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Mark5B disk data format

Taken from Mark5B System User's Manual (9 June 2006) Section 5.

Data on disk is divided into equal-length disk frames (DF). Each DF has a header of 4 32-bit words followed by 2500 32-bit words of data (10000 bytes). The DF boundary is aligned with the UT second tick.

Disk Frame Header

Word 0	Synchronization word (0xABADDEED)
Word 1	Bits 31-16: User specifed
	Bit 15: T - tvg data (test data if set)
	Bits 14-0: DF # within second
Word 2-3	VLBA BCD Time code and 16 bit CRC

Sync word (32 bit)
User-specifed (16 bits)	T	Frame# within second (starting at 0)
VLBA BCD Time code word 1 ('JJJSSSSS')
VLBA BCD Time code word 2 (16 bit) ('.SSSS')	CRC 16 bit

Disk Data Format

Raw VLBI data is packed within a 32 bit word, with the earliest time sample corresponding to the least significant bits .