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Trace: » how_do_i_view_my_vehicles_using_maps_on_my_phone » how_do_i_zoom_in_on_vehicles_or_a_particular_part_of_a_vehicle_s_path » how_does_my_gps_device_report_speed
Driver safety is always an important issue for fleet-based companies, and one of the most important aspects of driver safety is Speeding. GPS Insight offers several Speeding Alerts and Speeding Reports to our users in order to help monitor driver behavior. This guide is meant to help supply a better understanding of how the GPS device reports speed.
GPSI-3900s, GPSI-4000s, and Other Non-Diagnostic Devices
These devices calculate and report speed by using data from GPS satellites. The GPS device, communicating constantly with the GPS satellites (~4x/sec), analyzes the straight-line distance traversed by the vehicle between two geographic points and divides this by the time traveled to get the mph of the vehicle.
Why is my device reporting inaccurate speeds?
Though rare, there are some situations that will reduce the accuracy of the speed calculations.These include: driving into “urban canyons” or topographic canyons, very poor atmospheric conditions such as heavy snow or some types of dense fog, satellite “down time”due to service or software changes, and physical installation errors such as poor antenna placement and tangible/wireless antenna interference.
L3500 and H3500 Diagnostic Devices
These devices report speed values directly provided by the vehicle’s engine computer.
Note: there can be slight discrepancies between GPS Insight’s speed value and your vehicle’s speedometer as the speed reported by speedometer is only accurate within ~2-3% of the engine computer’s value.
Speeding Terms and Definitions
- Instant Speed (Instantaneous Speed) - the speed the vehicle was traveling at the precise moment the update was sent.
- Max Speed (Maximum Speed) - the highest speed the vehicle drove during the defined update interval for the device (i.e. if the update interval is every 2 minutes then the max speed is the highest speed attained during that 2 minute interval).
- Avg Speed (Average Speed) - the average speed the vehicle traveled during the defined update interval for the device.
- Posted Speed – this data is based on currently available speed limit information provided by NAVTEQ and pertains to the speed posted at the precise location the vehicle updated from.
“Technical Information Bulletin: Speed Data,” URL = <http://ww.networkflet.com/media/support/install/speed_data.pdf>
