What data is sent from GPS satellites to receivers?
2017年8月9日 · Each satellite is sending exact (atomic) time, and GPS receiver calculates thanks to it, it's position. There is also some additional data, like position of satellite (almanac) which is also required to perform calculations, and a few minor things.
Why does GPS positioning require four satellites?
29. You need four satellites because each data from one satellite put you in a sphere around the satellite. By computing the intersections you can narrow the possibilities to a single point. Two satellites intersection places you on a circle. (all points possible) Three satellites intersection places you on two possible points.
Is GPS more accurate on specific hours of the day?
2017年8月9日 · NAVCOM GPS Satellite Predictor Tool. Great tool if you require a certain level of (x)DOP for GPS Data Collection, to prevent spending an entire day in the field due to poor (x)DOP of GPS Satellites. Of course this tool can not calculate other external factors which will …
Does the strength of GPS weaken in rural areas?
2013年11月19日 · To clarify: Unlike mobile phones (GPRS) who normally use ground based towers, the GPS signal comes from satellites orbiting the earth. So long as you can see the sky above you, you should be able to receive the GPS signals. – Rob Lodge. Nov 19, 2013 at 16:56. Anecdotally, the hand-held Garmin unit I carried to the foot of Uluru in the outback ...
satellite - Why is GPS a free service? - Geographic Information …
2014年12月12日 · 37. The Global Positioning System (GPS) is a free service that is owned and operated by the U.S. Government and is always available. When we buy a GPS device, we don't pay a monthly fee or pay a tax for GPS support. We only pay the price of the device.
gps - Satellite data to position coordinates - Geographic …
2018年6月15日 · In order to be answered, questions need to show an appropriate level of research, and an attempt to solve the problem. All questions should specify the GIS software in use. What've looked at so far was taking the raw satellite data and trying to find how a GPS converts them to coords.
Determining GPS Position from Elevation, Azimuth, SNR
2016年12月5日 · This gentleman here can compute the location of a GPS satellite given receivers location, satellite elevation and azimuth. I want to merely do the reverse, given satellite location (from almanac), azimuth and elevation, compute receiver's location. Another link on azimuth / elevation and Android.
wgs84 - What causes the GPS offset/shift in China? - Geographic ...
2015年4月6日 · After sifting through the noise, two recurring symptoms are that: GPS coordinates (WGS-84) plot poorly on Chinese maps, with an offset ranging from 50 to 1000 meters. Google and Apple Maps in China have severe misalignment between their street maps and satellite imagery (live example) Various sources make contradictory claims:
Seeking Public API to get GPS satellite's position?
2019年4月12日 · To solve this you've got to use a satellite future position predictor but the only API for that I've found only allows a projection of 300 seconds, so to make predictions up to the current time you've got to wait potentially for 4-5 minutes.
In hyperbola model of how GPS equations are solved, why do 3 …
2015年9月23日 · Older GPS units may take up to an hour to search for satellites, download the almanac and ephemeris data and obtain an initial position, though newer GPS units may require much less than this. If the GPS receiver has moved several hundred kilometres, its assumptions about which satellites to use will be incorrect and it will have to search for ...