推荐一款GPS——MAGELLAN315、320

GPS即全球卫星定位系统。它是由空间站、地面站和用户三部分组成。
1、空间站是由美国发射的24颗GPS专用卫星组成，它们位于地球上空201832公里轨道，均匀分布在6条倾斜角为55度的地球同步轨道上，连续发射GPS信号。
2、地面站由一个主控站和五个监控站组成，用来对GPS卫星进行监视、遥测、跟踪和控制，以纠正卫星轨道、姿态和工作特性的变化。
3、用户部分只适用于各种用途的GPS接收机。
Accurate
The GPS 320 gets a precision fix on your exact location, even in heavy cloud cover, by tracking up to 12 GPS satellites simultaneously. Equipped with a super sensitive quadrifilar antenna designed for fast satellite signal locking, the GPS 320 is accurate to within 15 meters or better.

Easy to use
An intuitive interface provides easy setup, and dedicated function buttons put the power of GPS at your fingertips.

Navigation database
Navigate with a database of coordinates for 11,000 nautical markers, buoys, lighthouses, and other nautical navigation aids, as well as nearly 3,000 coordinates of major U.S. cities. Easily upload thousands of additional points of interest with Magellan DataSendTM software. World-wide points of reference are also included for navigation abroad.

Full Featured Navigation
Nine graphic navigation screens show heading, bearing, speed, direction, ETA, and your exact position in a number or formats, including longitude/latitude, Universal Transverse Mercator, Military Grid and Ordnance Survey of Britain Conversion.

Advanced power and memory management
You get up to 15 hours of continuous operation on two AA batteries, while the 10 year lithium backup battery ensures that you never lose your stored data.

Save routes and waypoints
Store up to 20 routes, with 500 waypoints, to easily find your way back again.

NorthFinderTM
NorthFinder technology shows your direction even when standing still.

Fish and game calculator
Want to know when the fish are likely to be biting in your little corner of the world? By tracking phases of the sun and the moon, the Magellan GPS 320 can tell you.

Satellite status
The GPS 320 displays all satellites in view of the receiver and gives you a little info on their status.

DGPS ready
The GPS 320 accepts RTCM 104 signals from your DGPS receiver, for even better accuracy.

Data exporting
Use your favorite PC navigation software with easy, standard data exporting and a GPS 320 data cable.

Built to perform on the most challenging and rigorous adventure.

Large backlit display
Easily view all the GPS information you need to make your adventure fun and safe, even at night.

Rugged construction
Rubber armored, impact resistant plastic allows you to confidently take your GPS 320 on that next great adventure.

Weather-proof
GPS 320 is sealed to IEC-529 IPX7 specifications ?and it floats!

1-year warranty
We pride ourselves on building rugged and reliable navigation products that you can depend on, backed by a full one-year warranty.

http://www.magellangps.com/en/products/product.asp?PRODID=96