JPH03250457A - Fm modulator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is applicable to, for example, an audio device of a VTR.
This invention relates to an M modulation device.

[Summary of the invention]

The present invention is suitable for application to, for example, a VTR audio device.
Regarding the M modulation device, a first setting means sets a frequency division ratio according to the first and second carrier waves, and a third and fourth setting means sets the frequency division ratio of the input signal from the first setting means. a second setting means for setting the frequency division ratio of the input signal from the first setting means according to the carrier wave; a third setting means for setting the frequency division ratio of the input signal from the first setting means according to the third and fourth carrier waves; a first selector for selecting each output signal from the third setting means in accordance with the first and second carrier waves;
a selection means, a fourth setting means for setting a frequency division ratio according to the third and fourth carrier waves, a frequency division means for dividing the input signal by a predetermined frequency division ratio, and a fourth setting means. and second selection means for selecting each output signal from the frequency dividing means according to the first and second carrier waves, and comparison means for comparing the phases of each output signal from the first and second selection means. The frequency of the first or second carrier wave is changed based on the comparison result of the comparison means, and the input signal supplied from the input terminal is modulated by the first or second carrier wave with the changed frequency. With a highly accurate carrier wave by having a modulation means,
In addition to being able to perform FM modulation on the input signal, it can also be used in common with both monaural and stereo systems for the audio signals of VTRs, for example, NTSC and PAL systems.

[Conventional technology]

Conventionally, in VTRs and the like that record and reproduce monaural audio signals, the frequency of the carrier wave of the audio signal is around 1.5 MHz. During recording, an FM modulation device is used that FM modulates the human voice signal using a 1.5 MHz clock signal, ie, a carrier wave signal, from a voltage controlled oscillator or the like to obtain an FM modulated signal. This FM modulation signal is superimposed with the video signal and pilot signal. This superimposed signal is then supplied to a magnetic head and recorded so as to form an inclined track on the recording surface of the magnetic tape.

[Problem to be solved by the invention]

By the way, the above-mentioned FM modulation device is used as a so-called monolithic integrated circuit. However, in this case, the oscillation frequency of the voltage controlled oscillator may differ from circuit to circuit due to variations in the monolithic integrated circuit. Therefore, VTs that record and reproduce monaural audio signals
In R, even if the oscillation frequency of the voltage controlled oscillator is slightly different, there is no problem in use because the carrier wave frequency of the audio signal is only 1.5 MHz. However, in a VTR that records and plays back stereo audio signals, the left audio signal The frequency of the carrier wave of the signal (L+R), which is the sum of the left and right audio signals, is approximately 1.5 MI (z
The frequency of the carrier wave of this difference signal <L-R> is approximately 1.
Since the frequencies of 714 Hz are very close to each other, if the precision of the carrier wave is poor, there is a problem in that the sound quality of each audio signal and the R signal deteriorates.

The present invention has been made in view of the above points, and is capable of FM modulating an input signal using a highly accurate carrier wave. This paper attempts to propose an FM modulation device that can be used in common.

[Means to solve the problem]

As shown in FIGS. 1 and 2, for example, the present invention includes first setting means (4), (5), and (6) for setting the frequency division ratio according to the first and second carrier waves, The second setting means sets the frequency division ratio of the input signal from the first setting means (4), (5), and (6) according to the third and fourth carrier waves.
Setting means (8), (9), (1,2) and
Third setting means (1,0) for setting the frequency division ratio of the input signal from the first setting means (4), (5), (6) according to the third and fourth carrier waves, <11 ),, (1
3), and second and third setting means (8), (9),
(12) and (10), (11), and (13) a first selection means (14) for selecting each output signal from the first and second carrier waves according to the first and second carrier waves; Fourth setting means (22), (2
3), (24), frequency dividing means (21) for dividing the input signal by a predetermined division ratio, and fourth setting means (22>,
(23), (24) and a second selection means (25) for selecting each output signal from the frequency dividing means (21) according to the first and second carrier waves; Means (1
4>, (25) Comparing means (16), (27), (28) for comparing the phases of each output signal from modulating means (18) for changing the frequency of the first or second carrier wave and modulating the input signal supplied from the input terminal (17) with the first or second carrier wave whose frequency has been changed; It has the following.

[Effect]

According to the present invention described above, the first and second selection means (1
Comparing means (16), (27), and (28) compare the phases of each output signal from 4) and (25), and
Based on the comparison results of the comparison means (16), (27), and (28), the modulation means (18) changes the frequency of the first or second carrier wave, and also changes the frequency of the first or second carrier wave and inputs the input signal from the input terminal (17). By modulating the signal with a first or second carrier wave whose frequency is changed, the input signal can be FM-modulated with a highly accurate carrier wave, and, for example, NT
This system can be used in common with both monaural and stereo systems for audio signals of SC and PAL VTRs.

〔Example〕

An embodiment of the FM modulation apparatus of the present invention will be described in detail below with reference to FIG.

In this Figure 1, (1) is a color subcarrier signal (NTS
Approximately 3.58 Mtlz in the C method and 4.43 MHz in the PAL method) is the input terminal for the manually inputted color subcarrier signal, and the carrier signal supplied to this carrier signal input terminal (1) is passed through a 172 frequency dividing circuit ( 2) is supplied to the 1/4 frequency divider circuit (3).

The 174 frequency divided signal from this 1/4 frequency divider circuit (3) is 17
The signal is supplied to the 12 frequency divider circuit (4) and the 1718 frequency divider circuit (5), respectively.

The output side of this 1712 frequency divider circuit (4) is connected to the selector switch (
Connect to the NTSC side fixed contact (6n) of 6),
The output side of the frequency dividing circuit (5) is changed to PAL of the switch (6).
Connect to the side fixed contact (6p) and turn this changeover switch (6)
The movable contact (6s) is connected to the input side of the 172 frequency dividing circuit (7).

1/12 frequency division signal from the 1712 frequency division circuit (4) or
The 1718 frequency divided signal from the 1718 frequency dividing circuit (5) is 1
72 frequency divider circuit (7). The 1/2 frequency divided signal from this 172 frequency divider circuit (7) is transmitted to the 1751 frequency divider circuit (8
), 1745 frequency divider circuit (9), 1/42 frequency divider circuit (10
) and 1737 frequency divider circuit (11), respectively.

The output side of this 1751 frequency divider circuit (8) is connected to the selector switch (
Connect to the 1.5MHz side fixed contact (12A) of 12),
Connect the output side of the 1/45 frequency divider circuit (9) to the 1.7MHz side constant contact (12r), and press this selector switch (12r).
Connect the movable contact (12S) of ) to the NTSC side fixed contact (14n) of the changeover switch (14).

The output side of this 1/42 frequency divider circuit (10) is connected to the 1.5MHz side fixed contact 13β) of the changeover switch (13), and the output side of this 1737 frequency divider circuit (11) is connected to the changeover switch (13). Connect to the fixed contact (13r) on the 1.7MHz side of the switch, and connect the movable contacts (1, 3
3) Connect the PAL side fixed contact of the selector switch (14) (
14p).

In addition, the movable contact (14S) of this changeover switch (14)
is connected to the input side of the 1/2 frequency divider circuit (15).

1751 frequency divider circuit (8), 1/45 frequency divider circuit (9), 1
/42 frequency divider circuit (10), 1. /37 frequency divider circuit (11
) is supplied to the 172 frequency divider circuit (15), and the 1/2 frequency divided signal from the 172 frequency divider circuit (15) is sent to the comparator circuit (28) through the D-type flip-flop circuit (16). ).

(17) is an audio signal input terminal, and the audio signal from this audio signal input terminal (17) is supplied to a voltage controlled oscillation circuit (18). In this voltage controlled oscillation circuit (18), its free oscillation frequency is approximately 1.5 MHz or approximately 1.7 MHz.
M) tz, and this approximately 1.5MHz or approximately 1.7MHz
The oscillation frequency of the voltage controlled oscillation circuit (18) is controlled by the audio signal from the audio signal input terminal (17) to perform FM modulation on the carrier wave signal of z, and the FM modulated signal is supplied to the FM modulated signal output terminal (30).

Further, the carrier wave signal from this voltage controlled oscillation circuit (18) is supplied to a 1/2 frequency divider circuit (19). The 1/2 frequency divided signal from this 172 frequency dividing circuit (19) is transferred to the 1/3 frequency dividing circuit (
The 173 frequency divided signal from this 173 frequency dividing circuit (20) is supplied to the 1/684 frequency dividing circuit (21) and the 1/684 frequency dividing circuit (21).
682 frequency divider circuit (22) and 1/681 frequency divider circuit (23)
) are supplied respectively.

The output side of this 1/684 frequency dividing circuit (21) is connected to the NTSC side fixed contact (25n) of the changeover switch (25). Then, the output side of this 1/682 frequency dividing circuit (22) is connected to the 1.5 MLIz side fixed contact (24j2) of the changeover switch (24), and this 1/681 frequency dividing circuit (23
> output side by switching switch (24) 1. Connect to the IMHz side fixed contact, and connect the movable contact (24s) of this changeover switch (24) to the PAL side fixed contact (25ρ) of the changeover switch (25). Also, the movable contact (25S) of this changeover switch (25) is divided into 1/2 [.

Connect to the input side of the line (26).

1/684 frequency divider circuit (21), 1/682 frequency divider circuit (2
2) A frequency-divided signal from either the ζ1/681 frequency divider circuit (23) is supplied to the 1/frequency divider circuit (26). This 172
The 172 frequency divided signal from the frequency dividing circuit (26) is supplied to the comparator circuit (28) through a D-type flip-flop circuit (27).

The comparison circuit (28) is a D-type flip-flop circuit (16).
) and (27), respectively, and the frequency-divided signal of the approximately 1.5 MHz or approximately 1.7 MHz carrier wave signal from the voltage controlled oscillation circuit (18). Compare and output the difference. This differential output signal is passed through a low-pass filter (29) to a voltage controlled oscillation circuit (
18).

In the above modulation device, a VTR to which this device is applied
is NTSC system and %/ral (1.5MHz)
If the method is selector switch (6), (14), (
25) each movable contact (6s), (14s), (25
s) is each NTSC side fixed contact (6n>).

(1, 4n), (25n), respectively, and each movable contact (12s), (13s), (24s) of the changeover switch (12), (13), (24) is connected to one
, 5Mtlz side fixed contact (12A'), (13Il)
, (24A). The approximately 3.58 MHz color subcarrier signal supplied to the color subcarrier signal input terminal (1) is sent to the 1/2 frequency divider circuit (2>, the 1/4 frequency divider circuit (3), and the 1712 frequency divider circuit). (4), 172 frequency divider circuit (7
), 1751 frequency divider circuit (8), 1/2 frequency divider circuit (15)
The frequency is divided through the flip-flop circuit (16
) is supplied to the comparator circuit (28).

On the other hand, about 1.5M) from the voltage controlled oscillation circuit (18)
The carrier wave signal of z is frequency-divided through a 172 frequency divider circuit (19), a 173 frequency divider circuit (20), a 1/684 frequency divider circuit (21), a 172 frequency divider circuit (26), and this is a flip-flop circuit (27). The signal is supplied to the comparator circuit (28) through.

In this case, the frequency of the carrier wave signal to be FM modulated is approximately 1.5
0025824MHz, a frequency with very little error.

In the modulation device described above, this device is applied to V T
Ri)<NTSC system and Mol/7
MHz) method, selector switch (6), (14
), (25) each movable contact (6s), (14s),
(25s) is each NTSIr side fixed contact (6n).

The movable contacts (12s), (13s), (24s> of changeover switches (12), (13), (24) are connected to (14n>, (25n>), respectively, and 1 and 7
MHz side fixed contact (12r), (13r), (24
r) connected to. The approximately 3.58 MHz color subcarrier signal supplied to the color subcarrier signal input terminal (1) is transmitted to a 1/2 frequency divider circuit (2), a 174 frequency divider circuit (3),
1712 frequency divider circuit (4), 172 frequency divider circuit (7), 17
The frequency is divided through a 45 frequency divider circuit (9) and a 1/2 frequency divider circuit (15), and is supplied to a comparison circuit (28) through a flip-flop circuit (16).

On the other hand, about 1.7MHz from the voltage controlled oscillation circuit (18)
The carrier wave signal of 172 frequency divider circuit (19), 1/3 frequency divider circuit (20), 1/61114 frequency divider circuit (21),
The frequency is divided through a frequency divider circuit (26) and supplied to a comparison circuit (28) through a flip-flop circuit (27).

In this case, the frequency of the carrier wave signal to be FM modulated is approximately 1.7
002872M)lz, which is a frequency with very little error.

In the above modulation device, a VTR to which this device is applied
'b<PAL system and monaural (1,5M1(z)
If the method is selector switch (6), (14), (
25) each movable contact (6s), <14s), (25
s) is each PAL side fixed contact (6p>, (14p),
(25ρ), respectively, and a selector switch (12),
(1, 3), (24) each movable contact (12s), (
13s), (24s) are each 1.5MRz side fixed contact (
12A>, (13A>, (24A)).

The approximately 4.43 MHz color subcarrier signal supplied to the color subcarrier signal input terminal (1) is transmitted to the 1/2 frequency divider circuit (2), the 174 frequency divider circuit (3), and the 1718 frequency divider circuit (5).
), 1/2 frequency divider circuit (7), 1/42 frequency divider circuit (10)
, 172 is divided through the frequency divider circuit (15), and this is divided through the flip-flop circuit (16) and the comparator circuit (28).
is supplied to

On the other hand, about 1.5 Mfl from the voltage controlled oscillation circuit (18)
The carrier wave signal of z is frequency-divided through a 1/2 frequency divider circuit (19), a 1/3 frequency divider circuit (20), a 1/682 frequency divider circuit (22), and a 172 frequency divider circuit (26), and this is a flip-flop. It is supplied to a comparator circuit (28) through a circuit (27).

In this case, the frequency of the carrier wave signal to be FM modulated is approximately 1.4
The frequency is 9988168MHz, which has very little error.

In the above modulation device, a VTR to which this device is applied
If it is a PAL system and a monaural (1.7MHz) system, selector switches (6), (14), (25>
Each movable contact (6s), (14s>, (25s) is the PAL side fixed contact (6p), (14ρ), (25
p) respectively, and the changeover switches (1, 2), (1
3), (24) each movable contact (12s), (13s
), (24s) are each 1.7M [Iz side chamber constant contact 12
r), (13r), (24r).

The approximately 4.43 MHz color subcarrier signal supplied to the color subcarrier signal input terminal (1) is then passed through the 172 frequency dividing circuit (
2), 1/4 frequency divider circuit (3), 1718 frequency divider circuit (5)
, 1/2 frequency divider circuit (7), 1737 frequency divider circuit (11),
The frequency is divided through a 1/2 frequency divider circuit (15) and supplied to a comparison circuit (28) through a flip-flop circuit (16).

On the other hand, about 1.7MHz from the voltage controlled oscillation circuit (18)
The carrier wave signal is divided through a 172 frequency divider circuit (19), a 1/3 frequency divider circuit (20), a 1/681 frequency divider circuit (23), and a 1/2 frequency divider circuit (26), and this is a flip-flop circuit. (27) and is supplied to the comparison circuit (28).

In this case, the frequency of the carrier wave signal to be FM modulated is approximately 1.7
The frequency is 0002116MHz, which has very little error.

When the above-described FM modulation device is used in a stereo VTR, it is constructed as shown in FIG.

In addition, in this Fig. 2, the parts that overlap with Fig. 1 are as follows.
The same reference numerals with L and R are given to them, and their repeated explanation will be omitted.

In FIG. 2, (IR) and (IL) are input terminals for color subcarrier signals, respectively. (17R) and (17
L) is an input terminal to which a right audio signal and a left audio signal are respectively supplied.

Further, (30R) and (30L) are output terminals to which the right FM modulation signal and the left FM modulation signal are supplied, respectively.

Also, voltage controlled oscillation circuit (18R) and (18L)
are made to oscillate at approximately 1.7 MHz and approximately 1.5 M)Iz, respectively.

In FIG. 2, if the modulation device is used for an NTSC stereo VTR, the movable contacts (6S) of the right selector switches (6R), (14R), and (25R).

(14s), (25s> is each NTSC side fixed contact (6
n), (14n), and (25n>, respectively, and the left side selector switch (6L).

(14L), (25L) movable contacts (6s),
(14s), (25s) are each NTSC side fixed contact (
6n), (14n), and (25n), respectively.

On the other hand, the right side selector switch (12R), (13R),
(24R) each movable contact (12s>, (13s)
, (24s> is each 1.7MHz side fixed contact (12"
), (13r), (24r) respectively,
Left side selector switch (12L), (1, 31), (2
4L) each movable contact (125) (13s), (2
4s) are fixed contacts on each 1.5MHz side (12I,
(13β).

(24β), respectively.

Approximately 3.5B is supplied to the color subcarrier signal input terminal (IR)! JflzO color subcarrier signal is divided into 172 frequency divider circuit (2R), 174 frequency divider circuit (3R), 1/12 frequency divider circuit (4R), 172 frequency divider circuit (7R), 1/45 frequency divider circuit (9R), The comparison circuit (
28R).

On the other hand, approximately 1.7 from the voltage controlled oscillation circuit (18R)
MHz carrier wave signal is divided by 172 circuit (1,9R)
, 1/3 frequency divider circuit (2OR) 1. The comparison circuit (
28R).

In this case, the frequency of the right carrier signal to be FM modulated is approximately 1.7002872! , lHz.

The approximately 3.58 MHz color subcarrier signal supplied to the color subcarrier signal input terminal (IL) is transmitted to the 172 frequency divider circuit (2L), the 1/4 frequency divider circuit (3L), and the 1/12 frequency divider circuit. (4L), 172 frequency divider circuit (7L), 1151 frequency divider circuit (8L), 1/2 frequency divider circuit (15L), comparison circuit (28L) through flip-flop circuit (16L)
is supplied to

On the other hand, approximately 1.5 from the voltage controlled oscillation circuit (18L)
MHz carrier wave signal is divided by 1/2 circuit (19L)
1/3 frequency divider circuit (2OL) 1/684 frequency divider circuit (
21L), 1/2 frequency divider circuit (26L), and comparison circuit (28L) through the flip-flop circuit (27L).
is supplied to

In Fig. 2, when these modulation devices are used in a PAL stereo VTR, the movable contacts of the right selector switches (6R), (14R), and (25R) (
6s), (14s), and (25s) are the fixed contacts (6p) on each PAL side.

(14p), (25p), respectively, and left side selector switches (6L), (14L), (25p).
Each movable contact (6S) (14s>, (25s) of L)
is each PAL side fixed contact (6p), (14p) (25
p>, respectively.

On the other hand, the right side selector switch (12R), (13R),
(24R) each movable contact (12s), (13s)
, (24s) is 1.7M each) Iz side side window constant contact 1
2r), (13r>, (24r), respectively, and the left side selector switches (12L), (13L), (
24L) each movable contact (125) (13s), (
24s) is 1.5Mt each (z side constant contact (12A),
, (131).

(24A) respectively.

The approximately 4.43 MHz color subcarrier signal supplied to the color subcarrier signal input terminal (IR) is then passed through a 172 frequency dividing circuit (
2R), 174 frequency divider circuit (3R), 1/18 frequency divider circuit (5R), 1/2 frequency divider circuit (7R), 1/37 frequency divider circuit (IIR), 1/2 frequency divider circuit (15R) , and is supplied to the comparison circuit (28R) through the flip-flop circuit (16R).

On the other hand, approximately 1.7 from the voltage controlled oscillation circuit (18R)
MHz carrier wave signal is divided by 172 circuit (19R)
1/3 frequency divider circuit (2OR) 1/681 frequency divider circuit (
23R), 1/2 frequency divider circuit (26R), and flip-flop circuit (27R) to the comparison circuit (28R).
) is supplied to

In this case, the frequency of the right carrier signal subjected to FM modulation is approximately 1.70002116 MHz.

The approximately 4.43 MHz color subcarrier signal supplied to the color subcarrier signal input terminal (IL) is transmitted through a 1/2 frequency divider circuit (2L), a 174 frequency divider circuit (3L), and a 1/18 frequency divider circuit. (5L), 1/2 frequency divider circuit (7L), 1/42 frequency divider circuit (IOL), 1/2 frequency divider circuit (15L),
It is supplied to a comparison circuit (28L) through a flip-flop circuit (16L).

On the other hand, about 1.5M from the voltage controlled oscillation circuit (18L)
Hz carrier wave signal is divided by 1/2 frequency divider circuit (19L) 1
/3 frequency divider circuit (2OL>1/682 frequency divider circuit (2OL)
2L), a 1/2 frequency divider circuit (26L), a flip-flop circuit (27L) and a comparison circuit (28L).
) is supplied to

Therefore, even when applied to stereo systems, NTSC and PA
Not only is this method effective for any of the L methods, but the carrier wave accuracy at that time is as high as around ±200 Hz.

Note that in the above embodiment, the NTSC system and PAL
The case where the method is applied to the NTSC system, SECAM system, PAL system, and S E CA 1.
Either method can be applied, and the frequency is 1.5MHz.
Of course, the frequency is not limited to 1.7 MHz and 1.7 MHz, and other frequencies and combinations thereof can be used.

Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention described above, since the reference signal can be switched and used by dividing the frequency at the optimum frequency division ratio, a highly accurate carrier signal can be FM modulated by the input signal, and it is possible to perform FM modulation using the input signal, for example. system and PAL system VT
It can be used in common for both monaural and stereo R audio signals.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the FM modulation apparatus of the present invention, and FIG. 2 is a block diagram showing an example in which the example shown in FIG. 1 is used in a stereo system. (1), (17) are input terminals, (2), (3)
, (4), (5), (7), (8). (9), (10), (11), (15), (1
9), (20), (21), (22), (23
). (26) is a frequency dividing circuit, (6), (12), (13)
, (14) and (25) are changeover switches, (18) is a voltage controlled oscillation circuit, (28) is a comparison circuit, (29) is a low-pass filter, and (30) is an output terminal. Agent Hidemori Matsukuma

Claims (1)

[Claims] First setting means for setting a frequency division ratio according to the first and second carrier waves; and third and fourth setting means for setting the frequency division ratio of the input signal from the first setting means. a second setting means for setting the frequency division ratio of the input signal from the first setting means according to the third and fourth carrier waves; a first selection means for selecting each output signal from the second and third setting means according to the first and second carrier waves; and a first selection means for setting a frequency division ratio according to the third and fourth carrier waves. 4 setting means, a frequency division means for dividing the input signal by a predetermined frequency division ratio, and each output signal from the fourth setting means and the frequency division means is divided into the first and second carrier waves. a second selection means that selects the output signals according to the first and second selection means; a comparison means that compares the phase of each output signal from the first and second selection means; An FM modulation device comprising modulation means for changing the frequency of a carrier wave and modulating an input signal supplied from an input terminal with the first or second carrier wave having a changed frequency.