ARA STATION / IRS RAW EVENT BLOCK FORMAT

This is the event as it is formed inside the programmable
logic.  Events are generally of variable length due to a
variable number of IRS blocks readout and the variable 
number of channels per block.  However, it seems that the
most likely number of channels is 5 and the number of blocks
readout (64 samples per block, at 3-3.5 GHz/sample) is
20.  And, there are in the full ARA stations going to be
4 parallel readout DDA paths. In this case the event size 
would be 51544 bytes.

NB: multi-byte words in little endian format [TBR]

SIZE | OFFSET | DESCRIPTION
-----+--------+-----------------------------------------------
   4 |      0 | # of bytes contained in this record
   4 |      4 | record ID 0x00000052
   8 |      8 | timestamp
   4 |     16 | Event ID
   2 |     20 | Trigger word
   2 |     22 | # of readout blocks
   N |     24 | Block readout #0
   N |   N+24 | Block readout #1
   … |      … | … 


READOUT BLOCK FORMAT

Each block contains the address of the block (0-511), a
pattern of channels included in the readout, and the sample
data zero-padded and stored as 16-bit words.

SIZE | OFFSET | DESCRIPTION
-----+--------+-----------------------------------------------
   2 |      0 | IRS block number
   1 |      2 | Channel mask
   1 |      3 | ATRI / DDA module number [0-3]
   2 |      4 | Channel(0) sample 0
   2 |      6 | Channel(0) sample 1 
   … |      … | … 
   2 |    130 | Channel(0) sample 63
   2 |    132 | Channel(1) sample 0
   2 |    134 | Channel(1) sample 1
   … |      … | …