Simple Comparison for GPS Modules: Ublox, Sirf III and MTK GPS


Simple Comparison for GPS Modules: Ublox, Sirf III and MTK GPS


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:

MTK GPS

newcomer in GPS tracking business, and fast-growing. it has a little bad performance in GPS signal acquisition and stability. If the vehicle comes out of tunnel, it may take some time to get the GPS signal. But the cost is good.

Sirf III GPS

the cost and performance are between Ublox and MTK GPS. Globalsat and RoyalTek GPS modules are based on the Sirf Star III. The techniques may be a little old comparing to the Ublox GPS module nowadays. The accuracy of GPS signal when the vehicles are still would be a little wild sometimes.


Ublox GPS

it works very stable and good performance. it acquires GPS signal very fast whatever the vehicles are moving or still. Also the GPS signal acquisition is best if the vehicles come out of the tunnels. and GPS accuracy is best. The craftsmanship and appearance of Ublox are better. But the cost is higher.



You want to know the uBLox GPS accuracy in real life? Checking below!

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 ↓

<ublox gps dead-reckoning ublox gps dead-reckoning in tunnels

GPS tracker shows the dead-reckoning between containers in sea port ↓

ublox gps dead-reckoning on sea port ublox gps 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.


What can we do to improve the GPS performance?

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

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

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.


better device placement

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.



MTK gps chip MT3337 GPS All-in-one:
 • Specifications
-22 tracking / 66 acquisition-channel GPS receiver
-Supports up to 210PRN channels
-Supports WAAS/EGNOS/MSAS/GAGAN
-12 multi-tone active interference cancelllers(ISSCC2011 award)
-RTCM ready
-Indoor and outdoor multi-path detection and compensation
-Supports FCC E911 compliance and A-GPS
-Max. fixed updata rate to 5Hz
 • Advanced software features
-AlwaysLocateTM advanced location awareness technology
-EPOTM orbit prediction
-Support logger function  •Reference oscillator
-TCXO
   •Frequency: 16.368 MHz, 26 MHz
   •Frequency variation: +/-2.0ppm
 •RF configuration
-4-bit IF signal
-SoC, integrated in single chip with CMOS process
 •ARM7EJ-S CPU
-Up to 98MHz processor clock
-Dynamic clock rate control
 •Pulse-per-second(PPS) GPS time reference
-Adjustable duty cycle
-Typical accuracy:+/- ns
 •Power scheme
-A 1.8 volts SMPS build-in SOC
-Direct lithium battery connection(2.8-4.3 volts)
-Self build 1.2 volts RTC LDO, 1.2 volts core LDO, and 2.8 volts TCXO LDO
 •Build-in reset controller media Confidential
-Does not need of external reset control IC
 •Internal real-time clock(RTC)
-32.768 KHz +/-ppm crystal
-Timer pin for external device on/off control
-1.2volts RTC clock output
 •Serial interface
-UART: 4800/9600/38400/115200 bps
-GPIO interface(up to 16 pins)  •NMEA
-NMEA 0183 standard V3.01 and backward compliance
-Supports 219 difference data
 •Superior sensitivities
-Acquisition:-148 dBm(cold)/-163dBm(hot)
-Tracking: -165dBm
 Ultra-low power consumption
-Acquisition: 25mW
-Tracking: 18mW
-AlwaysLocateTM: 3mW
 •Package
-VFBGA: 4.3m*4.3m, 57balls, 0.5mm pitch
 •Sim hardware design
-52mm2 solution footprint with all software features inside
-9 passive external components



| low cost gps tracker: AT05 | gps tracker: AT07 | GPS tracker + TPMS: AT09 | 3G GPS tracker: AT07-3G | 3G GPS tracker + TPMS: AT09-3G | solar powered TPMS: TP08 | LED tire pressure monitor: TP03 | capacitance fuel level sensor:FL05 |