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Python library to read the SCOS-2000 header

Project description

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:

one of the following sub-object:

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.

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