How to set up the PolaRx5TR for timing applications?

In time and frequency transfer applications, the receiver is fed with a 10 MHz reference and a PPS signal originating from an external clock. The 10 MHz reference signal is connected to the REF IN connector, and the PPS signal is connected to the PPS IN connector of the PolaRx5TR. This has the effect of aligning the receiver time with the time of the external clock, bypassing the receiver’s internal clock.
 

It is important that the PPS input signal and the 10 MHz REF IN reference are generated from the same external clock and that the PPS input signal be roughly synchronized to UTC (offset with UTC should be smaller than 0.5 milliseconds). It is also necessary that the REF IN and PPS IN signals are present from the start-up of the receiver. Plugging in a PPS input signal when the receiver is already operating will lead to erroneous measurements.
 

A typical setup is shown in Figure 1. The various delays involved in time-transfer applications are also indicated in the figure.

Figure 1: Typical setup for time-transfer applications showing relevant delays

 

Note that, the 10 MHz reference signal must have a peak-to-peak amplitude (unloaded) ranging from 0.5V to 10V (-8dBm to +18dBm on a 50 Ohm load).
Connecting or disconnecting the external 10 MHz reference is preferably done with the receiver switched off. If the 10 MHz reference is connected or removed during operation, the receiver will reset.
For the PPS IN, the input signal level should not exceed 5.5V. VIH>2.3V and VIL<1.0V. There is an internal 10-K Ohm pull down resistor.