ashtech HDS800, Reference Manual

Page: 620 / 678

604
Data Output
SAW: SBAS Almanac Data
This message contains almanac data for one SBAS satellite.
The message is as follows:
$PASHR,SAW,<structure>
The message’s binary structure is described in the table
below.
Reminder on How
to Output SAW
Messages
Use the $PASHS,RAW command with the syntax below:
$PASHS,RAW,SAW,<port_ID>,ON,<Rate>
For more details on the $PASHS,RAW command, refer to the
Set Command Library Chapter.
Type Name Size Contents
char Id 1 Data ID
char Health 1
Satellite Health&Status bitwise meaning is:
Bit0 – Ranging On(0), Off(1)
Bit1 – Corrections On(0), Off(1)
Bit2 – Broadcast Integrity On(0), Off(1)
Bit3 – Reserved
Bit4-7 – SBAS provider ID (0-15):
0 – WAAS,
1 – EGNOS,
2 – MSAS,
3-13 – Not assigned yet,
14-15 – Reserved
long T0 4
Almanac data reference time within the day
expressed in the SBAS time scale (seconds)
float 3*4 Satellite ECEF X,Y,Z coordinates (meters)
float 3*4
Satellite ECEF velocity X’, Y’, Z’ coordinates
(m/s)
long Tow 4
Time within week in GPS time scale when
SBAS almanac was received
char Wn 1
Week number in GPS time scale modulo 256
when SBAS almanac was received
char Prn 1 Satellite number (33 to 51)
Unsigned short
Check-
sum
2
The checksum is computed by breaking the
structure into 18 unsigned shorts, adding them
together, and taking the least significant 16
bits of the result.
Total 38