User's Manual - Cornell Lab of Ornithology - Cornell University

Chapter 6: MeasurementsIn the waveform, the amplitude-weighted central time of the selected interval.Center Time for a waveform selection is computed asn∑t i⋅x i2i= 1n2x i∑i= 1(6.1)where n is the number of samples in the selection, t i is the time (in sec from thebeginning of the signal) of the ith sample in the selection, and x i is the value ofthe ith sample in the selection. In the spectrogram, the amplitude weightingsare limited to the selected frequency band. Units: sec.Correlation Peak (correlation)(Range) The maximum value of a correlation function in the selected range.Correlation Value (correlation)(Point) The value of the correlation function at the point in time correspondingto the horizontal position of the mouse pointer.Dynamic Range (spectrogram, spectrum)The difference between the amplitude floor and ceiling of a spectrogram.Units: dB for logarithmic spectrograms; watts/m 2 /Hz for quadraticspectrograms of acoustic signals; watts/Hz for quadratic spectrograms ofelectric signals. See also Amplitude Ceiling, Amplitude Floor.End Time (waveform, spectrogram, correlation)(Range) The time (from the beginning of the signal) at which the selectionends. For correlations, time is measured from the beginning of the firstcorrelation file. Units: seconds.Energy (electric waveform, spectrogram, spectrum)(Range) The total energy in the selection. For a stationary signal (one with aspectrum that does not change over time), the energy in a given time intervalequals the average power (in watts) times the length of the interval (inseconds). For a waveform, the energy is calculated as⎛⎜⎜⎝t 22∑x tt=t 1⎞⎟⎟⎠1R L f s(6.2)where t 1 and t 2 are the sequence numbers of the first and last samples in theselection, x t is the voltage of the tth sample, R L is the line impedance (inohms), and f s is the sampling rate (in Hz). For a logarithmic spectrogram,energy is calculated as94 Canary 1.2 User’s Manual