Deutsche Thomson-brandt Gmbh

Harman Becker Automotive Systems Gmbh

Xsys Interactive Research Gmbh

Hermann Link

Gunter Gleim

Friedrich Heizmann

Axel Marzluf

Stefan Schradi

Detlef Teichner

Jurgen Kaaden

Erich A Geiger

Michael Zahm

Guenter Gleim

Philippe Mace

Philipp Wöhrle

Walter Sturm

Stefan Koehler

Michael Bildl

The invention relates to the reproduction of a television signal on a distant reproduction device. The received television signal is encoded and transmitted in a digital data format over a communication link to the reproduction device. The reproduction device decodes the received video information for display on a display screen. The invention is particularly intended for use in mobile vehicles, coaches and trains, where the signal strength of a received television signal during travel is continuously varying and signal distortions occur frequently. In order to reduce the effect of signal distortions on the perceived image and audio quality, the invention inserts a compressed pre-stored video or audio data into the data stream transmitted from the television receiver to the reproduction device upon detection of a television signal distortion. Thus, the decoding procedure at the display device can be maintained in spite of a received television signal of insufficient signal strength.

Mobile television receiver

A system is presented for the multipath reception of video signals, including sound an/or image signals. The system includes at least two receivers and a diversity unit. At least one receiver receives and processes analog video signals, while the one or more remaining receivers receive and process digital video signals. The system may further include an analog selector unit for selecting the highest quality analog signal, and/or a digital selector unit for selecting the highest quality digital signal. The diversity unit receives the processed analog and digital video signals and combines them to produce a resulting video signal having a quality at least as high as the better of the processed analog and digital video signals. The diversity unit may combine the received video signals by performing a weighted addition of the signals.

Multipath video reception system

A diversity receiver system includes a plurality of radio receivers that each provide a uniquely associated receiver output signal and a uniquely associated receiver control signal indicative of the amount of gain applied by the associated radio receiver to create the uniquely associated receiver output signal. A selection mechanism receives the receiver control signals, and determines which of the radio receivers has applied the smallest gain correction to its associated receiver output signal, and provides a diversity receiver output signal indicative of the receiver output signal associated with the receiver that applied the smallest gain correction.

Apparatus for selecting a receiver among a plurality of receivers in a diversity receiver system based upon automatic gain correction

The receiving device contains at least two television channel selection devices to convert high-frequency signals into intermediate-frequency signals, at least two video demodulation devices to convert the intermediate-frequency signals into picture signals, at least two audio demodulation devices to convert the intermediate-frequency signals into audio signals, and one intermediate-frequency switching device to switch the audio- and video-demodulation devices to the television channel selection devices.

In order to be able to identify television or video images (VV) as identical, predeterminable parameters (HH) of the images (VV) to be tested are compared with each other. Images whose parameters, preferably the average brightness (HH), fall within a predeterminable tolerance range, are identified as identical images. Thus, e.g. in a television reception equipment, particularly a mobile one, the images of all receivable transmitters are tested. Images identified as identical are allocated to the same transmitters or the same programs, the channels of which are stored as alternative channels. When there is bad reception or bad image quality an alternative channel is switched to.

Process for the identification of identical television or video images

The invention concerns a method for determining the quality of a video and/or television image signal. In diversity reception installations comprising several receivers, it is necessary to establish a criterion for assessing the reception signals, so as to select the receiver with the best reception. In order to determine the quality of a television image, the interfering impulses appearing in a line after a horizontal synchronization impulse are detected then their parameters are evaluated. The invention is applicable to television receivers, video recorders, diversity reception installations, in particular for mobile installations.

Method for determining the quality of a video and/or television image signal

In one embodiment, data are converted, with the aid of corresponding rules and headers, into data having a fixed block length in such a way that, with the CTL bit definition, no clashes with known data structures of the CTL track such as VISS and VASS occur. The effect achieved by this is that any desired data can be stored on the control track.

Method for recording information on the control track of a storage medium

A video recorder capstan drive motor is controlled for slow-motion, freeze-frame and similar operations by setting a rate of acceleration or braking. A speed parameter is measured during an initial acceleration phase and is compared to a predetermined desired value. Based on the result of such comparison, current to the drive motor is limited, or an existing current limitation value is increased or reduced, so as to alter the acceleration or braking and bring the tape speed more nearly to the predetermined value. A representative current value can be stored in nonvolatile storage and used for such current limitation control, for so long as conditions remain unchanged. The value can be changed when conditions change, for example due to loading of a different tape cassette or a change in operational temperature.

Adaptive tape drive control in a video recorder

Temperature monitoring process and device

A method of breaking a motor includes the step of applying a pulse width modulated signal to the winding of the motor. A switching voltage is used to intermittently reverse the poles of the motor for selected time periods. The time periods are separated by pauses the duration of which is dependent upon the breaking force needed to stop the motor.

Method for the control of a motor

An arrangement for monitoring an alternating signal with respect to its state as mark-to-space ratio or direct-current component, in which the alternating signal is modified so that its mark-to-space ratio or direct-current component can be detected by simple comparison with reference signals. Various information is then transmitted over a line, and the operation of the stage that generates the alternating signal can also be monitored.

Method and apparatus for monitoring an alternating signal

Machine for recording and playing back information with a tape-storage medium comprising a tape-counting device for determining locations on the storage medium representing a beginning, an end or a section of a recorded information and labeling the locations as data. The labeled locations are stored in memory and marked. Selective winding to a chosen recording section which is associated with one of the marks occurs by means of the tape-counting device and the stored labeled data, together with another one of the marks which is detected and used as a reference, wherein, due to the detection of this reference mark, the tape-counting device is set to the data which was determined with the setting of the reference mark, and wherein the mark associated with the chosen recording section is dependent on the data of this reference mark. A tolerance window arranged symmetrically with respect to the reference mark is included to assist in the detection of the reference mark.

Correction of the tape-counting devices of a recorder

In the case of a motor controller for electronically commutated DC motors, an additional current and/or an additional voltage is passed at the commutation instant to that winding of the motor which is active at that time, in order to prevent torque drops. In order to compensate for torque drops at different motor loads, the duration and/or amplitude of the additional current and/or of the additional voltage are/is determined from the actual motor load.

Motor controller electronically commutated DC motors in order to

A first input signal has successive zero amplitude crossings. A first comparator generates a first bilevel output signal responsive to the first input signal. The first comparator has a hysteresis characteristic which is switched on at each said zero crossing of the first input signal and switched off prior to each occurrence of the next following zero crossing. A second input signal has successive zero amplitude crossings and is displaced in phase relative to the first input signal. A second comparator generates a second bilevel output signal responsive to the second input signal. The hysteresis characteristic is switched on by level transitions of the first bilevel output signal and switched off by level transitions of the second bilevel output signal. The first and second input signals may be sinusoidal. The hysteresis characteristic may controlled by first and second flip/flops, which are set by the first bilevel output signal and reset by the second bilevel output signal.

Circuit arrangement for genrating square-shaped signals

An output signal of a magnetoelectrical transducer of a capstan DC motor used in a magnetic tape recorder includes a DC offset voltage. The output signal of the transducer is coupled to a non-inverting input of a first operational amplifier. The output signal is also coupled to an inverting input of a second operational amplifier, operating as a comparator. The non-inverting input of the second operational amplifier is coupled to an output terminal of the first operational amplifier that amplifies an AC voltage component of the transducer output signal. By means of two anti-parallel coupled diodes in a negative feedback branch of the first operational amplifier, a DC amplification of unity is obtained as soon as a first peak of the output signal of the transducer is reached.

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Donaueschingen, Germany

Hermann Link