I just tried a quick test with my HP 5334A, with a LPRO to TVB divider on channel A and an Oncore UT+ on channel B. frequency difference: measured on the falling edge: 37E-9 Hz measured on the leading edge: 6.7E-9 Hz Both measurements are from the rising or falling edge of the 1 PPS of the GPS, 100 sample average. cheers, glenn