2 Layer FR4 PCB for GPS Module

1. What is the meaning of 20 channels of GPS module?

The GPS module has a parameter of channel number, such as 20 channels. It means that the module can establish communication with 20 satellites at the same time. Three satellites are 2D positioning, and the data is unstable. The module can obtain the correct positioning data only after receiving more than three satellite signals at the same time. If the number of satellites communicating at the same time is more, the module will be faster and more accurate In the general urban environment on the earth's surface, the positioning data can be communicated with 4-11 satellites at the same time.

2. Why does GPS module get positioning data for a long time after starting up?

If the GPS module has been powered on for the first time, if the GPS module has been powered on for more than three times, it is necessary to start the GPS module again when the GPS module is turned on for the first time S-87 has built-in button battery, which can store ephemeris data in the module. When the module works next time, it can quickly locate. Generally, s-87 only needs 1-3 seconds to achieve new positioning. This kind of positioning is called hot start. If the power-off time of the module exceeds 4 hours, the internal RTC has no real-time power supply Then starting up again is equivalent to a cold start.

3. What to do if cold start positioning is not possible for a long time?

Then it is necessary to check whether the GPS antenna is placed in an open environment and whether the GPS data output by the GPS module can be read? Can GPS satellite signal state be observed in GSV statement of GPS data? From these aspects, we can judge where the specific problems are! The module can output the positioning data of $gpgga $gpgsa $gpgsv $GPRMC once per second. We usually use $GPRMC to output this information, which contains the important information of the target: longitude, latitude, speed (nautical miles per hour), direction of motion, year, month, hour, minute, second, millisecond, whether the positioning data is valid or invalid, Most of the chips of GPS module mainly use sirfiii series, which has the largest market share in the world. The sirfiii chip is 20 channels and has strong real-time calculation ability. This part of the module market is very common: Huantian, dagama, ublox and so on.

4. What about antenna condition monitoring?

What should be done when the antenna is short circuited? The best way is that the GPS module can output the statement of antenna open and short circuit status to prompt customers to check in this aspect. The advantage of this method is that the customer can easily check the problem points and protect the module from high current impact. Many such applications on the market, such as s-87, S-90, s-93 and ublox, some modules also have such functions, but the difference is UB LOX needs to build peripheral devices to realize this function, while gamma does not need any peripheral devices. It seems that this function can only be realized in flash version, while IO port cannot be configured in ROM version, so this function cannot be realized.