SCOSpy 0.4.4

Python library to read the SCOS-2000 header

SCOSpy

SCOSpy is a python library for the Satellite Control and Operation System 2000 (SCOS-2000) header written as hexadecimal string.

Current version is 0.4.4

Library Installation

$ pip install SCOSpy

Usage

from SCOS.SCOS import SCOS
a = SCOS(packet)

where packet is the hexadecimal string rapresentation of the Telemetry packet.

Limitation

At the moment the software works only for Telemetry and Telecommand packets (Packet Types 1 and 2) for the BepiColombo ESA Mission. It is possible add a new Mission ID and Spcecraft ID. For example to add the JUICE Mission :

form SCOS.SCOS import SCOS, MissionID, SpacecraftID

MissionID[844]={'id':844, 'description': 'JUICE'}
SpacecraftID[844]={'id':844, 'description': 'JUICE'}

obj=SCOS[data]

In the next versions other missions will be implemented.

Data Structure

The SCOS object contain:

• Common Packet Header Structure (CPH)

one of the following sub-object:

• Telemetry Packet Header (TMPH)
• Telecommand Packet Header (TCPH)
• Event Packet Header (EPH) (not implemented)

and the attribute

• data with the data in the packet as hex string

Many of the entries of the objects are dictionary. Usually the structure is the following: {'id': x, 'description': 'blablabla'} ad is reported in the tables.

Common Packet Header Structure (CHP)

In the CHP are present the following fields.

Field	Description
CTree	Used in earlier version of SCOS-2000 by c-tree to support packets storing in files and be kept for backward compatibility.
AccessF	Storing mode, see Access Flag Table
SimFlag	Simulated packet, see Simulated Packet Table
FilingTime	Filing Time. For TM this is the timestamp. For TCs, this is the release time.
CreationTime	Creation Time. This is a secondary retrieval key and for TM is the time at which the SCOS-2000 packet was created, which is also approximately the time that the packet was received by the MCS and stored. For TCs, this is its (estimated) execution time.
CreateID	Used by the old SCOS-2000 archive for generating a retrieval key and set by the application which generated the packet.
SCID	In the case of telemetry, Spacecraft ID. See Spacecraft ID Table
GSID	In the case of telemetry, the ID and name of the ground station which receives the frame containing this packet. See Ground Stations Table
PSize	Packet Size. Size of the entire SCOS-2000 packet, including all headers and the packet data.
PType	Determines the type of SCOS-2000 packet. See Packet Types Table
Version	The version of this packet structure.
FilingFlag	Set to 1 if this packet is to be filed in the MCS archive, otherwise 0.
DistFlag	Set to : 1 if this packet is to be distributed to the MCS applications, otherwise 0.
TSPolicy	Determines the timestamp policy for spacecraft TM, i.e. what will be set in the Filing Time fields above. See Timestamp Policy Table
TQ	Time quality of the timestamp, used only if the TsPolicy is set to 2. See Time Quality Table.
StreamID	The datastream identifier in the MCS, which for TM maps to VCs. See Stream IDs Table
SeqCounter	Internal MCS counter used for detecting gaps – not related to the spacecraft source sequence count value in the PUS header.
SPID	the numerical packet ID which identifies the packet structure, and maps to packet definitions in the TM/TC MIB database. Note: For TC packets, SPIDs 100 and 200 are used.
MissionID	For telemetry, the MCS mission identifier. See Mission IDs Table

Access Flag Table

ID	Description
0	inserted packet
1	update

Simulated Packet Table

ID	Description
0	non-simulated packet generated by the spacecraft
1	simulated packet generated by a Simulator or test tool.

Spacecraft ID Table

ID	Spacecraft	Band
816	BepiColombo	TM received over X-Band.
817	BepiColombo	TM received over Ka-Band.

Ground Stations Table

ID	Description
21	Kourou
22	Perth
23	New Norcia
24	Cebreros
25	Malargue
30	Maspalomas
97	Usuda
98	Uchinoura

Packet Types Table

ID	Description
1	Telemetry
2	Telecommand
3	Event

Timestamp Policy Table

ID	Description
0	packet is time-stamped with the creation time – i.e. SCOS-2000 packet creation
1	The packet is time-stamped with the time of transmission of the frame it was received in, i.e. Earth Reception Time minus the propagation delay (applicable to spacecraft TM only)
2	the correlated SCET (for spacecraft TM only)

Time Quality Table

ID	Description
0	Good
1	Inaccurate
2	Bad

Stream IDs Table

ID	Description
1	Used for TC stream
1000	VC0 Real-Time Non-Science (online)
1001	VC1 Playback Non-Science (online)
1002	VC2 Science (online)
1003	VC3 File-Transfer (online)
2000	VC0 Real-Time Non-Science (offline)
2001	VC1 Playback Non-Science (offline)
2002	VC1 Playback Non-Science (offline)
2003	VC2 Science (offline)
65535	is used for internal non spacecraft TM packets, which should be ignored by external users.

For EVs stream 1000 and 1001 are used.

Mission IDs Table

ID	Mission
816	BepiColombo

Telemetry Packet Header (TMPH)

If the CHP.PType is equal to 1, the packet is a telemetry. In this case is present the TMPH onject.

The object has the following structure:

Attribute	Description
TPSD	Structure identifier for variable length packets.
RouteID	The LSB of the RouteID field is used by SCOS-2000 to identify the Data Unit Type of Telemetry packet and its qualifier
PUSAPID	The value of the 11-bit Application Process ID, copied from the spacecraft source packet’s primary header
PUSSSC	The value of the 14-bit Source Sequence Count, copied from the spacecraft source packet’s primary header
PUSService	The value of the 8-bit Service Type, copied from the spacecraft source packet’s secondary data field header. The old key PUSST is deprecated.
PUSSubService	The value of the 8-bit Service Sub-type, copied from the spacecraft source packet’s secondary data field header. The old key PUSSST is deprecated.

Telecommand Packet Header (TCPH)

If the CHP.PType is equal to 2, the packet is a telecommand. In this case is present the TCPH onject.

The object has the following structure:

Attribute	Descriprion
UplinkTime	Uplink Time – initially set to the release time (FT), but updated with the timestamp copied from the radiation ground station response message providing the actual time of uplink from the antenna.
ExecTime	Execution Time – For time-tagged commands this is the UTC user provided execution time. For immediate commands this is the release time + propagation delay and later updated to be Uplink time + propagation delay.
LUTime	Last Update Time, this is the MCS system time at which the TC packet was last updated with a change of status.
RequestID	Internal MCS identifier.
ReqElemIdx	Internal MCS sub-identifier.
VarAddSz	Combined size of the fixed and variable parts of the command details data.
PUSAPID	The value of the 11-bit Application Process ID, copied from the spacecraft source packet’s primary header.
PID	Process ID.
PCAT	Packet Category.
PUSSSC	The value of the 14-bit Sequence Count, copied from the spacecraft source packet’s primary header.
PUSService	Service Type - The value of the 8-bit Service Type, copied from the spacecraft source packet’s secondary data field header. The old key PUSST is deprecated.
PUSSubService	Sub-Service Type - The value of the 8-bit Service Sub-type, copied from the spacecraft source packet’s secondary data field header. The old key PUSSST is deprecated.
PUSAck	The value of the 4-bit Ack, copied from the spacecraft source packet’s secondary data field header. See Aknowledge Table.
UplinkFlag	Uplink Flag. See Uplink Codes Table.
SourceHost	Numerical ID of the MCS machine running the command source.
SourceType	Enumeration providing the type of the command source.
ReqDetFixedSize	Size of the fixed part of the command details data.

Aknowledge Table

ID	Description
0	No Acknowledge required for acceptance and execution.
1	Acknowledge required for acceptance.
8	Acknowledge required for execution
9	Acknowledge required for acceptance and execution

Uplink Codes Table

ID	Description
1	if the command is to be released (passed PTV)
0	if the command is not to be released (failed PTV)

Event Packet Header (EPH)

If the CHP.PType is equal to 3, the packet is a event. In this case is present the EPH onject.

NB: the EPH is not yet implemented.

Change Log

Version 0.4.3

• fixed a data type in te database

Version 0.4.0

• the fields of the subobject are now dict type.
• improved prefomace
• implemented the method to add a new mission dinamically.

Version 0.3.0

• tested on Python 3
• minor bug fixef

Version 0.2.2

• bug fix, old call to database removed
• update of the user manual

Version 0.2.1

• minor bugs fixed

Version 0.2.0

• Introduced the TCHP
• First version of the README file.