
VITA-49 Radio Transport Protocol
•
Given the big-endian bytes 0x0018FFFE, then I
24
= 0x18FFFFE.
•
Given the big-endian bytes 0xFF800034, then I
24
= 0x800034 (or -8388556).
•
Compute fractional value if needed: i/2
23
.
Trailer Word Format
Table 33:
Trailer Word 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
Enables
State and Event Indicators
E Associated Context
Packet Count
DV
RL
SI OR SL
DV
RL
SI OR SL
State and Event Indicators and the associated Enable bits shall be positions as indicated
in
1. For each Indicator bit in the State and Event Indicators field, there is a
corresponding Enable bit at the same position in the Enables field.
2. When an Enable bit is set to 1, the corresponding indicator shall
function as shown
. Otherwise, the corresponding indicator shall
not be considered valid.
3. Unused bits in the Enables field and the Indicators field shall be set to 0.
4. The E field shall be set to 0 to specify the Associated Context Packet Count field as
undefined.
5. The Associated Context Packet Count field is unused and shall be set to 0.
Table 34:
Trailer Indicator and Enable Bits
Enable Bit Position
Indicator Bit Position
Indicator Name
30
18
Valid Data Indicator
29
17
Reference Lock Indicator
26
14
Spectral Inversion Indicator
25
13
Over-range Indicator
24
12
Sample Loss Indicator
6. The
Valid Data Indicator
, when set to 1, shall indicate that the data in the packet
is valid. When set to zero, it shall
indicate that some condition exists that may
invalidate the data.
7. The
Reference Lock Indicator,
when set to 1, shall indicate all PLLs in the system
are locked and stable, and when set to 0, shall indicate one or all of the PLLs is not
locked or unstable. It is very crucial to check this indicator bit.
8. The
Spectral Inversion Indicator
, when set to 1, shall
indicate that the signal
conveyed in the data payload has an inverted spectrum with respect to the
spectrum of the signal at the system Reference Point. When processing the data
payload, for plotting purpose for instance, follow the suggested solution in
to properly display the spectrum.
Important Note:
SHN, the spectral inversion indicator is available through the GPIO port. Contact
ThinkRF's Support for further details (or see “Synchronized Sweep with IQout” AppNote
for important information).
40
ThinkRF WSA5000 Wireless Signal Analyzer Programmer's Guide