| 摘要 |
FIELD: physics; measurements. ^ SUBSTANCE: present invention pertains to measuring techniques and can be used for detecting and measuring small sinusoidal voltages against a background of noise. The device comprises three subtractors and three measuring channels, each of which contains series-connected resonant type band-pass filter and a device for measuring mean square voltage. Each of the filters is in form of a passive or active three-terminal network with a transfer function given by a mathematical expression. The filters have the same Q-factor and the same transfer constant at their resonance frequency. The sum of the resonance frequencies of the filters of the second and third channels is equal to double the resonance frequency of the filter of the first channel, tuned to the frequency of the measuring signal. Due to this, the device provides for compensation of not only thermal and shot noises, which have uniform spectral density on frequency, but flicker-noise as well. ^ EFFECT: compensation of not only thermal and shot noises, which have uniform spectral density on frequency, but flicker-noise as well. ^ 6 dwg |
