Young, Ken 
to:	Chunhua Qi ,
Mark Gurwell ,
Jun-Hui Zhao ,
Glen Petitpas ,
Rurik Primiani 
date:	Wed, Apr 27, 2016 at 3:04 PM
subject:	Upcoming changes to the SMA Data Format


Hi,

I plan to install a new version of dataCatcher on May 15 
(the start of our next semester).    
The new dataCatcher will handle two new SWARM formats, 
and will have another minor change:

1) In the sp_read file, the field "spareint1" will be renamed "correlator".   
It will be set to 0 if the chunk was produced 
by the ASIC correlator, and 1 if the chunk was 
produced was produced by SWARM.   Note that 
this integer has been set to 0 in all data sets so far.   
It is not clear that we really need to be able to distinguish 
between SWARM and ASIC chunks, but I can think of no harm 
recording that information would cause. Until we decide 
we need to know which correlator produces a chunk, 
this field can be ignored.

2) SWARM chunk numbering:  Right now, the numbering of SWARM chunks 
does not make sense, because frequency does not monotonically 
increase or decrease with SWARM chunk number.   
This will change with the new dataCatcher, 
which will number SWARM chunks as follows:

ChunkNumberIfASICActive  ChunkNumberIfASICInactive  IF Region
     49                            1                4 ->  6  GHz
     50                            2                6 ->  8
     51                            3                8 -> 10
     52                            4               10 -> 12

Note that we currently have only two SWARM quadrants, and when 
two receivers are active SWARM chunks 49 (1) and 52 (4) will not exist.

3) The new dataCatcher will support three modes of SWARM operation: 

1) Single receiver 
2) Dual receiver and 
3) Full polarization.  
 
It will also support operation without the ASIC correlator active.
Please let me know if you see any problem with any of the above.

Thanks.

Taco