From Repair Mobile
Satellites set up systems
Global Positioning System
The Global Positioning System (GPS) is a Global Navigation Satellite System (GNSS) developed by the United States Department of Defense. It is the only fully functional GNSS in the world. It uses a constellation of between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals, which allow GPS receivers to determine their current location, the time, and their velocity[1] - thanks to wikipedia.org More details.
Basic concept of GPS
A GPS receiver calculates its position by precisely timing the signals sent by the GPS satellites high above the Earth. Each satellite continually transmits messages containing the time the message was sent, precise orbital information (the ephemeris), and the general system health and rough orbits of all GPS satellites (the almanac). The receiver measures the transit time of each message and computes the distance to each satellite.[2] - thanks to wikipedia.org More details.
Correcting a GPS receiver's clock
The method of calculating position for the case of no errors has been explained. One of the most significant error sources is the GPS receiver's clock. Because of the very large value of the speed of light, c, the estimated distances from the GPS receiver to the satellites, the pseudoranges, are very sensitive to errors in the GPS receiver clock. This suggests that an extremely accurate and expensive clock is required for the GPS receiver to work.[3] - thanks to wikipedia.org More details.
System segmentation
Space segment
The space segment (SS) comprises the orbiting GPS satellites, or Space Vehicles (SV) in GPS parlance. The GPS design originally called for 24 SVs, eight each in three circular orbital planes,[10] but this was modified to six planes with four satellites each.[4] - thanks to wikipedia.org More details.
Navigation signals
Each GPS satellite continuously broadcasts a Navigation Message at 50 bit/s giving the time-of-week, GPS week number and satellite health information (all transmitted in the first part of the message), an ephemeris (transmitted in the second part of the message) and an almanac (later part of the message). The messages are sent in frames, each taking 30 seconds to transmit 1500 bits.[5] - thanks to wikipedia.org More details.
Satellite frequencies
- 1 (1575.42 MHz): Mix of Navigation Message, coarse-acquisition (C/A) code and encrypted precision P(Y) code, plus the new L1C on future Block III satellites.
- L2 (1227.60 MHz): P(Y) code, plus the new L2C code on the Block IIR-M and newer satellites
L3 (1381.05 MHz): Used by the Nuclear Detonation (NUDET) Detection System Payload (NDS) to signal detection of nuclear detonations and other high-energy infrared events. Used to enforce nuclear test ban treaties.[6] - thanks to wikipedia.org More details.
Skyhawk Portable Satellite Systems!
Skyhawk is the brain-child of Don Hays, a full-time RV'er who, like so many of you, just wanted to enjoy one of life's simple pleasures while on the road...TV! For no man should be without TV! (No offense ladies, it just sounded good that way!)
Here's how Don actually puts it..[7] - thanks to hot-springs-ar-info.com More details.
L-antenna Sinusoidal Vibration Test
On October 6, the L-band antenna sinusoidal vibration test was completed at the Structural Test Building at the Tsukuba Space Center.
A vibration test is an important gateway to a successful launch as it verifies if onboard equipment is performing normally[8] - thanks to jaxa.jp More details.
Boeing Satellites
Boeing Space and Intelligence Systems (S&IS) is the world's leading manufacturer of geostationary satellites. The factory, known as the Satellite Development Center, (SDC) is headquartered in El Segundo, Calif. Boeing manufactures the body-stabilized Boeing 601 satellite and the body-stabilized Boeing 702, the world's most powerful communications satellite[9] - thanks to boeing.com More details.
Global navigation satellite system
Global Navigation Satellite System (GNSS) is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage. A GNSS allows small electronic receivers to determine their location (longitude, latitude, and altitude) to within a few metres using time signals transmitted along a line-of-sight by radio from satellites. Receivers on the ground with a fixed position can also be used to calculate the precise time as a reference for scientific experiments.[10] - thanks to wikipedia.org More details.
Accuracy enhancement
Augmentation methods of improving accuracy rely on external information being integrated into the calculation process. There are many such systems in place and they are generally named or described based on how the GPS sensor receives the information. Some systems transmit additional information about sources of error (such as clock drift, ephemeris,[11] - thanks to wikipedia.org More details.
