Picosecond Timestamp Words Format
The two 32-bit words timestamp allotted for picoseconds are arranged as below.
Table 29:
64-bit or Two Words Picosecond Timestamp Format
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
Timestamp
– picoseconds, Word 1 (63..32)
Timestamp
– picoseconds, Word 2 (31..0)
Data Payload Format
The data payload of an IF Data packet contains a contiguous sequence of the Data
Samples from an IF Data Sample stream. The number of words in the data payload is
variable from packet to packet, and can be determined at the receiving end of the link
from the Packet Size by subtracting the number of words dedicated to the header, trailer,
and other additional fields. The presence or absence of these fields can be determined
entirely from information in the header.
52. The maximum number of data payload 32-bit words shall be 2
16
-16 and must be a
multiple of 16. Limitation due to embedded data transferring engine.
53. The data payload shall consist of an integer number of contiguous 32-bit words.
54. IF Data Packets convey either the time domain in-phase (I or real) and/or quadrature (Q
or imaginary) components forming the Complex Cartesian samples.
{I
14
Q
14
} Data Payload Format
55. Each I or Q data is a signed two's-complement 14-bit data with signed extended into 16-
bit. Thus, each component is an integer ranging from -8192 to +8191 (or ±2
13
).
56. The I-component is in the upper 16-bit of each data word followed by the Q-component in
the lower 16-bit, as seen in
Table 30
.
Table 30:
{I
14
Q
14
}
Data Payload Arrangement with Upper 2-bit of Each Item Signed Extended to
{I
16
Q
16
}
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
0bxx
Item 1 (Sample 1 I
14
)
0bxx
Item 2 (Sample 1 Q
14
)
0bxx
Item 3 (Sample 2 I
14
)
0bxx
Item 4 (Sample 2 Q
14
)
0bxx
Item 5 (Sample 3 I
14
)
0bxx
Item 6 (Sample 3 Q
14
)
.
.
.
.
.
.
.
.
.
.
.
.
Example conversion, given the big-endian bytes 0x0018FFFE received:
Split into two data items (i = 0x0018, q = 0xFFFE)
Parse signed two's complement (i = 24, q = -2)
Compute fractional value if needed: i/2
13
and q/2
13
{I
14
} Data Payload Format
57. Each I data is a signed two's-complement 14-bit sample with signed extended into 16-bit.
Thus, each component is an integer ranging from -8192 to +8191 (or ±2
13
).
58. The first I sample is in the upper 16-bit of each data word follows by the second I sample
in the lower 16-bit, as seen in
Table 31
.
