Global Positioning System: Description and Operation

System Description
The Remote Emergency Satellite Cellular Unit (RESCU) module controls the system. It is hardwired to the vehicle's cellular phone system, radio, restraint control module (RCM), message center, console RESCU switch, and Global Positioning Sensor (GPS) antenna. The RESCU module uses the cellular phone system to place calls to the Lincoln Security Response Center. It mutes the radio upon placing a call and un-mutes the radio when the call is ended. It monitors an input from the RCM to determine if an airbag has deployed and it provides the user with visual feedback during an activation by displaying status messages on the message center.

The console RESCU switch provides the user with two buttons (SOS and i) for activating the system. The console RESCU switch SOS button is used to place a call for emergency assistance and the console RESCU switch i button is used to place a call for roadside assistance.

The GPS antenna receives data from a group of GPS satellites and is used by the RESCU module to determine the location of the vehicle when one of the activation buttons is pressed or an airbag is deployed.

Powering Up
The VEMS powers up when the ignition switch is turned to RUN. During power up, the RESCU module will carry out a check of the system. The system check takes about 15 seconds. If a failure is detected, the RESCU module will display RESCU FAILURE on the message center for five seconds.

If the cellular phone is not detected, the RESCU module will display RESCU FAILURE on the message center for five seconds, followed by CELLULAR PHONE REMOVED and RESCU FEATURE DISABLED. Each of these messages will be displayed on the message center for five seconds.

Pressing SOS, Pressing i, and Airbag Deployment
When the console RESCU switch SOS or i button is pressed, or one of the airbags is deployed, the VEMS will try to take control of the cellular phone system and inform the user that an activation is in progress by displaying SOS REQUEST or INFO REQUEST on the message center. The VEMS also mutes the radio causing PHONE to be displayed on the radio display.

If the VEMS determines that the cellular phone is not correctly connected, the message center will display CELLULAR PHONE REMOVED followed by RESCU FEATURE DISABLED then UNABLE TO PLACE CALL and INSTALL PHONE TO CONTINUE.

If the cellular phone is connected, but the VEMS determines that the phone is not RESCU compatible, NON-RESCU PHONE will be displayed on the message center.

Upon determining that the cellular phone is connected and communication with it can be established, the VEMS checks to see if cellular service is available (a cellular signal is sensed by the vehicle's cellular phone).

If cellular service is not available, the VEMS will continue to check for service for up to two minutes. During this time, NO CELLULAR SIGNAL followed by WAITING TO ACQUIRE are continually displayed in rotation on the message center. If service is still not available after two minutes, UNABLE TO PLACE CALL is displayed on the message center and the activation is terminated.

If service is available, the VEMS places a data call to the Lincoln Security Response Center's central computer and CALL IN PROGRESS is displayed on the message center.

If the call has trouble going through because the cellular system is busy, the VEMS will continue trying to place the call for up to one minute. During this time, CELLULAR SYSTEM BUSY followed by PLEASE WAIT are continuously displayed in rotation on the message center, and then the activation is terminated. If the data call goes through, RINGING RESPONSE CENTER is displayed on the message center.

Once the data call is answered by the response center, the VEMS sends it an electronic data message. This message includes: the type of activation (SOS, i, or airbag), a customer identification number, the most recently recorded location (latitude and longitude), the speed and direction of travel of the vehicle, the time at which the location and speed data was taken, and the system's cellular phone number. While this data is being transmitted, the system updates the message center with SENDING LOCATIONDATA.

After the data has been received by the response center, DATA RECEIVED will be displayed on the message center. The call will then be displayed on the message center. The call will then be forwarded to the response center's operator switchboard.

If the data call fails to go through, the VEMS will carry out a voice call redial to the Lincoln Security Response Center's operator switchboard. While this call is being placed, REDIAL IN PROGRESS will be displayed on the message center. While the system is waiting for an operator to answer, WAITING FOR OPERATOR will be displayed on the message center.

Upon answering the call, the operator will attempt to talk with the caller to determine the level of assistance required. The operator will contact the appropriate emergency assistance provider if the call was made due to a console RESCU switch SOS button press or an airbag deployment. If the call was caused by pressing the console RESCU switch i button, the operator will provide directions to the location asked for by the caller.

Throughout the rest of the call CID... AT..., and LON... data that was sent to the response center will be continually displayed in rotation on the message center.

If the call is initiated by pressing the console RESCU switch SOS button or by the deployment of an airbag, the caller has no control of the phone and all communication with the response center operator will occur hands-free. If the call is initiated by pressing the console RESCU switch i button, communication with the response center operator defaults to hands-free but may be switched to private mode (using the phone's internal speaker and microphone) by removing the phone from its cradle.

When the RESCU call is ended, the message center will return to displaying vehicle information and the radio will un-mute and return to its previous operating mode.

Powering Down
When the ignition switch is turned from RUN to OFF, or from RUN to ACC, the VEMS may be powered off so no status messages will be displayed. If the ignition switch is turned from RUN to OFF or ACC while the VEMS is in a call, the call will continue, but the message center will be turned off. After the call is ended, the VEMS will remain on for six minutes. After the six minutes have expired, the VEMS will power OFF. To reuse the VEMS after this time, the ignition switch will have to be turned back to the RUN position.