Abstract: In a television receiver in which image frequency signals for desired signals are removed when television broadcasting signals are frequency-converted through a local oscillator and mixers, the local oscillator generates biaxial orthogonal signals to be frequency-converted by respective mixers, an output signal of one mixer being phase-shifted to be added to an output signal of the other mixer so as to thereby offset only the image frequency signals. The local oscillator and a phase shifter operate so as to follow the frequency change of the intermediate frequency signal so as to thereby stabilize the suppression of the image frequency signal.

Abstract: A television signal receiving apparatus receives a new standard television broadcasting signal in an environment in which conventional standard television broadcasting signals are present. A first tuner coupled to a first antenna extracts a first television signal which contains a new standard television signal and a conventional standard television signal of the specific channel at a first ratio, and a second tuner coupled to a second antenna extracts a second television signal which contains the new standard television signal and the conventional standard television signal of the specific channel at a second ratio. In an operation unit, a multiplier multiples the second television signal by a predetermined coefficient, and a subtracter subtracts an output signal of the multiplier from the first television signal. An output signal of the subtracter becomes the new standard television signal when the coefficient has a specific value.

Abstract: Radio waves used in broadcasting and communications making use of broadcasting satellite and communication satellite are FM signals, and the frequency shift and exclusive bandwidth vary depending on the modulation signal. The satellite broadcasting receiver is designed to control the frequency shift so that the amplitude of the demodulation signal is constant, thereby making the bandwidth of the intermediate frequency filter, so as to be capable of receiving using just one filter. At this time, the frequency shift can be controlled continuously, from large to small one, in a predetermined exclusive bandwidth. When further expanding the frequency shift, since the exclusive bandwidth is extended, the noise electric power is increased and the receiving sensitivity is lowered as compared with the exclusive machine. Accordingly, when expanding the frequency shift, the noise bandwidth is narrowed in the PLL demodulator, thereby enhancing the receiving sensitivity.

Abstract: A signal of the same frequency band as an ordinary NTSC signal of the video signals is transmitted with the conventional frequency band but the other frequency components are frequency-converted to a frequency higher than the sound subcarrier as the multiplex signal. The ordinary video signal, sound subcarrier and multiplex signal are frequency-multiplexed and the main carrier is transmitted by angle modulation as the modulation signal. In this case, as the multiplex signal, a signal other than the ordinary signal may directly be frequency-multiplexed and the signal may be multiplexed. Using amplitude or angle modulation to improve the demodulation accuracy or S/N through the angle modulation. The ordinary signal is regenerated like in the conventional system, without influence on the conventional receiver. In addition, since the ordinary video signal and the multiplex signal are separated in the frequency band, these may be used as the independent new transmission bands.

Abstract: The invention relates to a television receiving tuner for receiving television signals of VHF band/UHF band, a CATV signal, and a satellite television broadcasting signal. As a circuit for receiving the television signals of the VHF band/UHF band and the CATV signal as a first input signal, there is provided a double super type tuner of the up/down converter system including a first local oscillator (6) and a first mixer (5) which construct an up converter and a second local oscillator (10) and a second mixer (9) which construct a down converter. When the satellite television broadcasting signal as a second input signal is received, the first local oscillator (6) and the first mixer (5) in the up converter section are switched by switching circuits (12, 13) and used as a down converter.

Abstract: There is provided a wide band transmission system which, by using two or more filters and gain control circuits, is operated so as to determine the gain control amount of the gain control circuits according to an intensity and frequency band of a signal which is desired to be received. Further, a bias circuit increases the attenuation amount of the gain control circuit connected to the filter whose pass band is out of the band of the desired signal.

Abstract: A signal receiver which is capable of receiving and demodulating a satellite broadcasting signal which is an FM signal and a terrestrial broadcasting signal which is an AM signal is disclosed. FM and AM signals are frequency-converted into signals having frequencies in a same intermediate frequency band by making common use of a radio frequency amplifier, a mixer, a local oscillator and an intermediate frequency filter. At the time of reception of an FM signal, the FM signal is demodulated in a phase-locked loop circuit, and a local oscillator is subjected to frequency modulation by a part of the demodulated signal, thereby constituting an FM negative feedback loop, and thus narrowing the occupied bandwidth of the FM signal. At the time of reception of an AM signal, the phase-locked loop circuit is used to regenerate a carrier, and the output signal of the phase-locked loop circuit is input to a multiplier to effect synchronous detection of the input signal.