Command/Response Formats
125
Com
m
and
s
where Table 6.39 defines the measurement structure.
If both GPS and GLONASS satellites are locked during a session and the absolute
current time is available from GPS data download, then the day number can be
calculated through WN (GPS week number).
If only GLONASS satellites are locked and processed during a session, the receiver
checks whether a GLONASS almanac is available. If there is no GLONASS almanac
Table 6.39: SNG GLONASS Ephemeris Data Structure
Type
Size in
Bytes
Content
long
4
Start time of the 30-second frame in satellite time scale t
k
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 parameter t
b
(t
b
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
γ
η
of the on-board frequency standard at t
b
(dimensionless)
float
4
Bias t
n
between satellite time scale and GLONASS system time scale at t
b
(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
τ
c
(seconds)
char
1
Age of ephemeris parameter E
n
(interval from moment when ephemeris data
was last uploaded to t
b
)
char
1
Combined 3-bit flag (contains Ï1, Ï2, Ï3, see GLONASS ICD)
char
1
Satellite health status flag (0 = good, 1 = bad)
char
1
Satellite frequency channel number [-7,...,24]
short
2
Satellite system number (satellite number [1,...,24])
unsigned
short
2
Word checksum computed by breaking the structure into 40 unsigned shorts,
adding them together, and taking the least significant 16 bits of the result.
Total
82 bytes
(95 for structure plus header and <CR><LF>)
Содержание GG Surveyor
Страница 14: ...xiv GG Surveyor GPS GLONASS Reference Manual...
Страница 38: ...20 GG Surveyor GPS GLONASS Reference Manual...
Страница 62: ...44 GG Surveyor GPS GLONASS Reference Manual...
Страница 86: ...68 GG Surveyor GPS GLONASS Reference Manual...
Страница 232: ...B 6 GG Surveyor GPS GLONASS Reference Manual...
Страница 236: ...C 4 GG Surveyor GPS GLONASS Reference Manual...
Страница 246: ...E 6 GG Surveyor GPS GLONASS Reference Manual...