TB9400/TN9275 Installation and Operation Installation 85
© Tait International Limited May 2023
Figure 4.12 BNC goal post adaptor (part number 240-06913-00)
4.6.7 Connecting a 1PPS Source
A 1PPS signal is required for simulcast and P25 Phase 2 base stations. Use
a 50
coaxial cable (RG58 or RG223) to connect the source to the base
station’s 1PPS input. You can daisy-chain up to eight base stations using
BNC goal post adaptors (see Figure 4.12). We recommend that the cable
length between the first and last load is kept to a minimum. This will reduce
any propagation variation between base stations. The maximum overall
cable length is 30m. Terminate the last connection (including single base
stations) with a 50 resistor, otherwise reflections of the 1PPS pulse may
occur.
Notice If 1PPS is used then 1PPS and NTP must both be derived
from the same time base. Normally this will be a GPS disciplined
source.
Figure 4.13 Daisy-chaining a 1PPS input
The longest length of cable must be between
the source and the first base station
use short lengths of cable
between each base station
maximum of eight base station
loads on one 1PPS output
50 termination
(also needed for
single base stations)
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