-time atmospheric pressure value and convert it to the digital signal, reading the signal from micro-processor chip, designing a algorithm to research the relationship between atmospheric pressure, temperature and height, obtaining the height value finally, the receivers can achieve the objective of the height measurement and aidednavigation.Finally,the paper design two experiments to verify the pressure and temperature’s collecting accuracy,and height measurement accuracy.In addition,the paper analysis the experiment data.The experiment result shows the barometric altimeter’s height measurement accuracy deviation less than 10 m and satisfies the demand of engineer.