KR0123764B1 - Common use of system l b/g broadcasting formula - Google Patents

Abstract

Disclosed is a public receiving circuit using system L,B/G broadcasting method. The public receiving circuit comprises a L,B/G selection portion which selects an exclusive saw filter for system L and an exclusive saw filter for system B/G in accordance with the exclusive saw filter for system L having wide band width and an exclusive saw filter for system B/G having narrow band width and a control of a MICOM and thereby an adjustment equipment and an adjustment operation are decreased and a coil and a switching circuit are used instead of a trimmer and are switched according to system L,L'. Thus, the temperature characteristic and the reliability are improved.

Description

System L. Non / Digital Broadcast Receive Circuit

1A and 1B are waveform diagrams showing the frequency spectrum of a general system L broadcast system.

2A and 2B are waveform diagrams showing frequency spectrums of a general system B / G broadcasting system.

FIG. 3A is a waveform diagram showing characteristics of a common wideband saw filter of system L and B / G broadcasting, and FIG. B is a waveform diagram showing characteristics of a saw filter of system B / G broadcasting.

4 is a common receiving circuit diagram of a conventional system L and B / G broadcasting system.

5 is a block diagram showing a common reception circuit of the system L, B / G broadcasting system according to the present invention.

FIG. 6 is a detailed circuit diagram of the system L and B / G selector of FIG.

FIG. 7 is a detailed circuit diagram of the oscillation selector of FIG.

8 is a table showing control signals output from the microcomputer according to the present invention.

* Explanation of symbols for main parts of the drawings

10: tuner 100: key matrix

200: micom 300: transpose amplification

400: L, B / G selection part 500: Sour filter for system L

600: saw filter for system B / G 700: receiver

800: first oscillator 900: second oscillator

1000: Oscillation selection part T: Trimmer

C1 to C4: condenser L1, L2: coil

D1 to D7: diodes Q1 to Q4: transistors

The present invention relates to a television capable of simultaneously receiving a system L broadcast system and a system B / G broadcast system, and more particularly, to a surface acoustic wave filter (SAW FILTER) exclusively for a system L. .) And the system B / G dedicated saw filter simultaneously receive the system L broadcasting system and the system B / G broadcasting system at a lower price, and select the system L and L 'by the variable coil so that the stable temperature characteristics are achieved. It relates to a common reception circuit of the system L, B / G broadcast system having a.

In the above description, the surface acoustic wave refers to an elastic wave propagating along the surface of the elastic body, and the saw filter is a foot provided thereon using a substrate or thin film (eg, modified LiNbO ₃ , ZnO, etc.) having piezoelectric characteristics as a transmission medium for surface acoustic waves. A filter that obtains the required frequency characteristics by devising the structure and position of the shaped electrode transducer.

Generally, televisions have NTSC, PAL, SECAM… And N, B / G, H, L, D / K, I, N, etc. according to the broadcasting method. I am sharing my back.

France, which uses a unique broadcasting method called SECAM L, uses the Secam L broadcasting system and the arm B / G to receive PAL B / G broadcasts transmitted from neighboring countries or satellites in addition to its own system L broadcasting. There is a need for a broadcast reception circuit capable of simultaneously receiving a G broadcast method.

FIG. 1 (a) shows the high frequency spectrum of the system VHF-LOW broadcasting method, wherein the frequency bandwidth (i.e., channel bandwidth) between the near video frequency f _ap and the current video frequency f _p is 8 MHz, and the luminance bandwidth is 6.5 MHz, and FIG. 2 (b) takes a modulation scheme opposite to that of the system VHF-LOW system of FIG. 1 (a), wherein the audio frequency f _s is earlier than the image frequency f _p . Incoming frequency bandwidth is shown in FIG.

FIG. 2 (a) shows the high frequency spectrum of the system B broadcast method, wherein the frequency bandwidth between the proximity video frequency f _ap and the current video frequency f _p is 7 MHz, the luminance bandwidth is 5.5 MHz, and FIG. b) shows a high-frequency spectrum of the system G broadcasting method, wherein the frequency bandwidth between the proximity video frequency f _ap and the current video frequency f _p is 8 MHz, and the luminance bandwidth is 5.5 MHz.

At this time, in order to stably receive the system L having a high frequency format as shown in Figs. 1 (a) and (b) and the system B / G having a high frequency format as shown in Figs. A wide band saw filter is used, such as 3 degrees (a).

However, the wide band saw filter of FIG. 3 (a) does not solve the problem of Side Channel Rejection of System B of FIG. 2 (a) with a relatively narrow high frequency bandwidth.

4 is a common receiving circuit diagram of the conventional system L and B / G broadcasting methods for improving side channel rejection of the system B, and uses the microcomputer 2 and the lower frequency gain attenuation trap part 3 of the saw filter. It was.

That is, a preamplifier 1 for amplifying the intermediate frequency pressurized by the tuner, a saw filter 4 for filtering the intermediate frequency amplified by the preamplifier 1, and an output of the saw filter 4 The receiver 5 is configured to receive the video signal based on the oscillation frequency.

The first oscillator 6 and the second oscillator 7 which selectively perform oscillations according to the systems L and L 'are connected between the receiver 5 and the microcomputer 2, and the microcomputer 2 and the saw. Between the filter input stage, a switch S1 which is turned on / off under the control of the microcomputer 2 and a trap part 3 which is driven according to the on / off of the switch S1 are connected.

In addition, the first oscillator 6 has a capacitor C1 and a coil L1 connected to the receiver 5 in parallel, and the second oscillator 7 has a capacitor C3, C4 and a trimmer (variable). The capacitor T is connected in parallel with the first oscillation unit 6.

The micom 2 recognizes a key input for selecting a broadcast method of a key matrix (not shown) and outputs a logic signal. That is, when a key corresponding to the system B is input, the microcomputer 2 outputs a high level signal to the control panel of the switch S1 to turn on the switch S1.

When the switch S1 is turned on, the trap unit 3 is driven to attenuate the gain of the lower frequency of the intermediate frequency input from the tuner to the saw filter 4 through the preamplifier 1. Output to the filter (4).

When the switch S1 is turned off under the control of the microcomputer 2, the trap part 3 does not affect the input intermediate frequency signal.

However, in the case of using the trap 3, there is a problem in that the adjustment equipment and the man-hour are increased in view of production.

On the other hand, when a key corresponding to the system L 'is input to the microcomputer 2, the microcomputer 2 outputs a high level signal to the second oscillator 7 and outputs the trimmer T of the oscillator 7. Control was made to oscillate the reference frequency (34.45 MHz) for the system L '.

However, the trimmer (T) has a problem in that the temperature characteristics are poor, reducing the reliability of the receiver.

The present invention has been made to solve this problem, and an object of the present invention is to use system L and system B / G dedicated saw filters, and to reduce the number of adjustment facilities and man-hours by switching to suit each broadcasting system. / G provides a common receiving circuit of the broadcast method.

It is still another object of the present invention to provide a highly reliable system L, B / G broadcast receiving circuit having stable temperature characteristics by using a coil and a switching circuit instead of a trimmer and switching according to the system L, L '. have.

Features of the present invention for achieving this object, a tuner for converting the high frequency received from the antenna to an intermediate frequency and output, a pre-amplification unit connected to the output terminal of the tuner to amplify the intermediate frequency output from the tuner; A key matrix for inputting a channel to be received using a key, a microcomputer connected to an output terminal of the key matrix and outputting a control signal according to a key signal input to the key matrix, and an output terminal of the preamplifier part at an input terminal of the key matrix; An intermediate frequency amplified by the preamplifier by being connected to a L, B / G selector connected to the control unit and connected to a first output terminal of the microcomputer on or off, and to a first output terminal of the L and B / G selector; A sawing filter for a wide-band system L for filtering a and a second amplified portion of the L / B / G selector and amplified by the preamplifier. System L, which consists of a narrow-band system B / G saw filter for filtering frequencies and a receiver connected to the output of the system L and B / G saw filters to detect a video signal based on an intermediate frequency reference frequency. It is in a common receiving circuit of B / G broadcasting system.

In still another aspect of the present invention, there is provided a key matrix for inputting a channel desired to be received using a key, a microcomputer connected to an output terminal of the key matrix and outputting a control signal according to a key call input to the key matrix; An oscillation selector connected to a second output terminal of a microcomputer and being turned off when a control signal corresponding to the system L 'is provided through the second output terminal of the microcomputer; and a system L connected to one side of the oscillation selector and turned off when the oscillation selector is turned off. A first oscillator for tuning oscillation, a second oscillator for connecting to the other side of the oscillator and the oscillation selector and the oscillator selector when the oscillation selector is turned on in parallel with the first oscillator for system L, B / G tuning oscillation The system L and the B / G broadcasting system of the oscillation unit is a common receiving circuit.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

5 is a block diagram showing a common receiving circuit of the system L, B / G broadcasting system according to the present invention, is connected to the microcomputer 200 for controlling the entire system and the input terminal of the microcomputer 200 is connected to the microcomputer ( The key matrix 100 for outputting a key input that can be determined by the 200, the preamplifier 300 for amplifying the intermediate frequency output from the tuner 10, and the preamplifier 300 at the input stage A L, B / G selector 400 connected to a control terminal connected to a first output terminal POSCTL of the microcomputer 200 and controlled according to the control of the microcomputer 200, and the L and B / G selections. Saw filter 500 for system L connected to the first output terminal of the unit 400, and S / s B system for the system B / G connected to the second output terminal (L 'CTL) of the L and B / G selector 400. It is connected to the filter 500 and the output of the system L, B / G saw filter 500, 600, the system L, based on the reference frequency of the intermediate frequency, Receiving unit 700 for detecting the video signal from the output of the B / G saw filter (500, 600), and the oscillation selector (1000) connected to the second output terminal of the microcomputer 200 and switched in accordance with the system L, L ' And a first oscillator 800 connected between the receiver 700 and the oscillation selector 1000 to oscillate at 34.45 MHz, and connected to the oscillation selector 1000 to turn on the oscillation selector 1000. The second oscillator 900 is connected in parallel with the first oscillation selector 800 and oscillates at 38.9 MHz.

FIG. 6 is a detailed circuit diagram of the L and B / G selector 400. Transistors Q1 and Q2 turned on / off by receiving a control signal from the microcomputer 200 and the power amplifier 300. FIG. A capacitor C1 connected to an output terminal of the power amplifier 300 to DC-couple the output of the power amplifier 300, and a connection between the capacitor C1 and the power voltage terminal B + to turn on the transistors Q1 and Q2. The resistors R1 and R2 for dividing the power supply voltage B +, and the resistors R3 and R4 for dividing the power supply voltage B + when the transistors Q1 and Q2 are turned off. It consists of 1st-4th diodes D1-D4.

In this case, the anode terminal of the first diode D1 is connected to the contact B, which receives the power supply voltage when the transistor Q2 is turned on, and the cathode terminals of the first and second diodes D1 and D2 are capacitors ( C3) is commonly connected to the input terminal of the saw filter 600 for system B / G. The anode end of the second diode D2 and the cathode end of the third diode D3 are commonly connected to the capacitor C1, and the anode end of the third and fourth diodes D3 and D4 is the capacitor C4. The common terminal is connected to the input terminal of the S L filter 500 for the system L, and the cathode terminal of the fourth diode D1 is connected to the contact A, which receives the power supply voltage when the transistor Q2 is turned on.

FIG. 7 is a detailed circuit diagram of the oscillation selector 1000. An anode terminal of diodes D5 and D6 is connected to both output terminals of the first oscillator 800, respectively, and each of the diodes D5 and D6. The second oscillator 900 is connected to the cathode of the transistor, and the transistors Q3 and Q4 turned on / off according to the control signal of the microcomputer 200 are connected to the second oscillator 900 through the diode D7. do.

FIG. 8 illustrates an example of control signals output from the microcomputer 200 and a control signal output to the L and B / G selector 400 through the first output terminal POS CTL of the microcomputer 200. Outputs high level signal regardless of VHF and UHF if system L, and low level signal if system B / G.

In addition, the control signal output to the oscillation selector 1000 through the second output terminal L 'CTL of the microcomputer 200 outputs a high level signal only when the system VHF-L, and the rest is of a low level. Output the signal.

In the present invention configured as described above, the intermediate frequency output from the tuner 10 is amplified to compensate the gain attenuated when passing through the saw filter in the preamplifier 300, and then L, B / G selector 400 ) Is output to the input terminal of). In this case, if the channel to be received by the user is the system L, the user inputs a key corresponding to the system L using the key matrix 100, and the microcomputer 200 uses the first output terminal POS CTL in FIG. Outputs a high signal to a control terminal of the L and B / G selector 400, and the L and B / G selector 400 to a first output terminal connected to the saw filter 500 for system L. The intermediate frequency switched and output from the preamplifier 300 is input to the S L filter 500 for the system L.

Meanwhile, when the microcomputer 200 recognizes a key signal corresponding to the system B / G, the microcomputer 200 selects the low signal as shown in FIG. 8 through the first output terminal POS CTL, and selects L and B / G. Output to the control stage of the unit 400, the L, B / G selector 400 is switched to a second output stage connected to the system B / G saw filter 600 and the preamplifier 300 The intermediate frequency output from is input to the saw filter 600 for the system B / G.

The saw filter 500 for system L is a wide bandwidth filter as shown in FIG. 3 (a), and the filter 600 for the system B / G system has a relatively narrow bandwidth as shown in FIG. 3 (b). This filter is applicable to the high frequency of B.

The receiver 700 detects a video signal from a signal output from the system L filter 500 or the system B / G filter 600 based on the intermediate frequency reference oscillation frequency.

Meanwhile, when a key corresponding to the system L 'is input through the key matrix 100, the microcomputer 200 outputs a high signal to the oscillation selector 1000 through the second output terminal L ′ CTL and the system L. Or outputs the low signal to which the key corresponding to system B / G is input.

At this time, when the high signal is input to the oscillation selector 1000, the oscillation selector 1000 is selected to be turned off to operate only the first oscillator 800 to oscillate 34.45 MHz, which is an intermediate frequency of the system L '. It serves as a reference frequency of the receiver 700.

On the other hand, when the low signal is input to the oscillation selector 1000, the oscillation selector 1000 is turned on. Accordingly, the coil L1 of the first oscillator 800 and the coil L2 of the second oscillator 900 are provided. The parallel connection is performed to oscillate 38.9 MHz, which is an intermediate frequency for system B / G, to act as a reference frequency of the receiver 700.

Referring to Figure 6 look at the operation of the L, B / G selection unit 400 in more detail as follows.

When the high signal is inputted to the base terminal of the transistor Q1 through the first output terminal POS CTL and recognizes that the system L is from the microcomputer 200, the transistor Q1 is turned on and the transistor Q1 is turned on. The transistor Q2 is also turned on so that the 12V which is the power supply voltage B + is applied to the contacts A and B. Then, 12V is divided by the resistors R1 and R2, and 6V is applied to the contact C.

Therefore, the first diode D1 is turned on so that the potential of the contact B flows to the resistor R5. As a result, the intermediate frequency amplified by the preamplifier 300 is turned on by the third diode D3. It is provided to the saw filter 500 for the system L through the condenser C4.

On the other hand, when the low signal is input to the base terminal of the transistor Q1 through the first output terminal POS CTL by recognizing that it is a system B / G from the microcomputer 200, the transistors Q1 and Q2 are turned off and the contact point is turned on. A and B are applied with potentials in which the power supply voltage B + is divided by the resistors R3 and R4.

At this time, if the resistance (R3)> resistance (R4), the second diode (D2) is turned on and the intermediate frequency amplified by the preamplifier 300 is the system through the second diode (D2) and the capacitor (C3) It is provided to the saw filter 600 for B / G.

Meanwhile, the operation of the oscillation selection unit 100 will be described in more detail using FIG. 7 as follows.

When the high signal that recognizes the system L 'from the microcomputer 200 is input to the base terminal of the transistor Q3 of the oscillation selector 1000 through the second output terminal L' CTL, the transistor Q3 is turned on. When the transistor Q3 is turned on, the transistor Q4 is also turned on to apply the power supply voltage B + to the diode D7. Accordingly, the diodes D5 and D6 are turned off, so that the first oscillator 800 and the second oscillator are turned off. The oscillator 900 is open.

34.45 MHz is oscillated by the following Equation 1 and provided to the receiver 700.

When the low signal that recognizes the system L from the microcomputer 200 is input to the base terminal of the transistor Q3 of the oscillation selector 1000 through the second output terminal L 'CTL, the transistors Q3 and Q4 Since the diode D7 is turned off and the diode D7 is turned off, the diodes D5 and D6 are turned on so that the coil L of the first oscillator 800 and the coil L2 of the second oscillator 900 are connected in parallel to each other. The MHz is oscillated by the following Equation 2 and provided to the receiver 800.

That is, when the coils are connected in parallel, the inductance value of the coils is lowered and thus the frequency is increased.

As described above, the present invention uses the system L and system B / G dedicated saw filters, and switches to suit each broadcasting system, thereby reducing the adjustment equipment and man-hour, and using the coil and the switching circuit instead of the trimmer, the system L, By switching according to L 'has a stable temperature characteristics and has the effect of increasing the reliability.

Claims (8)

A tuner 10 converting the high frequency received from the antenna into an intermediate frequency and outputting the intermediate frequency, and a preamplifier 300 connected to an output terminal of the tuner 10 and amplifying the intermediate frequency output from the tuner 10; The microcomputer 100 for inputting a channel to be received using a key and a key signal connected to an output terminal of the key matrix 100 and outputting a control signal according to a key signal input to the key matrix 100 ( 200 and the input terminal, the output terminal of the preamplifier 300 is connected, and the control terminal, the first output terminal (POS CTL) of the microcomputer 200 is connected, on, off L, B / G selector 400 And a wide-band saw filter 500 for system L connected to a first output terminal of the L and B / G selector 400 to filter the interlayer frequency amplified by the preamplifier 300; The preamplifier 300 is connected to the second output terminal of the L and B / G selector 400. It is connected to the output of the narrow B / G saw filter 600 for filtering the intermediate frequency amplified in the, and the S, L, B / G saw filter (500, 600) for the video based on the intermediate frequency reference frequency Common receiving circuit of the system L, B / G broadcast system consisting of a receiver 700 for detecting a signal. 2. The transistor of claim 1, wherein the L and B / G selector 400 is connected to a first output terminal POS CTL of the microcomputer 200 and is turned on / off by the transistors Q1 and Q2. When Q1 and Q2 are turned on, the resistors R1 and R2 and the transistors Q1 and Q1 which divide the power supply voltage B + by half to make the contact point C are at a half potential of the power supply voltage B +. When turned off, the resistor R3 and R4 divide the power supply voltage B +, and the first to fourth diodes D1 to D4 which serve as a switching element, and the anode terminal of the first diode D1 is When the transistor Q2 is turned on, it is connected to the contact point B, which is applied with the power supply voltage, and the cathode stages of the first and second diodes D1 and D2 are connected to the sour filter 600 for the system B / G through the capacitor C3. The common terminal is connected to the input terminal, the anode terminal of the second diode D2 and the cathode terminal of the third diode D3 are connected in common with the condenser C1, and the anode terminal of the third and fourth diodes D3 and D4 is a condenser. (C4) System L and B / which are commonly connected to the input terminal of the saw filter 500 for the system L, and the cathode terminal of the fourth diode D1 is connected to the contact A which is supplied with the power supply voltage when the transistor Q2 is turned on. G broadcasting system common receiving circuit. The key matrix 100 for inputting a desired channel using a key and the microcomputer 200 connected to an output terminal of the key matrix 100 and outputting a control signal according to a key signal input to the key matrix 100. And an oscillation that is turned off when the control signal corresponding to the system L 'is provided through the second output terminal L' CTL of the microcomputer 200 and is connected to the second output terminal L 'CTL of the microcomputer 200. A first oscillator 800 connected to one side of the selector 1000 and the oscillation selector 1000 to perform oscillation for system L 'when the power generation selector 1000 is turned off, and the oscillation selector ( A system L consisting of a second oscillation part 800 connected to the other side of the oscillation selector 1000 when the oscillation selection part 1000 is turned on and connected in parallel with the first oscillation part 800 to perform oscillation for system L and B / G tuning; Common receiving circuit of B / G broadcasting system. The common receiving circuit of claim 3, wherein the first oscillator (800) comprises a capacitor (C1) and a coil (L1) connected in parallel. The common receiving circuit of the system L, B / G broadcasting method according to claim 3, wherein the second oscillator (900) comprises a coil (L2). 4. The method of claim 3, wherein when the oscillation selector 1000 is turned off, the coil L1 of the first oscillator 800 and the coil L2 of the second oscillator 900 are opened to have a system L 'week frequency. A common reception circuit of the system L, B / G broadcasting method, characterized in that the MHz oscillation is performed by the following equation. According to claim 3, When the oscillation selector 1000 is turned on, the coil L1 of the first oscillator 800 and the coil L2 of the second oscillator 900 are connected in parallel to the system L, B / G A common reception circuit of a system L, B / G broadcasting system, characterized in that an intermediate frequency of 38.9 MHz is oscillated by the following equation. The oscillation selector 1000 is connected to a second output terminal L ′ CTL of the microcomputer 200 and is turned on / off by the transistors Q3 and Q4 and the first oscillator 800. Anode terminals are respectively connected to both terminals of the second oscillation unit, and cathodes D5 and D6 are respectively connected to the terminals of the second oscillator 900 and the transistors Q3 and Q4 are turned on to be turned on. The first oscillator 800 and the second oscillator 900 are opened by turning off the D5 and D6. When the transistors Q3 and Q4 are turned off, they are turned off to turn on the diodes D5 and D6. A common reception circuit of the system L, B / G broadcasting system comprising a diode (D7) connecting the oscillator 800 and the second oscillator 900 in parallel.