Principles Digital Communication System & Computer Networks (Charles River Media Computer Engineering)

32.5 COMMERCIAL GPS RECEIVERS

Initially, when the U.S. Department of Defense introduced the GPS, the cost of the receiver was nearly US$30,000. Over the past decade, the cost has come down drastically due to the availability of chipsets from major semiconductor vendors. Now the cost of a chipset is very low, and this has paved the way for GPS receivers to become a consumer item. This low cost is drawing many solution providers into developing interesting applications. GPS receivers are now being integrated with laptops, cellular phones, pagers, and even wristwatches to display positional information.

Commercial GPS receiver hardware is available with an RS232 interface or a USB interface. GPS receiver chips are also being integrated into consumer items such as watches and mobile phones.

To develop application software using the GPS, GPS receivers come in three different forms:

• A PC add-on card that can be plugged into the motherboard.

• GPS receiver hardware with an RS232 interface. This receiver can be connected to the RS232 port of the PC, and the port can be programmed to decode the GPS data for subsequent processing.

• GPS receiver hardware with a USB interface. This receiver can be connected to the USB port of the PC, and the port can be programmed to decode the GPS data for subsequent processing.

Using the driver software and the associated application software, GPS receiver data can be used for developing software to meet user requirements.