JPH0564101A - Receiver with at least two kinds of demodulation circuits sharing tuner device - Google Patents

Abstract

PURPOSE:To simplify the circuit configuration and to obtain a miniaturized receiver whose cost is reduced and whose number of components is decreased by sharing a tuner even when the signal of a different modulation system (e.g. FM modulation or MSK modulation) is received. CONSTITUTION:The tuner (composed of a high frequency amplifier circuit 3, a variable tuning filter 5, a mixer circuit 8, IF amplifier circuits 9, 13, an intermediate frequency filter 11, a local oscillation circuit 10, an AGC circuit 14, a channel selection circuit 15) is shared for an FM demodulation circuit 20 and an MSK demodulation circuit 21. A switching circuit 22 selects either of the demodulation circuits by using data inputted to a terminal 35 in relation to channel selection data imparted to the channel selection circuit 15 from a terminal 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver provided with at least two types of demodulation circuits sharing a tuner device. An FM demodulation circuit is required to receive an FM-modulated video signal (video and sound) from a broadcasting satellite, and an MSK demodulation circuit is required to receive an MSK-modulated music signal from a communication satellite. Although necessary, the present invention relates to a receiving device provided with, for example, two types of demodulation circuits such as these by sharing a tuner device.

[0002]

2. Description of the Related Art In the prior art, for example, in a satellite broadcasting receiver, one first intermediate frequency signal received by down conversion is converted into a second intermediate frequency signal, and then demodulated. As shown in Japanese Patent Laid-Open No. 63-30049, the structure of a tuner device having an input terminal for inputting two first intermediate frequency signals and a circuit for converting the first intermediate frequency signal into a second intermediate frequency signal is Although disclosed, there is no disclosure of a configuration including two types of demodulation circuits and switching and using them.

[0003]

The receiver according to the prior art described above has a plurality of input terminals, but receives a signal of a different modulation system because the received signal is one type of modulated signal. In that case, there is a problem in that tuner devices are required for the number of the modulation methods, resulting in a complicated configuration and high cost.

The present invention solves the above problems and allows a tuner device to be shared even when receiving signals of different modulation systems, which simplifies the configuration and reduces the cost. To provide.

More specifically, for example, an FM-converted video signal using a broadcasting satellite and an MSK-modulated (one of orthogonal modulation methods) music signal using a communication satellite are frequency-converted by an outdoor converter. When inputting as a 1 GHz first intermediate frequency signal and selecting an FM modulated video signal, F
When outputting an M demodulation signal and selecting an MSK modulation music signal, it is possible to output an MSK demodulation signal. SUMMARY OF THE INVENTION It is an object of the present invention to provide a receiver capable of operating a demodulation circuit corresponding to each modulation method only for the demodulation circuit and outputting a demodulation signal.

The MSK demodulation is described in detail by Ohmsha's published series of illustrated electronic circuits, "Basics of Digital Modulation / Demodulation Circuits", Supervision by Kiyasu, and Seizo Seki. Refer to it if necessary. I want to be done.

[0007]

The above object can be achieved by dividing an output of a tuner device for frequency-converting an input signal into two and connecting a demodulation circuit of another system to each output. At this time, in the gain control of the tuner device, the respective reference voltages corresponding to the input signal levels required for the two demodulation circuits are set, and the gain control circuit of the tuner device is configured to be shared, and the channel selection is performed. In the frequency synthesizer of the circuit, the comparison frequencies can be selected according to the two demodulation circuits.

When an input signal is transmitted by two cables, the tuner device has two inputs,
The intermediate frequency filter is configured as a filter having two filters having different bandwidths built therein, and the filters are switched and used.

Further, the signal connection between the circuits is a balanced transmission system. In particular, when the demodulation circuit used is a phase-locked loop type FM demodulation circuit and a quadrature signal demodulation circuit, the 90 ° phase shifter of the synchronous detection circuit forming the quadrature signal demodulation circuit in the phase-locked loop of the phase-locked loop type FM demodulation circuit. It is configured to be used as.

[0010]

According to the present invention, in the receiving device that selectively receives signals of different modulation systems, demodulates them, and outputs the baseband signal, the demodulation circuits make the input signal center frequencies equal. Therefore, even if different modulation methods are used, the tuner device for converting the input signal into the intermediate frequency signal can be commonly used, and the voltage controlled oscillator which is a constituent element of the demodulation circuit can be shared.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, AGC is Automat
ic Gain Control (automatic gain control circuit), PLL is Phase Locked Loop
It is an abbreviation for (phase locked loop).

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, 1 is an input terminal, 3 is a high frequency amplifier circuit, 5 is a variable tuning filter, and 7 is a variable gain R.
F amplifier circuit, 8 mixer circuit, 9 variable gain IF amplifier circuit, 10 local oscillation circuit, 11 intermediate frequency filter,
13 is a variable gain IF amplifier circuit, 14 is an AGC circuit, 1
5 is a channel selection circuit, 20 is an FM demodulation circuit (first demodulation circuit), 21 is an MSK demodulation circuit (second demodulation circuit), 22
Is a switching circuit, 32 is a channel selection data input terminal, and 35 is a control terminal.

The present embodiment is a front end that receives a high frequency signal and outputs a baseband signal, has a single high frequency input terminal, and is capable of selectively demodulating an FM modulated signal and an MSK modulated signal. Can be said to have shown.

Referring to FIG. The input signal to the input terminal 1 is amplified by the high frequency amplifier circuit 3. A variable tuning filter 5 for suppressing unnecessary waves is arranged at the subsequent stage of the high frequency amplifier circuit 3, and a tuning voltage from a tuning circuit 15 is applied to vary the pass band center frequency. In the subsequent stage, a variable amplification gain RF amplification circuit 7, a mixer circuit 8, a variable gain IF amplification circuit 9, an intermediate frequency filter 11, and a variable gain IF amplification circuit 13 are connected, and the tuning circuit 15 selects a channel. Depending on the voltage
By inputting the signal of the local oscillation circuit 10 that oscillates a desired frequency to the mixer circuit 8, the mixer circuit 8 constitutes a frequency conversion circuit.

The tuning circuit 15 is a circuit for generating a tuning voltage according to tuning data input to the terminal 32. In addition, the AGC circuit 14 allows the variable gain IF amplifier circuit 1
The respective amplification gains of the variable amplification gain RF amplification circuit 7, the variable gain IF amplification circuit 9, and the variable gain IF amplification circuit 13 are controlled so that the output level of 3 becomes a constant level.

The output of the variable gain IF amplifier circuit 13 is input to the switching circuit 22, one of the outputs of the switching circuit 22 is input to the FM demodulation circuit 20, and the other is output to the MSK demodulation circuit 2.
1 and connect the demodulated outputs to the output terminal 16 and the output terminal 17, respectively. The FM demodulation circuit 20 and the MSK demodulation circuit 21 are circuit units that demodulate the input intermediate frequency signals of the respective modulation methods and output a baseband signal. The switching circuit 22 selects the demodulation circuit to be connected according to the data input to the terminal 35 in association with the tuning data applied to the terminal 32.

According to the configuration of this front end, since the input center frequencies of the two demodulation circuits are equal, a circuit for selecting a desired signal from the input signals, that is, the high frequency amplifier circuit 3 to the variable gain IF amplifier circuit 13 is selected. Since the tuner section can be used in common regardless of the subsequent modulation method, a compact front end with a small number of parts can be obtained. Also, by incorporating a tuning circuit and a demodulation system control circuit into the front end, a front end with excellent usability can be obtained.

FIG. 2 is a block diagram showing a second embodiment of the present invention. In the figure, the same components as those in FIG. 1 are designated by the same reference numerals. The embodiment shown in FIG. 2 corresponds to the intermediate frequency filter 11 in the first embodiment shown in FIG.
To the intermediate frequency filter (12
-1) and an intermediate frequency filter (12-2) having a second pass band width are connected in parallel.
The intermediate frequency filter (12-1) and the intermediate frequency filter (12-2) are related to the tuning data applied to the terminal 32, and one pass bandwidth is generated by the voltages applied to the control terminals 33 and 34. To be selected.

According to this configuration of the front end, since the input center frequencies of the two demodulation circuits are equal, the tuner section can be made common regardless of the modulation system, the intermediate frequency bandwidth or the modulation degree. A compact front end with few parts can be obtained. Also, by incorporating a tuning circuit and a demodulation system control circuit into the front end, a front end with excellent usability can be obtained.

FIG. 3 is a block diagram showing a third embodiment of the present invention. The present embodiment is a front end that receives a high frequency signal and outputs a baseband signal, and can be said to be a system that has two high frequency input terminals 1 and 2 and demodulates an FM modulated signal and an MSK modulated signal.

Two high-frequency input terminals 1 and 2 are provided so that the antenna for receiving the broadcasting satellite and the antenna for receiving the communication satellite are provided separately. Since broadcasting satellites and communication satellites are separate satellites, the optimum azimuths for receiving are usually different.In such a case, it is desirable to provide a dedicated antenna for each. is there.

Referring to FIG. The high frequency amplifier circuit 3 amplifies the input signal to the input terminal 1, and the high frequency amplifier circuit 4 amplifies the input signal to the input terminal 2. In connection with the tuning data applied to the terminal 32, only one high frequency amplifier circuit is operated by the control voltage applied to the control terminals 30 and 31, and the signal input to the input terminal 1 and the input signal to the input terminal 2 are input. One of the signals to be selected.

The outputs of the high frequency amplifying circuit 3 and the high frequency amplifying circuit 4 are connected to a variable tuning filter 5 for suppressing unnecessary waves, and the tuning voltage from the tuning circuit 15 is applied to the variable tuning filter 5 to pass band. Vary the center frequency. In the subsequent stage, a variable amplification gain RF amplification circuit 7, a mixer circuit 8, a variable gain IF amplification circuit 9, an intermediate frequency filter 11, and a variable gain IF amplification circuit 13 are connected, and the tuning circuit 15 selects a channel. The frequency conversion circuit is configured by inputting the signal of the local oscillation circuit 10 that oscillates a desired frequency by the voltage to the mixer circuit 8.

The tuning circuit 15 is a circuit for generating a tuning voltage according to tuning data input to the terminal 32. In addition, the AGC circuit 14 allows the variable gain IF amplifier circuit 1
The amplification gains of the variable amplification gain RF amplification circuit 7, the variable gain IF amplification circuit 9, and the variable gain IF amplification circuit 13 are controlled so that the output level of 3 becomes a constant level.

The output of the variable gain IF amplifier circuit 13 is input to the switching circuit 22, one of the outputs of the switching circuit 22 is input to the FM demodulation circuit 20, and the other is output to the MSK demodulation circuit 2.
1 and connect the demodulated outputs to the output terminal 16 and the output terminal 17, respectively. The FM demodulation circuit 20 and the MSK demodulation circuit 21 are circuit units that demodulate the input intermediate frequency signals of the respective modulation methods and output a baseband signal. The switching circuit 22 selects the demodulation circuit to be connected according to the data input to the terminal 35 in association with the tuning data applied to the terminal 32.

According to the configuration of this front end, since the input center frequencies of the two demodulation circuits are the same, the tuner section can be shared regardless of the modulation system, and the signals of the two modulation systems are input through different transmission lines. However, since most of the tuner section can be used in common, a compact front end with a small number of parts can be obtained. In addition, it is equipped with multi-functionality to switch the high frequency input internally, and by incorporating the tuning circuit and the demodulation control circuit in the front end, a front end with excellent usability can be obtained.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention. In the figure, the input signal to the input terminal 1 is amplified by the high frequency amplifier circuit 3, and the input signal to the input terminal 2 is amplified by the high frequency amplifier circuit 4. In relation to the tuning data applied to the terminal 32, only one high frequency amplifier circuit is operated by the control voltage applied to the control terminals 30 and 31, and the signal input to the input terminal 1 and the input terminal 2 are input. One of the input signals is selected.

The output of the high frequency amplifying circuit 3 is connected to a variable tuning filter 5 for suppressing unwanted waves, and the output of the high frequency amplifying circuit 4 is connected to a variable tuning filter 6 for suppressing unwanted waves, and the variable tuning filter 5 and The tuning voltage from the tuning circuit 15 is applied to the tunable filter 6 to vary the pass band center frequency. At this time, the voltages applied to the variable tuning filter 5 and the variable tuning filter 6 are different voltages, and when one is a voltage in the pass band, the other is a voltage in the attenuation range from the tuning circuit 15.

In the subsequent stage, the amplification gain variable RF amplification circuit 7, the mixer circuit 8, the gain variable IF amplification circuit 9, the intermediate frequency filter 11, and the gain variable IF amplification circuit 13 are connected, and the tuning circuit 15 The mixer circuit 8 constitutes a frequency conversion circuit by inputting the signal of the local oscillation circuit 10 which oscillates a desired frequency by the tuning voltage of the above into the mixer circuit 8.

The tuning circuit 15 is a circuit for generating a tuning voltage according to tuning data input to the terminal 32. The output of the variable gain IF amplification circuit 13 is input to the switching circuit 22, one of the outputs of the switching circuit 22 is input to the FM demodulation circuit 20, and the other is input to the MSK demodulation circuit 21, and the respective demodulation outputs are output terminals. 16 and the output terminal 17. The FM demodulation circuit 20 and the MSK demodulation circuit 21 are circuit units that demodulate the input intermediate frequency signals of the respective modulation methods and output a baseband signal. The switching circuit 22 selects the demodulation circuit to be connected according to the data input to the terminal 35 in association with the tuning data applied to the terminal 32.

According to the configuration of the present front end, in addition to the effect similar to that of the third embodiment shown in FIG. 3, the characteristics of the tuning filter are attenuated with the pass band on the selected input side and the non-selected input side. Since it can be set to the range, unnecessary signal leakage from the input can be reduced, and a front end having excellent isolation characteristics between input terminals can be obtained.

FIG. 5 is a block diagram showing a fifth embodiment of the present invention, in which the variable tuning filter 5 for suppressing unnecessary waves shown in the first embodiment of FIG. 7, the mixer circuit 8, the variable gain IF amplifying circuit 9, the intermediate frequency filter 11, the variable gain IF amplifying circuit 13, and the local oscillation circuit 10 are each configured as a balanced type circuit, and the inter-circuit connection of the variable tuning filter 5 and thereafter is performed. This is an example of a balanced type.

According to the configuration of the present front end, in addition to the effect described in the first embodiment of FIG. 1, since the tuner is composed of the balanced circuit, leakage of the local oscillation signal to the input side or the output side is prevented. Since the leakage of the oscillation signal of the voltage controlled oscillator used for the demodulation circuit to the tuner is small, the front end having excellent interference characteristics can be obtained.

FIG. 6 is a block diagram showing a sixth embodiment of the present invention, and the AGC circuit 14 of the first embodiment of FIG.
The detection circuit 40, the comparison circuit 41, the amplification circuit 42, the first
Comparison voltage generation circuit 43, second comparison voltage generation circuit 4
4, the control terminal 36, and the switching circuit 45.

In FIG. 6, a variable gain IF amplifier circuit 1 is provided.
The output level of 3 is detected by the detection circuit 40, and the output voltage is input to one input side of the comparison circuit 41. A switching (SW) circuit 45 switches between the output voltage of the first comparison voltage generation circuit 43 and the output voltage of the second comparison voltage generation circuit 44.
And the desired voltage is input to the other input side of the comparison circuit 41.

The comparison circuit 41 outputs the difference voltage between the two input voltages, the amplification circuit 42 amplifies it, and then the amplification gain variable RF.
Amplifier circuit 7, variable gain IF amplifier circuit 9, variable gain I
It outputs to the F amplifier circuit 13, respectively. The output voltage of the first comparison voltage generation circuit 43 and the second comparison voltage generation circuit 44
Which output voltage is selected is determined by a control signal applied to the control terminal 36.

According to the configuration of this front end, in addition to the effect described in the first embodiment of FIG. 1, the first demodulation circuit 20 is also provided.
And the input level of the second demodulation circuit 21,
Even if the optimum values are different, most of the AGC circuit 14 can be used in common, so that further simplification of the circuit is achieved.

FIG. 7 is a block diagram showing a seventh embodiment of the present invention, in which the tuning circuit 15 of the first embodiment of FIG.
Frequency divider 51, programmable frequency divider 52, phase comparator 5
3, a low pass filter 54, a crystal oscillator circuit 55, a programmable frequency divider 56, a tuning signal processing circuit 57, and a control terminal 32.

In FIG. 7, the oscillation signal of the local oscillation circuit 10 is passed through a frequency divider 51 and a programmable frequency divider 52,
Frequency division is performed according to the frequency division ratio setting signal from the channel selection signal processing circuit 57. On the other hand, the oscillation signal of the crystal oscillation circuit 55 is frequency-divided by the programmable frequency divider 56 according to the frequency division ratio setting signal from the channel selection signal processing circuit 57. Then, the signal from the programmable frequency divider 52 and the signal from the programmable frequency divider 56 are compared by the phase comparator 53, and the output of the difference is applied to the local oscillation circuit 10 via the low-pass filter 54. The oscillation frequency is controlled.

The tuning signal processing circuit 57 uses the tuning data input to the control terminal 32 to program the programmable frequency divider 5
A circuit that determines the frequency division ratio of 2, and further includes an FM demodulation circuit 20.
Also has the function of changing the frequency division ratio setting of the programmable frequency divider 56 depending on whether the MSK demodulation circuit 21 is operated.

According to the configuration of this front end, in addition to the effect described in the first embodiment of FIG. 1, the oscillation characteristics required for the local oscillation circuit, for example, the oscillation spectrum, can be obtained by the signals of the two modulation methods. Even if the purity, the phase noise, and the minimum frequency step width are different, most of the front end can be shared, which has the advantage of simplifying the circuit.

FIG. 8 is a block diagram showing an eighth embodiment of the present invention. In this embodiment, the FM demodulation circuit of the embodiment of FIG. 1 is a PLL type FM demodulation circuit, and the MSK demodulation circuit is The Costas loop system MSK demodulation circuit is used as the PLL circuit of the PLL system FM demodulation circuit.
It can be said that the front end also serves as the 90 ° phase shifter of the K demodulation circuit.

In FIG. 8, reference numeral 60 is a switching circuit, and 61.
Is a phase comparator, 62 is a loop amplifier, 63, 69, 7
0 and 71 are low pass filters, 65 and 66 are voltage controlled oscillators, 67, 68, 72 and 73 are multipliers, 74 and 75 are determination circuits, 76 is a clock recovery circuit, 77 is a digital signal processing circuit, Is.

The loop of the phase comparator 61, the loop amplifier 62, the low pass filter 63 and the voltage controlled oscillator 65 constitutes the PLL type FM demodulation circuit 20, and the baseband signal is output from the output terminal 16. Control terminal 35
When the FM demodulation circuit 20 is selected according to the data input to the switching circuit 22 and 60, the variable gain IF
Switching is performed so that the output side of the amplifier circuit 13 (the output side of the tuner device) and the input side of the phase comparator 61 are connected.

On the other hand, when selecting the MSK demodulation circuit,
In the switching circuit 22, the output signal of the variable gain IF amplifier circuit 13 (the output signal of the tuner device) is multiplied by the multipliers 67 and 68.
The multipliers 67 and 68 multiply the signals of the voltage controlled oscillators 66 and 65, respectively, perform synchronous detection, and use the first low-pass filter 69 and the second low-pass filter 70 to generate high-frequency components. Except
The so-called I and Q baseband signals are used.

These signals are judged as 1 or -1 by the first judgment circuit 74 and the second judgment circuit 75, passed through the digital signal processing circuit 77, and then output from the demodulation output terminal 17. The I and Q baseband signals are multiplied by the multiplier 73, and the clock recovery circuit 76 and the multiplier 72 are multiplied.
To the low-pass filter 63 while controlling the voltage-controlled oscillator 66 via the low-pass filter 71.
Composite with the output of.

Further, the switching circuit 60 is connected so as to input the oscillation signal of the voltage controlled oscillator 66 to one input side of the phase comparator 61 by the data inputted to the control terminal 35, and the MSK demodulation circuit is constituted. To be done.

According to this embodiment, when the MSK demodulation circuit is constructed, the PLL circuit (20) operates as a 90 ° phase shifter, and the phase difference between the signals of the voltage controlled oscillator 66 and the voltage controlled oscillator 65 is It becomes 90 °, and stable characteristics can be obtained.

FIG. 9 is a block diagram showing a ninth embodiment of the present invention. In this embodiment, the FM demodulation circuit of the first embodiment of FIG. 1 is used as a PLL type FM demodulation circuit, and the MSK demodulation circuit is used. It can be said that the front end is a Costas loop type MSK demodulation circuit.

In FIG. 9, 61 is a phase comparator, 62 is a loop amplifier, 63, 69, 70 and 71 are low-pass filters, 65 and 66 are voltage controlled oscillators, 67, 68 and 7.
Reference numerals 2 and 73 are multipliers, 74 and 75 are determination circuits, 76 is a clock recovery circuit, 77 is a digital signal processing circuit, and 78 is a 90 ° phaser.

The control circuit 80 and the control circuit 81 receive voltage control oscillators 65 and 6 according to a signal input to the control terminal 35.
The oscillation operation of 6 is turned on and off. When the PLL system FM demodulation circuit 20 is configured by the loop of the phase comparator 61, the loop amplifier 62, the low-pass filter 63, and the voltage control oscillator 65, and the FM demodulation circuit 20 is selected by the signal input to the control terminal 35, The switching circuit 22 connects the variable gain IF amplification circuit 13 and the phase comparator 61,
The voltage controlled oscillator 65 is turned on by the control circuit 80, the voltage controlled oscillator 66 is turned off by the control circuit 81, and the baseband signal is output from the output terminal 16.

On the other hand, when selecting the MSK demodulation circuit,
The signal input to the control terminal 35 causes the control circuit 81 to turn on the voltage controlled oscillator 66, and the switching circuit 2
2, the output of the IF amplification circuit 13 having a variable gain and the multiplier 67,
68 is connected, and the input signals are multiplied by the signals of the voltage controlled oscillator 66 and the signal of the 90 ° phase shifter 78 by multipliers 67 and 68, respectively, and synchronous detection is performed, and the first low pass filter 69 and the second The low pass filter 70 is used to remove high frequency components, and so-called I and Q baseband signals are output.

These signals are outputted from the demodulation output terminal 17 after being judged as 1 or -1 by the first judgment circuit 74 and the second judgment circuit 75 and passed through the digital signal processing circuit 77. The I and Q baseband signals are multiplied by the multiplier 73, output to the clock recovery circuit 76 and the multiplier 72, multiplied by the recovered clock signal of the clock recovery circuit 76, and then passed through the low-pass filter 71. The voltage controlled oscillator 66 is controlled. Further, the voltage controlled oscillator 65 is turned off by the control circuit 80 by the signal input to the control terminal 35.

According to the present embodiment, even if each demodulation circuit has a voltage controlled oscillator, the voltage controlled oscillator of the demodulation circuit that is not selected is turned off, so there is no interference. Therefore, it is possible to obtain stable characteristics without a beat due to an interfering signal or deterioration of an error rate.

[0055]

As described above, according to the present invention,
A configuration in which a tuner portion of a receiver that receives and demodulates signals of two different modulation methods, such as an FM modulated signal and a quadrature signal modulated signal, is used in common and a part of two demodulation circuits is also used in common. Therefore, the circuit can be simplified, and one receiving device can cope with transmission signals of different systems. Therefore, it is possible to provide a small and inexpensive receiving device with excellent usability.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a seventh embodiment of the present invention.

FIG. 8 is a block diagram showing an eighth embodiment of the present invention.

FIG. 9 is a block diagram showing a ninth embodiment of the present invention.

[Explanation of symbols]

1, 2 ... Input terminals, 3, 4 ... High frequency amplifier circuit, 5, 6 ...
Variable tuning filter, 7 ... Gain variable RF amplifier circuit, 8 ...
Mixer circuit, 9, 13 ... Variable gain IF amplifier circuit, 10
… Local oscillator circuit, 11… Intermediate frequency filter, 14… A
GC circuit, 15 ... Tuning circuit, 22 ... Switching circuit, 20
... FM demodulation circuit (first demodulation circuit), 21 ... MSK demodulation circuit (second demodulation circuit), 16, 17 ... Output terminal, 3
0, 31, 32, 33, 34, 35 ... Control terminals

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Yamamoto 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Video Media Research Laboratory, Hitachi, Ltd. (72) Masaki Noda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Incorporated company Hitachi Ltd. Media Research Institute

Claims (9)

[Claims] 1. A receiving device comprising at least two types of demodulation circuits sharing a tuner device, comprising: an input high frequency amplifier circuit (3); and a fixed or variable tuning filter (5) for passing an output of the amplifier circuit. A variable local oscillation circuit (10), a frequency mixing circuit (8) for inputting the output that has passed through the tuning filter and the oscillation output from the variable local oscillation circuit and performing frequency conversion, and a frequency from the mixing circuit. An intermediate frequency amplifier circuit (9, 13) for amplifying and outputting the converted signal, an intermediate frequency filter (11) arranged between the stages of the intermediate frequency amplifier circuit, and a channel selection signal are selected when input. And a tuner circuit including a tuning circuit for generating a tuning voltage corresponding to the channel and instructing the variable tuning filter and the variable local oscillation circuit, and the tuner device. A gain control circuit (14) for detecting the output signal level of the receiver and controlling the amplification gain in the tuner device accordingly, at least two types of demodulation circuits having different demodulation methods, and A tuner device comprising: switching means for switching the output of the tuner device to any one of the two types of demodulation circuits and inputting the output of the tuner device according to a switching command determined depending on a channel selection signal. A receiver including at least two types of demodulation circuits sharing the same. 2. The receiving device according to claim 1, wherein the intermediate frequency filter has a first bandpass filter having a first passband width and a second bandpass filter having a second passband width. A receiver comprising: a filter; and a selection switching means for selectively activating one of the both bandpass filters. 3. The receiving device according to claim 1, wherein the input high frequency amplification circuit is a first input high frequency amplification circuit, a second input high frequency amplification circuit, or both input high frequency amplification circuits. A receiving device, comprising: a selection switching means for selectively activating one of the two. 4. The receiving device according to claim 1, wherein the input high frequency amplification circuit is composed of a first input high frequency amplification circuit and a second input high frequency amplification circuit, and the variable tuning filter is A first variable tuning filter connected to the output side of the first input high frequency amplifier circuit and a second variable tuning filter connected to the output side of the second input high frequency amplifier circuit; A switching means for selectively switching between the first input high frequency amplifier circuit and the second input high frequency amplifier circuit is provided, and when the first input high frequency amplifier circuit is selectively used, the output from the channel selection circuit As a tuning voltage, a voltage different from the tuning voltage applied to the first variable tuning filter is applied to the second variable tuning filter, and when the second input high frequency amplifier circuit is selected and used, the tuning channel is selected. As the output tuning voltage from the road, to the first variable tuning filter, the receiving device, characterized in that the as applying a tuning voltage different from the voltage applied to the second variable tuning filter. 5. The receiving device according to claim 1, 2, 3, or 4, wherein each circuit from the fixed or variable tuning filter to the output of the tuner device is configured as a balanced type circuit, and between the circuits. A receiver comprising a balanced connection of. 6. The receiving device according to claim 1, 2, 3, 4, or 5, wherein the gain control circuit detects a detection circuit for detecting an output level of the tuner device, and a detection signal from the detection circuit. A comparison control circuit for inputting the first reference signal level or the second reference signal level, comparing the detection signal with the reference signal level, and controlling the gain in the tuner device according to the result, and the switching means for the two types of the comparison control circuit. Of the demodulation circuits, the first reference signal level is selected when the first demodulation circuit is selected, and the second reference signal level is selected when the second demodulation circuit is selected. A receiving device, comprising: a selection switching unit for inputting to the. 7. The receiving device according to any one of claims 1 to 6, wherein the tuning circuit includes a reference frequency oscillator, a phase comparator, and
A first frequency divider that takes in the output signal from the local oscillation circuit and directly or divides it and inputs it to one input side of the phase comparator; and an output signal from the reference frequency oscillator directly or frequency-divided. A second frequency divider for inputting to the other input side of the phase comparator, and a low-pass filter for filtering the output of the phase comparator and applying it to the control voltage terminal of the local oscillator circuit. The frequency division ratio of the first frequency divider or the second frequency divider depending on whether the first demodulation circuit is selected or the second demodulation circuit is selected depending on the channel selection signal. Alternatively, a means for changing the oscillation frequency of the reference frequency oscillator to change the signal frequency output from the tuner device, the receiving device. 8. The receiving device according to any one of claims 1 to 7, wherein a first demodulation circuit of the two types of demodulation circuits outputs an output signal from the tuner device to one of the two types. A phase comparator (61) supplied to the input side, and a loop amplifier (62) which inputs and amplifies and outputs the output from the phase comparator,
A first low-pass filter (63) for filtering and outputting an amplified output from the amplifier, and a frequency corresponding to the tuner device output frequency are generated by inputting the output of the first low-pass filter as a control voltage. And a first voltage controlled oscillator (65) for supplying to the other input side of the phase comparator (61), and a PLL circuit which uses the output of the first low pass filter as a demodulation output. An FM demodulation circuit, wherein the second demodulation circuit of the two types of demodulation circuits includes a second voltage controlled oscillator (66) for generating a frequency corresponding to the tuner device output frequency, and an output from the tuner device. And a first multiplier (67) which receives the output from the second voltage controlled oscillator, multiplies the two, and outputs the result.
A second output for filtering and outputting the output of the first multiplier
Low-pass filter (69), and a second multiplier (6) which receives the output from the tuner device and the output from the first voltage-controlled oscillator (65) and multiplies both to output.
8) and a third low-pass filter (70) for filtering and outputting the output of the second multiplier, and using the synchronous detection circuit, the second low-pass filter (69)
And an output of the third low-pass filter (70) to obtain a demodulation output from the quadrature signal demodulation circuit. When selecting the first demodulation circuit, the output from the tuner device When supplying to one input side of the phase comparator (61) in the demodulation circuit and selecting the second demodulation circuit, the output from the tuner device is supplied to the first and second output circuits of the second demodulation circuit. When selecting the first switching means (22) for switching the connection to supply to the second multiplier (67, 68) side and the second demodulation circuit, the phase comparison in the first demodulation circuit Instead of inputting the output from the tuner device to one input side of the device (61),
A second switching means (60) for switching the connection so as to input the output of the second voltage controlled oscillator (66), and the receiving device further comprising: 9. The receiving device according to claim 1, wherein the first demodulation circuit of the two types of demodulation circuits outputs an output signal from the tuner device to one of the two types. A phase comparator (61) supplied to the input side, and a loop amplifier (62) which inputs and amplifies and outputs the output from the phase comparator,
A first low-pass filter (63) for filtering and outputting an amplified output from the amplifier, and a frequency corresponding to the tuner device output frequency are generated by inputting the output of the first low-pass filter as a control voltage. And a first voltage controlled oscillator (65) for supplying to the other input side of the phase comparator (61), and a PLL circuit which uses the output of the first low pass filter as a demodulation output. An FM demodulation circuit, the second demodulation circuit of the two types of demodulation circuits is a second voltage controlled oscillator (66) that generates a frequency corresponding to the tuner device output frequency, and a 90 ° phase shifter ( 78)
And a first multiplier (67) which receives the output from the tuner device and the output from the second voltage controlled oscillator, multiplies the both, and outputs the output, and the output of the first multiplier. Second low-pass filter (69) that outputs after filtering
And an output from the tuner device and an output obtained from the second voltage controlled oscillator (66) through the 90 ° phase shifter (78) are input, and the outputs are obtained by multiplying both.
A multiplier (68), and a third low-pass filter (70) for filtering and outputting the output of the second multiplier,
Using a synchronous detection circuit consisting of the output of the second low-pass filter (69) and the third low-pass filter (7).
0) to obtain a demodulation output from the quadrature signal demodulation circuit, and when the first demodulation circuit is selected, the output from the tuner device is supplied to the phase comparator (61) in the first demodulation circuit. When the second demodulation circuit is selected by supplying the output from the tuner device, the output from the tuner device is supplied to the first and second multipliers (67, 68) of the second demodulation circuit. A first switching means (22) for switching the connection so as to supply power to the side, and the first voltage controlled oscillator (65) is turned on when the first demodulation circuit is selected, and turned off when not selected. Second control means (81) for turning on the second voltage controlled oscillator (66) when selecting the first control means (80) and the second demodulation circuit, and turning off when not selecting the second demodulation circuit. And, And a receiver.