[Gb-ccb] 1PPS signal specifications

[John Ford]

Martin Shepherd writes:
 > 
 > On Thu, 4 Sep 2003, John Ford wrote:
 > > I think a good setup would be a grounded BNC connector, a ferrite bead
 > > on the center conductor inside your enclosure, and a good
 > > double-shielded cable between your box and the 1 PPS signal source.
 > > The cable will be about 22 meters long.
 > 
 > So a loose ferrite bead is sufficient for this connection, whereas a
 > pi filtered connector was needed for the signal and control lines. Is
 > this because the remote end of the 1PPS coax terminates outside the
 > receiver room, whereas the former lines terminate inside the receiver
 > box?

No, it's because of the coaxial double-sheilded cable, and the fact
that the other end terminates in a shielded box.  The receiver analog
section, where the data cables originate, will not be in a shielded
box.
 > 
 > How about the analog power-supply lines? Am I correct that these will
 > need pi filters, because the power supplies are shared with the
 > receiver?

Yes, the power supply lines entering the CCB box will need filtered.
Not because they are shared with the receiver, but because they will
radiate energy into the receiver room.

 > 
 > Also, you mentioned in an email last week that there would be "a big
 > fat ground bus" between the receiver and CCB boxes. Are you thinking
 > of a thick cable (how thick?) bolted to the two cases?

We will use a thick braid (3/4 or 1") between the receiver chassis and
the CCB box.

John