摘要:
The present invention relates to a television tuner capable of receiving television broadcasting, CATV and satellite broadcasting. The television tuner includes a double superheterodyne tuner for receiving television signals, having an up-converter, a down-converter and a coupler for coupling the up-converter and down-converter, and the television tuner also includes a BS second mixer portion and a FM demodulator, for receiving signals from a broadcasting satellite. The double superheterodyne tuner, the BS second mixer portion and the FM demodulator are disposed in a housing, a combination of the up-converter and the BS second mixer portion is desiredly separated from the down-converter, the coupler is disposed in a space between the combination and the down-converter, and the FM demodulator is disposed in the remaining space of the housing.
摘要:
A tuner station apparatus includes a first mixer for combining an input signal and a first local oscillation signal, and a second mixer for combining an output of the first mixer and a second local oscillation signal. The first and second local oscillation signals are generated by first and second PLL circuits, respectively. Each of the first and second PLL circuits include a frequency divider, a variable frequency divider, a phase comparator, a low pass filter, and a voltage controlled oscillator. The frequency divider of the first PLL circuit has a higher frequency division ratio than that of the second PLL circuit.
摘要:
In an amplifier for a high frequency signal used to amplify a signal having a high frequency in a television tuner, a receiver for satellite broadcasting, and the like, at least two stages of dc-coupled grounded-emitter type amplifiers (Q.sub.1, Q.sub.2) are configured in an integrated circuit, a resistor (R.sub.13) is connected between an emitter of the grounded-emitter amplifier (Q.sub.2) in the second stage and the grounding, a terminal for connecting an external device is disposed to be connected via a bonding wire to the emitter of the grounded-emitter amplifier (Q.sub.2) in the second stage, and a filter circuit (11) including an inductance of the bonding wire and developing a low impedance for a particular frequency is disposed between the terminal and the external grounding.
摘要:
A mixer for use in a double superheterodyne tuner which can receive either ground broadcasting channels or the satellite broadcasting channels is provided with frequency mixing diodes for the ground broadcasting signal and frequency mixing diodes for the satellite broadcasting signal. Switching diodes are provided between each of the frequency mixing diodes and output terminals of a balun transformer having an input terminal for receiving a local oscillation signal. When the ground broadcasting signal is received, the switching diodes connected to the frequency mixing diodes of the ground broadcasting are turned ON, with the switching diodes connected to the frequency mixing diodes of the satellite broadcasting are turned OFF, so that the leakage of the local oscillation signal to the satellite broadcasting signal when the ground broadcast signal is received is greatly reduced.
摘要:
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. At least the first local oscillator (6) and the first mixer (5) are commonly used both for reception of the television signals of the VHF band/UHF band and the CATV signal and for reception of the satellite television broadcasting signal, thereby accomplishing the simplification of the construction and the low costs.
摘要:
Disclosed is a local oscillator using a dielectric coaxial resonator (27), which is availably used as a fixed local oscillator in double-spot tuners and CATV converters, and which is arranged so that an AFC voltage is applied to a variable-capacitance diode (23) from an output terminal (E) of a frequency control circuit through a first resistor (35), the variable-capacitance diode having its one end being connected to a center conductor of a dielectric coaxial resonator (27) through a capacitor (25) and its other end being AC grounded, and that a first reference potential (V.sub.A) lower than a source voltage (V.sub.CC) by a predetermined value is given to the variable-capacitance diode (23), the one end of the variable-capacitance diode (23) being connected to the source voltage (V.sub.CC) through a second resistor (22), whereby the voltage impressed across the variable-capacitance diode (23) can be kept constant regardless of a variation in the source voltage to thereby prevent the oscillation frequency from fluctuating.
摘要:
The present invention relates to a receiving apparatus which can be used in receiving a satellite broadcast by using a cable television system. The receiving apparatus uses a double-super type converter or tuner (2) having a first frequency-conversion portion (15) and a second frequency-conversion portion (19). A conversion output terminal (G) for feeding a signal to a BS tuner (5) is provided at the output side of the first frequency-conversion portion (15). A BA signal converted into a UHF band or a superhigh band is fed to the first frequency-conversion portion (15) through a cable, so that, after frequency conversion, a BS-IF signal is taken out from the conversion output terminal (G). Thus, the BS-IF signal can be fed to the BS tuner (5) without using any special up-converter.
摘要:
The present invention is directed to a shielding device of a double-sided printed substrate used in a circuit for processing a high frequency signal such as a television tuner circuit and the like, which is arranged such that a first grounding conductor film (12a) is formed on one side of the substrate (11), a second grounding conductor film (12b) is formed on the other side of the substrate (11), both the conductor films (12a, 12b) are connected by a through-hole conductor (15b), an opening portion of a through hole (15a) at at least one side is covered and closed by a solder resist (16), and the shielding plate (13) is mounted on the conductor film (12a) on the one side and both members are soldered. In particular, when a ceramic substrate is used as the substrate (11), it is arranged so as to obtain reliable soldering and satisfactory shielding effects while ensuring the strength thereof.
摘要:
On an upper surface of a substrate (20) a band-pass filter (29) is provided, and on the opposite (lower) surface of a substrate (20) a low-pass filter comprising a conductive layer pattern (27) and capacitors (22,23) is provided, wherein a conductive layers (27) are provided on substantially the entire area of the upper surface excluding portions for terminals and on the lower surface excluding portions for the low-pass filter and the terminals, and by connecting both conductive layers by means of a row of through-hole connections, the input terminal (24) and the output terminal (25) are shielded from each other.
摘要:
A channel selection apparatus having a double superhet tuner section (15) for converting one of a plurality of television channels contained in an input signal to a fixedly predetermined channel, includes an AFC circuit (11) for producing a frequency control voltage to execute closed-loop frequency control of the second local oscillator (5) of the tuner section while an AFC switch (16) is set in a first condition, whereas when the AFC switch is set in a second condition, a fixed frequency control voltage is applied to the second local oscillator and the frequency control voltage is applied to adjust the oscillation frequency of the first local oscillator (2) of the tuner section such as to compensate for any offset in the transmission frequency of a currently selected channel.