| The integration variable in Eq. 1 may be any spectral variable, wavelength, wave number, energy or frequency. |
| Because of the nature of the integrand, v may represent any spectral variable. |
| The spectral variability of natural materials has been known for a long time from laboratory studies. |
| To maintain the continuity of the record it is necessary that the cycled radiometers have the same spectral responsivities. |
| An optimum radius of the curvature ensuring the best spectral resolution was determined for a nonsymmetric diffractor scheme. |
| Linear amplifiers are much less efficient but pass complex transmission signals with minimum distortion, thus preserving spectral utilization. |
