Abstract: In digital data packets comprising a first datum from which a second datum can be unequivocally computed, e.g. an error correction value, one or a plurality of additional data can be introduced by manipulating said second datum without altering the structure of the data packet. For this purpose, one or a plurality of bits of the second datum are modified in an unequivocally reversible manner, e.g. inverted, according to the additional datum which is also digital. The recuperation of the additional data is effected by comparing comparative values which are obtained by reversing all possible combinations of additional data in a received data packet to a value which is computed from the first datum of the data packet: The presence of the corresponding combination of additional data results from the consistency of the latter with one of said comparative values. Another possibility is to limit the inquiry to a fraction of the possible combination.

Abstract: In an ATM switch, the total required buffer storage is concentrated in a central memory which is used by all input and output channels. The connection between the input and output channels and the memory is established by a synchronous bus. The time allocation on the bus is designed in such a manner that within the transmitting time of a data cell according to the ATM norm, e.g., over a wide band network, a time slice which is sufficient for the transfer of a complete data cell between an input or an output and the memory is allocated to each input and output. The memory is fixedly divided into areas of the same size, each of the areas serving as a buffer for a respective input. Due to the simple time allocation of the bus it is possible to combine a plurality of input and output channels in an input/output unit and to still realize the latter in a small number of integrated circuits. For the memory, unexpensive standard memory devices can be used.

Abstract: A Doppler measuring device for measuring the flow velocity of a fluid which carries particles which reflect ultrasonic waves is described. The device includes an ultrasonic transducer for insonating the fluid with ultrasonic wave pulses in response to corresponding transmit pulses supplied to the transducer at a predetermined pulse repetition rate. A transmitter connected to a transducer and adapted to produce transmission pulses which excite the transducer to deliver the ultrasonic wave pulses is present. The device also includes a receiver connected to the transducer to receive and process echo signals corresponding to at least two groups of echo waves reflected by particles in the fluid, and an evaluator connected to the output of the receiver to derive from the Doppler information obtained by the receiver an output signal corresponding to the flow velocity.

Abstract: A method and apparatus for producing a compound ultrasound cross-sectional picture of a body, in which method a plurality of partially overlapping body scans are carried out line-wise by the pulse-echo method in one scanning plane, thereby producing image signals in digital form corresponding to the received echoes. For the real-time display of the compound cross-sectional pictures, the set of image signals produced with each scan is stored in a separate digital storage unit, at least some of the stored sets of image signals are immediately combined with one another to generate a new set of image signals corresponding to a compound real-time cross-sectional picture, and the new set of image signals is immediately fed to a television monitor in order to display the compound real-time cross-sectional picture.

Abstract: An ultrasonic imaging apparatus for operation in either or both linear and sector scan modes is disclosed which employs a common array of transducers. Circuitry is provided for controlling the order and timing of pulse echo transmission and reception, which further include control circuitry to operate variable delay and switching circuitry to generate transmission signals to be applied to the transducers, and to direct echo signals received by the transducers for processing to provide the image of the structures being inspected. Suitable interconnection/switching circuitry is provided so as to minimize prior art requirements for use of different elements for the separate scanning modes, with concomitant expenses associated with the larger number of components being reduced.

Abstract: A method of determining flow velocities by measuring the phase difference between Doppler signals derived from wave pulses and reflected by substantially the same reflector at two different times, the interval between the times being predetermined, a pair of electric signals being derived according to the method from each Doppler signal by modulation in quadrature, the signals jointly bearing information relating to the phase of the Doppler signal, and a device for performing the method. In order to make full use of the possible measuring range, even at a relatively poor signal/noise ratio, at least a first and a second pair of signals are combined to form a third pair of electric signals which together bear an item of information depending on the phase difference between the Doppler signals.

Abstract: A method for producing cross-sectional images using an ultrasonic imaging unit operating on the pulse-echo principle, which unit includes a transducer system having a stationary elongated array of adjacent transducer elements with transverse electrode segments adjacent one another on one side of the array. Successively and cyclically selected groups of adjacent elements are energized to produce an ultrasonic beam as a result of pulsed signals being applied to the corresponding electrode segments.