In the GPS tracking business, many manufacturers and designers use GPS modules as below: Ublox, Sirf Star III and MTK GPS.
Below are the comparisons between the three GPS chips based on our designing and manufadturing experience:
With Ublox GPS chip M8U or M8L, we developed a wonderful feature: dead-reckoning, which allows you to track your car in underground parkings or in tunnels. Even in severe environment with plenty of containers and weak GPS signal, NEO-M8U or NEO-M8L still has good performance
GPS tracker shows the dead-reckoning in underground parking and tunnels ↓<
GPS tracker shows the dead-reckoning between containers in sea port ↓
These three GPS chips are popular on the market especially in Chinese GPS tracking manufacturers. In view of different and specific needs for GPS tracking, people would choose the right modules for their customization. GPS tracking business is more like the niche market. Clients’ needs are not same mostly because most of them are trying to control and manage their own different vehicles or fleets.
These drawbacks for Sirf III and MTK GPS (even uBlox) can be avoided by the good algorithm in firmware or the delicate hardware design or professional installation especially the better gps antenna location. So manufacturers can make most of the three GPS modules meeting client’s need.
Good algorithm in firmware means a robust firmware structure which can handle most known or unknown bugs. GPS drifting issue can't be eliminated due to the restriction of GPS by US military and GPS signal reception. But we can filter these driftings by monitoring other important factors like engine on/off status, trembles status intensity level and time of duration----no trembles or slight trembles indicate no car running, speed offered by GPS----car can't drive 200km/h instaneously when it was 0km/h seconds ago, mileage taken----car can't fly hundreds miles away in seconds. One good method is that keeping using the same old position coodinates in coming data string when engine status is off or no trembles.
Delicate hardware design requires the experienced hardware engineers' work. in the design trends, GPS part is designed smaller and internal in devices. So engineers would consider much more on layout of PCB. The GPS part should be placed away from other metal components and other chip components, resistors, capacitors, inductors. Make sure GPS part lives in clean and quiet environment: no any type of components under it; or it could be accetable worsely: make sure gps part on the top of all components. The metal shieldingcover should Electroplated and connected to Ground well. Keep away from the EMC noising sources like CPU, SDRAM, oscilators DC/CD, power source. Car explosion-proof membrane would affect GPS signal, too. In one word, GPS part should be treated well.
External GPS antenna is better than internal one. Active GPS antenna is better than passive one. Try to place the gps antenna outside of car , on top of car. or on dashboard, under windshield. arched side faces sky, and flat side towards ground. Actually the gps coordinates indicates the position where the gps antenna is, not the installed gps tracker position.