Memorex RX 1 Smart Installationshandbuch PDF herunterladen (Seite 13)

About GPS Navigation | 11

1 About GPS Navigation

This GPS receiver is a precision navigation instrument utilizing the latest technology

available today to provide optimum performance from the GPS satellite and Beacon

land signals received. As with all other forms of radio signals, the ultimate navigation

result is dependent upon the quality of these signals. Radio signals may, on occasion,

be distorted, jammed, or otherwise incorrect. As a result, your position accuracy may

occasionally be less than that which can normally be expected.

The Navstar Global Positioning System, commonly referred to as GPS, is a satel lite

navigation system developed by the U.S. Department of Defense to provide both military

and civilian users with highly accurate, worldwide, three dimensional navigation and

time. By receiving signals from orbiting GPS satellites, authorized users are able to

continuously navigate with an accuracy on the order of 5 meters 2D RMS or better

A technique referred to as Differential GPS (DGPS), allows users to obtain maximum

accuracy from the GPS system. DGPS requires the use of two GPS receivers. One

receiver, known as the Reference Station, is placed at a surveyed location, the

coordinates of which are precisely known. The purpose of the differential GPS system

is to use the reference station to measure the errors in the GPS signals and to compute

corrections to remove the errors. The corrections are then communicated in real-time

to the navigators, where they are combined with the satellite signals received by the

navigators, thereby improving their navigation or positioning. The geographic validity of

these corrections decreases with distance from the reference station, but the corrections

are valid for navigators hundreds of kilometers from the reference station.

Marine radio beacons operating in the 283.5 to 325.0 KHz frequency range are in

widespread use for direction finding in coastal navigation. Because the beacon system

has been in place and widely used for many years, it provides an effective means for

the transmission of DGPS signals. Depending on their local environment and power

output, their signals may be usable to several hundred miles. Marine beacons provide an

economical means of obtaining DGPS accuracy for coastal navigators. GPS receivers with

built-in beacon receivers are designed to provide low cost reception of DGPS corrections

broadcast (normally free of charge) by coastal authorities.

Special notes

GPS

Never rely solely on any single navigational aid. Always use whatever information is

available, and cross-check information when possible. GPS expected position accuracy is

better than 30 meters (95% of the time) but may be up to 100 meters occasionally. The

derived speed and course readings may be hampered accordingly. The GPS system was

declared operational in 1994; however, the system’s availability and accuracy are subject

to change at the discretion of the US Department of Defense.

DGPS

This GPS receiver’s position accuracy is improved to 1 meter or better for 95% of the time,

subject to the availability, accuracy, and control of the DGPS correction transmission from

the Beacon Station.

The beacon radio signal which carries the DGPS corrections may be hampered by weather

conditions such as heavy rain, snow, and thunder storms. The beacon radio signal may

also be interrupted by powerful radio transmitters operating in long wavelength bands.

Charts and Navigational Aids

Positions obtained from charts are not always as accurate as your navigator (due to

environmental changes, the dates of charts, and datum offsets if the datum differs from

the one in use by the navigator). The position of a floating aid can differ due to tide, set

and drift

Compass Safe Distance

1 meter.

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 ... 199 200

Kommentare zu diesen Handbüchern

Keine Kommentare

Memorex RX 1 Smart Installationshandbuch Seite 13

Kommentare zu diesen Handbüchern