Abstract: The digital predistorter multiplies the input signal with coefficients obtained from look-up tables. To reduce the amount of storage required, the coefficients are stored in partial form and are either reconstituted by addition of a constant (44, FIG. 3b) prior to application to the input signal or the retrieved coefficients are applied directly to the input signal and the resulting modified signal is then combined with the original input signal (34, FIG. 2a).

Abstract: The control scheme uses the input and output signals of an amplifier (10) to control a lineariser (24) operating on the amplifier (10). The input and output signals are sensed and used to develop assay signals that have ideal inter-relationships when the amplifier is operating as desired. The control scheme modifies the operation of the lineariser to account for any departures observed in the relationships.

Abstract: A method and an apparatus for determining analytical data concerning the inside of a scattering matrix, in particular of a biological sample. In a detection step detection measurements are carried out in which light is irradiated into the matrix as primary light at an irradiation site (12) through an interface bounding the scattering matrix (6) and light emerging out of the scattering matrix through the interface is detected as secondary light at a detection site (13) at a predetermined measuring distance from the irradiation site, in order to determine as a measurement variable a measurable physical property of the light which varies due to the interaction of the light with the scattering matrix, which measurement variable is a measure of the analytical data to be determined. In an evaluation step the analytical data are determined on the basis of the measurement variable measured in the detection step.

Abstract: A spectrometric technique is described for quantitatively determining the change in concentration of a substance which is contained in a medium which both absorbs and scatters spectroscopically interrogated radiation, and in particular to the specific case in which the change in concentration of the substance occurs in one spatially distinct region of the medium. The medium includes a plurality of such regions displaying potentially different absorption and scattering properties to the radiation. Specific applications are disclosed involving the noninvasive determination of changes in concentration of the substances oxyhemoglobin and deoxyhemoglobin and/or changes in the redox state of the substance cytochrome oxidase within the brain or skeletal muscle, and in cases where the brain or skeletal muscle is interrogated by radiation in the near-infrared part of the electromagnetic spectrum through intervening surface tissues, i.e.

Abstract: A diagnostic apparatus includes light sources which emit near infrared light rays of different wavelengths. The light rays are introduced into human brain to be subjected to diagnosis and the light rays transmitted through the brain are picked up. There are provided a first detector which detects occurrences of respirations of the subject and outputs a respiration signal, and a second detector which detects occurrences of heartbeats of the subject and outputs a heartbeat signal. The light transmitted through the brain is derived in synchronism with both the respiration signal and the heartbeat signal and first and second modulated light transmission signals are produced which are respectively modulated by the respiration signal and the heartbeat signal. The first and second modulated light transmission signals are separately analyzed to provide variations in concentration of oxygenated media .DELTA.X.sub.02 and disoxygenated media .DELTA.X contained in venous and arterial blood of the brain, respectively.

Abstract: An optical examination apparatus for optically examining density, distribution, etc.