QZSS ephemeris report
The QZSS ephemeris report is sent when Command Packet 54h is used to request the ephemeris for one QZSS satellite or all QZSS satellites. The GETSVDATA SUBTYPE byte (byte 4) is set to fourteen (14) to request the report. The first following table shows the additional records provided in Report Packet 55h when QZSS ephemeris data is included.
The ephemeris data follows the standard defined by the ICD200, except for CUC, CUS, CIS, and CIC. These values must be multiplied by p to become the units specified in the ICD document. The ephemeris flags are described in the second following table.
|
Subtype 14: QZSS ephemeris data |
||||
|---|---|---|---|---|
|
Byte |
Item |
Type |
Value |
Meaning |
|
6 |
DATA SOURCE |
1 (byte) |
|
Valid values are: 0: L1CA |
|
8–9 |
WEEK NUMBER |
2 (bytes) |
|
GPS Week Number |
|
10–11 |
IODC |
2 (bytes) |
|
|
|
12 |
Reserved |
1 (byte) |
|
|
|
13 |
IODE |
1 (byte) |
|
|
|
14–17 |
TOW |
4 (bytes) |
|
|
|
18–21 |
TOC |
4 (bytes) |
|
|
|
22–25 |
TOE |
4 (bytes) |
|
|
|
26–33 |
TGD |
8 (double) |
|
|
|
34–41 |
AF2 |
8 (double) |
|
|
|
42–49 |
AF1 |
8 (double) |
|
|
|
50–57 |
AF0 |
8 (double) |
|
|
|
58–65 |
CRS |
8 (double) |
|
|
|
66–73 |
DELTA n |
8 (double) |
|
|
|
74–81 |
M sub 0 |
8 (double) |
|
|
|
82–89 |
CUC/PI |
8 (double) |
|
Multiply by π to obtain ICD units. |
|
90–97 |
ECCENTRICITY |
8 (double) |
|
|
|
98–105 |
CUS/PI |
8 (double) |
|
Multiply by π to obtain ICD units. |
|
106–113 |
SQRTA |
8 (double) |
|
|
|
114–121 |
CIC/PI |
8 (double) |
|
Multiply by π to obtain ICD units. |
|
122–129 |
OMEG sub 0 |
8 (double) |
|
|
|
130–137 |
CIS/PI |
8 (double) |
|
Multiply by π to obtain ICD units. |
|
138–145 |
I sub 0 |
8 (double) |
|
|
|
146–153 |
CRC |
8 (double) |
|
|
|
154–161 |
OMEGA |
8 (double) |
|
|
|
162–169 |
OMEGADOT |
8 (double) |
|
|
|
170–177 |
IDOT |
8 (double) |
|
|
|
178–181 |
EPHEMERIS FLAGS |
4 (long) |
|
See below. |
|
---------- End of Subtype 14 ---------- |
||||
Where FLAGS is encoded as a 32-bit value given by the following table:
NOTE – Not all these flags are relevant for QZSS and so are transmitted as constant values by QZSS. To facilitate code sharing with GPS almanac code, these constants are propagated through the system and all the relevant flags below are in the same place as for GPS.
|
Bit(s) |
Description |
Location |
|---|---|---|
|
0 |
Data flag for L2 P-code (fixed at 1 for QZSS) |
Sub 1, word 4, bit 1 |
|
1–2 |
Codes on L2 channel (fixed at 10b for QZSS) |
Sub 1, word 3, bits 11–12 |
|
3 |
Anti-spoof flag: Y-code on: from ephemeris (fixed at 0 for QZSS) |
Sub 1–5, HOW, bit 19 |
|
4–9 |
SV health: from ephemeris |
Sub 1, word 3, bits 17–22 |
|
10 |
Fit interval flag |
Sub 2, word 10, bit 17 |
|
11–14 |
URA: User Range Accuracy |
Sub 1, word 3, bits 13–16 |
|
15 |
Block II: Alert flag: SV URA may be worse than indicated |
Sub 1–5, HOW, bit 18 |
|
16–18 |
SV configuration: SV is Block I or Block II |
Sub 4, page 25, word and bit depends on SV. |
|
19 |
Anti-spoof flag: Y-code on |
Sub 4, page 25, word and bit depends on SV. |