Abstract
A noise generator of known output is very convenient in noise measurement. At low audio frequencies, however, all devices, including noise sources, may be affected by excess noise (1/f noise). It is therefore very desirable to be able to check the spectral density of a noise source before it is used for measurement purposes. The spectral density of a noise source may be found by measuring its rms output over a known noise bandwidth. Such a bandwidth may be provided by a passive filter using accurately known elements. For example, the parallel resonant circuit with purely parallel damping has a noise bandwidth Bn = π/2 × (3dB bandwidth). To apply this method to low audio frequencies, the noise bandwidth of the low Q parallel resonant circuit has been found, including the effects of both series and parallel damping. The method has been used to calibrate a General Radio 1390-B noise generator, for the range 30-10 000 Hz. The results found agree well with the specified performance of the generator.
Original language | English |
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Journal | IEEE -Trans on Audio & Electroacoustics |
Volume | 14 |
Issue number | 2 |
Pages (from-to) | 96-100 |
ISSN | 0018-9278 |
DOIs | |
Publication status | Published - 1966 |