JPS61172446A - Stereophonic modulator - Google Patents

Abstract

PURPOSE:To obtain a stereophonic modulator generating the 1st sound carrier and the 2nd sound carrier not attended with deterioration in the separation at demodulation by applying frequency mixture to outputs of an fLFM oscillator frequency-modulated by a left signal and an fRFM oscillator frequency-modulated by a right signal. CONSTITUTION:Since a left signal L component included in the 1st sound carrier f1 and a left signal L component included in the 2nd sound carrier f2 are both obtained by applying frequency modulation to an fLFM oscillator 1, both of them have no difference. Since a right signal R component included in the 1st sound carrier f1 and a right signal R component included in the 2nd sound carrier f2 are both obtained by applying frequency modulation to an fRFM oscillator 2, both have no difference. Thus, even when the modulation sensitivity of the fLFM oscillator 1 and the modulation sensitivity of the fRFM oscillator 2 have a difference, the deterioration in the separation of the 1st sound carrier f1 and the 2nd sound carrier f2 is not caused at demodulation from the principles of operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a stereo modulator, and in particular, the present invention relates to a stereo modulator, and in particular, a first audio carrier frequency modulated by a sum signal L+R of a left signal R and a right signal R. The present invention relates to a stereo modulator in a stereo broadcasting system using a second audio carrier f2 frequency-modulated by a difference signal LR between a right signal R and a right signal R.

[Prior Art] In a conventional stereo modulator of this kind, for example, as shown in FIG. Next, the sum signal +R is introduced into the f1 FM oscillator 32 which is frequency modulated by the sum signal L+R to obtain the first audio carrier f+, while the difference signal [, -R is generated as the difference signal L- The fz frequency modulated by R is introduced into the FM oscillator 33 to obtain the second audio carrier wave f2. The first audio carrier wave f1 and the second audio carrier wave f2 obtained in this way are subjected to frequency discrimination in a demodulator (not shown), and the sum signal L+R and the difference (L+R)-(
L-R) and □ are amatrixed and separated into left signal 1 and right signal 1 (1).

[Problems to be Solved by the Invention] However, in such a conventional stereo modulator, the modulation sensitivity of the f+ FM oscillator 32 and the f2F
If there is a difference in the modulation sensitivity of the M oscillator 33, for example, the left signal component (or right signal R component) contained in the first audio carrier f+ and the left signal component (or right signal R component) contained in the second audio carrier f2. A difference △L (or ΔR) occurs between the R component and the left signal in the demodulator.
Even if dematrixing is performed to erase the R component of the right signal, the difference ΔL (or ΔR) remains without being erased, and the degree of separation between the left and right signals deteriorates. Moreover, in general, f + FM
It is extremely difficult and practically impossible to always make the modulation sensitivity of the oscillator 32 and the modulation sensitivity of the f2FM oscillator 33 perfectly match. carrier f1 and second
There is a problem in that it is practically impossible to generate the audio carrier wave f1.

The present invention solves the problems of the conventional devices described above, and provides a stereo modulator that can generate the first and second audio carrier waves f2 using the first audio carrier wave, which in principle does not cause deterioration of the degree of separation when demodulated. The purpose is to provide

Further, the present invention provides stereo modulation that is capable of generating a first audio carrier f+ and a second audio carrier f2, each of which has a predetermined maximum value of frequency shift, without deteriorating the degree of separation in principle when demodulated. The purpose is to provide equipment.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an fLFM oscillator whose frequency is modulated by the left signal 1-, an fRFM oscillator whose frequency is modulated by the right signal R, and the f.

A frequency mixer is provided which frequency mixes the output of the FM oscillator and the output of the fRFM oscillator and outputs a first audio carrier wave f1 and a second audio carrier wave f2.

The present invention also includes an f2 frequency mixer whose frequency is modulated by the left signal and the f1 frequency mixer (where ml, m2.nl, n2 # p+ 1p2 *
Q+ + Q2 are all positive integers, and ml =
nl, m,, =n2 *I)+ =QI #
Except for the case where all of p2 ==q2 hold true. ), 2 is output on the second audio carrier wave having the frequency shift.

Further, in the present invention, the f2 frequency mixer in the output layer of the fRFM oscillator which is frequency modulated with the left signal and frequency modulated with the signal R, and the f1 frequency mixer p+eE)2 are both positive integers, Also nl.

n2 * Q+ + 02 are all O or positive integers, and all of the old, nz, Q+, q2 are the second sound carriers that output the first sound carrier f1 having a frequency deviation of O. It is designed to output f2.

[Function] By employing the above means, this invention can achieve f.
Even if there is a difference between the modulation sensitivity of the FM oscillator and the modulation sensitivity of the fRFM oscillator, the left signal component included in the first audio carrier f1 and the left signal component included in the second audio carrier f2 are both fLFM. Since the oscillator is frequency modulated, there is no difference between the two, and the right signal R component matched to the first audio carrier wave f1 and the right signal R component included in the second audio carrier wave f2 both change the frequency of the fRFM oscillator. Since they are modulated, there is no difference between the two, and therefore, in principle, there is no deterioration in the degree of separation when demodulated.

ml, m2, nl, n21 p+ in
l I)2.

By appropriately selecting Q+ and Q2, the maximum value of the frequency deviation of the first audio carrier wave f+ and the maximum value of the frequency deviation of the second audio carrier wave f2 can be set arbitrarily.

By appropriately selecting p+ #p2 e q+ *Q2, the maximum value of the frequency deviation of 1 in the first audio carrier wave and the maximum value of the frequency deviation of the second audio carrier wave f2 can be set arbitrarily.

[Example 1 Embodiments of the invention shown in the drawings will be described below.

FIG. 1 shows an embodiment of the present invention, in which 1 is an fLFM oscillator whose frequency is modulated by the left signal, 2 is an fRFM oscillator whose frequency is modulated by the right signal R, and 3 is the output of the fFM oscillator 1 and the fRFMR1 type. This is a frequency mixer that frequency-mixes the output power of the second audio carrier wave f1 and the second audio carrier wave f2.

Next, the operation of the above embodiment will be explained.

Now, the modulation sensitivity of fLFM oscillator 1 and fRFMR type 1 2
Assume that there is a difference between the modulation sensitivity and the modulation sensitivity. But in this case,
Both the left signal component included in the first audio carrier wave f1 and the left signal component included in the second audio carrier wave f2 are fLF.
Since the M oscillator 1 is frequency modulated, there is no difference between the two, and the right signal R component included in the first audio carrier f1 and the right signal R component included in the second audio carrier f2 are both fRFMR1 type 2. There is no difference between the two because they are frequency modulated. Therefore, f.

Even if there is a difference between the modulation sensitivity of the FM oscillator 1 and the modulation sensitivity of the fRFMR type 1 type 2, in principle, there will be no deterioration in the degree of separation when the first audio carrier wave f+ and the second audio carrier wave f2 are demodulated. Become.

FIG. 2 shows another embodiment of the present invention, in which 11 is an fLFM oscillator whose frequency is modulated by the left signal R, 12 is an fRFM oscillator whose frequency is modulated by the right signal R, and 13 is an f2 oscillator which is frequency-modulated by the right signal R.
A frequency mixer, 19, outputs a first audio carrier f+ with f+ frequency mixing frequency shift, and a second audio carrier f2.
It is designed to output . However, ml, m2
, nl, n2, DI 1p2, Q+ *
02 are all positive integers, ml −nl,
The case where all of mt=n2, p+ -q+*D2=q2 hold true is excluded.

Next, the operation of the above embodiment will be explained.

Now, the frequency deviation of the first audio carrier wave f1 is O~±25k
Hz, and the frequency deviation of the second audio carrier f2 is O
~±22.5kHz, and the maximum value of the frequency deviation of the first audio carrier wave f1 and the maximum value of the frequency deviation of the second audio carrier wave f2 are in the ratio of 25:22.5, that is, 10:9. To achieve this with a stereo modulator configured as shown in Figure 2, there are two main methods: frequency division and multiplication, each of which requires multiple specific methods as listed below. An example is given.

<Method by frequency division> In this case, the output of the fLFM oscillator 11 and the fRFM
The output of the oscillator 12 is set to the maximum value of the frequency deviation of the first sound carrier f, ±25 k 112 - (i.e., the maximum value of the frequency deviation of the second sound carrier f2, ±22.5 to 1
±112.5kllz, which corresponds to -) of 1z.
put. In this way, the left signal R frequency modulates the output of the fLFM oscillator 11 at ±112.5kHz, while the cloth signal R modulates the output terminal 112.5kHz of the fRFM oscillator 12.
Frequency modulate lZ-. Next, the output of the fLFM oscillator 11, which is frequency modulated by the left signal, is ±1L25kll.
It becomes z. On the other hand, the right signal R is frequency-divided by the frequency modulation 14 to ±12.5kHz, and is frequency-divided by the circuit 16 to be ±1L25kflz. The output (±12.5kHz signal frequency-modulated with right signal R) is frequency-mixed (L+R) by f1 frequency mixer 17 and becomes O~±2.
with a frequency deviation of 5 kHz (±1 L25 kHz frequency modulated with left signal)
kHz signal) is frequency-mixed (L-R) by a two-frequency mixer 18 to produce a second audio carrier wave having a frequency deviation of 0 to ±22.5 kHz. Moreover, Karini f
Even if there is a difference between the modulation sensitivity of the LFM oscillator 11 and the modulation sensitivity of the fRFM oscillator 12, in principle, there will be no deterioration in the degree of separation when the first audio carrier wave f1 and the second audio carrier wave f2 are demodulated. Become.

In this case, the output of fLFM oscillator 11 and fRFM
The output of the oscillator 12 is set to one of the maximum frequency deviation of the first sound carrier f1 ±25 kHz (that is, the maximum value of the frequency deviation of the second sound carrier f2 ±22.5 kHz).
It is assumed to be ±56.25kHz, which corresponds to . If this is done, the first audio carrier wave f1 and the second audio carrier wave f2 similar to the case (2) will be output.

(2) From the above (2) and (2), it is easily understood that the case where nl xj12 is 3 or more and 9 or less is also possible.

In this case, the output of fLFM oscillator 11 and fRFM
The output of the oscillator 12 is ±11 as in the case of ■.
Set it to 2.5kHz. If τ is set in this way, the output of the fLFM oscillator 11 frequency-modulated by the left signal R and the output of the fRFM oscillator 12 frequency-modulated by the right signal R do not simply pass through each other, but are one-frequency mixed. Frequency mixing (
L+R) with a frequency deviation of O~±225kllz19
The first audio carrier wave f1 having a frequency deviation of 0 to ±25 kHz is output as the first audio carrier wave f1, which is frequency-mixed (
L-1≧) to become a second audio carrier wave having a frequency shift of 0 to ±225 kHz, and also to be output as a second audio carrier wave f2 having a wave number shift. Furthermore, even if there is a difference between the modulation sensitivity of the fLFM oscillator 11 and the modulation sensitivity of the fRFM oscillator 12, in principle, the separation degree of both the first audio carrier f+ and the second audio carrier f2 will deteriorate when demodulated. There will be no.

In this case, the output of fLFM oscillator 11 and fRFM
The output of the oscillator 12 is ±56.
Set it to 25 kHz. If this is done, the first audio carrier wave f1 and the second audio carrier wave "2" similar to the case (2) will be output.

(2) From the above (2) and (2), it is easily understood that the case where Q+=.ql is 3 or more and 9 or less is also possible.

■Also, the f1 frequency mixer 17 shown in the above ■~■
It is also possible to combine the method of frequency division at the front stage of the f1 frequency mixer 17 and the method of frequency division at the rear stage of the f1 frequency mixer 17 shown in ■ to ■. It is easily understood that it is also possible to perform frequency division at a later stage.

■Furthermore, the frequency division method shown in ■~■ above,
It will be easily understood by reading the explanation of the method using multiplication that it is also possible to appropriately combine it with the method using multiplication, which will be described later.

Method using multiplication> When ql qP −, ---=1: p+ D2 In this case, the output of the fLFM oscillator 11 and the fRFM
The output of the oscillator 12 is set to −G of 25 kHz above the maximum frequency deviation of the first audio carrier f2 (i.e., ± the maximum frequency deviation of the second audio carrier f2).
It is assumed that ±L25kHz corresponds to -) of 22.5kHz. If you do this, you should get a left signal.

Frequency modulation of the output ±L25kHz of the FM oscillator 11,
On the other hand, the cloth signal R is the output of fRFM oscillator 12 ± L25k
Frequency modulate llZ. Next, the output of the fLFM oscillator 11 frequency-modulated by the left signal becomes 1L25kHz. -I, the output of the fLFM oscillator 12 frequency-modulated with the right signal R is the output (±12.5kHz frequency-modulated signal of ±12.5kHz frequency-modulated with the left signal) is the f1 frequency mixer. Frequency mixed (L+R) at 17 to 0~±25kHz
1 on the first audio carrier with a frequency deviation of (signal of ±1L25kllz frequency modulated with the right signal R)
As expected, the signal is frequency mixed (L-R) in the two-frequency mixer 18 and outputted after simply passing through a frequency deviation of 0 to ±22.5 kllz. Moreover, even if there is a difference between the modulation sensitivity of the fLFM oscillator 11 and the modulation sensitivity of the fRFM oscillator 12, the separation degree of both the first audio carrier f1 and the second audio carrier f2 will not degrade in principle when demodulated. There was a lot of yelling for not following along.

In this case, the output of fLFM oscillator 11 and fRFM
The output of the oscillator oscillation is set to the maximum value of the frequency deviation of the first audio carrier wave f1 ±25kHz2 (that is, the maximum value of the frequency deviation of the second audio carrier wave f2. If this is done, The first sound carrier f1 and the second sound carrier f1 as in the case of
Audio carrier wave f2 is output.

(2) From the above (2) and (2), it is easily understood that the case where m+=mz is 3 or more and 9 or less is also possible.

In this case, the output of fLFM oscillator 11 and fRFM
As in the case of ■, the output of R1 type 12 is ±L2.
Set it to 5kHz. In this way, the output of the fLFM oscillator 11 frequency-modulated by the left signal is frequency-mixed (L+R) by the fRFM frequency mixer 17 frequency-modulated by the right signal R, resulting in a frequency deviation of 10 to ±2.5kllz. The first audio carrier having a frequency shift of 0 to ±25 kHz is frequency mixed (L-R) by the f2 frequency mixer 18 to have a frequency shift of 0 to ±2.5 kHz. At the 220th point, it is multiplied to -0~±22.
The second sound carrier wave f2 having a frequency deviation of 5 kHz is output. Moreover, even if there is a difference between the modulation sensitivity of the fLFM oscillator 11 and the modulation sensitivity of the fRFMR type 1 12, in principle, both the first audio carrier wave f1 and the second audio carrier wave f2 are accompanied by deterioration of the degree of separation when demodulated. There will be no.

In this case, the output of fLFM oscillator 11 and fRFM
As in the case of ■, the output of the generator 12 is 2°5 above.
Let it be kHz. If this is done, the first audio carrier wave f1 and the second audio carrier wave f2 similar to the case (2) will be output.

(2) From the above (2) and (2), it is easily understood that the case where D+ = p2 is 3 or more and 9 or less is also possible.

■Also, the f1 frequency mixer 17 shown in the above ■~■
It is also possible to combine the method of multiplying at the front stage of the f1 frequency mixer 18 with the method of multiplying at the rear stage of one f1 frequency mixer shown in (1) to (3). It is easily understood that multiplication at a later stage is also possible.

■Furthermore, the multiplication method shown in ■～■ above,
It is easily understood that it is also possible to appropriately combine the above-mentioned frequency division method.

FIG. 3 shows still another embodiment of the present invention, in which 21 is an fLFM oscillator whose frequency is modulated by the left signal, 22 is an fRFM oscillator whose frequency is modulated by the right signal R, and a two-frequency mixer, 29 The f1 frequency mixer outputs the first audio carrier f1 with a 27 shift, while the second audio carrier f2 is outputted by the first one.

However, m+, m2. Both I)+ and I)2 are positive integers, and "+ + n21 q+ * Q2
are all 0 or positive integers, n+, n2
.

The case where all of Q + + 02 are 0 shall be excluded.

Next, the operation of the above embodiment will be explained.

Now, the frequency deviation of the first audio carrier wave f1 is O~±25k
llz, and the frequency deviation of the second audio carrier wave f2 is O~±22.5kHz, and the maximum value of the frequency deviation of the first audio carrier wave f1 and the maximum value of the frequency deviation of the second audio carrier wave f2. Assuming a ratio of 25:22.5, or 10:9, in order to achieve this with a stereo modulator configured as shown in Figure 3, various methods as listed below are necessary. Specific examples are given.

In this case, the output of fLFM oscillator 21 and fRFM
The output of the oscillator 22 is the second audio carrier wave, which corresponds to the maximum frequency deviation of 22.5 kHz (-).
Let 1L be 25kHz. If this is done, the left signal 1- will be 1L25kHz on the output of the fLFM oscillator 21.
is frequency modulated, while the cloth signal R is fRl:M oscillator 22
The output ±IL25kllz is frequency modulated.

Next, it passes through the fLFM oscillation frequency modulated by the left signal R, and its frequency ±1 which is frequency modulated by the right signal R.
The − of L25kHz2, that is, L25kHz, is frequency mixed (L+R) by the frequency mixer 21 to produce O~±25ktl.
The output of the first N voice carrier having a frequency shift of z, that is, the output of the 1111M oscillator 22 is f22 frequency mixer 28
The signals are frequency mixed (L-R) and output as a second sound having a frequency deviation of 0 to ±22.5 kHz. Furthermore, the modulation sensitivity of the fIFM oscillator 21 and fR
Even if there is a difference in the modulation sensitivity of the FM oscillator 22, in principle, there will be no deterioration in the degree of separation when the first and second audio carriers f2 are demodulated using the first audio carrier.

In this case, the output of fLFM oscillator 21 and fRFM
As in the case of ■, the output of the oscillator 22 is ±1L2 in both cases.
Set it to 5kHz. If this is done, the output of the fLFM oscillator 21 frequency-modulated by the left signal R and the fRFM frequency mixer 21 frequency-modulated by the right signal R.
The frequency is mixed (L+R) at 0 to ±22.5'kHz.
The first sound wave number with a frequency deviation of +/-22.5 kllz - i.e. 2.5 kllz is added to +/-25 kHz.
The first audio carrier wave f1 having a frequency shift of z is output, and the second audio carrier wave fe is output in the same way as
is output.

■It is easily possible to combine the method of adding at the front stage of the f11 frequency mixer 27 shown in (■) above with the method of adding at the stage after the f11 frequency mixer 27 shown in (■). be understood.

In this case, the output of fLFM oscillator 21 and fRFM
The outputs of the oscillator 22 are both ±12.
Set it to 5kHz. By doing this, the fLFM oscillator ±12.5kHz frequency modulated by the left signal - that is, L25kllZ is subtracted and passed through, and the fR frequency ±12.5k frequency modulated by the right signal R is passed through.
llz - i.e. L25 subtract kllz Mixed mold 2
Frequency mixed (L-R) at 8 to O~±22.5kHz2
the second audio carrier output or fR with a frequency deviation of
The output of the FM oscillation vS22 is frequency-mixed (L+R) by the f+frequency mixer 27 to become a first audio carrier wave having a frequency deviation of 0 to ±25 kllz. Moreover, f [modulation sensitivity of FM oscillator 21 and fRFMR
Even if there is a difference in the modulation sensitivity of type 1 22, in principle, neither the first audio carrier wave f+ nor the second audio carrier wave f2 is accompanied by a deterioration in the degree of separation when demodulated.

In this case, the output of fLFM oscillator 21 and fRFM
The output of R1 type 22 is ±12.
Set it to 5ktlz. If this is done, the output of the fLFM oscillator 21 frequency-modulated as the left signal and the fRFM frequency-modulated as the right signal R will be used as the two-frequency mixer 2.
8, the second voice having a frequency deviation of 0 to ±25 kHz is output as a second voice carrier f2 having a frequency deviation of ±22.5 kHz, and on the other hand, Similarly, the first audio carrier wave f+ is output.

■It is easily possible to combine the method of subtracting before the f2 frequency mixer 28 shown in ■ above with the method of subtracting after the f2 frequency mixer 28 shown in ■. be understood.

In this case, the output of fLFM oscillator 21 and fRFM
The outputs of the R1 type 22 are both the maximum value of the frequency deviation of the first audio carrier wave f1, ±25 k If z, and the maximum value of the frequency deviation of 2, ±22.5 kllz, of the second audio carrier wave. If this is done, the output of the fLFM oscillator 21 frequency-modulated by the left signal will be −, that is, 0.62
5kHz is added to ±12.5kHzQ, resulting in ±1L25 kllZ, and the output of the fRFMR1 type 22, which is frequency-modulated with the right signal @R, is -, that is, 0.625kHz is added to ±12.5kllZ±1.
The − of L875k11z, that is, 0.625kllz is subtracted, and the output of the circuit 23 is frequency mixed (L+R) in the circuit 27 to 0~±25kHz.
The first sound carrier f1 has a frequency deviation of 1±
- The output of the circuit 26 is simply passed through the circuit 29 and output, while the output of the circuit 26 is frequency mixed (L-R) by the f22 frequency mixer 28.
It simply passes through the frequency shift circuit 30 of 0 to ±22.5 kHz and is output. Moreover, Karini f
Even if there is a difference between the modulation sensitivity of the FM oscillator 21 and the modulation sensitivity of the fRFM oscillator 22, in principle, there is no deterioration in the degree of separation when demodulating both the first δ voice carrier f1 and the second voice carrier f1. becomes.

pl 1υ 92
1υ In this case, the output of the fLFM oscillator 21 and the output of the fRFM oscillator 22 are both set at ±11°875 kHz as in case (2). If you do this, the fLl:M oscillator 2 frequency-modulated by the left signal
1 and the output of the fRFM oscillator 22 frequency-modulated by the right signal 1 do not simply pass through the path 24, but are frequency-mixed (L + R) in the 1-frequency mixer 27 and output from O to ±23. 75kl
The first audio carrier wave has a frequency deviation of 1z, i.e., 1.25kHz is added to give a frequency deviation of 0~±25kHz7.
The first sound carrier wave f1 having a frequency shift of
The second audio carrier 23 with a frequency deviation of ±23.75 kHz, 75 kHz - i.e. L25 kHz is subtracted and the second audio carrier f2 with a frequency deviation of ±22.5 kHz is outputted. Become.

■1 frequency mixer 27 and f2 as shown in ■ above
The method of adding and subtracting at the front stage of the two-frequency mixer 28, and the f11 frequency mixer 27 and f22 frequency mixer 28 shown in ■
It is easily understood that it is also possible to combine the method of adding and subtracting at the subsequent stage.

J 2 It is easily understood that it is also possible to make them one or more.

Although several embodiments of the present invention have been described above, it is clear that the present invention is not limited to these embodiments. That is, the frequency deviation of the first sound carrier f1 is not limited to 0 to ±25kHz, and the frequency deviation of the first sound carrier f1 is not limited to 0 to ±25kHz, and
The frequency deviation of 2 in the voice carrier wave is not limited to O ~ ±22.5 kllz, and furthermore, the ratio of the maximum value of the frequency deviation of the first voice carrier wave f1 and the maximum value of the frequency deviation of the second voice carrier wave f2 is It is not limited to 10:9. In addition, various specific examples of frequency division or multiplication shown in the embodiment of FIG.
It is also within the scope of the present invention to appropriately combine various specific examples of addition or subtraction shown in the illustrated embodiments. In addition, it goes without saying that the present invention can be modified in various ways to the above-mentioned embodiments.

[Effect of the invention] Since this invention is configured as described above, f F
Even if there is a difference between the modulation sensitivity of the M oscillator and the modulation sensitivity of the fRFM oscillator, both the left signal component included in the first audio carrier f1 and the left signal QL component included in the second audio carrier f2 are fLFM. Since the oscillator is frequency modulated, there is no difference between the two, and the right signal R component contained in the first voice carrier wave f1 and the right signal R component contained in the second F5 voice carrier f2 are both f, FM. Since the oscillator is frequency modulated, there is no difference between the two, and therefore, the first audio carrier wave f1 and the second audio carrier wave f2 can be generated without deterioration of the degree of separation when demodulated in principle. It has a positive effect.

n2. p+, ID? By appropriately selecting I Q+ + q2, the maximum value of the frequency deviation of the first audio carrier wave f1 and the maximum value of the frequency deviation of the second audio carrier wave f2 can be set arbitrarily. , the first audio carrier waves f which, in principle, do not cause deterioration of the degree of separation when demodulated and each have a predetermined maximum value of frequency deviation.
This has the advantage of being able to generate the first and second audio carrier waves f2.

By appropriately selecting p+ * p2 * Q+ * Q2, the maximum value of the frequency deviation of the first audio carrier wave f1 and the maximum value of the frequency deviation of the second audio carrier wave f2 can be set arbitrarily, respectively. As a result, the first audio carrier wave f1 and the second audio carrier wave f2 having a predetermined maximum value of frequency deviation can be generated without deteriorating the degree of separation in principle when demodulated. It is effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the stereo modulator according to the invention, FIG. 2 is a block diagram showing another embodiment of the stereo modulator according to the invention, and FIG. 3 is a block diagram showing another embodiment of the stereo modulator according to the invention. FIG. 4 is a block diagram showing still another embodiment of the modulator. FIG. 4 is a block diagram showing an example of a conventional stereo modulator. 1...f FM oscillator, 2...fRFM oscillator,
[ 3... Frequency mixer, 11... fLFM oscillator, 2
2...-fRFM oscillator, 27... f1 frequency mixer, 28... f2 frequency mixer, 31... matrix circuit, 32... f+FM
Oscillator, 33...f2FM oscillator Applicant Eiden Co., Ltd.

Claims (1)

[Claims] 1. A first audio carrier f_1 frequency-modulated by the sum signal L+R of the left signal L and right signal R, and a first audio carrier f_1 frequency-modulated by the difference signal L-R between the left signal L and right signal R. Second audio carrier f_
In the stereo broadcast system using 2, an f_LFM oscillator whose frequency is modulated by the left signal L, an f_RFM oscillator whose frequency is modulated by the right signal R, and the output of the f_LFM oscillator and the output of the f_RFM oscillator are frequency-mixed and the A stereo modulator comprising: a frequency mixer that outputs a first audio carrier wave f_1 and a frequency mixer that outputs the second audio carrier wave f_2. 2. A first audio carrier f_1 frequency-modulated by the sum signal L+R of the left signal L and right signal R, and a second audio carrier f_1 frequency-modulated by the difference signal LR between the left signal L and right signal R.
In a stereo broadcast system using 2, an f_LFM oscillator whose frequency is modulated by the left signal L, an f_RFM oscillator whose frequency is modulated by the right signal R, and f_L(n_1/
m_1) circuit, an f_R (n_1/m_1) circuit that multiplies the output frequency of the f_RFM oscillator by n_1/m_1, and an f_R (n_1/m_1) circuit that multiplies the output frequency of the f_LFM oscillator by n_2/m_2.
The f_L(n_2/m_2) circuit that multiplies the f_RF
f_R( which multiplies the output frequency of M oscillator by n_2/m_2
n_2/m_2) circuit and the f_L(n_1/m_1
) circuit and an output of the f_R(n_1/m_1) circuit;
The output of the _L(n_2/m_2) circuit and the f_R(
an f_2 frequency mixer that frequency mixes the output of the f_1 frequency mixer, a q_1/p_1 circuit that multiplies the output frequency of the f_1 frequency mixer by q_1/p_1, and the f_2/m_2) circuit;
Multiply the output frequency of the two-frequency mixer by q_2/p_2 q
_2/p_2 circuit (however, m_1, m_2, n
_1, n_2, p_1, p_2, q_1, q_2 are all positive integers, m_1=n_1, m_2=n_
2, except when all of p_1=q_1 and p_2=q_2 hold true. ), the first audio carrier f_1 having a predetermined frequency deviation is output from the q_1/p_1 circuit, and the second audio carrier f_2 having a predetermined frequency deviation is output from the q_2/p_2 circuit. A stereo modulator characterized by: 3. A first audio carrier f_1 frequency-modulated by the sum signal L+R of the left signal L and right signal R, and a second audio carrier f_1 frequency-modulated by the difference signal LR between the left signal L and right signal R.
In the stereo broadcasting system using 2, an f_LFM oscillator whose frequency is modulated by the left signal L, an f_RFM oscillator whose frequency is modulated by the right signal R, and a frequency n_1/m_1 times the output frequency of the f_LFM oscillator is added or subtracted from the f_LFM oscillator. f_L[1±(n_1/m_1)] circuit and the f_L[1±(n_1/m_1)] circuit;
f_R [1±(n_1/m_1)] that adds or subtracts the frequency n_1/m_1 times the output frequency of the _RFM oscillator.
circuit and its n_ to the output frequency of the f_LFM oscillator.
f_L[1±(n_
2/m_2)] circuit, and an f_ which adds or subtracts a frequency n_2/m_2 times the output frequency of the f_RFM oscillator.
R[1±(n_2/m_2)] circuit and the f_L[1
±(n_1/m_1)] output of the circuit and the f_R[
1±(n_1/m_1)] f_1 frequency mixer which frequency mixes the output of the circuit, and the f_L(1±n_2/m_1)
2)] output of the circuit and the f_R[1±(n_2/m
_2)] f_2 frequency mixer that frequency mixes the output of the circuit, and the output frequency of the f_1 frequency mixer
1±(q_1/p_
1) A circuit and 1±(q_2
/p_2) circuit (however, m_1, m_2, p_
1, p_2 are both positive integers, and n_1, n
_2, q_1, and q_2 are all 0 or positive integers, except when n_1, n_2, q_1, and q_2 are all 0. ), the first audio carrier f_ having a predetermined frequency deviation from the 1±(q_1/p_1) circuit;
1, and outputs the second audio carrier wave f_2 having a predetermined frequency deviation from the 1±(q_2/p_2) circuit.