Showing papers on "Voltage-controlled filter published in 1967"
TL;DR: In this paper, the discrete filter to be used in place of a given analog filter so as to result in minimum mean-square error at the sampling instants is derived and two methods are described for placing this optimal discrete filter in rational form.
Abstract: In this paper, the discrete filter to be used in place of a given analog filter so as to result in minimum mean-square error at the sampling instants is derived. The spectra of the signals to be filtered are assumed to be either 1) band limited, or 2) of known rational form. The condition which the optimal discrete filter must satisfy is obtained by minimizing the expected value of the square of the error, formed by the difference between a digital and sampled analog channel. For rational spectra, the optimum discrete filter is a function of both the frequency characteristics of the analog filter and the spectrum of the process. The optimal discrete filter for this case can be placed in rational form. For band-limited spectra, it is demonstrated that the corresponding optimal discrete filter is dependent only upon the frequency characteristics of the analog filter. The optimal discrete filter for this case, however, cannot, in general, be placed in rational form. Two methods are described for placing this optimal discrete filter in rational form. One of these methods, which involves obtaining the best first-order rational approximation to the optimum transformation, reduces to the well-known Tustin transformation.
12 citations
TL;DR: In this article, an inductorless 16-20 kHz bandpass filter has been built to test the hypothesis that low-sensitivity filters can be constructed if all the inductors in an LC filter are replaced by their gyrator-capacitor equivalents.
Abstract: An inductorless 16–20 kHz bandpass filter has been built to test the hypothesis that low-sensitivity inductorless filters can be constructed if all the inductors in an LC filter are replaced by their gyrator-capacitor equivalents. The measured results show that this filter has low component sensitivity and excellent temperature stability and can be constructed from moderate-tolerance components.
10 citations
4 citations
TL;DR: In this article, a method of introducing self-tuning features in a filter with the characteristics of an LCR tuned circuit built up of analogue-computer components is described, which is suitable for low frequencies.
Abstract: A method of introducing self-tuning features in a filter with the characteristics of an LCR tuned circuit built up of analogue-computer components is described. The filter is suitable for low frequencies. Tracking and search facilities can be readily incorporated. In an experimental arrangement, the filter could search and track a signal over a range of frequencies in the ratio of 1:10, and a Q factor of 20 was obtained. Applications to Doppler radar-frequency measurements are envisaged.