[Gb-ccb] 17feb04 CCB telecon minutes

[John Ford]

Martin Shepherd writes:
 > 
 > On Thu, 19 Feb 2004, John Ford wrote:
 > > extra complexity invites extra problems.  I suggest we trust the
 > > reference signals.
 > 
 > How am I supposed to ensure that this thing works if it unnecesarily
 > depends on external conditions which rely on the lack of human error?

What if someone points the telescope off the source?  do you have a
plan to correct that?

What if the reference signals disappear?  How will you correct that?

 > Maybe this is a difference in philosophy between programming and
 > electronic engineering, but in my book one should always try to ensure
 > that something works predictably, regardless of what a human operator
 > might do.

It's not an operator thing.  We don't have idiots changing cables
willy-nilly around on the telescope. 

 > It seems to me that a single flip-flop ensuring correct
 > operation is far less complex than relying on somebody plugging in the
 > right coax cable, and seriously, if a single flip-flop is a considered
 > to be a liability, what of the 4 FPGAs with 100s of thousands of gates
 > and flip-flops each?

More parts mean more connections, more chance of failure.  Why not
just us a couple of the zillion gates inside the FPGA to do this if
you really want to resync it yet again?

John