The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite systems (GNSS) that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. Obstacles such as mountains and buildings block the relatively weak GPS signals.
The GPS does not require the user to transmit any data, and it operates independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the GPS positioning information. The GPS provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, and makes it freely accessible to anyone with a GPS receiver.The GPS project was started by the U.S. Department of Defense in 1973, with the first prototype spacecraft launched in 1978 and the full constellation of 24 satellites operational in 1993. Originally limited to use by the United States military, civilian use was allowed from the 1980s following an executive order from President Ronald Reagan after the Korean Air Lines Flight 007 incident. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of GPS Block IIIA satellites and Next Generation Operational Control System (OCX). Announcements from Vice President Al Gore and the Clinton Administration in 1998 initiated these changes, which were authorized by the U.S. Congress in 2000.
During the 1990s, GPS quality was degraded by the United States government in a program called "Selective Availability"; this was discontinued on May 1, 2000 by a law signed by President Bill Clinton.The GPS service is provided by the United States government, which can selectively deny access to the system, as happened to the Indian military in 1999 during the Kargil War, or degrade the service at any time. As a result, several countries have developed or are in the process of setting up other global or regional satellite navigation systems. The Russian Global Navigation Satellite System (GLONASS) was developed contemporaneously with GPS, but suffered from incomplete coverage of the globe until the mid-2000s. GLONASS can be added to GPS devices, making more satellites available and enabling positions to be fixed more quickly and accurately, to within two meters (6.6 ft). China's BeiDou Navigation Satellite System began global services in 2018, and finished its full deployment in 2020.
There are also the European Union Galileo positioning system, and India's NavIC. Japan's Quasi-Zenith Satellite System (QZSS) is a GPS satellite-based augmentation system to enhance GPS's accuracy in Asia-Oceania, with satellite navigation independent of GPS scheduled for 2023.When selective availability was lifted in 2000, GPS had about a five-meter (16 ft) accuracy. GPS receivers that use the L5 band can have much higher accuracy, pinpointing to within 30 centimeters (11.8 in). As of May 2021, 16 GPS satellites are broadcasting L5 signals, and the signals are considered pre-operational, scheduled to reach 24 satellites by approximately 2027.
a wiki type GPS library ?
Pretty much everyone has a GPS navigation system now, whether it be in their cell phone or in their car.
with all the new houses being built and new highways a lot of times you find yourself in the middle of a field according to the gps because that new road has not...
Hello, friends!
I've google about the question below but no success!
The question is:
Gps signals inside buildings are nonexistent or very weak, but mobile phone and am and fm radio signals are good, so the question is: why gps satellites and mobile phone comunications don't use emission...
GPS (Global Positioning System) satellites orbit at an altitude of 2.0×10^7 m.
Find the orbital period.(hours)I use the equation T=(2pi/sqrt(GM))r^(3/2).
Shouldnt that be the correct way of doing it? I know I am supposed to add the altitude to the radius of the earth, G is known, M of Earth is...
Homework Statement
The global positioning system GPS uses the fact that a receiver can get the difference of distances to two satellites. Each GPS satellite sends periodically signals which are triggered by an atomic clock. While the distance to each satellite is not known, the difference from...
I'm working through "Exploring Black Holes" by Taylor and Wheeler. Their first project is on the GPS system and how GR must be accounted for. At the end you arrive at the conclusion that the satellite atomic clock will advance approximately 38,700 nanoseconds a day with respect to an atomic...
Is it plausable to take into account the speed of the Earth's spin when calculating tmie dilation for satellites and GPS receivers?
You could take into account the satellites spining against the Earth's orbit, with the Earth's orbit and at an angle?
I put it into my project but is it a...
Hi all
I wasnt sure where to place this thread. I am currently doing a project on GPS and have deceided to take the root of studying the relativity side of GPS. All I am asking does anyone know of or have any ideas of some experiments I could do, or some computer programmes to perfrom a...
I've read that the GPS system has to take into account the Sagnac effect when sending signals from the satellites to the Earth. For those of us who are unfamiliar with the Sagnac effect, it is the delay in receiving(or shorter time in receiving) the signal due to the rotation of the Earth while...
Homework Statement
The GPS (Global Positioning System) satellites are approximately 5.18 m across and transmit two low-power signals, one of which is at 1575.42 MHz (in the UHF band). In a series of laboratory tests on the satellite, you put two 1575.42 MHz UHF transmitters at opposite ends...
[SOLVED] GPS and special relativity
Homework Statement
time dilation of gps receivers and satellites
Homework Equations
\Delta\tau = \gamma\Delta t
The Attempt at a Solution
so its a part of my project, my tutor has worked it out as using the above equation and has gotten...
[SOLVED] GPS and Special relativity (Graph)
Homework Statement
The image attached is a graph I'm supposed to be able to figure out. I'm supposed to be able to figure out the distance between a Satelite and a GPS reciever.
X axis: Time / seconds
Y axis: Signal strength / no unit
There is no...
So I'm doing a report on special relativity and GPS and kinda at a loss what to do:
1. I've actually found several sites denoting the need to calibrate for relativistic effects when calculating locations, and I'm writing a report on just the opposite, that how is the system effected / how...
This is an old video of the GPS launch back in Jan '97. The launch controllers sit in a blockhouse fairly near the launchpad, which is kind of cool. Working in a restricted area, they always got the good parking spaces.
http://shock.military.com/Shock/videos.do?displayContent=157296&ESRC=dod
Suppose i have two clocks on Earth showing 12:00 hours.
After, one of the clocks is put in a gps satellite for a year.
After one year that clock returns to earth.
Due to relativistic effect what time that clock shows? Less than 12:00?
If so why?
GPS modules produce a very accurate 1 second timebase signal, rms differency of about 20nS. How do you suggest of using that to split it into a 1000 pieces = 1000Hz = 1000ms ?
My idea is to make a generator with a quartz chrystal and drive it into a counter module, carefully selected divide...
The satellites of GPS sysstem had been adjusted so they compensate for
GR and SR dilation of time due their velocity and less gravity.
This is what I found on Internet ( Not all agree ).
Is that true ?
But I´d like to know if the frequency of the ground stations that
control the...
I am looking over the Project A: Global Positioning System is Exploring Black Holes; introduction to General Relativity by Taylor and Wheeler. At first, they convincingly suggest that the time dilation caused by the differences in radius from Earth clocks to the satelight clocks will cause the...
Hello there!
Am actually doing my end of year project on GPS and GR. It's actually a review of Ashby's work. I am kinda stuck with a term. In the choice of metric, Mr Ashby (God bless him! ;-) ) makes use of the Langevin metric. He propounds that it is well know. But lo and behold, on...
I heard somewhere that the satelites use by Global Position System (GPS) device is open for public use , is it right ? If the satelite is open for public use , then is it possible for me to make my own GPS and how to make the GPS ?
Quoted from http://hyperphysics.phy-astr.gsu.edu/hbase/gps.html#c1"
How do they know which of the points is the correct one? (see sentence in blod)
Thank you!:approve:
I've always been told that GPS does great horizontally, but not so great vertically. Is the reason simply because the Earth is blocking any satellites that would provide info below the receiver? Is vertical precision 1/2 as reliable as horizontal?
Hi friends,
I'm a user of Meade's 12" LX200GPS and I was looking for the software to connect my telescope to my pc, I installed "Starry night pro" version 4.5 and ACP3 but they didn't work. Starry night only had LX200 & AutostarII in the list it supported but not LX200GPS.
Does anybody know...
It has been said that a russian company has provided Iraq with a system that destroys GPS navagational status of onboard cruise missiles, rendering the missile to be co-ordinless?
As the first of these missiles that have been 'un-guided', how simple is it to actually 'jam' GPS sytems?..is it...