a frequency domain measure of stability and is usually expressed as the SSB spectral density in dBc/Hz. This is the single-sideband noise and is denoted by L(f). It is important in many applications and has direct correlation to the short term stability. Low levels of phase noise are achieved through careful circuit design and use of high-Q resonators. Typically, to measure the phase noise of a crystal oscillator an identical tunable oscillator is used as a reference and phase locked in phase quadrature to the oscillator being tested. This allows removal of the carrier signal while leaving the sidebands to be measured with a low frequency FFT analyzer. If the two oscillators have identical noise, the noise of each oscillator is 3 dB better than that measured for both.
The ratio of the power density of one phase modulation sideband to the total signal. It is usually specified as the single side band (SSB) power density in a 1Hz bandwidth at a specified offset frequency from the carrier. It is measured in dBc/Hz.
The amount of phase noise energy contained in a frequency carrier. Specified in dB/Hz, phase noise amplitude is usually characterized and plotted in 1 Hz increments, offset from the carrier.
Frequency representation of time-based jitter, typically expressed as a noise spectral density at a specific offset frequency from a carrier.
A measure of the short term frequency instability of the oscillator. It is measured as the single sideband noise, resulting from changes in frequency, in decibels below the amplitude at the operating frequency of the oscillator using a 1 Hz bandwidth (dBc/Hz) at two or more frequency displacements from the operating frequency of the oscillator. This measurement has particular application to the analog communications industry. There are three primary sources of this instability, steady-state (MIL-PRF-55310D, 184.108.40.206), random vibration (MIL-PRF-55310D, 220.127.116.11), and acoustic (MIL-PRF-55310D, 18.104.22.168).
A measure of the random phase instability of a signal.
Noise that would prevent coherent phase tracking of an RF signal in a QPSK or other phase dependant scheme.
Rapid, short-term, random fluctuations in the phase of a wave caused by time-domain instabilities in an oscillator.
In an oscillator, phase noise is rapid, short-term, random fluctuations in the phase of a wave, caused by time domain instabilities.