Phase Noise System
We have established a phase noise measurement system including
a phase noise standard (1,5,10,100 MHz), a single channel noise
detector, a delay line unit, and one single channel signal
analyzer. The noise reference is from the Hydrogen maser
and the noise level is about –165 dBc/Hz (5 MHz PM, at
Fourier frequency 100KHz). For passive device, the phase
noise standard can measure up to –177 dBc/Hz. For measuring
the carrier frequency different from 1, 5, 10, and 100 MHz,
we will use HP-8662A frequency synthesizer as the noise
reference. We also plan to measure the very short term
stability (τ ＜ 0.5 second)
by using this phase noise measurement system, since the
traditional time interval counter is applicable only
when τ is about 1 second. The cable delay at variable
carrier frequency can also be measured when signal
propagating through. Those capabilities provide a new
method for evaluating the performance of active device
like oscillator and power supply, or of passive device
like long cable and distribution amplifier.
In the future, we are planning to build up a cross-correlation
system, which can measure the noise 20 dBc/Hz below the phase
noise reference. All the primary national phase noise standard
will be finished and provided service in the year of 2001.