Showing papers on "Quadrature mirror filter published in 1982"
TL;DR: The decomposition of the wave front into Zernike polynomials provides a means for deriving the rms error of a corrected wave front in analytic form and a step filter approximation is derived.
Abstract: Adaptive optics correction of a wave front by a deformable mirror that acts as a lossless spatial filter is studied. The decomposition of the wave front into Zernike polynomials provides a means for deriving the rms error of a corrected wave front in analytic form. The spatial filter is given in a functional form related to deformable mirror characteristics. A step filter approximation is derived and the conditions where the approximation holds are examined. An example is provided to demonstrate the utility of the spatial filtering concept for adaptive optics systems analysis.
35 citations
Patent•
22 Apr 1982
TL;DR: In this article, a band pass filter for filtering a sound intermediate frequency (SIF) signal input to the device is coupled through a filter circuit to an integrated circuit having a limiter amplifier and an FM detector to output a sound signal from the SIF signal.
Abstract: A quadrature type FM demodulator device used, for example, in a television receiver, includes a band pass filter for filtering a sound intermediate frequency (SIF) signal input to the device. The output of the band pass filter is coupled through a filter circuit to an integrated circuit having a limiter amplifier and an FM detector to output a sound signal from the SIF signal.
6 citations
01 Jun 1982
TL;DR: In this paper, a non-recursive quadrature mirror filter with small deviation from the desired overall response is designed by imposing linear constraints at the midpoint of the filter frequency scale, in addition to the normal passband and stopband constraints.
Abstract: A new method of designing nonrecursive quadrature mirror filters with small deviation from the desired overall response is described. By imposing linear constraints at the midpoint of the filter frequency scale, in addition to the normal passband and stopband constraints, a solution that is very close (doubt) optimum is obtained. Satisfactory designs can thus be obtained without resorting to techniques involving the solution of nonlinear constraints. Some results of practical interests are presented.
4 citations