Abstract: The invention relates to a time domain method for obtaining transfer characteristics of a device under test (DUT). The method comprises the steps of applying a sine sweep and a cosine sweep to an input of the DUT, and measuring response signals at an output of the DUT. The sine sweep and cosine sweep together establish a complex input signal, whereby to each instant there is related a particular frequency. Similarly, the respective response signals together establish a complex response signal. The magnitudes and phases of both complex signals are calculated and the transfer characteristics of the DUT then follow from the magnitude ratio and the phase difference of the input signal and the response signal. The invention also relates to an arrangement for testing transfer characteristics of a DUT and to an integrated circuit comprising the necessary elements for testing a subcircuit contained therein.

Abstract: A transmission system wherein a plurality of digital signals are coded and the coded signals are used to amplitude modulate respective carrier waves. The amplitude modulated coded signals are then combined for conveyance over a non-linear transmission medium. Due to the transmission non-linearity there will be distortion of the received combined signal, thereby reducing the transmission capacity of the system. In order to increase the transmission capacity, coding of the digital signals is carried out in accordance with a code such that the amplitude of the modulated carrier for digital symbols of higher probability is reduced in relation to the amplitude thereof for digital symbols of lower probability of occurrence.

Abstract: In a quadrature receiver for phase and/or frequency modulated signals an intermediate phase signal is quantized to produce a quantized phase signal. The receiver includes a demodulator in which pulses are generated from the quantized phase signal and it is determined whether two successive pulses have different polarities, and if so, a reconstructed baseband signal transition is produced at a predetermined reconstruction instant between the two successive pulses. The reconstruction instant is chosen in the middle between two successive pulses for FSK modulation, and it is chosen at different positions between the two pulses for other types of modulation, such as GMSK or multi-level FSK.

Abstract: A method of non-recursive reconstruction of images in a High Resolution Electron Microscope (HRTEM). In an HRTEM a series of, for example, 100 images of an object is formed with each time a different setting of the astigmatism of the imaging lens or lenses. By subjecting these images to a Fourier transformation and multiplying the transformed images by a known filter function, a reconstruction of the object electron wave function is obtained by summing of the images thus filtered and transformed; said object electron wave function no longer contains the linear information which is undesirable for the reconstruction and the non-linear information which is not negligibly small for large thicknesses of the object is no longer present either.

Abstract: In a method for the iterative formation of an image of a specimen in a particle-optical apparatus a series of experimental images (the experimental series) is recorded with each time a different setting of an imaging parameter (for example, the focal distance), and a comparable series of images is calculated on the basis of the electron wave at the specimen (the estimation). The two series are compared and on the basis thereof an electron wave is calculated (the feedback) with which a new series of images is calculated which better approximates the experimental series. This iteration step is repeated until the correspondence between the experimental series and the calculated series is sufficient, after which the associated electron wave is considered to be the desired image of the specimen. A substantial gain as regards calculation time can be achieved during the estimation step as well as during the feedback step by executing the operation of the invention by means of FFTs.

Abstract: The values of incorrect samples of, for example, a digital audio signal are estimated by means of interpolation. For this purpose an appropriate sampling interval is determined from the number of incorrect samples, in which interval the incorrect samples are situated. Subsequently, a best-fitting recursion formula is determined from the values of the samples, a first estimate being taken for the values of the incorrect samples. By means of this recursion formula the value of a sample is expressed as a weighted sum of the values of a number of preceding samples and an error term. By means of the recursion formula thus found the values of the incorrect samples are subsequently estimated, in such a manner that they are best-fitting values for the recursion formula. The Application also discloses a device for carrying out the method.