Abstract: A warning radio receiver is adapted to receive not only a recognition signal for emergency broadcast but also two further recognition signals, namely a warning network transmitter recognition signal and a warning region recognition signal. If, for example, the currently tuned transmitter changes its warning region recognition signal, after the expiration of the timing period of a first timer 16, one or more seeking operations for other transmitters with the predetermined warning region recognition signal are started. If a predetermined number of such seeking operations remain unsuccessful, the reception readiness of the transmitter is demonstrated by switchover to a transmitter associated with a different warning region. If such other transmitters also cannot be found, exceeding another predetermined number of fruitless seeking operations results in the generation of a receiver malfunction indication.

Abstract: To prevent theft of a car radio (R), the radio unit itself is located in the vehicle (V) in a suitable secure location. The radio is controlled by a two-part control unit, in which one part of the control unit forms a connection part (1), secured to the vehicle, for example, by a goose-neck (5) or the like, and the other part forming a control part (21) which is separable from the connection part. Interengaging dovetail track-and-groove connections permit ready removal of the control part (21) from the connection part, so that a user may remove the control part, and thus not leave any indication in the vehicle that it contains a car radio. The control part contains the necessary control buttons and display functions to operate and control the car radio, the connection part merely including a plurality of contact terminals which, with the control part removed, are depressed below a top surface of a housing (2, 3) of the connection part.

Abstract: A radio warning receiver has a battery or accumulator (7) and means (8) for switching over to battery operation mode when network power (6) fails. Battery power is conserved by turning off (9) power to the end stage (3), placing the warning receiver in a so-called Stand-By Mode, until a control signal is detected (5) which indicates that a warning is to be broadcast. Then, power to the end stage is restored (11) for the duration of the warning broadcast.

Abstract: A motor vehicle windshield is formed with a transparent vapor-deposited metal coating for windshield heating and with an antenna for radio reception. Preferably, the metal coating is connected to an inner conductor of a coaxial cable leading to the radio receiver, while the outer conductor of the coaxial cable is connected to chassis or ground potential. A slot (10, 20, 30, 40, 55, 56) in the metal coating is dimensioned to have a length of some harmonic of one wavelength in the FM frequency band, a width smaller than a half wavelength, and a minimum spacing a from the supply buses on each side of the windshield.

Abstract: A programming unit (1) for ON-OFF switching of a siren or similar warning device can be provided with remote actuation capability by connecting it to a radio receiver tuner (27) and radio data signal decoder (25). The output of the signal decoder (25) is connected to a block decoder (12). Some of the block decoder outputs are connected to a comparison circuit (8) which attempts to match a broadcast siren address with a stored address uniquely identifying the associated siren program unit (1). In the event of a match, a set of flip-flops and gates controls loading of information at other block decoder outputs into a siren program buffer memory (4) and then into an end memory (3) attached to and controlling the program unit (1). After a siren program is performed, end memory (3) is reset.

Abstract: A received video signal, in which a complete picture is made up of two line-interlaced picture fields that are successively transmitted, is converted in two different ways into respective video signals of the same vertical scan frequency in which a full complement of television lines is provided in each vertical scan interval. In a first conversion favorable to picture contents in which there is considerable motion, there are added, to the lines of one picture field of the received signal, a set of interpolated lines derived from the lines of that field. In a second conversion designed to avoid flicker at horizontal edges in the picture, the lines of two successive picture fields of the received signal are used to make up a full complement of lines. Both conversions involve time-compressing the lines so that a full complement of lines can be transmitted in a vertical scan interval.

Abstract: To increase the fidelity of radio reception in a moving receiver, for example a car radio, the signals received from various antennas on the radio are mixed with a carrier in the receiver, and the resulting mixed signals, directly and 90.degree. phase-shifted, are added to a summing signal, in which, additionally, the phase positions of the direct and 90.degree. phase-shifted signals are changed in dependence on the phase difference between the respective intermediate frequency mixed signal and the overall summed signal in a direction to maximize the summed signal (u.sub.s).

Abstract: To improve the fidelity of reproduction of automobile radios during conditions of extraneous in the passenger compartment, noise signals are derived, for example from a microphone installed in the engine compartment of the vehicle. The audio program signals are conducted through a multichannel equalizer; the program audio signals and the noise signals are separated into a plurality of frequency bands, for example three bands, the envelope of which are demodulated and the derived demodulation signals are instantaneously compared to then control the transfer characteristics of the respective bands of the equalizer in accordance with the derived comparison between the respective bands of the noise and program signals. Preferably, amplitude, change of transfer amplitude and rate of change is controlled by weighting the comparison signals and the rate of change thereof in relation to the frequency bands and the extent of change of the signals.

Abstract: For diversity reception from a plurality of antennas, particularly in an automotive vehicle (FIG. 4), the respectively received signals are mixed with a local oscillator signal to form a plurality of IF signals (u.sub.1 . . . u.sub.n). The respective IF signals are weighted with a weighting coefficient which is derived from a sum circuit of all the IF signals, and the respective IF signal, which weighting circuit includes an integrator to minimize temporal variations in the amplitude of the sum signal. The sum signal forms the actual IF signal, for further processing, and demodulating to derive an audio signal. Preferably, the signals from the antennas are branched, and the branch signals phase-shifted 90.degree., which, again, are weighted by similarly generated weighting coefficients, and the weighted, phase-shifted signals are combined in the adding or summing circuit (70) to form said eventual IF signal for demodulation.

Abstract: To suppress tuning noise interferences, and particularly transients, such as whistles and the like, especially in FM receivers during returning of the receiver, an inter-station retuning muting circuit is, in accordance with the invention, modified by including therein a switchable filter (2) having a low-frequency cut-off (f.sub.g2) which is higher than the frequency of noise interference due to retuning of the receiver, the filter being switched to the higher frequency cut-off level for a period of time (T.sub.E) which exceeds the normal muting time (T.sub.E) of FM receivers.

Abstract: A wave digital filter has one input set to zero and a signal to be distortion-compensated or simply to be subdivided into signals occupying different frequency ranges is supplied at the other input. The attenuation/frequency characteristics of the respective paths from the signal input of the filter to the respective outputs have transmission functions that are complementary to each other. Further subdivision into frequency sub-bands is provided by cascading another such wave digital filter at one or both outputs of the first wave digital filter. The coefficients (g) of the wave digital filters can be used for control purposes. The several outputs of cascaded filters are multiplied by weighting factors and thereafter added together to provide an output compensated against variation of attenuation with respect to frequency to which the input signal has been subjected.

Abstract: In order to reduce the variety of connector bodies needed for connecting electrical apparatus such as an automobile radio to factory-installed cabling of a motor vehicle having a mating connector for connection to the electrical apparatus, a composite connector is provided having a front unit with two sets of contacts respectively interconnected by a circuit board, of which the first set is designed to interfit with the mating connector of the vehicle and the second set is designed to interfit with the contacts of a second unit of the composite connector. That second unit has a set of contacts connected to a circuit board which carries circuit components for protection of electrical circuits from external interference. A flat parallel conductor cable is introduced through a slot in the second unit for connection to its circuit board before the circuit board is put in place.

Abstract: To prevent overriding an electronic car radio theft disabling system by connecting an external battery to a car radio prior to theft thereof, the radio includes a measuring circuit (7, 7') measures the impedance of a connected accessory, for example a loudspeaker or loudspeaker system (8), and if the impedance of connected loudspeaker does not match the impedance stored in a memory (5) of the car radio, operation of the radio is inhibited until the appropriate code word--known only to the proper owner--is reinserted.

Abstract: To provide for continuity of audio output from a compact disc (CD) player, installed in an environment subject to shock or vibration, for example in a motor vehicle, the CD player includes an extra write-read memory (31), placed in the signal processing path of a signal scanned by an optical scanning system to a digital/analog converter in advance of an audio output system (AR), a repositioning system (36) to reposition the optical scanning optical system on a track which may have been lost due to a jolt or vibration, and a synchronizing system to synchronize writing in the write-read memory after repositioning of the optical scanning system at the end of previously written data in said write-read memory immediately in advance of tracking loss.

Abstract: To permit cooling of transistor push-pull bridge-type audio end stages in car radios, where heat dissipation and cooling of components is difficult to achieve, without entire interruption of signals being amplified, the temperature of a heat sink (HS) is being sensed by a temperature sensor (14), and, if a predetermined level is exceeded as determined, for example, by a threshold circuit (15), one of the bridge arms formed by a transistor (10) is controlled to become saturated, thereby grounding-out the applied signal, so that a loudspeaker (6) will operate at only half voltage and hence 1/4 power, to thereby permit cooling of components, while providing some reproduction of introduced audio signals from an audio input terminal (11).

Abstract: The primary winding of a high-voltage transformer is periodically connected to an operating voltage source at the television line scanning frequency. The secondary winding is subdivided into several component windings which are connected to each other through diodes. A further diode provides the output for the high voltage. A somewhat similar circuit with interposed diodes can provide a center tap and full-wave rectification. A control voltage derived by voltage division from the high voltage is supplied to regulating means for holding the high voltage constant by controlling the width of the driving pulses for the semiconductor switch or by directly controlling the operating voltage connected to the transformer through the semiconductor switch.

Abstract: When controlling the working point of video output stages in monitors, data display cathode ray tubes (CRTs) (10) and the like, in which the scanning raster is applied to the screen of the CRT entirely on the visible portion of the screen, and to permit control of the working point of the video output stage by strobing the beam current at a high brightness level, the vertical deflection of the beam during not-needed lines is so controlled that the beam is deflected beneath a still remaining frame or beyond the phosphor layer of the screen. The deflection is obtained by an additional auxiliary deflection pulse derived, for example, from a monostable multivibrator (45) receiving a pulse close to the beginning of the selected line, and superimposing its pulse to the deflection of the deflection current for the vertical coil 42.

Abstract: A T-network with a capacitor in the shunt branch and similarly poled diodes in the series branches provides an electronic switch for the IF signals in a VHF receiver exhibiting 58 dB of attenuation in the block condition and negligible attenuation when the diodes are conducting. The resistance across the input of the IF amplifier and, if necessary, a resistance in the switching voltage path, determine the amount of current through the diodes when they are conducting under application of the switching voltage. Low pass filtering in the switching voltage leads and blocking capacitors in the signal connections of the switch restrict signal and switching voltages to their respective paths. Applying a positive potential to one switching terminal closes the switch and applying it to the other switching terminal opens it.

Abstract: In a method for measuring the frequency of a signal, in which counting pulses are counted and the counting result is emitted in the form of a digital signal, the counting pulses are derived from clock pulses, and the frequency of all the counting pulses is equivalent to a multiple of the frequency of the clock pulses. The counting pulses appear at various taps of a delay chain and are counted with the aid of a plurality of counters. After at least one period or one portion of the period of the signal has elapsed, the contents of the counters are added together.

Abstract: To control the operating point of video output stages, and particularly of wide-band video output stages, a voltage corresponding to cathode beam current is applied to a standard video processor (22), for example of the type TDA 3301, which includes at least one sticking voltage or set point or cut-off automatic control circuit, preferably one for each of the respective red, green and blue chromaticity signals (1, 2, 3). The output signal from the sticking voltage or set point or cut-off automatic control circuit, in accordance with a feature of the invention, is superimposed on the video signals applied to the video output circuit. When color display apparatus or monitors are provided, three wide-band video output circuits are provided.