74 Installation TB7300 Installation and Operation Manual
© Tait International Limited December 2022
5.7.6 Connecting a 1PPS Source
A 1PPS signal is required for simulcast base stations. Use a 50Ω 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 5.7). 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 with a 50Ω 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 5.8 Daisy-chaining a 1PPS input
50Ω termination
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
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