Abstract: A method for operating a multi-beam particle microscope which operates using a plurality of individual charged particle beams, wherein the method includes the following steps: measuring the beam current; determining a deviation of the measured beam current from a nominal beam current; decomposing the determined deviation into a drift component and into a high-frequency component; and controlling the high-frequency component of the beam current via a first closed-loop beam current control mechanism and/or compensating an effect of the high-frequency component on a recording quality of the multi-beam particle microscope using different mechanism than a closed-loop beam current control mechanism. An electrostatic control lens arranged in the beam generating system between extractor and anode can be used as first closed-loop beam current control mechanism. Adapting an extractor voltage of the beam generating system can be avoided.

Abstract: The receiver contains a correlator (TIC) for the correlation of the received signal with a reference code (R(k)) and a digital signal processor for evaluating the results of the correlation. The correlator is constructed as digital, time-integrating, multistage correlator (TIC), the individual stages (Kl to KN) of which are connected on the one hand to a digital delay line (17) fed with the reference code (R(k)) and to which on the other hand a digital signal (S(k)) recovered from the received signal is applied, to length (D) of the delay line (17) being adapted to the maximum expected impulse response to the transmission channel.

Abstract: A base station (BS) and mobile user stations (MS) each with a transmitter (S), a receiver (E) for multipath reception and a control unit (ST) are provided in each cell. Exactly one set of several sequence sets of the auxiliary function used for spectrum spreading is allocated to each cell. Sequences of several sets in pairs have the property that the absolute values of the normalized periodic cross-correlation functions are much smaller than one and for sequences within a set the cross-correlation function in pairs is optimally small around the zero point. Data synchronous generation of the transmission signals takes place in the base station (BS) for all simultaneous connections and the data clock of the received signal is used as data clock of the transmission signal of the user station (MS).Application for digital data transmission in buildings and local areas for the configuration of a so called cordless LAN are considered.

Abstract: An apparatus for sorting lightweight from heavy material in mixtures of solid materials containing lumpy, granular, and pulverous constituents substantially comprises an upright slim container having a lower portion into which material for sorting is introduced. Pulsating air flows are introduced from the exterior into the container, resulting in an upward flow of pulsating air which loosens the material for sorting and produces a fluidized bed. Simultaneously, the apparatus is vibrated up and down in a linear manner by vibrators to assist in loosening the material. The lightweight material floating in the air stream is conveyed to a discharge channel at the top end of the container, whereas heavy material rapidly sinks down to a tubular member into which a second pulsating air flow is introduced in order additionally to sort the heavy material in a last treatment stage inside the tubular member.