in-dash navigation

A GPS navigation unit that replaces the factory head unit in a car. It offers navigation along with a raft of audio/video functions such as CD/DVD, MP3, iPod, hands-free cellphone via Bluetooth and XM or SIRIUS satellite radio.

The navigation maps are loaded via DVD or hard disk, and hard disk systems can typically rip a CD to an MP3 library while playing the songs.

Where To?
Not only can the system direct you to a specific street address, but it can guide you to the nearest gas station, hotel, restaurant or other point of interest (POI). Top-end units can hold 10 million or more POIs.

Voice Out and In
Navigation systems all offer voice output for turn-by-turn directions, but some include voice recognition for setting the route and controlling the unit. Voice commands allow the driver to concentrate on the road, while working the navigation and audio/video functions.

Speed Pulse Connection
One advantage of many in-dash units over portable navigation systems is that they monitor the speed of the automobile. Combined with a gyroscope, the unit can track the vehicle while it is in a tunnel, in the lower level of a two-level bridge, in a city or other location where line of sight to three satellites is not possible. The monitoring is accomplished by wiring the unit to the automobile's speed pulse signal, which can be a discrete wire or encoded frames in a digital bus. If the speed pulse is in the bus, adapters can tap the bus and extract the signal (see CAN bus). Most high-end, in-dash units use speed pulse, but some do not, relying solely on the GPS and auxiliary correction, such as WAAS, to pinpoint their location. See GPS and WAAS.

Turn-By-Turn Directions

All navigation systems, whether in-dash or portable, provide turn-by-turn directions both verbally and visually. This Eclipse after-market system switches to close-up view within a quarter mile of a turn and counts down in feet when 500 feet away.

Full-Featured In-Dash Nav

This split screen shows 2D and 3D views of the current location in Pioneer's AVIC-Z2 navigation system. Replacing the factory head unit, the Z2 is a sophisticated, yet easy-to-use, system that offers just about every feature a driver could want, including voice recognition, iPod, cellphone, CD ripping, DVD playback and XM or SIRIUS satellite radio. (Image courtesy of Pioneer Electronics USA Inc.)