Abstract: A mechanism for avoiding satellite transponder TWT saturation in an ALPC communication network detects the onset of a lockup condition through an avalanche detector. In response to avalanche detection, those links which have been identified as participating in a downlink fade have their ALPC attenuator settings placed at a minimum level, so that the operating point of the transponder TWT may be reduced below the avalanche threshold. Thereafter, as the fade recedes, those units whose ALPC attenuators have minimum power settings may be restored to normal operation. Because the orderwire which couples link quality data from a received terminal monitor unit to transmitter attenuator control units through the avalanche detection and recovery scheme may itself be impacted by a downlink fade, the foregoing scheme is augmented by a lockup detection and avoidance mechanism through which recovery from an actual lockup may take place.
Abstract: A system and method for detecting the level of random noise contained in a band-limited amplitude-modulated signal. A sychronizing signal is produced which is .pi./2 out of phase with respect to the carrier of the amplitude-modulated signal. The amplitude-modulated signal and the synchronizing signal are multiplied together. Only a low frequency component is extracted from the multiplication output, and the low frequency component is taken as an indication of the level of the random noise contained in the amplitude-modulated signal.
Abstract: A fixed length antenna rod projects from a housing enclosing a pre-amplifier circuit connecting it to the front end of a FM receiver. The antenna rod is mounted at an optimum signal reception attitude by the flange of a bracket to which the housing is secured and through which an output cable terminal of the pre-amplifier circuit extends. The preamplifier circuit is adjustably tuned to favor a specific frequency for subcarrier transmission and attenuated in signal gain to match antenna signal pick-up level.
Abstract: The invention relates to a circuit arrangement for a tuner, particularly a television tuner, for a change over switching between two frequency bands with the aid of a switching diode, said frequency bands, particularly the VHF band and the hyperband, being filtered out by means of bandpass filters (1,7). The bandpass filters have at their inputs and outputs capacitance diodes for the purpose of tuning. The filtered signals are applied to a common tunable circuit (15) on the secondary side of the bandpass filters. The bandpass filter for the hyperband is constructed and dimensioned such that the signal is switched through by means of a switching diode (83) arranged at the low end of the bandpass filter (1). When this diode (83) is conducting a smaller output reactance, whereas in the case of a blocking switching diode (83), this bandpass filter (1) cuts off the signal and has a larger output reactance.
Abstract: A frequency converter which is capable of rejecting unnecessary signals generated by image signals. The frequency converter has first and second local oscillation circuits which generate local oscillation signals whose frequencies are the same and whose phases are different by 90 degrees from each other. The converter further includes two mixer circuits, and a hybrid coupler. The mixer circuits generate two unnecessary signals whose phases are different by 90 degrees from each other. The hybrid coupler delays one unnecessary signal by a quarter of a wavelength to generate two unnecessary signals whose phases are different by 180 degrees from each other, so that they are cancelled by each other.
Abstract: A method and system for transferring information between a moving vehicle and a stationary information location having a vehicle detector system with a loop antenna by using the loop antenna as either the receiving antenna for signals transmitted from a moving vehicle or as the transmitting antenna for signals generated by a transmitter located at the vehicle detector site for transfer to a receiver mounted on a moving vehicle. The information is encoded on a carrier having a frequency outside the normal frequency range of the vehicle detector system, preferably by interrupted carrier pattern processing.
Abstract: A mixer circuit with a conventional very high frequency circuit for the reception of color television bands I and III, which is connected dependent on the band and which is provided with an NPN transistor. The NPN transistor operates via a collector resistor onto a two circuit band filter. Moire interferences in the band I region expanded for CATV are avoided by having the mixer current used to 0.3 to 0.6 mA via a counter coupling resistor disposed between base and hot end of the resistor 4. Thus the self-interference in band I is reduced by a value of about 60 dB. In case of band III operation the corresponding switching voltage is fed via a series connection of a diode 6 and a resistor 5 to the base and thus the base level is lifted up to higher mixing current, since in band III self-interferences cannot occur in the case of the presence of signals.
September 20, 1985
Date of Patent:
March 15, 1988
Deutsche Thomson-Brandt GmbH.
Gerhard Maier, Bertram Fischer, Erich Kirschner
Abstract: A radio receiver has a first radio receiving part which receives the signal of the desired radio broadcasting station, a first receiving field intensity detector which detects the receiving field intensity of the desired signal received by the first radio receiving part, a second radio receiving part which receives an interference signal having the frequency adjacent to the desired signal frequency, a second receiving field intensity detector which detects the receiving field intensity of the interference signal received by the second radio receiver, a receiving frequency controller which generates a control signal for controlling the frequency of the desired signal received by the first radio receiving part in such a direction to become more remote from the disturbing signal frequency based on the receiving field intensities of the desired signal and disturbing signal detected by the first and second receiving field intensity detectors, and a local oscillation frequency controller which controls a local osci
Abstract: The present invention provides an elastomeric headband containing an amplifier device such as stereophonic radio or a recording amplifier. The headband includes earphones which overlie the user's ears. The elastomeric band is suitably sized to be readily mounted and dismounted from the user's head. The headband may be floatable in water.
Abstract: A satellite television reception only receiver includes a programmable microprocessor which has a communications link for communicating between a plurality of receivers connected in a multiple receiver installation. An antenna is connected to only one receiver in the network, and it controls operation of the antenna, and the information relating to the antenna is transmitted to the other receivers to update them. The microprocessor further provides a means to programmably restrict access to particular satellites or transponders on satellites at each individual receiver, and vary the particular transponders or satellites restricted from receiver to receiver.
Abstract: A TVRO receiver for receiving frequency-modulated video signals, the receiver comprising a tuner including a superheterodyne circuit having a voltage-controlled oscillator (VCO), means for supplying a controlling input voltage to the VCO, and a mixer for combining incoming 1st IF signals with the output of the VCO to reduce the frequency of the 1st IF signals to a 2nd IF frequency which is sufficiently high to permit the output frequency of the VCO to be above the frequency range of the 1st IF signals, and a linear phase passband filter for passing a single video channel in the 2nd IF output from the mixer, the filter producing an output which is at least about 10 dB down from its peak at both +10 MHz and -10 MHz from the center of the passband of the filter.
Abstract: An improved portable two-way radio comprises a systems module and a removably connected, shielded RF module. Split universal device connector apparatus is provided having an RF connector portion associated entirely with the shielded RF module and a control connector portion associated entirely with the control module, the RF and control connector portions being located physically proximate to each other so that a single multi-pronged universal device connector can be electrically and mechanically connected to both the RF connector circuitry through the control systems module.
Abstract: A technique for surveying an audience. A portable signal detector unit picks up audible sounds reproduced by a radio set from signals transmitted by a given radio station. Among the broadcast signals is one unique to that particular station. The unit includes means capable of identifying that signal to automatically electronically record the fact that the station is being listened to by the carrier of the unit.
Abstract: A working on the zero IF principle is disclosed which contains a feedback circuit instead of a preselector for suppressing interfering signals. The interfering signals contained in the incoming signal (F.sub.E) are separated from the useful signal by filters in the baseband. They are then reconverted to the RF value, amplified, and substracted from the incoming signal (F.sub.E) by a subtracter (S1). In the steady state, the output of the subtracter (S1) provides the useful signal, which is converted into the baseband and then fed to a signal processor (SV).
April 21, 1986
Date of Patent:
January 5, 1988
Dietrich Rother, Dieter Wiechert, Manfred Moster
Abstract: An arrangement for combining the output signals from a plurality of transmission units (2, 3) tuned to the same frequency and included in the arrangement, while each arrangement is by itself capable of functioning as a transmission unit (2) whose output signal can be combined with that of another transmission unit (3). For each pair of transmission units (2, 3) to be combined the arrangement incorporates control circuitry (5) for generating a control signal used to effect combination of the output signals of the pair of transmission units (2, 3) in phase. The control circuitry (5) includes a sum and difference network (6) connected to the transmission units (2, 3) and a detector (7), for example a phase-sensitive detector, for deriving the control signal from the output signals of the sum and difference network (6), the sign of the control signal being of special importance.
Abstract: A data communication system for use in a CATV system or the like employing only simple data communications operations between a central control device and terminal units for effecting a descrambling function. The central control device is connected to the plural terminal units via respective transmission paths. When the central control device is unable to communicate with the terminal units, a transmission carrier is applied to the terminal units via the transmission paths. When a polling operation is to be carried out by the central control device, application of the carrier to the transmission paths is suspended to allow the central control device to communicate with the terminal units. In each of the terminal units, a transmission request thereto is detected from the fact that the carrier has been suspended. Upon the detection of a transmission request, an up-data transmission to the central control device is performed.
Abstract: A radio frequency circuit having at least one output terminal includes a plurality of non-linear elements, each having an output electrode. Means are provided for feeding at least one input signal to each one of the non-linear elements. The feeding means includes an electrical pathlength including at least one two port phase shifting element fed by at least the input signal, for providing a plurality of signal portions, each one fed to a corresponding one of the plurality of non-linear elements. These signal portions have a successively increasing phase shift related to the electrical pathlength of the two port phase shifting elements. The output electrodes of each non-linear element are interconnected by an input coupling means including at least one, different, two port phase shifting element, for successively electrically interconnecting the output electrode of each non-linear element.
Abstract: An A.F.C. control system for reception of wide-band F.M. transmission such as satellite transmissions, in which a center frequency of an F.M. I.F. signal is repetitively and alternately compared with an upper and a lower frequency limit value so long as the center frequency lies between these values, with the results of the comparisons being respectively stored in two latch memories, whose contents thereby indicate any error of the center frequency relative to the frequency limits. Any departure of the center frequency from between the limits is corrected by successive frequency shifts of the local oscillator frequency, with the results of correction being indicated by the latch memory contents and with the number of frequency shifts being determined accordingly.
September 18, 1986
Date of Patent:
November 24, 1987
Matsushita Electric Industrial Co., Ltd.
Abstract: A frequency multiplexed system for coupling a plurality of individual telephone sets to at least one subscriber telephone line. The system includes a line adapter unit for controlling use of subscriber lines and for assigning the use of frequency bands to the individual telephone sets. The system includes a two-conductor interconnection cable for coupling to each of the telephone sets and to the line adapter unit. The system has a power-down mode in which the loss of external power allows each of the individual telephone sets to use the subscriber line. The line adapter unit and each of the individual telephone sets employ transconductance amplifiers so that modulated current signals are produced on the interconnection cable, thus allowing a plurality of voice signals to be summed together by voltage addition for conferencing between the telephone sets and the subscriber lines.
January 15, 1985
Date of Patent:
November 10, 1987
Rockwell International Corporation
George A. Watson, Ramon S. Co, James L. Fuhrman, Frank Avella