Abstract: A frequency converting circuit which reduces the amount of leakage of oscillating signals to the output, includes a local oscillator; a mixer for mixing the input signal with the output of the local oscillator, and a variable trap circuit connected in the output of the mixer. The local oscillator includes a PLL circuit, and a tank circuit having a coil and a varactor diode whose capacity is controlled by the PLL circuit. The variable trap circuit also includes a coil and a varactor diode, and is controlled by the PLL circuit to resonate at an output frequency of the local oscillator.

Abstract: The present invention prevents a receiving signal from leaking to an LNB supply line to thereby deteriorate input VSWR characteristic. A capacitor of about 1000 pF for removing noise and a capacitor of about 1 pF for flowing a high frequency component which leaks to an LNB voltage supply line to the ground, are provided between the LNB voltage supply line and the ground. By the capacitor of about 1000 pF, a noise component included in the LNB voltage supply line is removed. Further, by the capacitor of about 1 pF, the high frequency signal component which leaks via a choke coil is bypassed to thereby reduce impedance of a node NA over a broad band and prevent a reflecting wave from being produced at the node NA and input VSWR from being deteriorated.

Abstract: An FM radio receiver comprises a radio frequency tuning circuit for selecting a frequency modulated signal from an antenna and a local oscillator tuning circuit for tuning to an oscillating signal so as to convert the frequency modulated signal to an intermediate frequency. In the radio frequency tuning circuit, a capacitance variable ratio is set so as to be capable of receiving continuously the frequencies of both a first FM receiving band used in Japan and a second FM receiving band used in the US and Europe. The local oscillator tuning circuit is so constructed that an inductance value and a capacitance variable ratio can be switched so that the receiver is set to lower heterodyne for reception in Japan or upper heterodyne for reception in the US or Europe. As a result, a single receiver design can be configured for reception of FM radio broadcasting in either Japan or the US or Europe using a common front-end circuit, without increasing the number of components.

Abstract: A receiving apparatus is presented, in which a channel frequency can be selected over a wide band with an increased attenuation at an image frequency and/or at a local oscillation frequency by including a tunable filter having a following construction. Microstrip lines are connected between either one of the input or the output terminal or both of the input and output terminals of the tunable filter; a plurality of resonant circuits are formed by each of a plurality of coils and a plurality of variable capacitance diodes; and the coils are electromagnetically coupled and where a voltage applied to each cathode of each of a plurality of variable capacitance diodes through each of a plurality of resistors is controlled to tune a frequency to be received.

Abstract: A balanced bandpass preamplifier assembly (23) is disclosed for use in a locator (10) for locating a beacon transmitter (18) housed within an underground boring device (12). The bandpass preamplifier assembly (23) includes a balanced bandpass filter (28) of the Butterworth type with second order filter characteristics. The preamplifier assembly (23) provides reception of beacon frequencies at two distinct frequencies, preferably 29.430 KHz and 32.768 KHz. The antenna (14) of the . locator (10) forms the series inductance in the bandpass filter (28).

Abstract: An unnecessary wave suppressing means suppresses unnecessary waves included in a reception high frequency signal in a frequency band that is changed in accordance with a switching signal. The unnecessary wave suppressing means changes the pass band by inserting a notch into a pass band at a range where a signal is to be suppressed, changing the pass band width so as to exclude a suppression band, retaining a plurality of narrow pass bands for respective frequency bands used and switching among those narrow pass bands in accordance with a frequency band of a receiving signal, or continuously changing the pass band by using a tuning filter.

Abstract: An antenna/amplifier includes a waveguide and an amplifier system. The amplifier and signal lines which terminate in orthogonal probes are carried on a common substrate. The orthogonal probes are spaced from a waveguide wall and isolated for good cross polarization by a post which extends from the wall. The probes have probe tips which are spaced from the post by a probe space. Parameters which include the probe space, the impedance of the signal lines and the length of the signal lines can be selected to present an optimum impedance to low-noise amplifiers of the amplifier system.

Abstract: A compensating/amplifying device for a window glass antenna for an automobile. The device utilizes heating wires, which remove fog formed on the automobile window glass, as an antenna and includes band-pass filter coils interposed between a battery of the automobile and the heating wires, and the band-pass filter coils and a floating capacity between the heating wires and ground are used as a part of an input band-pass filter of a compensating amplifier.

Abstract: A circuit prevents the interference of FM radio broadcasting with TV channel 6 broadcast. The circuit comprises a microprocessor for receiving channel selecting data output from a data input device and outputting phase locked loop (PLL) data. A control signal generating device receives the PLL data and generates a control signal to control an FM trap operation. A trap operation controlling device then controls the operation of an FM trap according to the control signal. According to the present invention, TV channel 6 broadcasting can be received without noise.

Abstract: Networks which remove the jamming signal from the television signal supplied to subscribers for a premium T.V. channel in a cable (CATV) or other subscription television system utilizes surface accoustic wave (SAW) devices arranged to provide a broadband all pass response across the entire band covered by all of the transmitted television channels except for a notch at the frequency of the jamming signal. The narrow band response of the filter in the premium channel is such that the notch presents insertion loss at the jamming signal frequency and over a frequency range to accommodate shifts in the frequency response of the SAW devices with respect to the frequency of jamming signal, which insertion loss is about 100 times the insertion loss at the picture carrier frequency of the television signal, even though the picture carrier and the jamming signal frequency may be within about 200 KHz apart from each other.

Abstract: A bandpass filter is disclosed which may be used in a superheterodyne receiver in front of the first mixer. The bandpass filter provides a narrow front end filter which is tuned automatically as the local oscillator frequency is changed. In the present exemplary embodiment, a series tuned reflective notch filter is coupled to a node of a balanced resistive bridge in such a manner that the tuned circuit presents a short circuit to the node at the filter's resonant frequency to thereby assure a maximum transfer of signal from the input to the output of the circuit at a desired frequency. At all other frequencies, the series tuned reflective notch filter will present essentially an open circuit across the node of the resistive bridge so that the node is balanced and no transmission occurs. The inclusion of the series reflective notch filter thereby produces a bandpass characteristic from the circuit input to output.

Abstract: A band pass filter for radio frequencies uses helical resonators arranged to have a transmission notch on the high frequency side of the pass band. A plurality of resonators housed in a shield are formed by quarter-wavelength transmission lines wound in a helix, with adjacent resonators being wound in opposite directions and grounded at opposite ends to provide a transmission notch at the high frequency side of the passband. One or more grounded shielding pins are arranged between adjacent resonators to adjust the frequency of the notch to be at or near an image frequency. The grounded end of each of the resonators may be coupled to a varicap diode network for electronically tuning the filter.

Abstract: The present invention is for a highpass input circuit for a television receiver having an additional trap at a predetermined frequency, e.g. CB frequencies. A M derived constant K high pass filter having an intermediate pi configured filter section is provided with an additional inductor in the shunt leg of the pi section for resonating with the bridge capacitance of the pi section and forming an additional trap at the predetermined frequency. The additional inductor is physically formed by an electrically conductive path etched on a printed circuit board.

Abstract: A towable broadband submarine antenna system for deployment in the ocean ing operation comprises an antenna element including a metallic termination tip and a length of single conductor buoyant cable. A broadband amplifier connects to the antenna element and provides separate paths for the VLF/LF and the HF/VHF signals with amplification provided only to the HF/VHF signals. The signal from the broadband amplifier is further transmitted on a coaxial cable.

Abstract: A compensating amplifier for an automobile antenna which is relatively short and free from interference from high frequency band television signals. The amplifier includes an inductive element in a primary serial tuning circuit of a multiple tuning circuit of an antenna which is connected in parallel to a condenser, and the parallel resonant frequency of a parallel circuit which is formed by the inductive element and the condenser is set at approximately the same resonant frequency as the resonant frequency of the antenna.

Abstract: Scrambling and descrambling systems utilizing jamming signals provide improved pictures with minimal distortion due to ghosts and artifacts. The television signal is combined with a jamming signal or signals located preferably in the vestigial sideband (VSB) of the modulated picture carrier and at about a null in the spectrum of the modulation of the picture carrier by the horizontal sync. The jamming signal or signals also preferably are placed between the harmonic components of the horizontal sync which define the horizontal sync spectrum and at frequencies which comply with governmental regulations respecting frequency locations of strong signals of CATV purposes. The jamming signals are generated by phase locking to the horizontal sync signals of the television signals or to a submultiple of the horizontal sync frequency.

Abstract: In a superheterodyne receiver, such as a typical television receiver, a radio frequency coupling arrangement includes a first resonant circuit coupled to receive the input signal and further coupled to a second resonant circuit by a first coupling. Both resonant circuits are tuned to the desired signal frequency. The capacitive branch of the first resonant circuit includes a circuit impedance for providing a neutralizing voltage, at least a portion of which is coupled by a second coupling to the inductive branch of the second resonant circuit. The circuit impedance is selected to cause cancellation in the inductive branch between image frequency components coupled by the first coupling and image frequency components coupled by the second coupling, without substantially affecting the desired signals.

Abstract: A wireless superheterodyne receiver is provided having an antenna for receiving wireless transmissions, a preamplifier having an input connected to the antenna and an output, a crystal filter having an input connected to the output of the preamplifier and an output, a demodulator having an input connected to the output of the filter, the demodulator having a single mixer, an oscillator having a second crystal connected to the single mixer of the demodulator wherein the demodulator supplies at an output a demodulated signal based upon the wireless transmissions.

Abstract: An antenna duplexer is made compact by a use of a SAW filter, and yet it eliminates the possibility that the SAW filter might be burned, and it avoids additional circuits, e.g., an impedance compensation circuit. The antenna duplexer comprises a local oscillation filter. A reception filter is coupled to the local oscillation filter. The coupled side is partly constituted by a SAW filter. A transmission filter is coupled to the reception filter and an antenna is coupled between the reception filter and the transmission filter.

Abstract: RF-input stage for TV receivers comprising a field effect transistor in grounded source circuit configuration and a frequency-dependent coupling network arranged between the gate electrode of the field effect transistor and an aerial input for selecting TV signals and transforming the signal impedance. The frequency-dependent coupling network is terminated with a resistor which is arranged between the gate electrode of the field effect transistor and ground and whose value has been chosen so that on the one hand this resistor terminates in conjunction with the input impedance of the field effect transistor the frequency-dependent coupling network with an acceptable reflection factor and on the other hand forms in conjunction with the output impedance of the frequency-dependent coupling network an impedance at which the noise contribution of the field effect transistor is at least substantially at its lowest.

Abstract: An improved antenna tuning circuit for a long and a medium wave AM radio receiver is disclosed. The antenna tuning circuit of the present invention comprises a tuning coil wound around a ferrite core, a variable capacitor connected in parallel with the tuning coil, and a field effect transistor. One end of the tuning coil is connected to the gate electrode directly or through an impedance means, while the other end of the tuning coil is grounded. The output signal of the antenna tuning circuit is taken out from a selected one of the source or drain electrode of the field effect transistor, whereby the signal to noise ratio may be remarkably improved.

Abstract: Apparatus for cancelling undesired signals for a radient energy receiver having first and second antennas which are spaced a distance apart and including a phase compensation circuit connected to one of the antennas and a variable phase shift circuit connected to the second antenna with the variable phase shift circuit comprising a plurality of series connected inductors wherein adjacent inductors are magnetically coupled together and a plurality of voltage variable capacitors with adjacent ones of the voltage variable capacitors connected between ground and the junction points between adjacent ones of the series connected inductors and adding means connected to the outputs of the phase compensation circuit and the variable phase shift circuit and means for supplying a variable DC voltage to the variable voltage capacitors to control their capacitance.

Abstract: A compact antenna system for use in connection with pay television reception comprises a resonant cavity including a small dipole, the latter being connected to a circuit board containing circuitry for converting the received pay television signal to a frequency usable by the television receiver of the subscriber. The member defining the cavity is affixed to the circuit board, which in turn is mounted upon a holder attached to the exterior of the structure in which the television receiver is located. The circuit board includes a preamplifier-filter stage to filter extraneous signals and to promote preamplification of the signal from the antenna. The preamplified signal goes to the input of a mixer and from there is filtered to the frequency of the channel selected by the user of the television receiver. At least one triangular circuit element is utilized in the preamplifier and in the mixer.

Abstract: In a television receiver, two tunable traps are incorporated between the RF input and the tuner to attenuate undesired signals symmetrically located in frequency below and above respective desired RF carriers. In one embodiment, the tunable traps are responsive to a tuning voltage for controlling the tuned circuits of the tuner so that the attenuation frequencies of the traps track the frequencies of the RF carriers associated with selected channels. In another embodiment the attenuation frequencies of the traps are moved with respect to the respective frequencies of desired RF carriers to optimize interference reduction.

Abstract: A noise-suppressing circuit suitable for insertion between a receiving antenna and an RF receiver to suppress noise in the RF signal received by the receiving antenna includes a bandpass filter circuit connected to receive as an input the RF signal received by the antenna, and connected in series to a blanking circuit which employs a JFET to remove from the filtered RF signal the unwanted noise spikes. The bandpass filter attenuates the components of the RF signal that have frequencies outside of the passband, and after the blanking circuit has removed the noise spikes, it passes the remainder of the filtered RF signal to the RF receiver. In a preferred embodiment, the bandpass filter circuit includes a parallel resonant circuit, and the blanking circuit includes a series resonant circuit connected between the drain and the gate of JFET of the blanking circuit.

Abstract: Apparatus for connecting a cable television system utilizing a multi-channel converter having a preselector switch and a preselected converter very high frequency output signal to a video cassette recorder and/or a television receiver. The apparatus includes an input for receiving the signals transmitted by the cable system; first and second conduits defining first and second flow paths, with the converter being disposed in the first flow path; a trap disposed in the second flow path for eliminating the preselected converter output signal from the signals transmitted by the cable system and passing through the second flow path; and a device for combining the preselected converter output signal in the first flow path and the signals transmitted through the second flow path and for transmitting the combined signal to the video cassette recorder and/or television receiver.

Abstract: A two terminal electronic filter network is provided for connection across TV antenna input terminals to reduce interference from noncommercial FM radio stations operating within a frequency band near the TV channel 6 frequency band. The two terminal electronic filter circuit which exhibits a rapid change of reactance for changes in frequency, and having a resonant frequency provides sufficient FM signal rejection without significant attenuation of any VHF channel by the provision of a highly reactive network tuned below the resonant frequency of the filter network as a whole.

Abstract: This disclosure is concerned with modulating the tuning of a picture carrier frequency trap to insure audible distortion of the sound signal in a subscriber television system irrespective of variations in circuit parameters caused by temperature or other changing tuning adjustments of the trap.

Abstract: An electrical frequency responsive circuit comprising a first coil constructed of wire having an insulating coating thereon wound in a single layer about an axis of generation, and a second coil, also constructed of wire having an insulating coating thereon wound about an axis of generation in a single layer, said coils being axially related and having diameters and/or pitch to provide inductance and capacitance between the coils which is at least initially adjustable whereby the circuit is responsive to an electric signal having a predetermined electrical frequency imposed across the coils to provide frequency band suppression about the predetermined frequency.

Abstract: A television signal processing circuit having an RF tuner includes a frequency responsive trap connected to a signal path of an IF amplifier to reject an undesirable interfering signal applied from the local oscillator of another tuner when the RF tuner and the other tuner are connected to a common antenna terminal.

Abstract: A VLF-VHF broadband in-line amplifier forms a portion of a towable buoyant able antenna system that is deployed in seawater from submarines. The amplifier is located between an antenna system and a coaxial cable. The coaxial cable is connected to the submarine. The VLF-VHF broadband in-line amplifier provides substantially uniform amplification for the frequency range of 10 kHz-160 MHz on signals received from the antenna system. The amplified signals are then transmitted to the submarine over the coaxial cable.