Phase Noise and Amplitude (AM) Noise - A Brief Introduction
Poseidon Scientific has been improving the phase and amplitude noise in oscillators for over 20 years. The summary below is a plain language distillation of that experience which may assist some website visitors.
All radio waves, microwaves, and light waves are electromagnetic waves which carry energy as a combined wave of electric and magnetic fields. In the ideal sense, all of these waves are formed as mathematically ideal sine waves.
In reality, nature does not allow the realisation of ideal, perfect waves and the forces of nature cause the waves generated by radios, radars, and satellites to be imperfect. The level of imperfection which can be tolerated in these systems is limited.
To measure these imperfections scientists and engineers have devised the concept of measuring the error between what the ideal wave would be and what the real wave actually does.
If the magnitude of the field in the real wave varies and from time to time is a little bigger or a little smaller than what the idealised magnitude of the wave is, then this variation of the magnitude is deemed to be an amplitude (AM) error. If the size of the error varies randomly, it is termed amplitude noise.
If the wave front of the electric field in the real wave varies from time to time such that it is a little ahead or a behind what the wave front of the idealised wave would be, then this variation is a variation in the phase of the wave, and deemed to be a phase error. If the size of this error varies randomly, it is termed phase noise.
PSI's oscillators have the lowest variation between the ideal electromagnetic wave and the real electromagnetic wave, and accordingly are the lowest noise oscillators available.
For more detailed information on phase noise, clock and oscillator performance important reading starts with the National Institute of Standards and Technology (NIST) Technical Note 1337. The introduction can be found here.