ashtech HDS800, Reference Manual

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593
Data Output
ION: Ionosphere Parameters
This message contains the ionosphere and GPS-to-UTC data
conversion parameters.
The message is as follows:
$PASHR,ION,<structure>
The message’s binary structure is described in the table
below.
The GPS broadcast ionosphere model (Klobuchar) is used.
Reminder on How
to Output ION
Messages
Use the $PASHS,RAW command with the syntax below:
$PASHS,RAW,ION,<port_ID>,ON,<Rate>
Type Name Size Contents
Float a0 4 Ionospheric parameter (seconds)
Float a1 4 Ionospheric parameter (seconds/semi-circle)
Float a2 4 Ionospheric parameter (seconds/semi-circle)
Float a3 4 Ionospheric parameter (seconds/semi-circle)
Float b0 4 Ionospheric parameter (seconds)
Float b1 4 Ionospheric parameter (seconds/semi-circle)
Float b2 4 Ionospheric parameter (seconds/semi-circle)
Float b3 4 Ionospheric parameter (seconds/semi-circle)
Double A1 8 First order terms of polynomial
Double A0 8 Constant terms of polynomial
Unsigned
long
Tot 4 Reference time for UTC data
Short Wnt 4 UTC reference week number
Short DtLS 2 GPS-UTC differences at reference time
Short WnLSF 2 Week number when leap second became effective
Short DN 2 Day number when leap second became effective
Short DtLSF 2 Delta time between GPS and UTC after correction
Short Wn 2 GPS week number
Unsigned
long
Tow 4 Time of the week (in seconds)
Short bulwn 2 GPS week number when message was read
Unsigned
long
bultow 4 Time of the week when message was read
Unsigned
short Check-
sum
2
The checksum is computed by breaking the struc-
ture into 37 unsigned shorts, adding them together,
and taking the least significant 16 bits of the result.
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