Bts Broadcast Television Systems Gmbh

U.S. Philips Corporation

Robert Boschgmbh

Ant Nachrichtentechnik Gmbh

Dft Digital Film Technology Holding Gmbh

Berthold Eiberger

Roland Mester

Broder Wendland

Axel Schulz

Rudolf Wulf

Manfred Hescher

Thomas Leonard

Michael Philipps

Rolf Schiffmann

Andreas Low

Kurt-Heiner Philipp

Hartmut Schroder

Martin Plantholt

Peter Ries

Arno Beckenbach

Thomas Herfet

Thomas Bonse

Wolfgang Paschedag

To be able to scan the sprocket holes of a film with improved precision by means of a film scanner, in which a correction signal is generated for compensating picture steadiness errors, it is proposed that the light source generates light in the infrared range, and that the scanning sensor(s) is (are) sensitive in the infrared range.

Infrared scanning of sprocket holes

A telecine scanner, with which the horizontal picture steadiness errors are reduced by the film guidance in the area of the film gate 5, includes a first guiding element 11 supporting one of the longitudinal edges of the film 4 at at least two points in the film gate 5 in the area of the radiation path 6. In addition, two guiding elements 12 are provided, which are spaced substantially centrically apart from the first guiding element 11 and engage the other longitudinal edge of the film 4.

Telecine scanning

A method of correcting picture steadiness errors (or film weave correction) in telecine scanning is proposed, in which, in a first step, at least one sample area of the picture contents of the video signal obtained by film scanning is determined by way of structure recognition, this sample area corresponding to a curvature in the picture contents. In a second step, it is checked, by way of comparison, whether the determined sample areas are recognizable in a search area of the sequential frame. In a third step, motion vector signals are generated when the sample areas are recognized again in the sequential frame, these motion vector signals defining the direction of motion and the extent of deviation of the position of the determined sample area from the position of the recognized sample area. In a fourth step, parameters of a transform function are determined by the motion vector signals. In a subsequent fifth step, motion vectors, which correspond to partial motions, are recognized and eliminated by comparing the transform function with the motion vectors. Steps four and five are performed several times, if necessary. In a sixth step, correction signals are derived by taking the temporal sequence of transform functions into account, and in a seventh step, these correction signals are applied to a control device, these correction signals correcting the stability errors in the picture signals.

Method and arrangement for correcting picture steadiness errors in

In a film scanner for optically scanning a film for obtaining a picture signal, which film is moved at a constant speed, an image position correction which is as motion-independent as possible, is ensured in that the film scanner at least doubly scans at least parts of each film image and determines image position errors by comparing the two scanning signals of the same nominal image content, and corrects the picture signal in dependence upon the determined image position error.

Film scanner which doubly scans to correct for film speed and position

Data signals recorded in oblique tracks on a magnetic tape, after they are picked up, preamplified and prefiltered, are rectified and converted to digital values representative of amplitude in respective segments distributed over track lengths. For each segment position in a track, the values are averaged and inverted by a ROM and stored in a RAM at track segment addresses. The values thus stored are converted into analog form and then used as multipliers in a multiplication stage following the preamplification and prefiltering. The output of the multiplier can readily be shaped into unambiguous data signals for further processing.

Apparatus for reproducing magnetically recorded signals with amplitude

For reliable playback of digital video signals in slow-motion operation over a wide range of slow-motion speeds, auxiliary playback heads are positioned closely behind normal playback heads and offset by half a track width therefrom. Each of the playback heads have a circuit for regenerating clock and data signals which includes a PLL circuit and all of the PLL circuits have an output for the signal that shows whether the PLL circuit is locked in or not. The lock-in signals are supplied to first address inputs of an ROM which has a principal output showing whether the normal playback heads or the auxiliary playback heads have the larger number of locked-in PLL circuits and the group of playback heads having that larger number of locked-in PLL circuits is selected for having the data and clock signal outputs passed on to playback channels for further processing. The control of the switching circuit is improved by having auxiliary outputs of the ROM fed back to second address inputs thereof.

Method and apparatus for slow-motion playback of digital video signals

To the phase locked loop for controlling the oscillator that regenerates a bit-rate clock signal from a data signal by means of a phase comparison circuit followed by a low pass filter, the output of which controls the oscillator frequency, a digital frequency comparison circuit is provided for assuring that the oscillator frequency will be brought into the capture range of the phase locked loop. The output of the digital frequency comparison circuit is converted from digital to analog form for being used in combination with the low pass filter output to control the oscillator. Frequency and phase control signals are applied to opposite electrodes of a variable capacitance diode in the frequency determining circuit of the oscillator. In order to improve the operation the frequency comparison circuit, delayed and undelayed oscillator output clock signals are sampled by transitions of the data signal for respectively incrementing or decrementing a counter, the state of which is then converted into an anlog signal for contributing to the control of the oscillator. The data signal also is provided in delayed and undelayed forms, and these are combined in an exclusive-OR gate, the output of which is used both in the phase comparison circuit and in the sampling portion the frequency comparison circuit. That portion of the frequency comparison circuit controls a pair of monoflops through D-flipflops so as to provide the necessary incrementing or decrementing pulses for the counter.

Circuit for obtaining a bit-rate clock signal from a serial digital data

When the relative speed of the head wheel to the tape transport is reduced for recording at a lower data rate, a resistance interposed between the stationary driver amplifier and the stator of a rotary transformer is reduced to produce a mismatch of the coupling between the driver amplifier and a recording amplifier on the head wheel. The latter is connected to the recording head. The mismatch lowers the upper cut-off frequency of transmission through the rotary transformer and shifts the frequency transmission band downward also lowering the lower cut-off frequency. A servo control which sets the relative speed of the head wheel circumference with reference to the moving tape provides a signal to a logic circuit which progressively switches in shunting resistors lowering the resistance interposed between the driver amplifier and the transformer stator, as the relative speed of rotary recording head to tape is reduced, for advantageous operation when the data rate is below the maximum data rate that can be used with the equipment. With a balanced circuit of the driver amplifier, an interposed resistance is connected on each side of the transformer stator and each of them is progressively shunted down by switching steps as the relative speed is reduced. At the highest relative speed, the output of the driver amplifier is matched to the input of the recording amplifier for good power transfer.

Broadband magnetic tape recording with compensation for bandwidth

To effectively eliminate cross-talk between the weak signals picked up by a tape transducer pick-up head with signals being applied to a recording head, a disk-like headwheel carrier has a disk-like headwheel secured thereto. The disk-like headwheel carrier is formed with a recess which defines a chamber (6) in which the preamplifier for the reproduced signals is placed. Transducer leads are passsed in a channel duct formed between the headwheel carrier and the disk-like headwheel, which is in plate form. Preferably, both the disk-like headwheel as well as the carrier are made of lightweight metal, such as aluminum, so that the reproducing amplifier is totally shielded. The recording amplifier can be placed on top of the disk-like headwheel, separated and shielded from the reproducing preamplifier.

Rotary magnetic tape transducer headwheel structure

The correction of broadband signals reproduced from magnetic tape are corrected for distortion by three stages in cascade, which the first serves to correct distortion in the group propagation time through the system of playback magnetic head and playback preamplifier, the second directs for amplitude distortion including a 90.degree. phase rotation and the third stage provides equilization to compensate for high frequency losses.

Distortion reduction circuit for video playback

Digital color television signals intended to be recorded in serial bit form are first subjected to predistortion to compensate for nonlinear distortion digitally computed for each serial bit on the basis of the pattern established by a predetermined number of precursor bits, which requires digital to analog conversion of the multibit parallel output of the predistortion computation. The converted output is then filtered on an analog basis to compensate for linear distortion, as by emphasizing the higher frequencies. In reproduction, the similar combination of analog and digital distortion compensation is used, first filtering and then, after retrieving the bit clocking frequency and phase, analog to digital conversion and compensation for nonlinear distortion by programmed interpretation of a parallel multibit input to select correctly the bits of an output serial bit stream. The latter can be subjected to conversion into the usual eight bit parallel color television signals. The combination of both programmed digital distortion compensation and analog compensation of linear distortion not only reduces the output bit error rate, but has the advantages of being adaptive in that a test bit sequence can be used to select the most effective program for correcting nonlinear distortion for a particular system of recording channel, record medium and reproduction channel, provided that the nonlinear distortion compensators use RAMs, so that the best variety of nonlinear distortion correction for a particular equipment and/or tape can quickly be selected.

Method for adaptive removal of distortion from binary coded digital

In the transmission of a television signal containing a luminance signal between a transmitting station and a receiving station of a television system, the picture resolution at the receiving station is compatibly increased by: effecting planar prefiltering of the luminance signal at the transmitting station and a corresponding planar postfiltering of the luminance signal at the receiving station; effecting offset sampling or offset modulation of the luminance signal at the transmitting station and a corresponding sampling conversion or demodulation of the luminance signal at the receiving station; deriving an additional signal from the luminance signal for increasing picture resolution, reducing the amplitude of the additional signal at the transmitting station and transmitting the additional signal together with the original luminance signal to the receiving station; and increasing the amplitude of the additional signal at the receiving station to an extent corresponding to the reduction performed at the transmitting station.

Method for a compatible increase in resolution in color television

In the transmission of a color television signal containing chrominance burst and sync signals over a Nyquist channel between a transmitting station and a receiving station, a method for modulating and synchronously demodulating the television signal according to the offset modulation and offset sampling principle. The chrominance burst or sync pulses are used as a reference signal for frequency recovery at the receiving station. An additional reference signal is generated at the transmitting station and transmitted over the Nyquist channel. The additional reference signal is utilized for phase recovery at the receiving station.

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Ober-Ramstadt, Germany

Berthold Eiberger