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Out in Front |
The
Global Positioning System (GPS) has found use in military and expensive
commercial applications for years, but problems with multipath signals and
interference from trees and buildings has hampered the technology's use in
consumer and PC applications. Now, the SiRFstar GPS chip set and software from
SiRF Technology overcomes those problems. You can add the device to car
navigation systems, portable PCs, cellular phones, entertainment systems, and
handheld devices. You can use the system with a CPU, digital map, and
destination database to provide local information or with a simple
microcontroller in a handheld device to plot a return path from a hike in the
wilderness.
The system's 24 GPS satellites transmit a spread-spectrum signal at 1.6 GHz giving position information. The receiver uses the location information from four of these signals to determine its own location within a few hundred feet. SiRFstar GPS has some patented algorithms that make it useful in mass-market applications. SiRF has improved the product's reacquisition time to reduce start-up time and improve mobility. SiRFstar can also continue to provide location information from a single satellite when that is all that remains available. A dual, multipath, signal-rejection scheme improves the quality of the system by reducing errors from reflected signals.
The product comprises a two-chip set, including an RF front-end IC and a DSP chip, and modular software. A $995 evaluation kit contains all the hardware, software, and documentation necessary to test performance. The SiRFstar costs $49.95 (10,000). —by Stephen Kempainen
SiRF Technology, Sunnyvale, CA. (408) 737-6607, fax (408) 737-6605.
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