Sanjai Kohli, Steven Chen

GPS Spread spectrum receiver

Non-European countries
Technical field
SiRF Technology
Devices with Global Positioning System (GPS) navigation have become part of everyday life. Through their innovative GPS chipset design, American engineers Sanjai Kohli and Steven Chen are major contributors to the success – and mass popularity – of GPS technology today.

Originally developed for military use in the late 1970s, GPS technology can now be found in all walks of life. GPS provides navigation for aeroplanes, ships, cars and individuals on the go via GPS-enabled mobile phones.

The global market for GPS devices is enormous: over 300 million units were sold in 2009, and over 400 million units are forecast for 2010. GPS-enabled mobile phones are the biggest growth market, moving over 77 million units in 2009.

The proliferation of GPS technology in everyday life received a major boost from powerful chipsets, invented by American engineers Sanjai Kohli and Steven Chen at US-company SiRF in San Jose.

Prior to this invention, GPS navigation - based on establishing a geographic position via feedback from a satellite - was expensive and faced severe limitations: early GPS receivers could only function properly with at least three or four satellites in range. If only one of these satellite signals became blocked, the receivers failed to navigate.

In 1995, Sanjai Kohli, a graduate of the Indian Institute of Technology in Bombay and Washington University in St. Louis, founded SiRF Technology Inc. to improve the technology. Working with Steven Chen, he came up with a new approach: inventing the physics of asynchronous signal processing to increase the signal processing power of a GPS chip over a 1000-fold. This enabled the weakest of GPS signals to be found within milliseconds and paved the way for the use of handheld GPS navigators in urban environments

The GPS system designed by Kohli and Chen can “fill in the blanks” by referring to alternative sources when satellite signals are down. As a result, they can operate with only one satellite in range. 

In 2002, Kohli and Chen’s high-performance but inexpensive GPS chipsets were released – and the consumer GPS market began taking off. By offering GPS chipsets with greater efficiency at lower cost, SiRF quickly became the world’s leading independent manufacturer of commercial GPS applications.

International companies using SiRF chipsets now include navigation system brands such as Garmin, Magellan, Sony, and Tom Tom, as well as mobile phone companies T-Mobile, Telecom Italia, Telefónica, Vodafone, and SoftBank Mobile.

In 2008, SiRF Technology employed nearly 600 people on several continents and reported net revenues of over $232.5m; a whopping 96% from the sale of GPS chipsets. In February 2009, SiRF was purchased by UK wireless chip company CSR for $136m. With this acquisition, CSR become the global leader in the GPS market.

Sanjai Kohli was the founder and Chief Technology Officer (CTO) at SiRF until March 2008. He founded and successfully ran two other technology companies – WirelessHome (data communication) and TrueSpan (mobile video) - and is currently working on his next venture.

Steven Chen was Director of Silicon at SiRF until June 2008 and now works as a patent attorney in Irvine, California.


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