Initial commit

ccsds.py

+#! /usr/bin/env python3
+from bitstring import BitStream
+import spiceypy as spice
+
+
+class PacketId:
+    def __init__(self,data):
+        pID = BitStream(hex=data).unpack('uint: 3, 2*bin: 1, bits: 11')
+        self.VersionNum = pID[0]
+        self.packetType = pID[1]
+        self.dataFieldHeaderFlag = pID[2]
+        self.Apid = pID[3].uint
+        self.Pid = pID[3][0:7].uint
+        self.Pcat = pID[3][7:].uint
+        pass
+    def serialize(self):
+        return [self.VersionNum, self.packetType, self.dataFieldHeaderFlag,
+                self.Apid, self.Pid, self.Pcat]
+
+class SeqControl:
+    def __init__(self,data):
+        sq = BitStream(hex=data).unpack('bin:2,uint:14')
+        self.SegmentationFlag = sq[0]
+        self.SSC = sq[1]
+
+    def serialize(self):
+        return [self.SegmentationFlag, self.SSC]
+
+class SourcePacketHeader:
+    def __init__(self,data):
+        # Read the Source Packet Header(48 bits)
+        # - Packet ID (16 bits)
+        self.packetId = PacketId(data[0:4])
+        # - Packet Sequence Control (16 bits)
+        self.sequeceControl = SeqControl(data[4:8])
+        """ 
+        - Packet Length (16 bits)
+        In the packet is stored Packet length is an unsigned word 
+        expressing “Number of octects contained in Packet Data Field” minus 1.
+        """
+        self.packetLength = BitStream(hex=data[8:12]).unpack('uint:16')[0]+1
+        # Based on BepiColombo SIMBIO-SYS
+        # ref: BC-SIM-GAF-IC-002 pag. 48
+    def serialize(self):
+        return [*self.packetId.serialize(), *self.sequeceControl.serialize(), self.packetLength]
+
+class DataFieldHeader:
+    def __init__(self,data):
+        # Read The Data Field Header (80 bit)
+        dfhData = BitStream(hex=data).unpack('bin:1,uint:3,bin:4,3*uint:8,uint:1,uint:31,uint:16')
+        self.pusVersion = dfhData[1]
+        self.ServiceType = dfhData[3]
+        self.ServiceSubType = dfhData[4]
+        self.DestinationId = dfhData[5]
+        self.Synchronization = dfhData[6]
+        self.CorseTime = dfhData[7]
+        self.FineTime = dfhData[8]
+        self.SCET = "%s.%s" % (self.CorseTime, self.FineTime)
+        if self.Synchronization == 0:
+            self.UTCTime = self.scet2UTC()
+        else:
+            self.UTCTime = '1970-01-01T00:00:00.00000Z'
+        pass
+
+    def serialize(self):
+        return [self.pusVersion, self.ServiceType, self.ServiceSubType,
+                self.DestinationId, self.SCET, self.UTCTime]
+
+    def scet2UTC(self):
+        et = spice.scs2e(-121, "{}.{}".format(self.CorseTime, self.FineTime))
+        ScTime = spice.et2utc(et, 'ISOC', 5)
+        return ScTime+'Z'
+
+class PackeDataField:
+    def __init__(self,data):
+        # Data Field Header
+        self.DFHeader = DataFieldHeader(data[0:20])
+        # Data
+        self.Data = data[20:]
+        pass  
+
+class CCSDS:
+    """ Reader for the CCSDS header """
+    """     Main Class   """
+    def __init__(self,data):
+        # Source Packet Header
+        self.SPH = SourcePacketHeader(data[0:12])
+        # Packet Data Field
+        self.PDF = PackeDataField(data[12:])
+        self.Data=self.PDF.Data
+
+        pass