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SAE J2735-Draft-Rev28 [issued: 11-10-08]
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86 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
vehicle has traveled. When the data frame is sent in the Part II section of the Basic Safety Message, the
vehicle's current position is used (and the optional position elements shown in the below need not be sent).
The breadcrumb data itself allow many options variants of data to be encoded Each possible set of
breadcrumb data elements is supported in a an octet blob style, and the sets of data in that type are sent in a
single final octet blob (in other words each octet is made up of N or more sets of inner data, using the same
encoding).
The lat-long offset units used in the breadcrumb stream support units of 1/8th micro degrees of lat and long.
The vertical offset units are in 20cm units. The time is expressed in units of 0.1 milliseconds. The
GPSstatus uses 4 bytes the relate the GDOP of the system. The heading and speed follow similar units to
their data element counterparts. All of these items are defined further in the relevant data entry.
ASN.1 Representation:
VehicleMotionTrail ::= SEQUENCE {
initialPosition FullPositionVector OPTIONAL,
currGPSstatus GPSstatus OPTIONAL,
posAccuracy PositionalAccuracy OPTIONAL,
-- below CHOICE could be removed (save 2 byes)
crumbData CHOICE {
-- select one of the possible data sets to be used
verboseDataSet SEQUENCE (SIZE(1..32)) OF
-- a set of all data elements, it is
-- non-uniform in size, each item tagged in BER
completeDataSet SEQUENCE (SIZE(13..416)) OF
-- a set of all data elements including:
-- lat, long, vert, time, accuracy, heading, and speed
-- sent as a packed blob of 13 bytes per crumb
dataSet-3 SEQUENCE (SIZE(11..352)) OF
-- a set of the following data elements:
-- lat, long, vert, time, and accuracy
-- sent as a packed blob of 11 bytes per crumb
dataSet-4 SEQUENCE (SIZE(7..224)) OF
-- a set of the following data elements:
-- lat, long, vert, and time
-- sent as a packed blob of 7 bytes per crumb
dataSet-5 SEQUENCE (SIZE(13..416)) OF
-- a set of the following data elements:
-- lat, long, vert, and accuracy
-- sent as a packed blob of 13 bytes per crumb
dataSet-6 SEQUENCE (SIZE(5..160)) OF
-- a set of the following data elements:
-- lat, long, and vert
-- sent as a packed blob of 5 bytes per crumb
dataSet-7 SEQUENCE (SIZE(10..320)) OF
-- a set of the following data elements:
-- lat, long, time, and accuracy
-- sent as a packed blob of 10 bytes per crumb
dataSet-8 SEQUENCE (SIZE(6..192)) OF
-- a set of the following data elements: