OnStar Technology

With more than two million subscribers, OnStar is the leading provider of telematics services in the United States. Telematics is the transmission of data communications between systems and devices. OnStar's in-vehicle safety, security, and information services use Global Positioning System (GPS) satellite and cellular technology to link the vehicle and driver to the OnStar Center. At the OnStar Center, advisors offer real-time, personalized help 24 hours a day, 365 days a year.

GM Automatic Crash Response System (ACR)

Image of a car showing front sensors, side sensors, Sensing Diagnostic Module, cellular antenna, OnStar module

Figure 1: The GM Automatic Crash Response (ACR) system uses front and side sensors as well as the sensing capabilities of the Sensing and Diagnostic Module (SDM) itself. The accelerometer located within the SDM measures the crash severity.

Image of a car 1 with arrows pointing from front to the OnStar module

Figure 2: In the event of a moderate to severe frontal or side-impact crash, data is transmitted from the affected sensors to the SDM. The SDM sensor also can identify a rear impact of sufficient severity. Regardless of whether the air bags deploy, the SDM transmits crash information to the vehicle's OnStar module.

Image of a car 1 with arrows pointing from OnStar module to cellular antenna.

Figure 3: Within seconds of a moderate to severe crash, the OnStar module will send a message to the OnStar Call Center (OCC) through a cellular connection, informing the advisor that a crash has occurred. A voice connection between the advisor and the vehicle occupants is established. The advisor then can conference in 911 dispatch or a public safety answering point (PSAP), which determines if emergency services are necessary. If there is no response from the occupants, the advisor can provide the emergency dispatcher with the crash information from the SDM that reveals the severity of the crash. The dispatcher can identify what emergency services may be appropriate. Using the Global Positioning System (GPS) satellite, OnStar advisors are able to tell emergency workers the location of the vehicle.

Number and location of sensors and SDM may vary depending on vehicle model.

How You Stay Connected:

  • Contact OnStar using the three-button system
  • Establish direct voice contact with an OnStar Advisor using the built-in microphone, cellular antenna in your vehicle, and cellular network
  • An Advisor can pinpoint your location using GPS technology. Based on model availability.)
  • If your air bag deploys, a message is sent to the OnStar module in your vehicle. The OnStar module then contacts the OnStar Call Center.* (Based on model availability.)
  • OnStar module connects vehicle computer to OnStar via cellular antenna
  • Cellular antenna connects vehicle through cellular network

OnStar Equipment:

All OnStar-equipped vehicles have one of three types of equipment, based on wireless network technologies:

  • Analog-Only:
    OnStar-equipped vehicles with analog-only equipment were designed to operate only on the analog wireless network and cannot be upgraded to operate on the digital network. Vehicles with this equipment will no longer be able to receive OnStar services beginning January 1, 2008. At that time, service will be available only through dual-mode (analog/digital) equipment. Analog-only vehicles cannot be upgraded to digital equipment.
  • Analog/Digital-Ready:
    OnStar-equipped vehicles with analog/digital-ready equipment operate on the analog wireless network, but can be upgraded to dual-mode (analog/digital) equipment if available for that vehicle. Beginning January 1, 2008, OnStar service will not be available on these vehicles unless the OnStar equipment has been upgraded to dual-mode (analog/digital) equipment.
  • Dual-Mode (Analog/Digital):
    OnStar-equipped vehicles with dual-mode (analog/digital) equipment operate on both the analog and digital wireless networks and will not require an upgrade in connection with the wireless industry's transition to the digital network.

GPS Technology
How GPS Works

Global positioning system (GPS) satellite technology measures how long it takes a radio signal from a satellite to reach a vehicle, and then calculates distance using that time. OnStar uses the latest GPS receiver and antenna technology to get the most accurate vehicle location. Additionally, in some vehicles the wheel speed and direction are also used to further enhance OnStar's ability on location technology.

OnStar services require vehicle electrical system (including battery), wireless service and GPS satellite signals to be available and operating for features to function properly. Subscription Service Agreement required. Call 1.888.4.ONSTAR (1.888.466.7827) or visit OnStar for OnStar's Terms and Conditions, Privacy Statement and system limitations and details. Additional information can be found in the OnStar Owner's Guide.

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