PUS Packet Preprocessor¶

A preprocessor for verifying and identifying ECSS PUS packets, according to ECSS-E-ST-70-41C.

Class Name¶

org.yamcs.pus.PusPacketPreprocessor

Configuration¶

dataLinks:
  - name: tm-in
    # ...
    packetPreprocessorClassName: org.yamcs.tctm.pus.PusPacketPreprocessor
    packetPreprocessorArgs:
      errorDetection:
         type: CRC-16-CCIIT
      useLocalGenerationTime: false
      timeEncoding:
         type: CUC
         epoch: CUSTOM
         epochUTC: "2010-09-01T00:00:00Z"
         timeIncludesLeapSeconds: true
      tcoService: tco0

Configuration Options¶

errorDetection (map)

If specified, a checksum at the end of each packet is checked to verify integrity. Detailed below.

useLocalGenerationTime (boolean)

If true, packets are timestamped with local mission time rather than the time extracted from the packets. Default: false.

timeEncoding (map)

Configure how time is read from the packet. See Time Encoding.

If unset, Yamcs defaults to the following configuration:

timeEncoding:
  type: CUC
  epoch: GPS

Which is equivalent to:

timeEncoding:
  type: CUC
  epoch: CUSTOM
  epochUTC: "1980-01-06T00:00:00Z"
  timeIncludesLeapSeconds: true

pktTimeOffset (integer)

Location in bytes where to find the time field.

Default: 13.

timePktTimeOffset (integer)

Location in bytes where to find the time field in PUS Time Packets. These packets do not have a secondary PUS header.

Default: 7.

tcoService (string)

Name of a Time Correlation Service.

performTimeCorrelation (boolean)

If true, send received packets to the configured tcoService for updating time synchronization coefficients.

Default: false

goodFrameStream (string)

When performTimeCorrelation is enabled, subscribe to this Yamcs stream producing good frames. This should match the name of the stream that the frame-based data link is publishing to.

Time packets from this stream are processed to find Earth Reception Time.

Default: good_frame_stream

Error Detection sub-configuration¶

type (string)

Required. Can take one of the values:

16-SUM: calculates a 16 bits checksum over the entire packet which has to contain an even number of bytes. This checksum is used in Columbus/ISS data.
CRC-16-CCIIT: standard CRC algorithm used in PUS and also in CCSDS standards for frame encoding.
ISO-16: specified in PUS as alternative to CRC-16-CCIIT.
NONE: no error detection will be used, this is the default if the errorDetection map is not present.

initialValue (integer)

Used when the type is CRC-16-CCIIT to specify the initial value used for the algorithm. Default: 0xFFFF.