¿How long is the pulse in a PPS signal? If you test some GPS units, you will find very different values. Some GPS produce a 100ms long pulse, but other ones produce pulses in the millisecond or microsecond area.
Usually, this is not a problem. A PPS signal works on the rising edge, so the circuit where the signal is used senses only the positive edge. In this way no matter how long the pulse is. It will work.