JP2000151449A - High frequency signal receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency signal receiver that is made small and employs less number of components. SOLUTION: A filter group 43 adopts a configuration where a through-circuit 51 that passes a CATV broadcast wave and a plurality of filter circuits 52, 53, 54 that have a comparatively smooth attenuation characteristic and pass a ground broadcast wave for each predetermined broadcast wave band are connected in parallel. Thus, the high frequency signal receiver that is made small can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency signal receiving apparatus for receiving both broadcast waves of cable television broadcasting and terrestrial broadcasting.

[0002]

2. Description of the Related Art A conventional high frequency signal receiving apparatus will be described below. As shown in FIG. 4, a conventional high-frequency signal receiving apparatus includes an input terminal 1, a switch unit 2 connected to the input terminal 1, a filter group 3 connected to the switch unit 2, and a filter group 3 connected to the switch unit 2. A switch unit 4 connected to the output and selecting one filter from the filter group 3; an automatic gain control circuit (hereinafter referred to as an AGC circuit) 5 connected to the output of the switch unit 4;
The tuner 6 includes a tuner 6 connected to the output of the circuit 5, a demodulator 7 connected to the output of the tuner 6, and an output terminal 8 connected to the output of the demodulator 7.
The switch unit 2 and the switch unit 4 are operated in conjunction with each other to select a filter of a broadcast wave band to be received from a plurality of filters, and the AGC is performed in accordance with the reception intensity of the broadcast wave received from the demodulation unit 7. The circuit 5 was controlled.

The filter group 3 includes a low-pass filter 9 for passing a low band in the VHF band, a band-pass filter 10 for passing a high band in the VHF band, and a UH
The high-pass filter 11 that passes the F band is connected in parallel.

Here, an example of a frequency band will be described with reference to FIG. First, terrestrial broadcast waves will be described. Reference numeral 13 denotes a low band of the VHF band, and its frequency band is from 54 MHz to 88 MHz. 14 is a high band of the VHF band, and its frequency band is from 174 MHz to 2
16 MHz. Reference numeral 15 denotes a UHF band, and its frequency band is from 470 MHz to 806 MHz. As described above, in terrestrial broadcasting, there is a portion without a broadcast wave between bands. On the other hand, a cable television broadcast wave (hereinafter, referred to as a CATV broadcast wave) 16 has a continuous broadcast wave from approximately 50 MHz to 860 MHz.

Therefore, a high-frequency signal receiving apparatus for receiving terrestrial broadcasting and CATV broadcasting receives CATV broadcasting waves continuously from about 50 MHz to 860 MHz, and receives signals from each frequency band when receiving terrestrial broadcasting. Each filter of the filter group 3 needs to have a steep attenuation characteristic (approximately octave 40 dB) so as not to interfere. FIG. 5B shows the filter characteristics. That is,
9a is a pass characteristic of the low pass filter 9, 10a is a pass characteristic of the band pass filter 10, and 11a is a pass characteristic of the high pass filter 11.

In order to obtain such a steep attenuation characteristic, for example, as shown in FIG. 6A, a low-pass filter 9 includes capacitors 22 and 23 between both ends of a parallel circuit of a capacitor 20 and an inductance 21 and the ground. A π-type low-pass filter is formed so that they can be connected to each other to pass a frequency of about 168 MHz or less, and three of them are connected in series to form a low-pass filter having an attenuation characteristic of about 40 dB octave.

The bandpass filter 10 is shown in FIG.
As shown in (b), the capacitor 2 is connected between both ends of the parallel circuit of the capacitor 24 and the inductance 25 and the ground.
6 and 27 are connected to each other to form a π-type low-pass filter capable of passing a frequency of about 378 MHz or less, and three of these are connected in series to form a low-pass filter having an attenuation characteristic of about 40 dB octave; 2
9 are connected in series, and an inductance 31 and a capacitor 30 are connected in series between the connection point thereof and the ground so that approximately 1
A T-type high-pass filter capable of passing a frequency of 68 MHz or higher is formed, and three T-type high-pass filters are connected in series to form a high-pass filter having an attenuation characteristic of approximately 40 dB octave. The low-pass filter and the high-pass filter are connected in series. Thus, the band-pass filter 10 that passes approximately 168 MHz to 378 MHz is formed.

The high-pass filter 11 is also shown in FIG.
As shown in (3), a capacitor 32 and a capacitor 33 are connected in series, an inductance 35 and a capacitor 34 are connected in series between the connection point and the ground, and a voltage of approximately 378 MHz
A T-type high-pass filter capable of passing the above frequencies is formed, and three of these are connected in series to form an octave of approximately 40 dB.
Thus, the high-pass filter 11 having the attenuation characteristic described above is formed.

[0009]

However, in such a conventional configuration, since the terrestrial broadcast waves are discrete, the continuous CATV broadcast waves are received. The frequency band must be continuously covered. Also, in order to receive terrestrial broadcast waves, interference from different bands must be removed.
In order to solve these two problems, the filter needs a steep attenuation characteristic, and in order to realize the steep filter characteristic, the number of parts of the filter is increased and the high-frequency signal receiving device is enlarged. was there.

An object of the present invention is to solve such a problem and to provide a miniaturized high-frequency signal receiving apparatus.

[0011]

In order to achieve this object, a filter group according to the present invention comprises a through circuit for passing a CATV broadcast wave and a plurality of filters for passing a terrestrial broadcast wave for each predetermined broadcast wave band. In which filter circuits having comparatively gentle attenuation characteristics are connected in parallel.

Thus, a downsized high-frequency signal receiving device can be realized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a CATV broadcast wave having broadcast waves continuously at substantially equal intervals, and an input terminal for inputting terrestrial broadcast waves having discrete intervals. A filter group supplied with the signal of the input terminal and covering the broadcast wave band, a switch unit for selecting one of the filter groups, and an output of a filter selected from the filter group. A tuner section, a demodulation section to which an output of the tuner section is supplied, and an output terminal to which an output of the demodulation section is supplied.
The filter group includes a through circuit for passing a CATV broadcast wave, and a plurality of filter circuits having relatively gentle attenuation characteristics for passing a terrestrial broadcast wave for each predetermined broadcast wave band, which are connected in parallel. It is a signal receiving device. Thus, it is only necessary to use a through circuit for the filter group and to connect in parallel a filter circuit having a relatively gentle attenuation characteristic. The high-frequency signal receiving device provided can be provided. Also, since it has a through circuit, CATV
It is possible to improve the input standing wave ratio (hereinafter, referred to as VSWR) in the entire reception band (50 to 860 MHz) when receiving broadcast waves.

According to a second aspect of the present invention, there is provided the high-frequency signal receiving apparatus according to the first aspect, wherein a wide-band amplifier circuit is provided between the filter group and the tuner unit. Therefore, even when the AGC circuit has a through characteristic at the time of receiving a terrestrial broadcast wave, impedance mismatch does not occur.

According to a third aspect of the present invention, an automatic gain control circuit is provided between the filter group and the wide band amplifier.
Since the automatic gain control circuit is provided in this way, even if a terrestrial broadcast wave input with a strong electric field is input, distortion in the broadband amplifier circuit is eliminated.

According to a fourth aspect of the present invention, there is provided a filter group comprising a through circuit formed only of a printed pattern, a parallel circuit of a capacitance and an inductance, and a capacitance provided between both ends of the parallel circuit and the ground. A first low-pass filter formed and passing a low band of the VHF band, a second circuit formed by a parallel circuit of capacitance and inductance, and a capacitance provided between both ends of this parallel circuit and ground.
And a first high-pass filter portion formed by a low-pass filter portion and a series circuit of two capacitances and an inductance provided between a connection point of the series circuit and the ground, and passes a high band of a VHF band. And a second high-pass filter formed by a series circuit of two capacitors and an inductance provided between a connection point of the series circuit and the ground and passing the UHF band. Claim 1
, A filter group can be formed with a very small number of components, which can contribute to miniaturization.

According to a fifth aspect of the present invention, there is provided a filter group comprising a through circuit formed only of a printed pattern, a parallel circuit of a capacitance and an inductance, and a capacitance provided between both ends of the parallel circuit and the ground. A first low-pass filter formed and passing a low band of the VHF band, a second circuit formed by a parallel circuit of capacitance and inductance, and a capacitance provided between both ends of this parallel circuit and ground.
And a first high-pass filter section formed of a low-pass filter section, a series circuit of two capacitances, and a series circuit of capacitance and inductance provided between a connection point of the series circuit and the ground. And a series circuit of two capacitors and a series circuit of a capacitance and an inductance provided between a connection point of the series circuit and the ground and pass the UHF band. 2. The high-frequency signal receiving device according to claim 1, wherein the high-frequency signal receiving device is formed by a second high-pass filter that is capable of forming a high-performance filter group with a small number of components, thereby contributing to downsizing.

According to a sixth aspect of the present invention, the tuner section is the high-frequency signal receiving apparatus according to the first aspect using a single tuner. Since a single super tuner is used as described above, a noise figure (hereinafter, referred to as a noise figure) will be described. NF). In addition, since it is a single super tuner, a reduction in price can be realized.

The tuner section of the invention according to claim 7 is the high-frequency signal receiving apparatus according to claim 1 using an up-down converter. Since the tuner section uses an up-down converter that is a double supermarket, A high-frequency signal receiving device with less image disturbance is obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the high-frequency signal receiving device. In FIG. 1, a high-frequency signal receiving apparatus according to the present embodiment includes an input terminal 41 for inputting both a CATV broadcast wave having broadcast waves continuously at substantially equal intervals and a terrestrial broadcast wave having discrete intervals. A switch unit 42 connected to the input terminal 41 for selecting an arbitrary band of the entire broadcast wave band, a filter group 43 covering the entire broadcast wave band supplied from the switch unit 42, A switch section 44 connected to the output of the group 43 and selecting one of the filters in conjunction with the switch section 42 from the output; an AGC circuit 45 to which the output of the switch section 44 is connected; A wide-band amplification circuit 46 to which an output is connected;
6, an AGC circuit 47 to which the output of the AGC circuit 47 is connected, a tuner 48 to which the output of the AGC circuit 47 is connected, a demodulator 49 to which the output of the tuner 48 is connected, and an output of the demodulator 49 And an output terminal 50. The control terminal 55 controls the switch unit 42 and the switch unit 44 in an interlocked manner, and selects one filter from the filter group 43. The demodulation section 49 controls the gains of the AGC circuits 45 and 47.

Here, the filter group 43 includes a through circuit 51 for passing a CATV broadcast wave, and a VH which is a terrestrial broadcast wave.
Low-pass filter 52 that passes the low band of the F band
, A band-pass filter 53 for passing a high band in the VHF band, and a high-pass filter 5 for passing in the UHF band.
4 are connected in parallel. These filters have relatively gentle attenuation characteristics.

That is, as shown in FIGS. 2A and 2B,
The CATV broadcast wave 16 has a continuous broadcast wave, and the through circuit 51 is used exclusively for the CATV broadcast wave in order to receive the approximately continuous broadcast wave of 50 MHz to 860 MHz. Next, terrestrial broadcast waves will be described. 13
Is the low band of the VHF band, and its frequency band is 54
MHz to 88 MHz. Reference numeral 14 denotes a high band of the VHF band, and its frequency band is from 174 MHz to 216 MHz. Reference numeral 15 denotes a UHF band, and its frequency band is from 470 MHz to 806 MHz. As described above, in terrestrial broadcasting, there is a portion without a broadcast wave between bands.
Therefore, as shown in FIG. 2B, for the reception of the terrestrial broadcast, the pass characteristic 52a of the low-pass filter 52 is VHF
Only the low band of the band (54 MHz to 88 MHz) may be passed. The pass characteristic 53a of the band-pass filter 53 is high in the VHF band (174 MHz to 216 MHz).
MHz), and the high-pass filter 54
Of the UHF band (470 MHz to 806 MHz).
Hz) only. That is, since the through circuit 51 is provided separately, there is no need to consider the pass characteristic 51a of the CATV broadcast wave band (50 MHz to 880 MHz). Accordingly, since there is no broadcast wave between 88 MHz and 174 MHz and between 216 MHz and 470 MHz with no terrestrial broadcast wave, the filter characteristic can be moderately attenuated. That is, an attenuation characteristic of about 20 dB per octave is sufficient, and the circuit can be simplified as shown in FIG.

FIG. 3 shows an example of such a simplified filter. As shown in FIG. 3A, the low-pass filter 52 connects capacitors 58 and 59 between both ends of the parallel circuit of the capacitor 56 and the inductance 57 and the ground, respectively, so that a frequency of about 88 MHz or less can be passed. Forming a first low-pass filter of the type.

The band-pass filter 53 is provided as shown in FIG.
As shown in (b), the capacitor 6 is connected between both ends of the parallel circuit of the capacitor 60 and the inductance 61 and the ground.
A second low-pass filter of π type, which can pass frequencies of about 216 MHz or less by connecting
And a capacitor 65 are connected in series, and a capacitor 66 and an inductance 67 are connected in series between the connection point and the ground to form a T-type first high-pass filter capable of passing a frequency of about 174 MHz or more. The band-pass filter 53 is formed by connecting the second low-pass filter and the first high-pass filter in series (there may be no T-type first high-pass filter capacitor 66).

As shown in FIG. 3 (c), the high-pass filter 54 also has a capacitor 68 and a capacitor 69 connected in series, and a capacitor 70 and an inductance 71 connected in series between the connection point and the ground. A T-type high-pass filter capable of passing the above frequencies is formed (there may be no capacitor 70). As described above, since it is only necessary to use the through circuit 51 and connect in parallel a filter having a relatively gentle attenuation characteristic to the filter group 43, the number of elements constituting the filter group 43 may be small, and a small-sized high-frequency signal receiving apparatus may be used. Equipment can be provided.
Also, since the through circuit 51 is provided independently, the CAT
The VSWR in the entire reception band (50 to 860 MHz) when receiving the V broadcast wave can be improved. In addition, since the through circuit 51 is formed only on the printed circuit board by the pattern wiring, no space is required, and the size and weight can be reduced.

Further, since the wideband amplifier circuit 46 is provided between the filter group 43 and the tuner section 48, impedance mismatch does not occur even if the AGC circuit 45 has a through characteristic at the time of receiving a terrestrial broadcast wave. Further, an automatic gain control circuit 45 is provided between the filter group 43 and the broadband amplifier 46.
Is provided, the distortion in the broadband amplifier circuit is eliminated even if there is a terrestrial broadcast input of a strong electric field.

Since the tuner section 48 uses a single tuner, the tuner section 48 is a high-frequency signal receiving apparatus with excellent NF. In addition, cost reduction can be realized. The tuner unit 4
If an up-down converter is used in 8, a high-frequency signal receiving apparatus with less image disturbance will be obtained.

[0028]

As described above, according to the present invention, it is only necessary to use a through circuit for a filter group and to connect filters having relatively gentle attenuation characteristics in parallel, so that the number of elements constituting the filter group is small. And a downsized high-frequency signal receiving device can be provided.

Also, since a through circuit is provided, CA
The VSWR at the time of receiving a TV broadcast wave can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a high-frequency signal receiving device according to an embodiment of the present invention;

FIG. 2 (a) is the same reception band diagram, and (b) is a characteristic diagram of the same filter.

3A is a circuit diagram of the low-pass filter. FIG. 3B is a circuit diagram of the same band-pass filter. FIG. 3C is a circuit diagram of the same high-pass filter.

FIG. 4 is a block diagram of a conventional high-frequency signal receiving device.

FIG. 5 (a) is the same reception band diagram, and (b) is a characteristic diagram of the same filter.

6A is a circuit diagram of the same low-pass filter, FIG. 6B is a circuit diagram of the same band-pass filter, and FIG. 6C is a circuit diagram of the same high-pass filter.

[Explanation of symbols]

 41 input terminal 43 filter group 44 switch section 48 tuner section 49 demodulation section 50 output terminal 51 through circuit 52 low-pass filter 53 band-pass filter 54 high-pass filter

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazutoshi Sato 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 5C025 AA21 AA25 CB03 DA01 DA04 5C056 FA02 FA08 HA15 5J103 AA05 BA06 BA07 CA08 CB05 DA10 FA09 5K062 AA07 AA08 AA10 AB10 AC08 AE05 BA01 BB06 BB10 BC02 BC04 BF07

Claims (7)

[Claims] 1. An input terminal for inputting a cable television broadcast wave having broadcast waves continuously at substantially equal intervals, an input terminal for inputting a terrestrial broadcast wave having discrete intervals, and a signal supplied from the input terminal to supply the broadcast signal. Filters that cover the waveband,
A switch unit for selecting one filter from the filter group, a tuner unit to which an output of a filter selected from the filter group is supplied, a demodulation unit to which an output of the tuner unit is supplied, and a demodulation unit An output terminal to which the output of the filter is supplied.The filter group includes a through circuit that allows a cable television broadcast wave to pass therethrough, and a plurality of comparatively gentle terrestrial broadcast waves that pass a terrestrial broadcast wave for each predetermined broadcast wave band. A high-frequency signal receiving device in which filter circuits having attenuation characteristics are connected in parallel. 2. The high-frequency signal receiving device according to claim 1, wherein a wide-band amplifier circuit is provided between the filter group and the tuner unit. 3. The high-frequency signal receiving apparatus according to claim 2, wherein an automatic gain control circuit is provided between the filter group and the wide band amplifier. 4. A filter group is formed of a through circuit formed only of a printed pattern, a parallel circuit of a capacitance and an inductance, and a capacitance provided between both ends of the parallel circuit and a ground, and a VHF band. , A second low-pass filter section formed by a parallel circuit of capacitance and inductance, and a capacitance provided between both ends of the parallel circuit and the ground, and two capacitances. VHF having a first high-pass filter portion formed by a series circuit of
A band-pass filter that passes the high band of the band;
The second high-pass filter according to claim 1, wherein the second high-pass filter is formed by a series circuit of the plurality of capacitances and an inductance provided between a connection point of the series circuit and the ground, and formed by passing a UHF band. High frequency signal receiver. 5. A filter group is formed by a through circuit formed only of a printed pattern, a parallel circuit of a capacitance and an inductance, and a capacitance provided between both ends of the parallel circuit and a ground, and a VHF band. , A second low-pass filter section formed by a parallel circuit of capacitance and inductance, and a capacitance provided between both ends of the parallel circuit and the ground, and two capacitances. And a first high-pass filter portion formed of a series circuit of capacitance and inductance provided between a connection point of the series circuit and the ground, and passing a high band in the VHF band. And a series circuit of two capacitances and this series circuit 2. The high-frequency signal receiving device according to claim 1, wherein the high-frequency signal receiving device is formed by a series circuit of a capacitance and an inductance provided between a connection point of a road and a ground, and formed by a second high-pass filter that passes a UHF band. . 6. The high-frequency signal receiving device according to claim 1, wherein the tuner section uses a single tuner. 7. The high-frequency signal receiving device according to claim 1, wherein the tuner section uses an up-down converter.