Comparison of high-precision frequency-stability measurement systems

The performance of two commercial high-precision frequency-stability measurement systems, timing solutions 5110A time-interval analyzer and Quartz lock A7 frequency and phase comparator, has been compared with two laboratory dual-mixer time-difference (DMTD) systems developed at the institute of radio engineering and electronics (IREE), Prague, and istituto elettrotecnico nazionale "Galileo Ferraris" (IEN), Turin, respectively. Two BVA oscilloquartz 5 MHz oscillators with Allan deviation (ADEV) around 1/spl times/10/sup -13/ at averaging intervals 1 s to 30 s were used as test-signal sources. In terms of the best-measurement-capability (BMC), the compared systems have shown the background noise at 5 MHz of ADEV=4.2/spl times/10/sup -14/ at 1 s in IREE-DMTD, 4.4/spl times/10/sup -14/ in IEN-DMTD, 7.4/spl times/10/sup -14/ in A7, and 8.8/spl times/10/sup -14/ in 5110 A, respectively. The 5110 A analyzer behaved the best concerning the dependence on departures from the BMC conditions.