DE19615390A1 - Radio frequency modulation circuit for use in the Pal method - Google Patents

Abstract

A radio frequency (RF) modulating circuit for video tape recorders, game apparatuses and the like belonging to the PAL method is disclosed. Different audio carrier frequencies f1, f2, f3 can be automatically selected in response to switch control signals produced by control section 40 receiving channel select signals CS1, CS2 and at the same time, precise TSG (test pattern) signals are formed by utilizing the audio carrier frequency. The frequency divider 70 (fig.6 not shown) including a cascaded chain of counters, Nand gate, latch circuit and a duty adjusting circuit variably divide the different audio carrier frequencies for the different PAL methods to supply a signal at the same frequency to the TSG circuit. A clamping circuit 51 fixes the potential of the synchronization tip of video signals Vin at a constant level. A switching section 52 selectively supplies the clamped video signals or the test pattern signals TSG to a mixer 56 also receiving frequency modulated audio signals and a carrier signal from oscillator 30.

Description

The present invention relates to a modulation circuit or circuit for a radio frequency (RF) for use with a video recorder (VTR) in gaming devices or the like, who work according to the PAL process. In particular, the present invention an RF modulation circuit for Use in the PAL process, in which different Sound carrier frequencies automatically on the Basis of the B / G process, the I process, the D / K process or the like can be selected in the PAL standard and at the same time accurate TSG signals using the Sound carrier frequency are formed.

As a television transmission method, the NTSC method is generally the PAL process and the SECAM process known. The first procedure is in Korea, the United States of America America and Japan used. The latter will be used in European countries. The PAL process of European countries contains several procedures, such as the B / G procedure, the I method and the D / K method. These Procedures are different depending on the individual states. Furthermore, the various Methods also used sound carrier frequencies different and contain 5.5 MHz, 6.0 MHz and 6.5 MHz as Frequencies.

In the PAL method, when a broadcast channel through a VTR is selected and when the reproduced signals of the VTR in TV signals suitable for the relevant radio channel The output appears to be RF modulated on a television, that appears reproduced picture of the VTR on the television screen under the Prerequisite that the relevant channel of the television is free is.  

A well known RF modulation circuit is shown in FIG. 1.

Referring to FIG. 1 through video signal Vin, will be reproduced as a BAS-signals by a VTR or a game machine by a clamping circuit section 1, which fixes the synchronization tip potential at a constant level. Then the video signals Vin pass through a switching section 3 , in which a group of signals is selected from the video signals and the TSG signals. The selected signals are mixed in a mixer 5 to be output to the television by an RF amplifier 6 . Furthermore, audio signals Ain of the audible band pass through a sound amplifier 2 and a frequency modulation section 4 to be frequency modulated. Then the modulated sound signals are mixed by a mixer 5 and pass through the RF amplifier 6 to be output to the television set.

The TSG signals are called "test signals" or "Test image signals" labeled and included Synchronization signals and video signals with black and White levels.

In the known RF modulation circuit is a mechanical switch Swi in a hidden place, like on placed on the back of a VTR or TV, due to the different sound carrier frequencies to match Broadcasting methods according to the PAL method are feasible. This is a fault-prone facility.

Furthermore, even if rarely by the general consumer The TSG signals are used to test the products formed during manufacture. For this purpose the known RF modulator a capacitor, a sawtooth resonator and a separate oscillator, whereby the Manufacturing costs grow.  

Fig. 2 shows another known RF modulation circuit.

The circuit of Fig. 2 is known from US-A-5 136 387. This RF modulation circuit performs channel selection without using a test pattern generator.

The RF modulator of Fig. 2 includes: an A / D converter for converting the television channel selection data into digital signals; an oscillation control circuit for controlling both the audio channel oscillation and an RF channel oscillation based on the digital channel selection data of the A / D converter; signal mixing means for mixing the amplitude-modulated video signals (which are modulated to match the RF carrier oscillation frequency) with the frequency / amplitude-modulated audio signals which are modulated to match the sound carrier oscillation; a channel capture device for capturing central areas of the channels of the channel selection data and a signal blocking device for blocking the video input signals in end areas which differ widely from the channel capture device.

In the known circuit described above, a capping control circuit 33 is used instead of a test pattern control circuit 34 . The capping control circuit 33 performs the same function as the test pattern control circuit 34 . In addition, an AM modulator 22 includes a clamp circuit 22 a, a clipping circuit 22 b and a modulation circuit 22 c.

This known circuit contains the cap control circuit 33 instead of the test pattern control circuit and this performs the same function as described above for the test pattern control circuit. That is, the clipping circuit performs the function of passing or blocking the incoming video signals. However, no test pattern generator is provided and therefore this known circuit can only be used with a device by means of which signals such as blue black or the like that can be used instead of the test pattern signals are output. Furthermore, the channels are selected by hand using a variable resistor VR. This makes operation of this device uncomfortable.

The present invention has set itself the goal of Disadvantages described above in the known techniques clear out.

The present invention is therefore based on the object an RF modulation circuit for use in the PAL method provide at the appropriate sound carrier frequencies simply in accordance with the B / G process, the I process and the D / K method of the PAL method can be selected are.

Another object of the present invention is Provision of an RF modulation circuit for use with the PAL method, in which the sound carrier frequency is divisible even without a separate resonance device, capacitor and Oscillator to form TSG signals.

Finally, it is an object of the present invention provide accurate TSG signals in which the errors minimal and the accuracy is high because of that in the TSG signals contained errors together with the TSG signals are frequency divided in the RF modulation circuit Use in the PAL process, the sound carrier frequency also without separate resonance device, capacitor and Oscillator is frequency divisible to form the TSG signals.

The RF modulation circuit has the solution to the above tasks for use in the PAL process according to of the present invention: a TSG production area  to generate TSG signals based on a certain input frequency; a clamping circuit for fixing the potential of the video signals Vin at a constant Level; a sound amplifier for amplifying the sound signals; an oscillator circuit with three Sound carrier oscillator circuits based on the Broadcasting process; a frequency modulation range for Frequency modulation of sound carriers by means of an oscillator the output signals of the sound amplifier; a mixer for Mixing the output signals of the frequency modulation range and the output signals of the clamping circuit and accordingly of the TSG production area with the frequencies of one Oscillators; and an RF amplifier to amplify the Output signals of the mixer, the RF modulation circuit continue to have a control area for reading externally entered channel selection signals for the output of Switching control signals and frequency divider control signals and has an oscillation range for selecting and Oscillate one of a variety of oscillating ones Resonance frequencies by means of the multitude of Oscillator resonant circuits of the oscillator resonant circuit area and by means of the switching control signals of the control area.

According to a further aspect of the present invention the RF modulation circuit for use in the PAL method on: A TSG generation area for generating TSG signals based on a specific Input frequency; a clamping circuit for fixing the Potential of the video signals Vin at a constant level; a sound amplifier for amplifying sound signals; one Three oscillator circuit area Sound carrier oscillator circuits based on the Broadcasting process; an oscillation range for oscillation the sound carrier of the oscillator circuit area; one Frequency modulation range for frequency modulation of Sound carriers of an oscillator using the output signals of the Sound amplifiers; a mixer for mixing output signals  the frequency modulation range and output signals of the Clamp circuit area and corresponding to the TSG generation area with frequencies of an oscillator; and one RF amplifier for amplifying the mixer output signals, the RF modulation circuit still being one Control area for reading externally entered Channel selection signals for the output of switching control signals and Frequency divider control signals and a frequency divider range for frequency dividing the oscillation frequency of the Oscillation range based on the frequency divided Control signals of the control area for output of the frequency-divided output to the TSG generation area.

In the following an advantageous embodiment of the Invention based on the figures enclosed in the drawing explained and described in more detail.

Show it:

Fig. 1 is a block diagram showing the construction of a conventional RF modulation circuit;

Fig. 2 is a block diagram showing the construction of another RF modulation circuit;

Fig. 3 is a block diagram showing the construction of an RF modulation circuit according to the present invention;

FIG. 4 shows a detailed circuit diagram of a control area according to FIG. 3;

Fig. 5 is a detailed circuit diagram of an oscillation area shown in Fig. 3; and

FIG. 6 shows a detailed circuit diagram of a frequency divider range according to FIG. 3.

Preferred embodiments of the present invention are described below with reference to FIGS. 3 to 6.

Fig. 3 is a block diagram showing the construction of an RF modulation circuit according to the present invention. A control area 40 reads externally input channel selection signals CS1 and CS2 and transmits switching control signals S1, S2 and S3 to an oscillation area 60 and frequency division control signals C11, C12, C21, C22, C31 and C32 to a frequency dividing area 70 .

An oscillator circuit section comprises a first one Oscillators C1 and L1, a second oscillator C2 and L2 and a third oscillator C3 and L3 to thereby on the Basis of the broadcasting process To form the sound carrier resonance circuit.

A clamp circuit 51 fixes the potential of the synchronization peak potential of the video signals Vin (which are BAS signals) at a constant level.

A switching area 52 switches the signals of the clamping circuit 51 and the signals of a TSG generation area by means of an external adjustment switch SWO. In the case where output signals of the TSG generating section 80 are selected, the switching section 52 has the functions of inactivating the sound amplifier and releasing the frequency dividing section 70 .

A sound amplifier 53 amplifies the sound signals Ain which belong to an audible frequency band.

A frequency modulation section 54 modulates the sound carriers selected from the output signals of the sound amplifier 53 by the oscillation section 60 .

A mixer 55 accordingly mixes the output signals of the frequency modulation section 54 and the output signals of the switching section 52 with the oscillation frequency of the oscillator 34 to output a radio frequency. An RF amplifier 56 amplifies the output signals of the mixer 55 .

An oscillation section 60 carries out the switching operations with the aid of the switching control signals S1, S2 and S3 of the control section 40 in order to oscillate by selecting a frequency from the resonance frequencies F1, F2 and F3 of the oscillator circuit section 50 .

A frequency divider area 70 is released by a signal of the switching area 52 and divides the oscillation frequency of the oscillation area 60 by means of the frequency divider control signals C11, C12, C21, C22, C31 and C32 of the control area 40 . As a result, the frequency dividing section 70 outputs a constant frequency to the TSG generating section at all times.

The TSG generating section 80 , which is a test signal generator, forms TSG signals using the frequency-divided frequency of the frequency dividing section 70 .

FIG. 4 shows a detailed circuit diagram of a control area according to FIG. 3.

The control section 40 includes a first comparison circuit section 41 having a plurality of transistors Q11-Q33 for comparing externally input channel selection signals CS1 and CS2 with an internal reference voltage Vref 1 to output switching control signals S1, S2 and S3, and a second comparison circuit section 43 of the differential type with one A plurality of transistors Q1, Q2, Q3, Q4, Q5 and Q6 for comparing the output signals of the first comparison circuit section 41 with an internal reference voltage Vref2 to output frequency divider control signals C11, C12, C21, C22, C31 and C32.

The frequency divider control signals C11, C12, C21, C22, C31 and C32's control area are in pairs of C11 and C12, C21 and C22 and C31 and C32 are formed and then in one Emitter-coupled logic circuit required.

FIG. 5 shows a detailed circuit diagram of an oscillation range according to FIG. 3.

The oscillation section 60 includes electronic switch sections Q11-Q14, Q21-Q24 and Q31-Q34 for connecting an oscillator circuit C1 and L1, C2 and L2 as well as C3 and L3 of the oscillator circuit section 50 to the oscillation circuits Q41 and Q43 of the oscillation section 60 in accordance with the switch control signals S1 , S2 and S3 of the control section 40 and the oscillation circuits Q41 and Q43 for oscillating the resonance frequency of the connected oscillator circuit.

FIG. 6 shows a detailed circuit view of a frequency divider region 70 according to FIG. 3.

The frequency dividing section 70 includes first, second, third and fourth counters 71 , 72 , 73 and 74 for performing counting operations corresponding to the sets of frequency dividing control signals C11, C21 and C31 or C12, C22 and C32 of the control section 40 ; a NAND area 75 for NANDing the signals from the counters; a lockout area 76 for maintaining the output of the NAND area 75 for a certain period of time, and an operation adjustment area 77 for adjusting the duty ratio of the output signals of the lockout area 76 to a certain value.

CK1 and CK2 are clock signals for Enable the counters, through Q11-Q34 transistors for  Comparison of signals with each other and with R1-R35 Bias resistors called.

The invention and its mode of operation and effects are described below with reference to FIGS. 3 to 6.

Before describing the operation of the present Invention, it should be noted that the channel selection signals CS1 and CS2 have opening and grounding concepts as they connected or disconnected between the Circuit connections and ground in their structures like that electrical circuits and the switches are. Indeed are the status signals to simplify the description of opening and grounding in the following in the form of logical Signals, d. H. "1" and "0" described.

According to FIG. 3, the control section 40 first reads the incoming channel selection signals CS1 and CS2. Then the difference comparison circuit 41 compares the read channel selection signals CS1 and CS2 with an internally set reference voltage Vref 1 . In accordance with the comparison results, switching control signals S1, S2 and S3 with high or low level are output to the oscillation region 60.

In connection with Fig. 4, the operation of the circuit in the following be described in detail.

When a voltage of approximately +5 V is supplied to a voltage source terminal + Vcc of the control section 40 , a voltage of approximately +4 V results at the common collector terminal of the transistors Q1, Q2 and Q3 and at the common collector terminal of the transistors Q4, Q5 and Q6 of the first comparison circuit area 41 . At the same time, a voltage of approximately +2 V is applied as the reference voltage Vref 1 to the base terminals of the transistors Q3 and Q4. Furthermore, a voltage of approximately +2.5 V as the reference voltage Vref2 is supplied to the common base connection of the transistors Q11, Q12, Q21, Q22, Q31 and Q32 of the second comparison circuit region 43 .

In the case described above, the case in which the channel selection signals are input in the form "01" will be described in particular. Due to the channel selection signal CS1 and the reference voltage Vref 1, the transistors Q1 and Q2 of the first comparison circuit region 41 of the control region 40 are switched off, while the transistor Q3 is switched on. Furthermore, on the basis of the channel selection signal CS2 and the reference voltage Vref 1, the transistors Q5 and Q6 of the first comparison circuit region 41 of the control region 40 are switched off and the transistor Q4 is switched on.

In accordance with the operation of the first comparison circuit section 41 of the control section 40 , the switching signals S1, S2 and S3 are output as "010".

Simultaneously with the operations of the first comparison circuit area 41 , the transistors Q33 and Q32 of the second comparison circuit area 43 are turned on and the transistor Q31 is turned off. As a result, the frequency divider control signals are output as "10". Furthermore, transistors Q23 and Q22 are off and transistor Q21 is on. As a result, the frequency divider control signals C21 and C22 are output as "01". Finally, transistors Q13 and Q12 are off and transistor Q11 is on, with the result that the frequency divider control signals C11 and C12 are output as "01".

The mode of operation is in view of the above description analyzed below.

Are the channel selection signals CS1 and CS2 in the form of "10" are entered, the frequency divider control signals C31 and C32  output in the form of "01", the frequency divider control signals C21 and C22 are output in the form "10" and the Frequency divider control signals C11 and C12 are in the form "10" output.

When the channel selection signals CS1 and CS2 are in the form "11" are entered, the frequency divider control signals C31 and C32 in the form "01", the frequency divider control signals C21 and C22 in the form "10" and the frequency divider control signals C11 and C12 output in the form "01".

In the meantime, 3 oscillate in the oscillator resonant circuit portion 50 of FIG., The first tank circuit C1 and L1 with a resonant frequency of 5.5 MHz, the second oscillator resonant circuit C2 and L2 with a resonant frequency of 6.0 MHz and the third tank circuit C3 and L3 having a Resonance frequency of 6.5 MHz. One of these resonance frequencies is selected by the oscillation section 60 in accordance with the circuit control signals S1, S2 and S3 of the control section 40 to perform vibrations. This is described in detail below.

The circuit control signals of the control area 40 according to FIG. 3 are supplied to the oscillation area 60 according to FIG. 4. Of the switching control signals S1, S2 and S3 of the control section 40 , only one is at a low level, while the rest are at a high level.

One of the resonance frequencies F1, F2 and F3 output from the oscillation circuit section 10 is selected in accordance with the low level control signal of the control section 40 and is based on the steady operation of each group of the transistors Q11-Q16, Q21-Q26 and Q31- Q36 of the electronic switching range. Then the selected frequency is supplied to the oscillation circuits Q41 and Q43. As a result, the oscillation circuits Q41 and Q43 oscillate at the resonance frequency of the oscillator oscillation circuits selected by the electronic switching regions Q11-Q36 of the oscillation region 60 before output.

The channel selection signals CS1 and CS2 supplied to the control area 40 are either control signals which are generated by an external microcomputer or status signals which are formed by external mechanical devices. Therefore, the RF modulation circuit according to the present invention can be controlled by external mechanical devices or external electronic devices such as a remote control.

Corresponding to the frequency dividing control signals C11, C12, C21, C22, C31 and C32 of the control area 40 , the frequency dividing area 70 divides 1:22 when a sound carrier with a frequency of 5.5 MHz is fed in at a ratio of 1:24. when it is fed at a frequency of 6.0 MHz and at a ratio of 1:26 when it is fed at a frequency of 6.5 MHz. Consequently, the frequency divider section 70 always feeds 250 KHz to the TSG generating section 80 under the control of the control section 40 . This TSG generation area 80 outputs TSG signals with the same frequency as the frequency supplied by the frequency dividing area 70 .

From the frequency divider control signals C11, C12, C21, C22, C31 and C32 have pairs C11 and C12, C21 and C22, respectively and C31 and C32 mutually inverse logic levels. The required logic levels are system dependent different and consequently two become inverse to each other logic level provided. It is assumed that the Frequency divider control signals C12, C22 and C32 at the present invention can be used.  

In Fig. 6, the case will be described in which the frequency dividing control signals C31 and C32 are output from the control section 40 in the form "10", the frequency dividing control signals C21 and C22 are output from the control section 40 in the form "01" and the frequency dividing control signals C11 and C12 by the control area 40 in the form of "01". That is, when the frequency dividing control signals C12, C22 and C32 are "110", the first counter 71 of the frequency dividing section 70 does not perform a frequency dividing operation, and the second and third counters 72 and 73 perform a frequency dividing operation in a ratio of 1: 2 during that fourth counter 74 performs a frequency divider operation in a ratio of 1: 2 all the time.

Consequently, a frequency division in a ratio of 1:11 occurs in the last counter 74 and in the NAND gate 75 . These 1:11 divided signals are passed through the blocking area 76 to be fed to a mode adjustment area 77 in which the signals are divided 1: 2 so that they are finally divided at a 1:22 ratio. In the meantime, the frequency of 5.5 MHz originating from the oscillation region 60 has been divided in a ratio of 1:22. As a result, signals of 250 KHz are supplied to the TSG generation area 80 .

Based on the processing principle described above, frequency division in a ratio of 1:12 is carried out in the last counter 74 and in the NAND gate 75 if the frequency divider control signals C12, C22 and C32 have the form "001". These 1:12 divided signals pass through the blocking area 76 to be supplied to the mode adjustment area 77 by dividing them in a 1: 2 ratio, thereby obtaining a final 1:24 split. The frequency of 6.0 MHz input from the oscillation area 60 is divided by 1:24, and as a result, signals of 250 KHz are supplied to the TSG generation area 80 .

If the frequency divider control signals C12, C22 and C32 have the form "101", a frequency division in the ratio of 1:13 is carried out in the last counter 74 and in the NAND gate 75 . These 1:13 divided signals pass through the blocking area 76 and are supplied to the mode adjustment area 77 by dividing them in a 1: 2 ratio to be finally divided in a 1:26 ratio. Accordingly, the 6.5 MHz frequency input from the oscillation section 60 is divided in a ratio of 1:26, and as a result, 250 KHz signals are supplied to the TSG generating section 80 .

If a known circuit has a frequency of 500 kHz used, the deviations are approximately ± 10 KHz. in the In contrast, the deviations in the present Invention using a frequency of 500 KHz approximately ± 1 KHz. However, since the present invention has a frequency used by 250 KHz, the deviations are halved reduced by ± 1 KHz. Consequently, according to the TSG signals provided by the present invention slight deviations.

The potential of the synchronization peak of the video signals Vin is fixed at a certain level by the input circuit section 51, and the circuit section 52 performs switching functions to selectively supply a quantity of the video signals or the TSG signals to the mixer 55 .

If the switching area 52 operates in such a way that the TSG signals are selected by an external adjustment switch SWO, the switching area 52 switches off the power supply of the sound amplifier 53 and activates the frequency dividing area 70 . As a result, the possibility of frequency variation of the sound carriers according to the incoming sound signals is eliminated in the case by frequency dividing the sound carrier frequency to be used as TSG signals.

Accordingly, only in the case where the video signals are selected by the switching section 52 , the sound signals Ain are amplified to a certain level by the sound amplifier 53 to be output to the RF modulation section 54 . This RF modulation area 54 modulates the frequency of the sound carrier waves into audio signals as described above to be fed to the mixer 55 .

The mixer 55 either mixes the incoming video signals and the modulated audio signals with the oscillation frequency of the oscillator 34 or mixes the TSG signals with the oscillation frequency of the oscillator 34 . The signals thus mixed are amplified to a certain level by the RF amplifier 56 to be output to an electronic device such as a television or the like.

According to the present invention described above a separate resonator or a separate capacitor for Generation of the TSG signals is not necessary. The sound carriers are frequency divided according to the broadcasting method and consequently, a constant frequency becomes the TSG circuit fed at all times to generate the TSG signals. While the known oscillator circuits and oscillators one Deviation of approximately ± 10 KHz, is according to the present invention, the deviation is therefore drastic reduced because the deviation along with the oscillating Frequency is frequency divided. The TSG signals are corresponding more accurate.

Furthermore, according to the present invention, it follows that different sound carrier frequencies simply according to the different broadcasting methods, d. H. B / G process, I process  and D / K methods of the PAL method are selected can be. Consequently, using the Sound carrier frequencies formed the TSG signals.

Furthermore, according to the present invention, more precise TSG signals without the use of separate resonators and Capacitors are obtained in the formation of the TSG signals. Likewise, the broadcasting method can be easily used of an electronic switch in the oscillation area can be switched.

The descriptions above show one preferred Embodiment of the invention and therefore are variations and modifications within the scope of the present invention possible.

Claims (17)

1. An RF modulation circuit for use in the PAL method, characterized by
a TSG generating area ( 80 ) for generating TSG signals based on a certain input frequency;
a clamp circuit ( 51 ) for fixing the potential of the video signals at a constant level;
a sound amplifier ( 53 ) for amplifying sound signals;
an oscillator circuit section ( 50 ) consisting of three sound carrier oscillator circuits based on the broadcasting method;
a frequency modulation section ( 54 ) for frequency modulating the sound carriers from an oscillator ( 60 ) by means of output signals of the sound amplifier ( 53 );
a mixer ( 56 ) for mixing the output signals of the frequency modulation section and the output signals of the clamping circuit section and the TSG generation section accordingly with a frequency of an oscillator; and
an RF amplifier ( 56 ) for amplifying the mixer output signals, the RF modulation circuit ( 54 ) further comprising: a control area ( 40 ) for reading externally input channel selection signals for outputting switching control signals and frequency dividing control signals and
an oscillation section ( 60 ) for selecting and oscillating a plurality of oscillating resonance frequencies by means of the plurality of oscillator circuits of the oscillator circuit section ( 50 ) and by means of the switching control signals of the control section ( 40 ). 2. The RF modulation circuit according to claim 1, characterized by
a switching area ( 52 ) for switching the signals of the clamping circuit and the signals of the TSG generating area ( 80 ) by means of an external adjustment switch; and
a frequency dividing section ( 70 ) for frequency dividing the oscillation frequency of a sound carrier oscillator by means of the frequency dividing control signals of the control section for supplying the divided frequency to the TSG generating section. 3. The RF modulation circuit according to claim 1, characterized in that the control area ( 40 ) comprises: a first comparison circuit section ( 41 ) consisting of a plurality of transistors for comparing externally input two channel selection signals with an internal reference voltage to output three switching control signals (S1, S2, S3); and
a second comparison circuit section ( 43 ) of the differential type consisting of a plurality of transistors for comparing the output signals of the first comparison circuit section ( 41 ) with a further internal reference voltage in order to output frequency divider control signals. 4. The RF modulation circuit according to claim 1, characterized in that the oscillation range ( 60 ) comprises:
electronic switching areas for connecting one of the oscillator resonant circuits (C1, L1; C2, L2; C3, L3) of the oscillator resonant circuit area ( 50 ) to oscillating circuits of the oscillating area ( 60 ) corresponding to switching control signals of the control area ( 40 ), the oscillating circuits (Q41, Q43) also the resonance frequency of the connected oscillator circuit oscillate. 5. The RF modulation circuit according to claim 1, characterized characterized that the entered in the control area Channel selection signals Control signals from an external Are microcomputers. 6. The RF modulation circuit according to claim 1, characterized characterized that the entered in the control area Channel selection signals Level signals from an external are mechanical switches. 7. The RF modulation circuit according to claim 2, characterized in that when selecting output signals of the TSG generation area ( 80 ) the circuit area ( 52 ) the sound amplifier ( 53 ) ineffective and the frequency divider area ( 70 ) switches effectively. 8. The RF modulation circuit according to claim 2, characterized in that the frequency divider range ( 70 ) comprises:
first, second, third and fourth counters ( 71-74 ) for performing counting operations in accordance with sets of frequency dividing control signals C11, C21 and C31 or C12, C22 and C32 of the control area;
a NAND gate ( 75 ) for NANDing the signals from the counters;
a blocking area ( 76 ) for maintaining the output of the NAND gate ( 75 ) for a certain period of time; and
an operating mode adjustment area ( 77 ) for adjusting the operating ratio of the output signals of the blocking area ( 76 ) to a certain value. 9. An RF modulation circuit for use in the PAL method, characterized by
a TSG generation area ( 80 ) for generating TSG signals based on a particular input frequency;
a clamp circuit ( 51 ) for fixing the potential of video signals at a certain level;
a sound amplifier ( 53 ) for amplifying sound signals;
an oscillator circuit section ( 50 ) consisting of three sound carrier oscillator circuits (C1, L1; C2, L2; C3, L3) based on a broadcasting method;
an oscillation section ( 60 ) for oscillating the sound carriers of the oscillator circuit section ( 50 ), a frequency modulation section ( 54 ) for frequency modulating the sound carriers from the oscillator by means of output signals of the sound amplifier;
a mixer ( 56 ) for mixing output signals of the frequency modulation section ( 54 ) and output signals of the clamping circuit section ( 51 ) and the TSG generation section ( 80 ) accordingly with a frequency of an oscillator; and
an RF amplifier ( 56 ) for amplifying the mixer output signals, the RF modulation circuit further comprising:
a control section ( 40 ) for reading externally input channel selection signals to output switching control signals and frequency divider control signals; and
a frequency dividing section ( 70 ) for frequency dividing the oscillation frequency of the oscillating section ( 60 ) based on frequency dividing control signals of the control section ( 40 ) for outputting the frequency divided signal to the TSG generating section ( 80 ). 10. The RF modulation circuit of claim 9, further characterized by:
a switching area ( 52 ) for switching the signals of the clamping circuit ( 51 ) and the signals of a TSG generating area ( 80 ) by means of an external adjustment switch; and
an oscillation section ( 60 ) for performing oscillations by selecting one of the resonance frequencies of a plurality of oscillator circuits of the oscillator circuit section ( 50 ) in accordance with switching control signals of the control section ( 40 ). 11. The RF modulation circuit according to claim 9, characterized in that the control area ( 40 ) comprises: a first comparison circuit section ( 41 ) consisting of a plurality of transistors for comparing two externally input channel selection signals with an internal comparison voltage for outputting three switching control signals; and
a second comparison circuit area ( 43 ) of the differential type consisting of a plurality of transistors for comparing output signals of the first comparison circuit area ( 41 ) with a further internal reference voltage for outputting frequency divider control signals. 12. The RF modulation circuit according to claim 9, characterized in that the frequency divider range ( 70 ) further comprises:
first, second, third and fourth counters ( 71-74 ) for performing counting operations corresponding to sets C11, C21 and C31 or C12, C22 and C32 of the frequency dividing control signals of the control section ( 40 );
a NAND gate ( 75 ) for NANDing the signals of the counters;
a blocking area ( 76 ) for maintaining the output of the NAND area for a certain period of time; and
an operating mode adjustment area ( 77 ) for adjusting operating conditions of the output signals of the blocking area ( 76 ) to a specific value. 13. The RF modulation circuit according to claim 9, characterized in that upon selection of output signals of the TSG generation area ( 80 ) the sound amplifier ( 53 ) is ineffective and the frequency divider area ( 70 ) is effectively switchable by the switch area ( 52 ). 14. The RF modulation circuit according to claim 1, characterized in that the oscillation region ( 60 ) comprises; electronic switching areas (Q11-Q14; Q28-Q24; Q31-Q34) for connecting one of the oscillator circuits (C1, L1; C2, L2; C3, L3) of the oscillator circuit area ( 50 ) to oscillation circuits (Q41, Q43) of the oscillation area ( 60 ) corresponding to switching control signals (S1-S3) of the control area ( 40 ), the oscillation circuits (Q41, Q43) oscillating at the resonance frequency of the connected oscillator circuit.