Some GPS
performance indicators you need to know when buying GPS
1. What is satellite trajectory?
The GPS Global Positioning and Navigation System has 24 GPS satellites orbiting the earth in six orbits (in groups of four), and generally no more than 12 satellites are on the same side of the earth. Most GPS receivers can track 8 to 12 satellites. At least 3 satellites are required to calculate LAT/LONG (2D) coordinates. One more gps locator can calculate 3-dimensional coordinates. For a given location, the GPS receiver knows which satellites are nearby at the time because it is constantly receiving updates from the satellites.
2. What is a parallel channel?
Some consumer GPS devices have 2-5 parallel channels to receive satellite signals. Because up to 12 satellites may be visible (the average is 8), this means that the GPS receiver must visit each satellite in sequence to obtain information about each satellite.
Most of the GPS receivers on the market are the 12-parallel channel type and the 20-parallel channel type, which allows them to continuously track the information of each satellite. The advantages of the 12-channel receiver include fast cold start and initialization of satellite information, gps locator and better reception in forested areas. Generally, a 20-channel receiver does not require an external antenna, but in enclosed spaces such as cabins and carriages, an external antenna is still required to ensure accurate GPS signal reception.
3. What is the positioning time?
Fix Time is the time it takes for the GPS receiver to determine its current location when the GPS receiver is restarted. For a 20-channel receiver, if you are near the location of the last fix, the fix time is generally 3 to 5 minutes for a cold start and 15 to 30 seconds for a hot start. For those who buy GPS for the first time, they need to know some GPS performance indicators in order to understand the product performance and make appropriate choices. The following is the author’s brief introduction to some important performance indicators of GPS.