JPS62208720A - Tuner for satellite broadcast reception - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the noise figure of an indoor receiver and of the voltage standing wave ratio by adding an electronic high frequency signal switching circuit between the two 1st intermediate frequency signal input terminal and the conversion circuit converting the 1st intermediate frequency into the 2nd intermediate frequency and containing them in a metallic case. CONSTITUTION:The 1st intermediate frequency signal from an outdoor frequency converter is impressed to an input terminal 1-H and a signal converted by other outdoor frequency converter is impressed to a signal input terminal 1-V. A signal switching circuit 9 switches either of two inputs, the result is amplified by a high frequency amplifier circuit 2 and a local oscillation frequency signal desired is oscillated by using a voltage impressed from a DC control terminal 7 at a local oscillation circuit 4. The signal is impressed to a mixing circuit 3, the 1st intermediate frequency signal is converted into the 2nd intermediate frequency signal and extracted to an output terminal 6 via an amplifier circuit 5. The gain control is applied by applying a signal to an AGC input terminal 8 so as to keep the signal level to the output terminal constant depending on the input signal level to the input terminal 1-H or 1-V.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a satellite broadcast reception tuner for converting into a first intermediate frequency signal of an outdoor frequency converter in a satellite broadcast indoor receiver.

(Prior Art) A conventional satellite broadcast reception tuner has a configuration that converts one intermediate frequency input signal to a second intermediate frequency. The following description will be made based on the drawings.

In FIG. 3, a first intermediate frequency signal is input to an input terminal 1 by an outdoor frequency converter, is amplified by a high frequency amplifier circuit 2, and is converted into a second intermediate frequency signal by a frequency mixing circuit 3 using a signal from a local oscillation circuit 4. and is taken out to the output terminal 6 via the second intermediate frequency amplification circuit 5. terminal 7
In order to convert the signal input to the input terminal 1 into a second intermediate frequency signal of the channel desired to be received, the local oscillation circuit 4 using a variable capacitance diode or the like is controlled, and the desired second intermediate frequency signal is extracted. . In addition, terminal 8 is AGC
It is a terminal.

C band (3,7G) Iz~4.2G&) in the US
Receiving TV signals from communication satellites in ordinary households is now in full swing, and an example is shown in FIG. The signal ■ from the satellite is received by the parabolic antenna ■, and converted to the first intermediate frequency by the outdoor frequency conversion converter ■.
It is connected to the indoor receiver (P and TV receiver ■) by a coaxial cable ■.In the US C-Pan 1-, the band 5 in the range 3.7 GHz to 4.2 GHz is used as shown in Figure 5.
At 00MHz, signal transmission power of up to 24 channels is possible, and by dividing the two types of horizontal polarization and vertical polarization, 40
Channels are arranged at MHz intervals.

(Problems to be Solved by the Invention) In such a conventional configuration, when receiving a signal received by a parabolic antenna via an outdoor converter,
A polarization converter is interposed in the outdoor converter to switch polarization according to the desired channel. In this method, the insertion loss of the polarization converter cannot be ignored, and there are cases where signals from weak satellites cannot be received with high image quality due to the system noise figure including the outdoor converter, as shown in Figure 6. In many cases, signals are received using an outdoor converter ■-H2■-V dedicated to each polarization. In Figure 6, ■-H2■-■ is an outdoor frequency conversion converter, ■-H9■-■ is a coaxial cable, ■ is an indoor receiver, ■ is a television receiver, ■ is a signal switching device, and ■ is a connection cable. It is. In this case, outdoor converter ■-H.

A signal switching device or multiplexer (2) is used between (1) and (2) and the indoor receiver.

In the case of a signal switching device, channel selection and interlocking are required, making it extremely expensive. Also, the multiplexer will cause inter-channel interference.

Inserting a signal switching device or a multiplexer (■) as described above will cause deterioration of the noise figure of the indoor receiver due to an increase in conversion loss of each device.Furthermore, signal cables for mutual signal connection will be connected. This causes deterioration of the voltage standing wave ratio, and in satellite broadcast reception using FM signals, there is a drawback that the deterioration of the standing wave ratio has an adverse effect on image and sound quality.

The present invention solves the above-mentioned problems, and provides high quality picture and sound quality without causing deterioration of noise figure or voltage standing wave ratio of indoor receivers in conventional systems.
- The purpose is to provide a satellite broadcast reception tuner that has a relatively simple and inexpensive configuration for receiving and reproducing satellite broadcasts.

(Means for Solving the Problem) In order to solve this problem, the present invention provides an input terminal for inputting two first intermediate frequency signals frequency-converted by an outdoor frequency converter for receiving satellite broadcasting.

A conversion circuit consisting of two high frequency amplifier circuits, one frequency mixing circuit, and one local oscillation circuit for converting the first intermediate frequency to a second intermediate frequency, and an output terminal for taking out the second intermediate frequency signal, and two An electronic high frequency signal switching circuit for passing one input signal of the first intermediate frequency signal and blocking the other input signal is connected to the two first intermediate frequency signal input terminals and the first intermediate frequency signal to the first intermediate frequency signal input terminal. It is added between the recordable conversion circuit for converting into two intermediate frequencies and housed in a metal casing.

(Function) With the above-described configuration, the present invention can be used as a satellite reception tuner in terms of the noise figure by adding the conversion loss of the switching device and the increase in mismatch loss due to the cable connection to the deterioration of the noise figure due to the conversion loss of the signal switching circuit. In contrast, by integrating the switching circuit with the frequency conversion section, it becomes possible to optimally design the noise figure with the high frequency amplification circuit at the subsequent stage of the switching circuit.

Furthermore, with the conventional method, there was an adverse effect due to the deterioration of the voltage standing wave ratio due to the cable connection, but with the built-in switching circuit, the impedance matching of the high frequency amplifier circuit and the switching circuit can be designed as a unit, which reduces the impact on the image quality. It can be reduced.

(Embodiment) FIG. 1 is a circuit diagram of a satellite broadcast reception tuner according to an embodiment of the present invention, and FIG. 2 is a block diagram thereof. 1
-H, 1-V are input terminals, 2 is a high frequency amplifier circuit, 3 is a mixing circuit, and 4 is a local oscillation circuit.

5 is a second intermediate frequency signal amplification circuit, 6 is an output terminal, 7 is a DC control terminal, 8 is a terminal, 9 is a signal switching circuit, IO is a signal switching control terminal, 11 a , 11 c , 11 e
, 11 g.

11h is a DC blocking capacitor, llb, lid, ll
f.

11 i , 11 j , 111 c , 11 Q are high frequency bypass capacitors, 12 b , 12 c , 12 e
, 12f , 12g , 12h , 12. j, 12 is a DC bias resistor, 13a to 13d are diodes,
12a and 12d are resistors for impedance correction, 12i are feedback resistors for broadband amplification, 14a and 14b are high-frequency choke coils, 15 is a transistor, and 11 is a DC power supply terminal r-
It is.

The outdoor frequency converter converts the first intermediate frequency (e.g. 9
50MHz ~ 1450MHz) signal input terminal 1-H
(e.g. horizontal polarization channel) and converted by another outdoor frequency conversion device, the signal is applied to the signal input terminal 1-
(For example, vertically polarized channel). The dotted line frame constitutes the signal switching circuit 9.

Positive and negative DC control voltages are applied from the signal switching control terminal 10 . When a positive potential is applied to the terminal 10, the high frequency switching diodes 13a and 13d are in the on state,
Diodes 13b and 13c are turned off and input terminal 1
The signal input to -H is cut off, and the signal input to input terminal 1-V passes through to the 0 point, and is passed through to the high frequency amplifier circuit 2 in the subsequent stage.
A signal is sent to.

On the other hand, when the signal switching control voltage is a negative potential, diode 1
3a and 13d are in an off state, and a diode 13b.

13c is turned on, and the input terminals 1.13c are turned on. - The signal input to H passes through to the 0 point, and the signal input to input terminal 1-V is cut off.

A signal obtained by switching one of the two inputs by the signal switching circuit is amplified by the high frequency amplifier circuit 2, and a desired local oscillation frequency signal is oscillated by the voltage applied by the DC control terminal 7 in the local oscillation circuit 4, and this signal is amplified by the high frequency amplifier circuit 2. By applying the signal to the mixing circuit 3, the first intermediate frequency signal is converted into a second intermediate frequency signal, which is outputted to the output terminal 6 via the second intermediate frequency signal amplifying circuit 5. Input terminal 1-
Gain control is performed by the AGC input terminal 8 so that the signal level to the output terminal is kept constant depending on the input signal level of H or 1-V.

In the conventional configuration as shown in Fig. 6, in impedance matching using the connection cable
In order to handle high-frequency signals in the GHz band, it is necessary to control the input impedance of the high-frequency input terminal of the switching device ■ and the indoor receiver ■, and to consider the length and wire type of the coaxial cable. According to the invention, the cable can be removed, and impedance matching with the amplifier circuit can be optimally selected by appropriately selecting the circuit constants of the impedance correction resistors 12a and 12d and the DC blocking capacitor lie. , the effect of preventing the adverse effects of noise figure deterioration and voltage standing ratio deterioration can be obtained.

(Effects of the Invention) As described above, according to the present invention, with a relatively simple configuration, deterioration in image quality and sensitivity due to deterioration in noise figure and deterioration in voltage standing ratio of a satellite broadcast receiving system can be reduced. Furthermore, according to the present invention, in the conventional receiving system as shown in FIG. It is necessary to consider the length and cable type, resulting in a very expensive system, but with the present invention, it can be configured as one high frequency circuit unit.
By using copper-clad laminated boards for these circuits, coaxial cables, high-frequency connectors, etc. for connection are not required, and a unit with stable characteristics can be realized. In addition, in such a configuration, by having two input terminals, it is not only possible to simultaneously receive both horizontally polarized and vertically polarized signals from one satellite, but it is also possible to receive both horizontally polarized and vertically polarized signals from one satellite, for example. C-band satellite broadcast signal on input, Ku on the other input
It is also possible to input and receive band satellite broadcasting signals, making it possible to increase the functionality of the indoor receiver.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a tuner of the present invention, FIG. 3 is a block diagram of a conventional satellite broadcast reception tuner, and FIG. FIG. 4 shows an example of a satellite broadcast receiving system, FIG. 5 shows an example of American C-band satellite signal channel frequencies, and FIG. 6 shows an example of a simultaneous vertical and horizontally polarized satellite signal receiving system. 1-H, 1-V...input terminal, 2...high frequency amplification circuit, 3...mixing circuit, 4...local rooting circuit,
5... Second intermediate frequency signal amplification circuit, 6... Output terminal, 7... DC control terminal. 8...Terminal, 9...Signal switching circuit, 10...
Signal switching control terminal, 11...DC power supply terminal. 11 a , 11 c , 11 e , 11 g , 1
1 h-DC blocking capacitor, llb, lid
, llf , lli , llj . 11 k, 11 Q...high frequency bypass capacitor, ILa, 12d... impedance correction resistor, 1
2b , 12c , 12e , 12f , 12g , 1
2h, 12j. 12i... Feedback resistor for broadband amplification, 12k... Resistor for DC bias, 13a to 13d... Diode, 14a, 14b... High frequency choke coil, 1
5...Transistor. Patent applicant Matsushita Electric Industrial Co., Ltd. Figure 2 Figure 3 Figure 4 Figure 5 ■-■

Claims (1)

[Claims] Two first intermediate frequency signal input terminals for inputting the first intermediate frequency signal whose frequency has been converted by the frequency converter for outdoor satellite broadcast reception, and a high frequency amplifier circuit for converting the first intermediate frequency to a second intermediate frequency. , comprising a conversion circuit consisting of a frequency mixing circuit and a local oscillation circuit, and an output terminal for taking out a second intermediate frequency signal, passing one input signal of the two first intermediate frequency signals, and passing the other input signal. An electronic high frequency signal switching circuit for cutting off the input signal is added between the two first intermediate frequency signal input terminals and the conversion circuit for converting the first intermediate frequency to the second intermediate frequency, and A tuner for satellite broadcast reception, characterized in that the tuner is housed in a metal casing.