Showing papers on "Spectrogram published in 1971"
TL;DR: In this paper, an instrument for measuring dynamic spectrograms is described, which involves the use of a spectrometer with ultrafast time response and has been used in an antisymmetric mode to measure frequency sweep rate as a function of wavelength.
Abstract: A dynamic spectrogram depicts intensity as a function of frequency and time simultaneously, subject to the classical uncertainty relation δωδt≈2π. For an optical pulse having the Fourier transform |g(ω)|eiφ(ω), high‐resolution spectroscopy gives |g(ω)|2, while the dynamic spectrogram gives knowledge of ∂φ(ω)/∂ω permitting reconstruction of many features of the amplitude and phase modulations of the original pulse. Linear, parabolic, and two sinusoidal spectrogram shapes are interpreted theoretically. An instrument for measuring dynamic spectrograms is described. It involves the use of a spectrometer with ultrafast time response and has been used in an antisymmetric mode to measure frequency sweep rate as a function of wavelength for picosecond laser pulses. The change in the dynamic spectrogram of a pulse brought about by linear pulse compression and the resultant change in pulse envelope shape have been computed for a typical picosecond pulse.
91 citations
TL;DR: A program to generate and display spectrograms on a computer-controlled scanned-display television monitor is described, which features computation of power spectra for selected time segments with the aid of the fast Fourier transform algorithm and four-level intensity quantization.
Abstract: A program to generate and display spectrograms on a computer-controlled scanned-display television monitor is described. The program features computation of power spectra for selected time segments with the aid of the fast Fourier transform algorithm, four-level intensity quantization controlled by a threshold under operator control, and flicker-free scanned display of the generated data. The computer-generated spectrograms suffer from intensity and spatial resolution limitations relative to conventional spectrograms. However, their rapid generation and flicker-free display makes their use appropriate in a man-computer interactive environment to complement aural evaluation of digitally synthesized or processed speech signals.
12 citations
01 Jan 1971
TL;DR: Spectrograms suffer from intensity and spatial resolution limitations relative to conventional spectrograms, but their rapid generation and flicker-free display makes their use appropriate in a man-computer interactive environment to complement aural evaluation of digitally synthesized or processed speech signals.
Abstract: A program to generate and display spectrograms on a computercontrolled scanned-display television monitor is described. The program features computation of power spectra for selected time segments with the aid of the fast Fourier transform algorithm, four-level intensity quantization controlled by a threshold under operator control, and flicker-free scanned display of the generated data. The computer-generated spectrograms suffer from intensity and spatial resolution limitations relative to conventional spectrograms. However, their rapid generation and flicker-free display makes their use appropriate in a man-computer interactive environment to complement aural evaluation of digitally synthesized or processed speech signals.