Global Positioning System: Description and Operation

The Remote Emergency Satellite Cellular Unit
The Remote Emergency Satellite Cellular Unit (RESCU) is a system that allows a user to request emergency assistance (police, ambulance, fire, tow truck) or other convenience services such as directions to a desired location at the touch of a button. Also, if any of the vehicle's airbags are deployed while the RESCU system is powered on, the system automatically issues a call for emergency assistance.

The RESCU module controls the system. It is hardwired to the vehicle's cellular phone system, radio, airbag module, and message center as well as to the switch assembly and Global Positioning System (GPS) antenna. The RESCU module uses the cellular phone system to place calls to the Lincoln Response Center. It mutes the radio upon placing a call and unmutes the radio when the call is ended. It monitors an input from the airbag module 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 switch assembly provides the user with two buttons (SOS and Info) for activating the system. The SOS button is used to place a call for emergency assistance and the Info button is used to place a call for convenience services. The switch assembly also contains an indicator lamp that provides system status. The lamp blinks during an activation and it remains on continually (while the RESCU system is powered on) if the RESCU module detects a failure with the system.

The GPS antenna is used to receive data from a constellation of GPS satellites so the RESCU module can determine the location of the vehicle when one of the activation buttons is pressed or an airbag is deployed.

Powering Up
The RESCU system powers up when the ignition switch is turned to run. During power up, the RESCU module illuminates the indicator lamp in the switch assembly and performs a check of the system. The system check takes about 15 seconds. If it passes, the indicator lamp is turned OFF. If a failure is detected, the indicator lamp remains on and "RESCU FAILURE" is displayed on the message center for five seconds.

If the cellular phone is not detected, the indicator lamp remains on and "RESCU FAILURE" followed by "CELLULAR PHONE REMOVED" and "RESCU FEATURE DISABLED" are each displayed on the message center for five seconds.

Pressing SOS, Pressing Info, Airbag Deployment
When the SOS or INFO button is pressed, or one of the airbags is deployed, the RESCU system takes control of the cellular phone system and informs the user that an activation is in progress by flashing the indicator lamp and displaying "SOS REQUEST" or "INFO REQUEST" on the message center. The RESCU system also mutes the radio causing "PHONE" to be displayed on the radio display.

If the RESCU system determines that the cellular phone is not properly connected, "CELLULAR PHONE REMOVED" followed by "RESCU FEATURE DISABLED" then "UNABLE TO PLACE CALL" and "INSTALL PHONE TO CONTINUE" are displayed on the message center. If the cellular phone is connected, but the RESCU system still cannot talk to it, "RESCU FAILURE" followed by "UNABLE TO PLACE CALL" are displayed on the message center.

If the RESCU system concludes 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 RESCU system checks to see if cellular phone service is available (a cellular signal is sensed by the vehicle's cellular phone).

If cellular service is not available, the RESCU system 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 RESCU system 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 RESCU system 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. If the cellular system is still busy after one minutes, "UNABLE TO PLACE CALL" is displayed on the message center and the call 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 RESCU system sends it an electronic data message. This message includes: the type of activation (SOS, Info, or Airbag), a customer identification number (CID), 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 forwarded to a response center operator.

If the data call fails to go through, the RESCU system will perform a voice call redial to the Lincoln Response Center's operator switchboard. While the 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 SOS button press or an airbag deployment. If the call was caused by pressing the Info button, the operator will provide directions to the location asked for by the caller.

Throughout the rest of the call the button indicator lamp will continue flashing and the "CID...", "LAT..." 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 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 Info 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, the indicator lamp will stop flashing, and the radio will unmute and return to its previous operating mode. If the indicator lamp remains on after an activation, a failure has been detected by the RESCU system.

Powering Down
When the ignition switch is turned from RUN to OFF or from RUN to ACC, the RESCU system will remain on for six minutes. During this six minute time period, the RESCU system may be activated by pressing SOS or Info, but the messages center will be powered off so no status message will be displayed. However, the indicator lamp will flash throughout the activation. If the ignition switch is turned from RUN to OFF or ACC while the RESCU system is in a call, the call will continue and the button indicator lamp will remain flashing, but the message center will be turned off. After the call is ended, the RESCU system will remain on for six minutes.

After the six minutes has expired, the RESCU system will power OFF. To reuse the RESCU system after this time, the ignition switch will have to be turned back to the RUN position.

RESCU System Limitations
The Lincoln RESCU System is powered by the vehicle battery and will not function if the battery is dead or disconnected.

The RESCU System determines the vehicle's location using signals received from GPS Satellites and saves the location in memory. If power to the RESCU module is lost because the vehicle's battery becomes discharged or disconnected, or if the RESCU module is disconnected, the vehicle location data will be lost. Once power to the RESCU module is restored, the vehicle must be placed outside in an unobstructed area with the Ignition in Run for five minutes in order for the RESCU System to determine the correct location of the vehicle.

Also, if the GSP signals become obstructed by tall building, tunnels, service garages, parking structures, etc., the accuracy in determining the location of the vehicle after servicing the RESCU System, the vehicle must be placed outside in an unobstructed area with the Ignition in Run for five minutes.

The RESCU System uses the vehicle's cellular phone for data transmission and voice communication. Therefore, the cellular phone must be properly connected to its coil cord and the cellular phone system must be operating correctly for the RESCU System to work.

Since the RESCU System uses the vehicle's cellular phone, it will only operate in areas that have cellular coverage and the cellular phone must be active (signed up for service through a cellular service provider).

Part of the data sent during an activation of the RESCU System is the Vehicle Identification Number (VIN). If the RESCU Module is replaced, the new module must be reconfigured with the vehicle's VIN using the scan tool.