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SAE J2735-Draft-Rev18 [issued: 06-26-07]
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177 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
9.11 Data Frame: DF_DTime
Use: The DSRC style time is a compound value consisting of finite-length sequences of integers (not
characters) of the form: "hh, mm, ss (sss+) (offset)" - as defined below. Because the length of each
element is known, no inner element tagging is normally used in transmission. Thus, this data frame
occupies 6 bytes in total, and 4 bytes when the time offset is not present. In typical use in DSRC
applications there is no need to send the offset representing the local time zone, so the most common
representation for the data frame occupies 4 bytes and provides a resolution of one millisecond over a range
of one day.
ASN.1 Representation:
DTime ::= SEQUENCE SEQUENCE {
hour DHour, -- 1 byte
minute DMinute, -- 1 byte
second DSecond, -- 2 bytes
offset DOffset OPTIONAL, -- 2 bytes, Time zone if present
}
XML Representation:
<xs:complexType name="DTime" >
<xs:sequence>
</xs:sequence>
</xs:complexType>
Used by: This entry is used directly by one other data structure in this standard, a DF called DF_ValueList
9.12 Data Frame: DF_DYearMonth
Use: The DSRC style year-month is a compound value consisting of finite-length sequences of integers
(not characters) of the form: "yyyy, mm" - as defined below. Because the length of each element is
known, no inner element tagging is normally used in transmission. Thus, this data frame occupies 3 bytes
in total.
ASN.1 Representation:
DYearMonth ::= SEQUENCE {
year DYear, -- 2 bytes
month DMonth, -- 1 byte
}
XML Representation:
<xs:sequence>
<xs:element name="year" type="DYear" />
<!-- 2 bytes -->
<xs:element name="month" type="DMonth" />
<!-- 1 byte -->
</xs:sequence>
</xs:complexType>
Used by: This entry is used directly by one other data structure in this standard, a DF called DF_ValueList
9.13 Data Frame: DF_PositionShort
Use: The localized position of the vehicle (with the upper 16 bits for each of lat and long not sent because
they are know by both parties). This results in two 16 bit values for the "short" lat-long which scale
directly from the standard ITS 32 bit value representation with the LSB as one micro degree.
ASN.1 Representation:
PositionShort ::= SEQUENCE {
lat ShortLatitude,
long ShortLongitude