Posts Tagged ‘used’

Mostly I want a gps for geocaching but since they cost around $200-300, I figure I could spend a few hundred more and get one that is good for driving as well. (One that plugs into the cigarette lighter bu then has an internal battery so that it can be used for hiking as well) Thanks!

What is the MOB feature used for on a Magellan 315 GPS?

I know it means man over board, but what is its intended purpose?

The GPS system is a global navigation system maintained by the United States military. The system consists of 24 Earth orbiting satellites, which can provide precise time, and positioning information anywhere on the face of the globe. This article provides an overview of how the GPS system can be used for computer time synchronisation solutions and describes the equipment required to provide a GPS time reference.

Each Earth orbiting GPS satellite has a highly accurate precisely synchronised real time clock onboard. This clock is used to calculate precise positioning through a triangulation technique. However, the GPS system clock can also be used for precise computer time synchronisation applications.

Each GPS satellite continously transmits positioning and timing data. The time and position information can be obtained anywhere on the face of the planet with a GPS receiver and antenna. GPS works in all whether conditions, anywhere in the world. The only costs involved in using the GPS system is equipment costs, there are no ongoing subscription fees. Many computer and network time synchronisation systems, such as NTP Server systems, utilise GPS as an accurate external timing reference.

GPS receivers are primarily designed to provide highly accurate positioning information. Typically, a GPS receiver can provide positioning information to an accuracy of better than 10m. Many GPS systems can also provide timing information to a resolution of a few nanoseconds.

The GPS signal transmitted from the satellites is a very weak low-power radio signal, with designated bands L1 and L2. Band L1 is designated as the civilian GPS band transmitted at 1575.42 MHz. The broadcast radio signals travel by line of sight and pass through clouds, glass and plastics but are blocked by objects such as metal and brick. Ideally, a GPS antenna should be located with the best view of the sky possible. Quite often, however, an antenna installed with a restricted view of the sky can still provide a regular signal lock. As a rule, the better the view of the sky, the more consistent the signal lock.

GPS antennas act as amplifiers to boost the weak GPS signal for transmission along a cable, usually coax, to a GPS receiver. GPS antennas provided with computer time synchronisation equipment generally utilise a pole-mounting system. The antenna screws to a threaded pole for installation on rooftops. The pole mount allows the antenna to be fixed permanently to a fixed wall mount and provides a sturdy mount. Most GPS antennas are compact devices which can easily be mounted in an unobtrusive manner. Patch type antenna’s are a cheaper alternative, but they are generally of a inferior quality and can be more difficult to mount securely.

The cable distance between a GPS antenna and receiver can be critical. Cable distance is largely dependant on the gain, or amplification, of the GPS antenna and the cable losses. A typical GPS antenna may have 36 db of amplification; typical low quality coax (RG58) has an attenuation of 0.64db/m at 1575MHz. Therefore, a cable run of up to, but not beyond, 55m can be used. High quality cables with lower attenuation losses can be used for longer cable distances. Additionally, GPS amplifiers can be utilised to increase the signal gain to extend cable runs even further.

GPS surge suppressors protect expensive time synchronisation equipment from lightning strikes and other potential electro-static discharges. A suppressor is mounted in-line on the GPS cable at the point where the antenna cable enters the building. To install, a suppressor only requires a low-impedance ground connection to dump any electro-static discharge.

To conclude, the Global Positioning System provides a precise and flexible solution to computer network time synchronisation.

ATT’s new phones have GPS support designed to interact with the proprietary TeleNav Navigator software. This software comes with a 9.99/month pricetag for it’s up-to-the-minute information on the fly. I want to know if there’s shelf GPS software that can read the Long/Lat and use built-in POS and map software.

GPS stands for Global Positioning System and was initially designed to be used by the U.S. military and is operated by the U.S. Defense Department. This system consists of 24 satellites, these satellites are 12,000 miles above us, are constantly moving in a precise orbit, have an atomic clock, and are solar powered. They do have a battery backup so they will continue to run in the event of a solar eclipse, and each satellites has a small rocket booster to maintain their orbit. The first satellite was launched in 1978 and it wasn’t until 1994 when there were a total of 24 satellites. Each satellite has a life expectancy of about 10 years, so new satellites are constantly being built and launched. Each satellite weighs about 2,000 pounds and is approximately 17 feet in width when the solar panels are extended. In the 1980s the GPS became available to the public, and although it is still maintain by the U.S. Defense Department there is no charge for its usage by the public.

These 24 satellites orbit the earth twice a day and continuously sends the location of the satellite. A GPS system can tell how far a satellite is away by comparing the time difference between the time a signal was transmitted and the time it was received, the longer it takes the signal to be received by a receiver, the farther away the satellite is. If a GPS is receiving signals from three satellites it can calculate latitude and longitude. Altitude can be determined if the GPS is receiving signals from four satellites.

GPS can be used for navigating your car through traffic day-to-day or tracking a fleet of vehicles. Not only can a driver use a GPS for directions the main office knows where that vehicle is and the speed of the vehicle. GPS can be used while on vacation for activities such as hiking, camping, or hunting. Is your passion fishing but get frustrated trying to find the fish? With a fish finder which uses both GPS technology and sonar you’ll know exactly where to go to find those fish. GPS technology is also being used as a way to track your pet if he wanders off or to safeguard a pet from being stolen.

Another use for GPS is as a child finder with a receiver in a child’s cell phone or wristwatch to ensure a child’s safety. It can be used in a teenager’s car in order to both know where they and how fast they are driving. This could also be used to keep track of someone who tends to ‘roam’ but is not capable enough to find there way back; i.e. someone with Alzheimer’s disease.

As GPS technology improves, it uses will increase. Who knows where it will take us next?

When you hear about General Positioning System (GPS) system, you should first consider the GPS receiver. It is the part of the device responsible of processing the signal sent by the satellite in the space to find out your actual location. The receiver is usually placed on the dashboard of your car or underneath it. It renders on a dedicated output device your screen your destination.

The entire GPS is a constellation of about 27 satellites rolling around the center of the Earth at a steady speed. Amongst these satellites, 24 of them are responsible of processing signals emitted by the receiver and the remaining satellites are used for storage purposes on case of an unplanned event. The GPS receiver is responsible of hooking up with satellites used for storage purposes and working out its position from that satellite by computing their distance. The mathematical tenet used for this purpose is named trilateration.

Trilateration can be achieved in two dimensions and also in three dimensions. The rationale of this mathematical principle is to work out a triangle where you are located at the center of it. As soon as the GPS receiver emits its position and makes a connection with other satellites, it immediately works out three nearest points and computes your position.

Three types of GPS receivers can be noticed: those which can be installed in a car, lightweight and mobile GPS receivers and tracking GPS receivers. It is obvious that portable receivers are a huge boon for outdoor activities.

Finally, it is good to know that the actual process of GPS receivers is a little bit more intricate than what was described in previous sections. However, throughout this article, although the main objective was to give a broad overview how they work in theory the next paragraph will delve into advanced details about GPS computations.

From previous sections, we learnt that the GPS receiver computes its distance to the nearest available satellites in space by noticing the time spent by the emission of a given signal from the receiver to the satellite. There are another category of GPS receivers that you have not mentioned throughout this article. In order to overcome the lack of precision of the traditional GPS receiver, differential GPS receivers were born. Their rationale is to estimate the level of GPS errors at a stationary receiver station with a location that was already computed before. Since the Differential GPS hardware at the station is already aware of its own location, it can work out its receiver’s level of errors in a straightforward way. The station then broadcasts a radio signal to all Differential GPS-equipped receivers in the nearby area, providing signal correction information for that area. In general, accessing this correction information makes Differential GPS receivers much more correct and precise than traditional GPS receivers.

The most essential function of a GPS receiver is to pick up the transmissions of at least four available satellites and combine the information in those transmissions with information in an electronic almanac, all in order to figure out the receiver’s position on Earth.