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Appendix E. EPD File Structure (continued)

4. CMS PHA Block

Source: T. P. Armstrong, March 1985

(Note: This is pre-Challenger information.)

This record contains the digitized (0-255) pulse heights and time of flight information from the CMS telescope. It is reformatted and tagged with angle and time information and blocked into large records for convenience. Also attached to this information is the count rate information necessary to normalize the numbers of events in the various priority classes.

There are two types of CMS PHA blocks according to the J/J' flag. The CMS electronics are toggled alternately between the 0 and 180 degree telescope directions. Since this generates entirely distinct rate channels and PHA events, two types of CMS PHA blocks will be accumulated over simultaneous time intervals in the case that J/J' is cycling, or one type will be accumulated if J/J' is not cycling.

CMS PHA blocks are also accumulated separately according to the step position of the EPD instrument. This maintains the angular information of the pulse height information in payload fixed spin coordinates. For a normal stepping sequence which includes all 8 stepping positions, a full set of CMS PHA logical output records would be 8. Further, if the J/J' cycling is in effect, there will be one set of 8 CMSPHA blocks for J and another for J'. Hence, a set of CMS PHA blocks will include from 1 to 16 records.

ItemDescriptionLength
1Spin rate at start1 4-byte real
2Spin rate at end1 4-byte real
3Number of spins in this average1 4-byte real
4Number of full sectors1 4-byte integer
5Step position of this record1 4-byte integer
6 R15(30,16) - Count rates for 30 channels at 15 sector positions
Units:Counts/second
Type:4 byte real numbers (DEC)
1CP1
2CP2
3CP3
4CA0
5CA1
6CA2
7CA3
8CA4
9CM0
10CM1
11CM2
12CM3
13CM4
14CM5
15CN0
16CN1
17CH0
18CH1
19CH2
20CH3
21CH4
22CH5
23CE1
24CE2
25CE3
26JA
27JB
28JC
29KS
30LS
480 4-byte reals
7 IDQR15(30) - Data presence/quality flags
Units:None
Type:2 byte integer
Contents:  
  Byte 2  
  0000 Data missing (not on EDR)
  0010 Data missing (wrong subcom pos.)
  0100 Data invalid (motor movement)
  0110 Data invalid (exceed max. rate)
  1000 Data invalid (discontinuity)
  1010 Data invalid (spare)
  1100 Data invalid (spare)
  1110 Data invalid (spare)
  0001 Data valid (nominal)
  0011 Data valid (high threshold)
  0101 Data valid (autocal. fault)
  0111 Data valid (spare)
  1001 Data valid (spare)
  1011 Data valid (spare)
  1101 Data valid (spare)
  1111 Data valid (spare)
  Byte 1 Unsigned integer # of samples in this average
N15(30,16) Array of flags for R15(30,16)
 
8NBLOCK - Number of valid PHA events to follow I*4  
9 IEVENT(4,1080) - Up to 1080 repetitions of the digitized pulse heights from a telemetry packet for a total of  17280 bytes.
First index: 1=4 bytes of time information SCLCK
2=Event #1 with bit definitions:
   0-7 = Delta E J
   8-15 = Delta E K
   16-23 = Time of Flight
   24-25 = J ID; 0=Jc, 1=Jb, 3=Ja, 2=unused
   26-27 = Priority; 0=I, 1=II, 2=III, 3=IV
   28-31 = Channel ID:
   0=CM5
   1=CN0
   2=CN1
   3=CH5
   4=CH2
   5=CH3
   6=CH4
   7=(unused)
   8=CM2
   9=CM3
   10=CM4
   11=(unused)
   12=CA2
   13=CA3
   14=CA4
   15=(unused)
   

Next: 5. LEMMS PHA Block

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Updated 10/14/04, T. Hunt-Ward
tizby@ftecs.com