MA28140 Datasheet, PDF (24/72 Pages) Dynex Semiconductor – Packet Telecommand Decoder

MA28140
4.6 TELEMETRY REPORTING
General Description
Telemetry reporting is essential to the normal operation of
the telecommand data communication system.
Data Reports are not modified during telemetry readout. In
particular they are not affected by the arrival of new report
data. If the telemetry interface sampling rate is slower than the
rate at which new data reports are generated, a double register
mechanism ensures that the complete data report is read out.
CLCW Status Report
The Command Link Control Word (CLCW) is a standard
reporting data structure of the Packet Telecommand System. It
is a four-octet word generated by the spacecraft, the PTD
generating only the 2 least significant octets of this CLCW
which are described hereafter.
Bits
0 (MSB)
1
2
3
4
5,6
7
8 - 15 (LSB)
Value
0
Meaning
No RF Available
No Bit Lock
Lock Out
Wait
Retransmit
FARM B Counter
Report Type
Report Value
• Report Value. This field is maintained by the FARM-1 and
contains the next expected frame sequence number V(R).
The first bit to be read in serial mode is Bit 0 (MSB). The
interface for reading the CLCW status is specified in
section 5.3.
CPDU Status Report
The CPDU Status report consists of 16 bits of status data
formatted as follows:
Bits
0,1
2 - 15 (LSB)
Value
00
01
10
11
all 1
all other
values
Meaning
Cold Start
Last TC Packet accepted legal
Last TC Packet accepted clean,
but erased as not legal
Last TC Packet erased as not
clean
Cold Start
Packet Sequence Count (or
Name) of last legal CPDU
Packet
The first bit to be read out in serial mode is Bit 0 (MSB).
Legal and Clean concepts are defined previously. The
telemetry interface used to read out the CPDU Status Report is
fully described in section 5.3.
Each CLCW field is specified in the next paragraphs:
• No RF Available. This field is dedicated to the Physical
Layer, i.e. the RF Transponders. When this field is 1, the
RF physical connection is not available through any of the
spacecraft transponders. When it is 0, the RF connection is
available through at least one of the spacecraft
transponders. This information is provided to the PTD by
an input pin called RFAVN.
• No Bit Lock. This field is dedicated to the Physical layers,
and monitors the presence of the spacecraft
demodulation. When this field is 1, all the TC Active Signals
(0 to 5) are zero at the PTD input pins. When it is 0, at least
one of the TC Active signals is set to 1.
• Lockout Flag. If 1, this field indicates that the FARM- 1 is
in the Lockout state.
• Wait Flag. If 1, this field indicates that the FARM- 1 is in a
Wait state.
• Retransmit Flag. If 1, this field indicates that an AD frame
has been lost in transmission or has been discarded
because there was no buffer space available.
• FARM B counter. This 2 bit field contains a wraparound
up-counter (modulo 4) of each TC frame of type BC or BD
declared valid by the Legal Frame Validation process, and
therefore acceptable by the FARM-1.
• Report Type. In the PTD it is always 0 in accordance with
reference 1.
AU Status Report
The AU Status Report consists of 80 bits (i.e. 10 octets) of
status data formatted as follows:
Bits
0,1
2 - 31
32,33
34 - 63
64
65 - 71
72 - 79 (LSB)
Value
00
01
0000000
Meaning
Permanently set to 00
Current value of the contents of
the Principal LAC counter. The
LSB of the LAC counter value is
in bit 31
Permanently set to 01
Current value of the contents of
the auxiliary LAC counter. The
LSB of the LAC counter value is
in bit 63
Key in use by AU:
0 fixed key in use
1 Programmable key in use
Permanently set to 0 (reserved
for future use)
Current value of the 8 LSBs of
the recovery LAC counter. The
LSB of the LAC counter value is
in bit 79.
The first bit to be read in serial mode is bit 0 (MSB).
The AU Status report is implemented by using a double
register mechanism located in the external RAM. In the case of
external AU, the external AU can write the AU Status in RAM.
The number of the buffer is given by the AUS pin and the
toggling mechanism of the AU Status buffer is locked by the
PTD when the signal AUST ( External AU Start) is high. The
telemetry interface used to read the AU status report is
described in section 5.3.
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