JPH0879114A - Detected signal output circuit - Google Patents

Abstract

PURPOSE: To make the amplitude and polarity of detected signals the same by a variable resistor and to mach an external connection equipment and an internal signal processing circuit. CONSTITUTION: A reference voltage divider circuit 2 constituted of plural resistors R1-R3, switching circuits SW1-SW3 and a variable resistor VR1 are connected to the reference voltage generation terminal 13 of a wide band amplifier 1 and further, a 1/2 reference voltage generation circuit 3 for generating a voltage which is 1/2 of a reference voltage is connected. By connecting the middle point of the variable resistor to the grain control terminal 14 of the wide band amplifier 1 and controlling the switching circuit corresponding to a receiving satellite, the gain and polarity of the wide band amplifier 1 are controlled and the amplitude and polarity of the detection signals as made the same.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection output circuit for satellite broadcasting and satellite communication receivers.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional satellite broadcasting and satellite communication receiver.
An example of a detection output circuit (hereinafter referred to as a receiver) will be shown.
In FIG. 3, 1 is an FM demodulation input terminal 11 and a detection output terminal
12, a wide band amplifier having a reference voltage generating terminal 13 and a gain control terminal 14, 2 has a resistor R1 connected in series, a plurality of variable resistors VR1 and VR2, and switch circuits SW1 and SW2 connected in parallel to the R1 and VR2. It is a reference voltage dividing circuit. Of the R1, VR1 and VR2 connected in series, one end of R1 is connected to the reference voltage generating terminal 13 and VR2
Is grounded at one end, and the variable sliding part of VR1 is at the gain control terminal 1
Connected to 4. Inputs 4 to 7 illustrated in FIG. 3 are satellites (1) to
Input signals 1 to 4 when (4) is received, the amplitudes and polarities of which are different from each other, and the output signal 8 is adjusted by the reference voltage dividing circuit 2 of the wideband amplifier 1 to obtain the inputs 4 to 7
Shows the state where the amplitude and the polarity of the detection signal are the same.

As described above, the detection output circuit of the receiver is
The detection output terminal 12 is provided for connection with an external device (not shown), but the FM differs depending on the satellites 1 to 4 to be received.
Corresponding to the modulation degree and the signal polarity after FM demodulation, it is necessary to make the amplitude and polarity of the detection signal the same to form the output signal 8. Further, in the internal signal processing, since the detection signals having the same amplitude and polarity are input to the subsequent circuit, the signal processing can be performed with low distortion.

Regarding the conventional example constructed as described above,
The operation will be described below. The ON / OFF operation of each of the switch circuits SW1 and SW2 of the reference voltage dividing circuit 2 is an example of the satellite.
This is performed by a control unit (not shown) according to (1) to (4).

When the receiver receives the satellite (1) and the input signal 1 of the input 4 is input to the wide band amplifier 1, the switch circuits SW1 and SW2 in the reference voltage dividing circuit 2 are turned on, and
At, the gain control voltage V of the wide band amplifier 1 becomes V1 and the gain G becomes G1.

When the receiver receives the satellite (2) and the input signal 2 of the input 5 is input to the wide band amplifier 1, the switch circuit SW1 in the reference voltage dividing circuit 2 is turned off and SW2 is turned on. 2, the gain control voltage V of the wide band amplifier 1 is V
2 and the gain G becomes G2.

When the receiver receives the satellite (3) and the input signal 3 of the input 6 is input to the wide band amplifier 1, the switch circuit SW1 in the reference voltage dividing circuit 2 is turned on, and SW2 is turned off. 2, the gain control voltage V of the wide band amplifier 1 is V
3 and the gain G becomes G3.

When the receiver receives the satellite (4) and the input signal 4 of the input 7 is input to the wide band amplifier 1, the switch circuits SW1 and SW2 in the reference voltage dividing circuit 2 are turned off,
, The gain control voltage V of the wide band amplifier 1 becomes V4 and the gain G becomes G4.

Switching of the gain and the polarity of the wide band amplifier 1 of the detection output circuit illustrated in FIG. 3 is performed by one resistor R1, a plurality of variable resistors VR1 and VR2, and switch circuits SW1 and S1.
This is performed only by the reference voltage dividing circuit 2 constituted by W2, and in order to absorb the variation in the gain of the wide band amplifier 1 itself, a switch circuit SW is provided by a control unit (not shown).
It was necessary to turn on and off 1 and SW2 and adjust two variable resistors VR1 and VR2 for each signal polarity after FM demodulation.

[0010]

As described above, in the conventional detection output circuit of the receiver, there are many adjustment points, and there is a problem that complicated work occurs in the production process of the receiver.

The present invention solves the above-mentioned problems of the prior art by adjusting the gain of a wide band amplifier with one variable resistor at an arbitrary signal polarity after FM demodulation, and with the other signal polarity. An object of the present invention is to provide an inexpensive receiver by simplifying the work in the production process of the receiver having an unnecessary detection output circuit.

[0012]

In order to achieve the above-mentioned object, the present invention corresponds to an FM modulation degree and a signal polarity after FM demodulation which are different depending on a receiving satellite in a satellite broadcasting or satellite communication receiver, and has an amplification degree. A wideband amplifier for changing the polarity so that the amplitude and polarity of the detection signal are the same, a 1/2 reference voltage generating circuit for generating a voltage of 1/2 of the reference voltage of the wideband amplifier, and a gain of the wideband amplifier. And a reference voltage dividing circuit composed of a plurality of resistors for controlling the polarity, a switch circuit and one variable resistor.

[0013]

According to the present invention, the detected signal can be adjusted by adjusting only one variable resistor to correspond to the FM modulation degree and the signal polarity after FM demodulation which differ depending on the receiving satellite, and by changing the amplification degree and the polarity of the wide band amplifier. It is possible to realize a detection output circuit in which the amplitude and the polarity are the same, and it is possible to provide an inexpensive receiver.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows satellite broadcasting in an embodiment of the present invention.
It is a block diagram of a detection output circuit of a satellite communication receiver. In FIG. 1, portions different in configuration from those in FIG. 3 will be described. The reference voltage dividing circuit 2 includes a plurality of resistors R1, R2, R3 connected in series, one variable resistor VR1 connected in parallel with the resistor R2, and a switch circuit SW1 connected in parallel with the resistors R1, R3. , SW3, and a switch circuit SW having one end connected to the connection point of the resistors R1, R2 and the other end grounded
It consists of two.

One end of the resistor R1 is connected to the reference voltage generating terminal 13 of the wide band amplifier 1, and the wide band amplifier 1 is connected.
The reference voltage for the operation of is output. Further, the variable sliding portion of the one variable resistor VR1 is connected to the gain control terminal 14 of the wide band amplifier 1, and the voltage divided by the reference voltage dividing circuit 2 is inputted.

Reference numeral 3 denotes a 1/2 reference voltage generating circuit, which generates a voltage of 1/2 of the reference voltage dividing circuit 2, so that the first terminal 3a has a resistance R1 of the reference voltage dividing circuit 2. The second terminal 3b is connected to one end of the resistor R3, and the third terminal 3c is grounded.

The gain characteristic of the wide band amplifier 1 is shown in FIG. As shown in FIG. 2, the gain G (vertical axis) changes according to the gain control voltage V (horizontal axis), but the input / output polarities are inverted at 1/2 of the reference voltage. Therefore, input signal 1
When the polarity of the output signal 8 is inverted with respect to 4 to 4, the gain control voltage V needs to be equal to or less than 1/2 of the reference voltage, and when the polarity of the output signal 8 is not inverted, the gain control voltage V is 1/2 of the reference voltage.
It is necessary to be above. Therefore, in the present embodiment, the above-mentioned 1/2 reference voltage generating circuit 3 is newly provided and connected to the reference voltage dividing circuit 2.

The operation of the present embodiment configured as described above will be described below. The on / off operation of each switch circuit SW1, SW2, SW3 of the reference voltage dividing circuit 2 is performed from the satellites 1 to 4 illustrated. This is performed by a control unit (not shown) according to the input signals 1 to 4 of.

In FIG. 1, satellite broadcasting and satellite communication receivers
When the satellite 1 is received by (hereinafter, referred to as a receiver) and the input signal 1 of the input 4 is input to the wide band amplifier 1, the switch circuit SW1 in the reference voltage dividing circuit 2 is turned off and the switch circuit SW2 is turned on. , The switch circuit SW3 is turned off, and the gain control voltage V of the wide band amplifier 1 becomes V1 in FIG.
The gain G is G1. Receiver receives satellite 2 and input 5
2 is input to the wide band amplifier 1, the switch circuit SW1 is turned off, the switch circuit SW2 is turned on, the switch circuit SW3 is turned on, and the gain control voltage V of the wide band amplifier 1 becomes V2 in FIG. Becomes G2. When the receiver receives the satellite 3 and the input signal 3 of the input 6 is input to the wideband amplifier 1, the switch circuit SW1 is turned on, the switch circuit SW2 is turned off, and the switch circuit SW3 is turned on. Gain control voltage V becomes V3, and gain G becomes G3. When the receiver receives the satellite 4 and the input signal 4 of the input 7 is input to the wide band amplifier 1, the switch circuit SW1 is turned off, the switch circuit SW2 is turned off, and the switch circuit SW3 is turned on.
At, the gain control voltage V of the wide band amplifier 1 becomes V4 and the gain G becomes G4.

In this way, FM that differs depending on the receiving satellite
Corresponding to the modulation degree and the signal polarity after FM demodulation, the resistance values of the resistors R1, R2, R3 and the variable resistor VR1 in the reference voltage dividing circuit 2 are optimized and combined with the operation of the switch circuits SW1, SW2, SW3. The gain and the polarity of the wide band amplifier 1 can be controlled by, and the detection signal of the same amplitude and polarity is output.

The variation in gain of the broadband amplifier 1 itself is
Although it can be absorbed by adjusting the variable resistor VR1, the amplitude of the output signal 8 is slightly different from the input signals 1 to 4 of the inputs 4 to 7 in FIG. However, it is a value that poses no problem in practice.

Incidentally, the variation in the resistance value of the variable resistor VR1 is usually ± 25% or more, and when the voltage is divided by the variable resistor VR1 as well, the change in the resistance value of the variable resistor VR1 is caused by the reference voltage dividing circuit 2. Greatly affect the characteristics of. In this reference voltage dividing circuit, the resistor R2 is connected in parallel with the variable resistor VR1 and the resistance value of the resistor R2 is made smaller than the resistance value of the variable resistor VR1 to suppress the influence of the change in the resistance value of the variable resistor VR1. ing. By using high-precision resistors for resistors R1, R2, and R3, a voltage divider circuit with precise voltage dividing characteristics is realized. Further, when receiving a plurality of satellites having different FM modulation degrees, this can be easily realized by increasing the number of combinations of resistors and switch circuits in the voltage dividing circuit.

[0023]

As described above, according to the present invention,
A wide band amplifier, a 1/2 reference voltage generating circuit for generating a voltage of 1/2 of the reference voltage of the wide band amplifier, and a gain of the wide band amplifier, which correspond to the FM modulation degree and the signal polarity after the FM demodulation that differ depending on the receiving satellite. And the amplitude of the detection signal by changing the amplification degree and the polarity of the wide band amplifier by using a detection output circuit consisting of a plurality of resistors for controlling the polarity, a switch circuit and a reference voltage dividing circuit composed of one variable resistor. Since the polarities can be the same, the work can be simplified in the production process of the receiver, and an inexpensive satellite broadcasting or satellite communication receiver can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a detection output circuit according to an embodiment of the present invention.

FIG. 2 is a gain characteristic diagram of the wideband amplifier of FIG.

FIG. 3 is a block diagram of a conventional detection output circuit.

[Explanation of symbols]

1 ... Wideband amplifier, 2 ... Reference voltage dividing circuit, 3 ... 1
/ 2 Reference voltage generation circuit.

Claims (1)

[Claims] 1. In a satellite broadcasting and satellite communication receiver, the amplitude and polarity of a detection signal are made the same by corresponding to the FM modulation degree and the signal polarity after FM demodulation that differ depending on the receiving satellite, and by changing the amplification degree and the polarity. A wide band amplifier, a 1/2 reference voltage generation circuit that generates a voltage that is 1/2 of the reference voltage of the wide band amplifier, a plurality of resistors and switch circuits that control the gain and polarity of the wide band amplifier, and one variable A detection output circuit comprising a reference voltage dividing circuit composed of a resistor.