Limited Live-time Measurements of Frequency Spectra
David A. Howe, Neil Ashby, Danielle G. Lirette, Archita Hati, Craig W. Nelson
Frequency-difference-of-arrival (FDOA) can be used to monitor and track an emitters location by observing Doppler frequency shifts of the carrier during short pulsed transmissions. This specific application needs to consider two frequency-stability levels: the short Τon-average frequency measurements and the sampling time interval between measurements, denoted by Τs. We show the advantage of using dynamic ThêoH for τon frequency measurements. Between Τon transmissions while powered off, the emitters reference-oscillator frequency will change due to power-start thermal variations, vibration, stress, and other frequency disturbances. If we regard long-term frequency instability as an uncertainty on an oscillator's expected or designated frequency, then the dominant error of frequency prediction is likely to be the error due to frequency drift and/or random-walk FM, indicating the non-stationary behavior or disturbances. A two-sample variance is devised, called Psi-variance, that has desirable statistical properties similar to the Allan variance. From this, we compute the power spectral density of frequency fluctuations, Sy(f), from which one can get phase noise, L(f).
Proceedings of the 2011 Joint IEEE International Frequency Control Symposium and European Frequency and Time Forum
May 1-5, 2011
San Fancisco, CA
Frequency Stability, Dead Time, Variance, Phase Noise, Dynamic variance, TCXO, Psi, Allan, Theo
, Ashby, N.
, Lirette, D.
, Hati, A.
and Nelson, C.
Limited Live-time Measurements of Frequency Spectra, Proceedings of the 2011 Joint IEEE International Frequency Control Symposium and European Frequency and Time Forum, San Fancisco, CA
(Accessed December 3, 2023)