ATTRIBUTE

Member of ENTITY: Subsample

- ATTRIBUTE-NAMESubpower frequency resultant magnetic field
- ATTRIBUTE-DESCRIPTIONThe combination of wavebands from 5 Hz to 55 Hz. The spectra are summarized consistent with the methodology of the original researchers, as follows. The waveforms of the three axes were used to independently compute magnetic field intensity at 5 Hz intervals using standard Fast Fourier Transform techniques. The resultant magnetic field intensity for each 5 Hz waveband was computed as the square root of the sum of the squares of the corresponding waveband of the three axes. The magnitude of each waveband component is divided by the square root of two in order to convert to a root-mean-square (rather than a peak-to-peak) value.The original researchers noted that this procedure results in some inappropriate leakage of spectral energy from the 60 Hz band into adjacent bands. Following the example of the original researchers, a correction is applied by diverting some energy found in adjacent wavebands back into the 60 Hz band. A factor for each nearby waveband was established by the original researchers. The square of the product of this factor and the observed 60 Hz component are subtracted from the square of the nearby waveband component and added back to the square of the 60Hz component. The factors (and corresponding waveband) used for the correction are as follows: 0.040 (40Hz); 0.052 (45Hz); 0.076 (50Hz); 0.141 (55Hz); 0.197 (65Hz); 0.090 (70Hz); 0.058 (75Hz); and 0.043 (80Hz).The spectral summaries are computed as the square root of the sum of the squares of the magnitude of corrected waveband components.
- ATTRIBUTE-ACCURACYApproximately 3%, but no better than about 0.1 milligauss.
- DOMAIN
- A positive real number, in units of milligauss.