User's Manual

Radio Activity S.r.l. 20 / 44
In the example above, 4 KAIROS are assembled in the same cabinet. Two GPS antennas are used realizing a
1+1 redundancy in the synchronization source. The timing signal, sent out from both KAIROS equipped with
the GPS receiver, is used from all the other ones. A special protocol on the 1-wire timing bus allows automatic
1+1 redundancy management.
Since the timing bus (pin2-PPS and pin6-GND) carries a very high precision signal, this cable must be as short
as possible and placed away from high power RF antennas. Strong RF signals applies near this cable may
corrupts the synchronization integrity.
Since the frontal led “RX1” flashes green synchronously with the PPS signal, this led should flash in the same
instant on all the equipments connected together. This immediately gives a feedback about the right
connection in the rack.
This configuration requires the following setup in the equipments:
KAIROS “A” and “D”:
1
st
choice
Internal PPS (GPS/GLONASS)
2
nd
choice
External PPS (full)
3
rd
choice
Internal PTP (if this protocol is supported by the IP network)
4
th
choice
Internal ref (full)
PPS to rear plug
Internal ref
KAIROS “B” and “C”:
1
st
choice
External PPS (full)
2
nd
choice
Internal PTP (if this protocol is supported by the IP network)