This read-only object reports the calculated PPS timing difference, in nanoseconds, between the default and secondary GNSS receivers on a model 5405 platform. Admins monitor this gap as an anti-spoofing check, since a sudden divergence between two independent receivers can indicate one is being fed a spoofed GPS signal. For example, a sharp jump in f3GPSReceiverPortSpoofingPpsDifference on a 5405 unit prompts the admin to investigate whether one of the two receivers is experiencing GPS spoofing or interference.