
VITA-49 Radio Transport Protocol
Table 9:
Receiver Context Packet Class Structure
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Pkt Type
0 1 0 0
C
R
T
S
M
TSI TSF Pkt Count
Pkt Size
Stream Identifier (1 word)
Timestamp - Integer Seconds (1 word)
Timestamp - Integer Picoseconds (2 words)
Context Indicator Field (1 word)
Context Fields (Variable Size)
1.
Pkt Type
shall be set to
0100
to indicate this is a context packet.
2.
C
shall be set to
0
to indicate there is no Class Identifier in the packet.
3.
R
shall be set to
00
, because they are reserved bits.
4.
TSM
(TimeStamp Mode) shall be set to
0
, indicating that context packet
timestamps are precise.
5.
TSI
(TimeStamp-Integer) field shall be set to
01
, indicating that integer (seconds)
part of the timestamps are in Coordinated Universal Time (UTC).
6.
TSF
(TimeStamp-Fractional) field shall be set to
10
, indicating that the fractional
part of the timestamp measures in real time picosecond resolution.
7.
Pkt Count
shall start at 0000 and increment once for each context packet, until
reaching 1111 (or 15), where it shall rollover to 0000 on the next count.
8.
Pkt Size
indicates the total number of 32-bit words in the entire context packet,
including all headers, the context indicator field and context sections.
9.
Stream Identifier
shall be the 32-bit word,
0x90000001
10.
Timestamp - Integer Seconds
shall be in UTC format and will represent the
number of seconds occurred since Midnight, January 1, 1970, GMT.
11.
Timestamp - Integer Picoseconds
shall count the number of picoseconds past
since the last increment of the Timestamp seconds field. See the Picosecond
Timestamp Words Format section for the format.
12. The
Context Indicator Field
shall follow the format indicated in
Table 10:
Receiver Context Indicator Field Positions
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9
8
7
6
5
4
3
2
1
0
I
R
-
F
-
G
-
T
-
13. The
Context Fields
section shall contain a context field for every field that is
indicated to be present in the Context Indicator Field.
The fields shall be ordered
in the identical order of their occurrence in the Context Indicator Field.
for the definition and associated value of each field.
Table 11:
Receiver Context Field Definition and Values
Bit Name
Context Field
# of Words in Field
Period of Validity
I
Context Field Change Indicator
0
N/A
R
Reference Point
1
Persistent
F
RF Reference Frequency
2
Persistent
G
Gain
1
Persistent
T
Temperature
1
Persistent
30
ThinkRF WSA5000 Wireless Signal Analyzer Programmer's Guide