[Handheld GPS] GPS Handheld Machine Use Skills Handheld Basic Knowledge

[Handheld GPS] GPS Handheld Machine Use skills Handheld Basic Knowledge

1. GPS basic knowledge

1. The principle of GPS

GPS is the abbreviation of Globol Position System (Global Positioning System), which is established by the US government and provides free services to global users.The complete GPS system is divided into two parts: heaven and underground: there are 24 satellites in the sky that are constantly turning, so that at least 3 satellites can be seen in any corner of the earth;The GPS receiver is the GPS that we often say.

When the GPS receiver receives three or more satellite signals, you can calculate the land coordinates where the receiver is located. If you receive four satellites, you can also calculate the altitude. At the same time, the time signal of the satellite system alsoIt is transmitted to the GPS. If you want to watch, the time on the GPS is the most reliable.

It should be noted that in addition to the US GPS system, Russia and Europe have also established their own global positioning systems, but the most commonly used in the United States is the GPS system.

2. The coordinate system used by GPS

When we describe the geographical location, the commonly used method is the latitude coordinates.The latitude and latitude coordinate system is based on the British Greenwich and equators as zero points of longitude and latitude.China is located in the scope of the about 70--120 degrees of about the east, within the north latitude -degree, and Xinjiang is located.

In the GPS system, the display method of latitude and longitude can generally choose according to your hobbies. Generally, there are "HDDD.DDDDDD" (degree. Degree), "HDDD*mm.mmm" (degree. Divide.), "HDDD*mm)"SS" (degree. Second. Second).

The meridian (connected from the Antarctic to the Arctic) length is 39940.67 kilometers.

The length of the equatorial circle is 40075.36 kilometers, the Beijing and Urumqi regions are about 40 degrees north latitude, and the long latitude circle is 40075*sin (90-40).Essence

3. The accuracy of GPS and SA policy

Theoretically, the positioning accuracy of GPS can be reached to the rice level. For security considerations, the American guy restricts the positioning of civilian GPS and formulated a SA policy (Selective availation.) When the SA policy is implemented, the positioning accuracy is only 20-30 meters, but the SA policy has been canceled, and the positioning accuracy of civil GPS can reach about 10 meters.

When receiving more than 4 valid satellite signals, GPS can achieve three -dimensional positioning, that is, it can be counted as high altitude, but I feel that the accuracy of the altitude is not reliable.

4. How to position handheld GPS

Generally, the Mark and GOTO keys are available on GPS.The Mark key is used for positioning, that is, the current coordinates are stored in the memory, and GPS will automatically make a name for this point; GOTO is used for navigation.Name, then press Goto and select the name of that point, you can calculate the straight line distance from this place to the known point.Mark and GOTO (that is, positioning and ranging) are the most basic features of GPS, and other functions are based on this or serving them.Generally speaking, as long as you know how to turn on the organ, know positioning and navigation, you can deal with it freely in outdoor activities.

5. The computer format of the GPS coordinate system

I can store 500 points in my GPS. Some GPSs have data cables, which can be transferred on the computer to the computer, vice versa.In this way, the data in GPS is very safe (imagine the workload of copying 300 GPS on the paper!).After the GPS point is imported, the GPS point database can be established after a certain data conversion, which is convenient for querying.Of course, you can also organize the manual input GPS dot into files on the computer, and then switch to the GPS, which is much more convenient than entering the GPS.Not only that, if there are GIS software (geographical information system) and electronic maps in the computer system, the GPS airpoint can also be projected directly to the electronic map.But this process is more complicated.

Garming provides a MapSource software with a global 1: 400000 electronic map that can directly project the GPS airpoint to the electronic map. However, for Outdoor enthusiasts, the electronic map of 1: 4000000 is useless.

A complete computer data line kit includes data cables, satellite antennas, vehicle power supplies (on the cigarette lighter), MAPSOURCE software and electronic maps (or GIS software and professional electronic maps).

Second, the cooperation of GPS and map

In Outdoor crossing activities, the most commonly used map ratio is 1: 250000 and 1: 100,000, and the 1cm on the map is equivalent to 2.5 kilometers and 1 km of actual distance.(About the Outdoor map, there will be a special article).The cooperation of GPS and maps has nothing more than the following two situations: one is to find the target point (such as the proportion of the Camping site and an important inflection point) on the map before departureWhen walking in the ancient road in 2001, he entered a set of GPS points); the other was to find the point on the map in the Outdoor activity after the important point was located to judge the current position.The coordinates found from the professional map are "hddd*mm" ss "(degree.. Second) format. If GPS uses" hddd*mm.mmm "Conversion.

3. Typical usage of GPS in outdoor activities

OK! Basic principles are finished. Now we have arrived outdoors. The eyes of the players are watching you and the GPS in your hands. Do you have confidence?If not yet, continue to see the introduction below.

1. How to position

Now that the team has reached the place of walking, how can you record the coordinates of the starting point!It's very simple. Open the GPS and take a few minutes to finish the dressing, GPS has completed the search satellite and automatically jumped to the data page. At this time, click Mark (positioning or small flag).The airpoint generated by the GPS automatic sequence, pressing confirmation, the point is stored.Of course, don't forget to let the secretary record this point.

2. How to determine the distance from the target point

At 3 pm, the team reached a place where the rest was.Hey, this is hard to fall. Before I set off, I boiled overnight and had already input the coordinates of the target point into the GPS. Remember that the point number seemed to be "first end".Take out the GPS and wait for the search satellite after booting. After a few minutes, the data comes out.FIRST END "point, press confirmation, at this time the screen display" distance target point "My end" 5523m ", good," we are 5.5 kilometers away from the target ", and announced loudly.After speaking, he glanced at the mountains and rugged mountain roads in front of him, adding "straight distance".At this time, just listening to fluttering and fluttering, players Zixin, Yang Ge, and VV fainted on the spot.

3. How to determine the distance of any two points

In the evening, I finally arrived at the Camping site that day.At this time, the team member drunk and danced to the sun: "Captain of the paste, from today's starting point to tomorrow's end point?" From the end point to the end point, that is, from 110 points Second End, this is a relatively distance, simple.Open the GPS, you don't have to wait for the satellite (wait 3 minutes, there is no face), find 110 points in the aircraft table, and then move the cursor to the reference point (Refenrence) column below, enter the Second End, OK!GPS comes out immediately, 110 points from the reference point Second End 16.8km.

4. Go to the right direction under the guidance of GPS

There is a great problem with most GPS, that is, there is no built -in compass. When you let it navigate -SECOND END, it will only tell you "3 kilometers from the target point and 80 degrees in terms of directional angle."3 kilometers well, how to find 80 degrees?Good hand, hold GPS, face its head to the north, (your head is also facing the north).What?Where is North?Look at the compass!

OK, found the North, at this time, GPS will have an arrow to the Secong End, which is about to point to your right hand.Understand!The ancestors of the GPS are based on the north as 0 degrees, the east is 90 degrees, the south is 180 degrees, and the west is 270 degrees.Let the maps, GPS, compass and your head facing north, it looks more convenient.If there is no compass, GPS can also measure your forward direction and speed in the movement state, so as to find "North", but if it is in the ravine, it is troublesome.I used to walk back and forth in the north in the straight gap below the chrysanthemum platform, and I fell 3 followers.), I also blame my eyes without long eyes. On cloudy days, there was no sun.Since then, I have 3 compass every time I go out.

5. Typical parameter settings of GPS

First of all, GPS must be set up as a public system. The American guy uses British, Mile, and 1 Mile about 17xx meters. How can we have our 1km = 1000 meters good calculation (so they invented the computer).

Secondly, adjust the latitude and longitude format to "hddd*mm" ss "(degree. Second) format or" hddd*mm.mmm "(degree. Divide.) Format.

Then, the map projection was confirmed to be WGS84, and the time zone was in District 8 (China in East 8th).

6. experience and skills

Generally, the battery can be used for 20 hours in a row. I usually open it when I use it. I walk down a day and open 7-10 times. In this way, a pair of batteries can be up to 10 mountains.

At each fixed point, it is best to record or recording (or ask the secretary to record), because the GPS point number is automatically generated by numbers, the point is too much, and no matter how good the brain is.

Be sure to use it with the compass. Otherwise, there is no GPS.

To use GPS, ravine, dense forests, you have to touch your luck.When taking the car, the window can be barely used.

Each activity, generally 5-10 points are almost the same.