Abstract: A wideband tuner for television signals in the VHF, CATV and UHF bands comprises a VHF tuning section coupled to a VHF receiving terminal, a CATV tuning section coupled to a CATV receiving terminal and a UHF tuning section. A switch selectively couples the UHF section to the output of the CATV tuning section or signals from a UHF receiving terminal. Each of the CATV and UHF tuning sections includes a differential mode modulator. In the CATV reception mode, the modulator of the CATV section converts the received CATV signal on an upper-side band differential mode to a UHF frequency, while the modulator of the UHF section converts the UHF frequency CATV signal to the standard intermediate frequency in a lower-side band differential mode. In the UHF reception mode, the UHF section modulator converts the UHF signal in an upper-side band differential mode to the standard intermediate frequency, while the CATV section is disabled.

Abstract: A multiband tuning system produces an IF signal from RF signals residing in, in the order named, a first broadcast band, a first cable band, a second broadcast band and a second cable band. A control device generates a tuning signal having a magnitude determined by the frequency of a selected channel. A first filter selects RF signals corresponding to channels selected in a first tuning band including the first broadcast band and a lower frequency portion of the first cable band in response to the tuning signal. A second filter selects RF signals corresponding to channels selected in a second tuning band including an upper frequency portion of the first cable band, the second broadcast and the second cable bands in response to the tuning signal. A selection device enables operation of the first filter when the selected channel is within the first tuning band and enables operation of the second filter when the selected channel is in the second tuning band.

Abstract: A RF signal converter circuit for connection to the aerial input of an RF superheterodyne receiver. In order to avoid a separate remote control of the converter circuit use is made of the local oscillator radiation which is present at the aerial input of a RF-superheterodyne receiver as an indication of the tuning frequency selected by the user with tuning portion of the said RF superheterodyne receiver. The converter circuit comprises a frequency search circuit in which the frequency of the oscillator radiation is detected, an RF signal selector which is controlled by the frequency search circuit and by means of which the desired RF signal is selected from the RF signals applied to the converter circuit, furthermore comprising a modulator which is also controlled by the frequency search circuit and in which the selected RF signal is modulated on a carrier frequency which is determined by the tuning frequency and the intermediate frequency of the RF superheterodyne receiver.

Abstract: A cable television up-down tuner includes a first frequency up conversion stage in which a first local oscillator, tunable over a wide frequency range, is coupled to a ring diode mixer having individual biasing networks in series with each diode. A combination high pass and low pass filter provides a bandwidth coupling of input signals to the mixer. An intermediate frequency amplifier couples the up converted signal to a second mixer. A fixed tuned second local oscillator down converts the intermediate frequency signal to a selected television channel frequency. The first local oscillator includes a printed circuit board transmission line resonator which is tuned by a varactor diode. The two local oscillators are positioned adjacent the corners of a quadrilateral housing and are isolated from each other by three wall-type shields.

Abstract: A double superheterodyne tuner for receiving television aural signals comprises first local oscillators by which an output of a first mixer receiving a VHF signal or a UHF signal is made a frequency between the VHF signal and the UHF signal, and a second local oscillator by which an output of a second mixer receiving a first intermediate frequency signal is made a frequency of 10.7 MHz. Oscillator frequencies are selected to avoid beat frequency interference for harmonics thereof up to and including the fifth order.

Abstract: A fully digitally-controlled system is disclosed which employs synthesized communications receivers to measure received signal frequency with greater resolution than that provided by the receiver alone. Variable frequency I.F. translation is used to provide this fine resolution. The operator has only one set of controls and one set of displays, with all other operations of the system being taken care of automatically without operator intervention. Proper performance of the associated one or two synthesized communications receivers is assured by continuous monitoring and display of the status of these receivers. In addition, the system may be remotely controlled; that is, it may report current frequency/bandwidth/mode settings to an external processor or it may receive commands from an external processor.

Abstract: A radar receiver for detecting quasi-harmonically related radar signals includes an antenna system (10) having a mixer (15) included therein. One harmonic from a local oscillator (20) mixes with a signal at a first frequency to produce an intermediate frequency, and another harmonic of the local oscillator mixes with an input signal at a second frequency also to produce an intermediate frequency. A second mixer (30) and local oscillator (40) may be provided. A bandwidth limited signal detecting system preferably includes a band pass filter (50), a limiting IF amplifier (55) and a frequency discriminator (60). The frequency of either the first or second local oscillator is repeatedly varied by a sweep generator (35) to insure that the presence of a radar signal will pass through the band pass filter (50) and be detected.

Abstract: In a communication receiver, a first mixing circuit, a first band-pass filter responsive to the output of the first mixing circuit, a second mixing circuit responsive to the output of the first band-pass filter, a second band-pass filter with a different center frequency from that of the first band-pass filter responsive to the output of the second mixing circuit, a first local oscillator, the output of which is applied to the first mixing circuit and a second local oscillator, the output of which is applied to the second mixing circuit. Various kinds of interference signals are eliminated by changing the output frequencies of the first and second local oscillators to thereby vary the effective bandwidth and center frequency of the signals which can pass through the receiver and thus eliminate interference. In addition, a third mixing circuit is responsive to the output of the second band-pass filter.

Abstract: A system which provides frequency conversion and continuously variable bandwidth control uses fixed filters to which opposite edges of the passband of the signal are applied in inverted frequency relationship. A channel contains the filters and three mixers to which injection signals derived from a single variable frequency oscillator and a fixed oscillator are applied to vary the bandwidth of the system without affecting the center frequency of the signal after processing in the system. The system may be designed to obtain either a variable bandpass or rejection band filtering characteristic.

Abstract: A first intermediate frequency amplifier stage which executes the amplitude limiting operation of a double-converting FM tuner employing the integrated circuit technology is constructed in the form of an integrated circuit. An output signal of the first intermediate frequency amplifier stage is put into a square pulse waveform on the basis of the amplitude limiting operation, and therefore has higher harmonic components of high frequencies. When the higher harmonic components are injected into a second mixer circuit in a second frequency converter circuit, various higher harmonic components which have frequencies higher than a second intermediate frequency appear at the output of the second mixer conduit. When the higher harmonic components at the output of the second mixer circuit are injected into an FM demodulator circuit, beat trouble is induced.

Abstract: A double superheterodyne receiver comprising a first mixer responsive to a frequency modulated signal and a first local oscillator signal for providing a first intermediate frequency signal having a frequency f.sub.1 and a positive side frequency deviation of +.DELTA.f.sub.1 and a negative side frequency deviation of -.DELTA.f.sub.2 where .DELTA.f.sub.1 =.DELTA.f.sub.2, a second mixer responsive to the first intermediate frequency signal and a second local oscillator signal having a frequency f.sub.s for providing a second intermediate frequency signal having a frequency of f.sub.2 and harmonics nf.sub.2 and (n+1)f.sub.2 where n is positive integer indicating the harmonic of f.sub.2 in the lower side of f.sub.1 which substantially deviates to f.sub.1 +.DELTA.f.sub.1 or to f.sub.1 -.DELTA.f.sub.2 and n+1 indicates the harmonic of f.sub.2 in the upper side of f.sub.1 which substantially deviates to f.sub.1 -.DELTA.f.sub.2 (when nf.sub.2 substantially deviates to f.sub.1 +.DELTA.f.sub.1) or to f.sub.1 +.DELTA.f.