GPS component manufacturers are in a race to produce GPS chip receivers at a lower cost and with increased sensitivity, reduced footprint size and reduced power consumption. Driving their efforts is the desire of mobile device manufacturers to integrate GPS into more devices and feed the expansion of location based services. To see where the market is at the moment, specifications from a number of GPS chip manufacturers were surveyed for comparison in the table below.
The number of chips available is growing and some manufacturers have more than one chip available (the best were selected). Judging by sensitivity alone is not enough to separate the contenders. The more prominent differences are in position accuracy. SiRF and u-Blox come out in front on position accuracy but, unfortunately TTFF data is not available for u-Blox to separate the two chips overall.
| Chip / Chipset | SiRFstarIII | Copernicus | S4E19863 | QinetiQ Q20 H | PMB 2520 | UBX-G5010 |
| Manufacturer | SiRF | Trimble | Seiko Epson | QinetiQ | Infineon | u-blox |
| Horozontal Accuracy Autonomous Assisted |
<2.5m <2.0m |
<3.0m na |
<10m na |
<5m na |
5m na |
2.5m 2.0m |
| Velocity Accuracy | <0.01 m/s | 0.06 m/s | na | <0.05 | na | na |
| TTFF Hot Start Warm Start Cold Start |
<1s <35s <35s |
9s 36s 39s |
2 -3s na na |
<1s <38s <45s |
<1s <38s <45s |
na |
| Sensitivity Autonomous Tracking |
-142dBm -159dBm |
-142dBm -150dBm |
-160dBm na |
-185dBm -189dBm |
na -160dBm |
-160dBm -160dBm |
| Channels | Up to 20 | 12 | na | 12 | 16 | 50 |
| Dimensions | 7 x 10 x 1.4mm | 19 x 19 x 2.54 mm | 13 x 8 x 1.28 mm | 22 x 26.5 x 3.3 mm | 7 x 7 mm | 8 x 8 x 0.9 mm |
Notes:
- na = not available
- Position accuracies given in the table are for outdoors
- Decibel per milliwatt (dBm) is an absolute value power expression. The lower the dBm value the more sensitive the GPS receiver is.
- 3GPP-compliant - compliant to 3rd Generation Partnership Project to shape third-generation (3G) mobile communication system standards
- Autonomous positioning is positioning performed without network assistance.
- Assisted positioning is where a server on a network accessed by the GPS receiver performs the position calculations.
- MS-Based - Assist data for position calculations is broadcast regularly by an attached cell network. Position calculations are performed by the mobile device.
- MS-Assisted - Position calculations are performed by a server on an attached cell network.
- A hot start is when the receiver has valid ephemeris, almanac, time and previous position data. A cold start is when the receiver starts a position determination without this information.
- Ephemeris data is position and timing data as part of a GPS satellites signal.
- Almanac is data transmitted by a GPS satellite on the orbits and health of the GPS satellite constellation.
- Time to first fix (TTFF) is the time for a receiver to complete its first position calculation.
U-blox UBX=G5010 GPS Receiver Chip
u-blox is a Swiss company with a range of GPS positioning receiver products covering Navigation, Automatic Vehicle Location, Security, Traffic Control, Location Based Services, Timing, Surveying. The UBX-G5010, one of a number of chips/chipsets produced by U-blox, was selected for the survey for its excellent performance specification. It was designed for mobile device applications and has a massively parallel one million correlators. Natrually for a mobile application, its power consumption is ultra-low at 50mW. The chip is Galileo (European GPS satellite constellation under construction) ready. It has what U-blox call and is intended to be used in indoor situations as well as outdoors. Automatic jamming suppression is a valuable inclusion.
Infineon PMB 2520 Hammerhead GPS Receiver
The PMB 2520 (Hammerhead) is a single chip GPS receiver being developed by Infineon Technologies with its partner Global Locate, Inc. The chip includes Global Locate’s IndoorGPS technology. The Hammerhead chip has been optimized for mobile handsets (mobile telephones, smart phones and PDAs) – minimal power usage and small footprint. The chip is capable of multiple modes of operation including assisted (A-GPS) and autonomous.
QinetiQ Q20 GPS Receiver Module
QinetiQ’s Q20 HS is an ultra-compact, GPS receiver module with fast acquisition and very low signal strength tracking capability. Its capable of sustained indoors operation without network assistance. QinetiQ’s high sensitivity GPS has been recognized with an award for “best new electronic, communication or internet protocol product” at the annual Security Industry Innovation Awards It has also won the IEEE 2005 Electronics Engineering Innovation Award.
Epson S3E19863 GPS Module
Seiko Epson Corporation (“Epson”) developed the single-chip global-positioning system (GPS) module, the S4E19863, with a small footprint and high sensitivity for application in next-generation mobile handsets.
The S4E19863 modules features include:
- High sensitivity (-160 dBm) enables acquisition of indoor location
- High-speed satellite search algorithm
- Support for three positioning modes in compliance with the 3GPP specification
- Miniature one-chip package
Trimble Copernicus GPS Module
Trimble’s Copernicus GPS module is a complete drop-in, ready-to-go GPS receiver which provides position, velocity and time data. It features Trimble’s own TrimCore navigation software for fast startup times and tracking performance in challenging environments such as urban canyons and under foliage. The Copernicus GPS receiver can autonomously acquire GPS satellite signals or accept assisted GPS (A-GPS) data. The module has been designed with a small footprint for next generation mobile GPS device integration.
Texas Instruments NaviLink 5.0 Single Chip GPS Receiver
The Texas Instruments (TI) NaviLink 5.0 was only announced in March. TI have designed their new single chip GPS receiver to have a footprint of only 25mm2 which they claim is the worlds smallest. There are no performance figures available yet but, it is capable of autonomous and assisted modes of operation. To quote TI ” it is capable of fast time to first fix (TTFF) in weak signal conditions typical in metropolitan areas and deep indoor environments”. As with other manufacturers, TI is intending its chip to be integrated into mobile handsets (including mobile phones) which are expected to be in greater demand as location based services availability increases.
SiRF Star III GPS Receiver Chipset
SiRF was early in transferring GPS circuitry onto silicon and the SiRF Star III family has proved a watershed innovation GPS chip architecture by offering impressive performance improvements to the GPS receiver manufacturing industry. They have also been adopted by other major GPS manufacturers including TomTom and Magellan. The SiRF Star III offers faster fix times, higher signal locking, higher tracking sensitivity and lower power requirements.
Further Reading
Find out more about Assisted GPS (A-GPS) and how networking is allowing less powerful receivers to achieve even greater accuracies.
Understand how Differential GPS improves GPS receiver accuracy.
