System and method for improved traffic flow reporting using satellite digital audio radio service (SDARS) and vehicle communications, navigation and tracking system

1. A method of providing traffic flow information comprising:

storing, at a vehicle, at least one data table comprising location data that corresponds to different segments of roadways over which traffic flow is monitored;

receiving, at a vehicle, a digital audio broadcast (DAB) signal comprising multiplexed audio programming channels and at least one data channel for providing traffic flow information, the traffic flow information comprising traffic data relating to a reported speed range for vehicles traveling on respective ones of the segments of roadways;

determining, at the vehicle, its current position data;

determining, at the vehicle, if its current position data is within one of the segments by comparing its current position data with the location data in the data table;

determining, at the vehicle, its current vehicle speed;

if the vehicle is determined to be traveling within one of the segments, then determining if its current vehicle speed is within the reported speed range for that segment;

generating, at the vehicle, a message reporting its current vehicle speed for transmission to a traffic flow information hub when its current vehicle speed is not within the reported speed range for that segment; and

controlling the vehicle to not send a message reporting its current vehicle speed when its current vehicle speed is within the reported speed range for that segment.

2. A method as claimed in claim 1 , further comprising transmitting the message immediately from the vehicle as a speed downgrade message when its current vehicle speed is below the reported speed range for that segment.

3. A method as claimed in claim 1 , further comprising:

determining when current vehicle speed is above the reported speed range for that segment;

determining when the vehicle has completed traversing that segment by comparing updates of its current position data with the location data corresponding to that segment in the data table; and

delaying generating and transmitting a speed upgrade message that indicates the current vehicle speed is above the reported speed range for that segment until the vehicle has completed traversing that segment.

4. A method as claimed in claim 1 , further comprising:

continuing receiving, at the vehicle, the digital audio broadcast (DAB) signal wherein the data channel provides revised traffic flow information with respect to previously received traffic flow information;

determining, at the vehicle, that a reported speed range for that segment in the revised traffic flow information is unchanged; and

delaying generation and transmission of a message until the reported flow speed for that segment changes.

5. A method as claimed in claim 1 , further comprising employing location codes for the location data in the data table and for the traffic flow information in the DAB broadcast signal.

6. A method as claimed in claim 5 , further comprising employing RDS-formatted location codes for the location data in the data table and for the traffic flow information in the DAB broadcast signal.

7. A method as claimed in claim 5 , further comprising employing RDS-formatted location codes to characterize the segments in the data table.

8. A method as claimed in claim 1 , further comprising updating the traffic flow information in the DAB signal based on messages reporting current vehicle speed received at the traffic flow information hub from corresponding ones of a plurality of vehicles.

9. A method as claimed in claim 8 , further comprising filtering the messages received at the traffic flow information hub from the plurality of vehicles to determine when to update the traffic flow information in the DAB signal.

10. A method as claimed in claim 9 , wherein filtering comprises updating the traffic flow information in the DAB signal when a number of the messages received at the traffic flow information hub and related to one of the segments of roadway exceeds a selected threshold.

11. A traffic flow reporting system, comprising:

a satellite digital audio radio service (SDARS) system for transmitting a digital audio broadcast (DAB) signal comprising multiplexed audio programming channels and at least one data channel for providing traffic flow information, the traffic flow information comprising traffic data relating to a reported speed range for vehicles traveling on respective ones of the segments of roadways;

a plurality of vehicles, each of the plurality of vehicles comprising

an SDARS receiving unit, and

a vehicle communications, navigation and tracking (VCNT) services unit configured to

store a data structure comprising location data that corresponds to different segments of roadways over which traffic flow is monitored

compare a present Global Positioning System (GPS) position of the vehicle with the traffic flow information received from the SDARS unit,

if the present GPS position is within one of the segments, compare a current vehicle speed with a corresponding received traffic flow speed range reported in the traffic flow information, and

if the vehicle speed is outside the received traffic flow speed range, generate a message with one of the location data for the segment and the present GPS position of the vehicle and current vehicle speed; and

an automated traffic flow aggregation system for receiving transmissions of messages from the plurality of vehicles and applying location-specific filters based on a number of messages received before forwarding a flow speed revision message to the SDARS system.

12. A traffic flow reporting system as claimed in claim 11 , wherein the SDARS system broadcasts a DAB signal comprising revised traffic flow information for the segment.

13. A traffic flow reporting system as claimed in claim 11 , wherein, when the comparison of vehicle speed to received traffic flow speed range by the VCNT services unit indicates a downgrade in speed, the message is transmitted immediately when encountered within the segment.

14. A traffic flow reporting system as claimed in claim 11 , wherein, when the comparison of vehicle speed to received traffic flow speed range by the VCNT system indicates a vehicle speed upgrade, the message is transmitted once the complete segment has been traversed.

15. A traffic flow reporting system as claimed in claim 11 , wherein the VCNT system is controlled to not send a message reporting its current vehicle speed when its current vehicle speed is within the reported speed range for that segment.