ashtech HDS800, Reference Manual

Page: 622 / 678

606
Data Output
SNG: GLONASS Ephemeris Data
This message contains the GLONASS ephemeris data for one
satellite.
The message is as follows:
$PASHR,SNG,<structure>
The message’s binary structure is described in the table
below.
Type Name Size Contents
Long 4
Start time of 30-second frame in satellite time
scale tk from which the ephemeris data is
derived; time modulo one day (seconds)
Short 2
Day number of 30-second frame; modulo
four-year period counting from beginning of
last leap year, which corresponds to parame-
ter tb (tb is set within this day number). This
parameter varies within the range 1 to 1461. If
day number=0, the day number is unknown
(absent in navigation frame)
Long 4
Ephemeris data reference time within the day
expressed in GLONASS system time scale =
UTC + 3 hours (seconds)
Float 4
Frequency offset gh of the on-board fre-
quency standard at tb (dimensionless)
Float 4
Bias tn between satellite time scale and
GLONASS system time scale at tb (seconds)
Double 3*8
Satellite ECEF (PZ-90) X, Y, Z coordinates
(km)
Float 3*4
Satellite ECEF (PZ-90) velocity X’, Y’, Z’ (km/
sec)
Float 3*4
Satellite perturbation acceleration X”, Y”, Z”
due to moon and sun (km/sec/sec).
Double 8
Bias between GLONASS system time scale
and UTC + 3 hours time scale tc (seconds)
Char 1
Age of ephemeris parameter En (interval from
moment when ephemeris data was last
uploaded to tb)
Char 1 Combined 3-bit flag (contains Ï1, Ï 2, Ï 3)
Char 1 Satellite health status flag (0=good, 1=bad)
Char 1
Satellite frequency channel number
[-7,…,6]
Short 2
Satellite system number (satellite number
[1,…,24])