KR940008596Y1 - Polarization wave controlling circuit of satelite broadcasting receiver - Google Patents

Abstract

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Description

Polarization Control Circuit of Satellite Broadcast Receiver

1 is a conventional polarization adjustment circuit diagram.

2 is a polarization adjustment circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

1: Timer 10: Micom

30: buffer 40: comparison unit

50: voltage output VR ₁ : variable resistor

The present invention relates to a polarization adjustment circuit of a satellite broadcast receiver that can adjust the polarization of the satellite broadcast signal received differently according to ambient conditions when receiving radio waves with an antenna.

The satellite broadcasting signal received through the antenna has a polarization slightly different according to the surrounding conditions, that is, the satellite channel transmitted, the weather, and the program of the transmitting side, so the antenna of the satellite broadcasting receiver has a polarizer to adjust it. .

Such polarizers include a mechanical method of adjusting a polarization by rotating a motor, and a magnetic method of adjusting a polarization by changing magnetization characteristics.

1 is a conventional polarization adjustment circuit diagram for controlling the mechanical polarizer. As shown therein, a timer 1 for generating a pulse, a resistor R ₁ (R ₂ ), and a variable for determining a charge / discharge time constant are shown in FIG. were composed of a resistance (VR), a capacitor (C ₁₎ and a capacitor (C _2), the resistance (R _3), diode (D ₁₎ connected to the timer (1).

In the conventional polarization control circuit configured as described above, when the power supply Vcc is input, the power supply passes through the resistor R ₁ , the variable resistor VR ₁ , and the resistor R ₂ , and is then charged in the capacitor C ₁ . In addition, it is applied to the trigger terminal Q _{1 of the} timer 1, and at this time, a low potential signal is output through the output terminal Q ₂ of the timer 1.

Here, the timer 1 is provided with a threshold value (Threshold Level) is so installed, the voltage charged in the capacitor (C ₁₎ when is still a voltage is charged to the predetermined threshold value, as the trigger input capacitor (C ₁₎ resistance ( R ₂ ) is discharged, and a high potential signal is output through the output terminal Q ₂ of the timer 1.

When the discharge proceeds and reaches the threshold value of the timer 1 again, the capacitor C ₁ is charged as described above while switching to the charging mode, and the above-described charging and discharging operation is repeated, and the circuit becomes an unstable multivibrator. It operates as (Astable Multivibrator) and outputs pulse signal with time constant (t _H ) (t _L ).

The number of charging time constant (t _H) is a _{t H = 0.693 (R 1 +} VR 1 + R 2) and a C _1, can discharge time constant (t _L) is t _L = 0.693R ₂ C ₁ so a variable resistor (VR ₁ ), It is possible to vary the pulse width t _W output by changing the charging time constant t _H.

Therefore, when the pulse signal is applied to the motor of the mechanical polarizer, fine adjustments to the polarization of the satellite broadcast signal can be performed.

However, this method initially sets the adjustment value of one satellite channel, so when the channel is changed, the variable resistance has to be adjusted each time, and the polarization varies according to the weather or the standby state. There has been a problem that the user has to be troublesome.

In addition, the conventional circuit has a problem that it is impossible to adjust the magnetic polarizer.

The present invention was devised to solve the above problems. When the channel is changed while the polarization adjustment data for each channel is stored, the adjustment data is selected, and the amount of current is varied according to this value. It is possible to adjust the polarization by changing the magnetization characteristics of the digging, with reference to the accompanying Figure 2 will be described in detail an embodiment of the present invention.

2 shows a polarization adjustment circuit of the present invention for controlling a magnetic polarizer.

Here, reference numeral 10 denotes a microcomputer for controlling the overall operation of the satellite broadcasting receiver, and the polarization adjustment data for each satellite channel is previously stored in the internal memory of the microcomputer 10.

Thus, when the value to be adjusted is selected by the remote control or the internal key operation, the microcomputer 10 outputs this value as binary data, and at the same time, the clock signal and the enable signal are digital / analog converters. Output to (20).

The digital / analog converter 20 converts the input binary data into an analog signal and outputs the analog signal. A reference numeral 30 denotes a buffer for stabilizing the output signal of the digital / analog converter 20. The digital / analog converter 20 The signal output from is applied to the non-inverting terminal (+) of the operational amplifier OP operating as a voltage follower while having a predetermined DC component by the resistor R ₅ (R ₆ ). The output terminal of the amplifier OP is connected to the inverting terminal (-) through the resistor R ₄ .

Reference numeral 40 is a comparator for comparing the output signal of the buffer 30 with a reference voltage and outputting the difference at an appropriate level. The comparator 40 is input to the inverting terminal (−) through the resistor R ₇ . A comparator (COMP) for comparing the output signal of the buffer 30 with a reference voltage set at the non-inverting terminal (+). Diode (D ₂ ) (D ₃ ) turned on and off according to the output of the comparator (COM), and the capacitor (C ₃ ) and the resistor (R ₈ ) fed back to the inverting terminal (-) at the output terminal of the comparator (COMP) Consists of.

Reference numeral 50 is a voltage output unit that adjusts the amount of current applied to the polarizer according to the output level of the cross section 40 and sets the reference voltage of the comparator 40.

The voltage output unit 50 includes a transistor TR ₁ and a capacitor C ₄ operating according to on and off states of the diodes D ₂ and D ₃ , and a diode D for output signal clamping. ₄ ) (D ₅ ) and a resistor (R ₉ -R ₁₁ ) connected to the non-inverting terminal (+) of the comparator (COMP), and the collector of the transistor (TR ₁ ) is a positive (+) polarizer. At the terminals, the connection points of the resistors R ₁₀ and R ₁₁ are respectively connected to the negative terminals of the polarizer.

Thus configured the output level of the voltage output portion 50 has transistors on the early (TR ₁₎ is therefore, the non-inverting terminal (+) of the comparator (COMP) Off (R ₁₀ + R _11), a comparator (COMP), a diode (D ₂ ) After be sufficiently low enough to turn on the (D _3), the diode (D ₂₎ (D ₃₎ is as interconnecting the base potential of the transistor (TR ₁₎ is lowered transistor (TR ₁₎ is conductive, the polarizer ( A voltage of 12V is applied to the + terminal and a voltage set by the resistors R ₁₀ and R ₁₁ is applied to the negative terminal of the polarizer.

The transistor becomes in accordance with the authenticity of the base (TR ₁₎ changes the amount of current Call factor transistor (TR ₁₎ flowing polarized groups, as well as the resistance is distributed by (R ₉ -R ₁₁₎ the non-inverting terminal of the comparator (COMP) ( The reference voltage applied to +) will also vary.

Therefore, the ferrite characteristic is changed according to the DC voltage level applied to the terminal (+) (-) of the magnetic polarizer to fine tune the polarization of the satellite broadcast signal.

As described above, the present invention sets the adjustment data for each channel and selects the corresponding data when changing the channel to adjust the polarization, thereby eliminating the need to adjust the variable resistor manually.

In particular, according to the present invention can be adjusted for the magnetic polarizer, it can also be configured in the form of a combination of the mechanical polarizer and the magnetic method.

Claims (2)

The microcomputer 10 which reads and outputs the data among the polarization adjustment data stored in advance according to the key input, the digital / analog converter 20 which converts the output data of the microcomputer 10 into an analog signal, and the digital / analog converter. The output signal of the buffer 30 and the output signal of the buffer 30 and the set reference are compared with the comparator COMP and the diode D ₂ (D ₃ ) is turned on according to the difference value. And a comparator 40 to be turned off and a voltage output part 50 to adjust the amount of current applied to the polarizer according to the output level of the comparator 40 and to set a reference voltage of the comparator 40. A polarization control circuit of a satellite broadcasting receiver. 2. The transistor TR ₁ and the capacitor C ₄ of claim 1, wherein the voltage output unit 50 operates in accordance with the on and off states of the diodes D ₂ and D ₃ to vary the amount of current to the polarizer. And a resistor (R _9- R ₁₁ ) for dividing the voltage according to the switching state of the transistor (TR ₁ ) to set the reference voltage of the comparator (COM), and a diode (D ₄ ) for clamping the output signal to the polarizer. And (D ₅ ) a polarization adjustment circuit of a satellite broadcasting receiver.