I asked a bunch of people around the office, but the exact meaning of that SP designation is very elusive. The best lead we could find is this page from a national stock number search tool:
which seems to indicate that this instrument had to pass the Navy's own set of quality control standards. I don't have access to those QC specifications. Most likely, there will be no noticible difference between your SP instrument and a normal 8920B system in standard operating conditions.
I hope this helps.
THANK YOU SCOTTLP, BUT IM STILL LOOKING TO SEE IF THIS UNIT HAS ANY OTHER OPTIONS.
Here is a list of the hardware options that were available for the 8920B. There may be a sticker on the back of the instrument which lists which of these options it has, if any.
This table is from the 8920B user guide on page 597.
THANK YOU AGAIN FOR YOU HELP WITH THE OPTION LIST
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