JPS6129589B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stereo multiplex signal generator in the FM-FM system, and in particular, it is capable of including a sine wave signal in its output signal and also having good separation characteristics. The invention relates to a multiplex signal generator.

Not only when the stereo multiplex signal generator described above is used for broadcasting, but also when used for adjusting receiving equipment for monitoring at broadcast stations, adjusting products at receiver manufacturers, etc., the output signal contains It is generally desired that the subcarrier signal be a sinusoidal signal.

By the way, as previously disclosed in Japanese Patent Publication No. 10721/1984, the applicant of the present invention has invented an FM-FM multiplex signal generating device which has good separation characteristics as shown in FIG.

Before explaining the present invention, a multiplex signal generator according to the above-described invention (hereinafter referred to as the conventional example) will be explained.

In the figure, symbols 1 and 2 are the left signal L, respectively.
and an input terminal for the right signal R, first, a frequency modulation oscillator 3 with an oscillation frequency of ₁ that modulates the frequency with the left signal L, and a frequency modulation oscillator 4 with an oscillation frequency of ₂ = ₁ - Fs that modulates the frequency with the right signal R. It is connected to the first frequency mixer 5, and one of the output terminals of this frequency mixer 5 has a center frequency of _{1-2 .}
=Fs via a first bandpass filter 6 to a frequency modulation oscillator 7 with an oscillation frequency of Fm-p/q ( ₁ + ₂ ), and the output terminal of this frequency modulation oscillator 7 is connected to a second frequency mixer 8. Let's connect it to. Further, the other output terminal of the first frequency mixer 5 is connected to a second bandpass filter 9 having a center frequency of ₁ + ₂ .
p/ which converts the frequency of the input signal with a constant ratio p/q
After connecting to the q frequency converter 10, it is connected to the second frequency mixer 8.

The above p/q frequency converter 8 converts the ratio of the frequency deviation Δ _{(L+R) due to the sum signal (L+R} ) of the frequency Fm to the frequency deviation due to the difference signal (L-R) of the frequency Fs to a predetermined standard. This is to match the value.

11 is a frequency difference detector, 12 is a center frequency
₁ is a bandpass filter, 13 is a third frequency mixer,
Reference numeral 14 denotes an oscillator that oscillates a standard subcarrier Fs, and these frequency difference detectors 11 to oscillator 14 control the oscillation frequency ₁ of the frequency modulation oscillator 3 to form a guarantee circuit of frequency ₁ - ₂ =Fs.

Further, reference numeral 15 is an output terminal, 17 is a frequency difference detector, and 18 is a high stability oscillator with an oscillation frequency of Fm.

As mentioned above, the conventional device does not pass both the left and right signals (L signal and R signal) through the matrix circuit at the low frequency stage, and once each signal is sent to each frequency modulation oscillator 3 which oscillates high frequency signals of oscillation frequencies ₁ and ₂ . and 4 to form a signal component modulated by the L signal and the R signal, and both signals are modulated by the first
Even if the modulation sensitivity of either frequency modulation oscillator 3 or 4 changes, the same signal components in both the sum and difference signals are changed accordingly, and the left and right signals are mixed. The separation characteristic is made good, and then the first
One of the output signals of the frequency mixer 5 is guided to the first bandpass filter 6 and modulated by the difference signal Fs.
±Δ _(LR) , and the other is guided to the second bandpass filter 9 and modulated with the sum signal ( ₁ + ₂ ) ±
Let Δ _(L+R) .

And both frequency deviations Δ _(L+R) and Δ _(L-
After adjusting the ratio of _R) to a predetermined standard value using a p/q frequency converter 10, both signals are again guided to a second frequency mixer 8 and a multiplexed signal is transmitted from an output terminal 15. be.

As mentioned above, the conventional device is guaranteed to be effective in improving the separation characteristics, but in order to make the waveform of the center frequency signal of the subcarrier included in the transmitted output signal a sine wave, The output Fs of the bandpass filter 6 must be a sine wave,
To do this, the input signal with the lower frequency of the two input signals to the frequency mixer 5 must be a sine wave signal. In other words, with recent circuit technology and element technology, 2 inputs ₁ ,
Since a frequency mixer with a very small amount of high-order waves combined with respect to at least one of the input signals of ₂ can be easily obtained, such a frequency mixer can be used as the frequency mixer 5; Input ₁ ,
If the lower frequency input signal of _{the two} is a sine wave signal, the output Fs of the band filter 6 can be a sine wave.

However, in the conventional device, each frequency modulation oscillator 3, 4
Since it is customary to attach a limiter to remove the amplitude modulation method remaining in the modulated signal,
The output signals of these frequency modulation oscillators 3 and 4 themselves are not sinusoidal signals.

Further, as described above, one input line in the second frequency mixer 8 has a center frequency of ₁ − ₂ =
Since the Fs bandpass filter 6 is interposed, if the bandwidth characteristic is configured to be relatively narrow and harmonic components of integral multiples of the center frequency are removed, this bandpass filter 6 The output signal from is a sine wave.

However, as an example, in the case of a current audio multiplex signal, the frequency Fs of the subcarrier is 31.5KHz, and its frequency deviation Δ is selected to be ±10KHz, so the bandwidth of the bandpass filter 6 is at least Fs±Δ=31.5. ±10KHz
Therefore, the harmonic component of 63 KHz, which is twice the center frequency, cannot be sufficiently removed.

For this reason, in the conventional example, even with the intervention of the bandpass filter 6, the output signal waveform could not be made into a sine wave, and in this respect, improvements in the conventional example were still desired.

In addition, in current stereo broadcasting, the frequency deviation of the main carrier wave (sum signal side) and the frequency deviation of the subcarrier wave (difference signal side) are up to ±25KHz, respectively.
The latter has a maximum of ±10KHz, and the ratio between the two is set at a constant value (standard value).

To deal with this, the frequency converter 10 in the conventional device sets its conversion ratio to p/q (p and q are both integers), and has a multiplication function with a multiplication ratio of P and a frequency division ratio of 1/
It also had a q frequency division function.

However, in recent years, there has been remarkable progress in ICs (integrated circuits) that have unit functions and are versatile enough to serve as system constituent units, and ICs that have the above-mentioned frequency division or multiplication functions as unit functions have been developed. Among these, the development of frequency division ICs has been remarkable, and ICs with various frequency division ratios have been developed.

Therefore, it has individual functions with versatility.
Using an IC is extremely economically advantageous not only for the IC itself but also for the entire multiplex signal generator as a system, and in addition to the above-mentioned request, a change in design was desired in this respect as well.

In addition to the above request, the conventional device uses only the p/q frequency converter 10 to convert the frequency deviation Δ _(L+R) of the main carrier wave Fm of the output signal at the ratio of p/q. However, in order to match the ratio of both frequency deviations to the standard value, it is necessary to convert the frequency deviation of the subcarrier in the output signal by a ratio of q/p, contrary to the above, to achieve the purpose. It was discovered that this technology could be achieved, and it was hoped that the technology would be realized in this respect as well.

The present invention is intended to provide an FM-FM multiplex signal generator capable of solving the various technical problems described above.

That is, the present invention first connects a frequency modulation oscillator with an oscillation frequency of ₁ , which is frequency-modulated by the right signal R, and an oscillator that oscillates a standard subcarrier Fs to a first frequency mixer, and connects a frequency modulation oscillator with a center frequency _{of 1} to this mixed output line.
-Fs and by interposing a bandpass filter with a relatively narrow bandwidth, the signal waveform of the subcarrier in the generated multiplex signal is made into a sine wave.

The present invention will be specifically explained below based on the embodiments shown in the drawings.

FIG. 2 shows an embodiment of the present invention. In the figure, numerals 1 and 2 are input terminals for the L signal and R signal, respectively, and U ₃ is a frequency modulation oscillator that modulates the frequency with the left signal L. frequency to ₁
(hereinafter referred to as the left signal modulation ₁ oscillator).

_U4 is a frequency modulation oscillator that modulates the frequency with the right signal R, and the oscillation frequency is also a high frequency of ₁ (hereinafter referred to as the right signal modulation ₁ oscillator). _U5
is an oscillator that oscillates a standard subcarrier Fs,
The oscillation frequency ₁ mentioned above is several 100KHz as an example.
It is set so that ₁ > Fs (Fs is, for example, 31.5 KHz in the case of an audio multiplex signal) at a frequency of about 10 MHz.

Then, the oscillator U ₅ and the right signal modulation ₁ oscillator U ₄ are connected to the first frequency mixer U ₆ , and the mixing output terminal is connected to the center frequency with a center frequency of ₁ − Fs = ₂ ( ₁ >
₂ > Fs) and is connected to one input terminal of a second frequency mixer U ₈ via a first bandpass filter U ₇ having a relatively narrow bandwidth. Also left signal modulation
₁ oscillator U ₃ is connected to the other input terminal of a second frequency mixer U ₈ .

U ₉ is a frequency difference detector.

Next, one of the output terminals of the second frequency mixer U ₈ is connected to a second bandpass filter U ₁₀ with a center frequency of Fs = ₁ - ₂ , and an oscillation frequency of Fm - p/q ( ₁ +
₂ ) through the frequency modulated oscillator
Connected to frequency mixer U ₁₂ .

The other output terminal of the second frequency mixer _U8 is connected to a third bandpass filter with a center frequency of ₁ + ₂ .
U ₁₃ and a p/q frequency converter U ₁₄ for frequency converting the other output signal from this third bandpass filter U ₁₃ , namely ₁ + ₂ ±Δ _(L+R), at a predetermined ratio p/q. It is separately connected to the third frequency mixer U ₁₂ through the following.

By the way, the conversion ratio p/q of p/q frequency converter U ₁₄
(p and q are both integers) do not have to be integers.

Reference numeral 15 is an output terminal, U ₁₇ is a frequency difference detector,
U ₁₈ is a high stability oscillator with an oscillation frequency of Fm.

The present invention has the above-described configuration, and each input of the L signal and R signal applied to the terminals 1 and 2 is immediately guided to the left signal ₁ and right signal ₁ oscillators U ₃ and U ₄ for oscillation. The high frequencies of frequency ₁ are each frequency modulated. At this time, since both frequency modulation oscillators U ₃ and U ₄ have the same oscillation frequency of ₁ , it is possible to obtain the effect that their modulation characteristics are the same.

Also, left signal ₁ oscillator U ₃ is frequency difference detector U ₄
Since the frequency difference with the right signal ₁ oscillator U ₄ is constantly detected and AFC controlled, both oscillators
The oscillation frequencies of U ₃ and U ₄ are controlled to always have the same value of ₁ .

By the way, the modulated output signal ₁ ±Δ _(R) from the right signal ₁ oscillator U ₄ is frequency-mixed with the standard subcarrier Fs by the first frequency mixer U ₆ and the frequency
₁ ±Fs±Δ _(R) signal, and this signal is the first
The signal is converted to ₁ −Fs±Δ _(R) via a bandpass filter U ₇ and then led to a second frequency mixer U ₈ .

Here, the first bandpass filter U ₇ has its center frequency
₁ −Fs= ₂ and has a relatively narrow bandwidth, and this first bandpass filter _U7 removes the signal component of the frequency ₁ +Fs±Δ _(R) and also removes the signal component of the frequency 2( ₁ +Fs) etc., harmonic components of integral multiples thereof are also removed. As described above, in the present invention, the frequencies have a relationship of ₁ > ₂ >Fs. In this way, the harmonics, which are distortion components, are removed from the output signal of the first bandpass filter _U7 , so the waveform of the output signal ₁ -Fs±Δ _(R) becomes a sine wave and the second frequency Guided into mixer U ₈ .

Then, as mentioned above, the modulated wave ₁ ±Δ _(L) frequency-modulated by the L signal and the modulated wave ₂ ±Δ _(R) frequency-modulated by the R signal are both introduced into the second frequency mixer U _8. Here, due to matrix action, the mixed output { ₁ ±Δ _(L) }±{ ₂ ±Δ _(
R) } is formed, which is then separated into component signals and component signals.

That is, due to the action of the second frequency mixer _U8 , the signal component of the difference between the mixed output ( ₁ - ₂ ) ± {Δ _(L) - Δ _(R) } and the mixed output ( ₁ + ₂ ) ± {Δ _{(L) )}
+Δ _(R) }, and the signal component is the sum of
At this time, the signal of frequency ₁ is frequency modulated by the L signal, while the signal of frequency ₂ is frequency modulated by the R signal, so the frequency ( ₁ −
₂ ) is frequency modulated with the difference signal (L-R), and the frequency ( ₁ + ₂ ) is the sum signal (L-R).
+R). After this, both of the above mixed signals are guided to the second and third bandpass filters U ₁₀ and U ₁₃ , respectively.
One is the modulated wave ( ₁ − ₂ ) ±Δ _(LR) = Fs
±Δ _(LR) signal, and the other one uses this as ( ₁ +
₂ ) The signal is ±Δ _(L+R) .

At this time, since one input signal waveform of the second frequency mixer _U8 is a sine wave as described above,
Both of the above mixed output signals are sinusoidal waves. In other words, as described above, by using a frequency mixer that contains very little high-order waves for at least one of the two input signals ₁ and ₂ as the frequency mixer _U8 , the above-mentioned result can be achieved. The mixed output signal of both becomes a sine wave.

In other words, as described above, as the frequency mixer _U8 , by using a wind wave number mixer that has a very low content of high-order waves for at least one input signal of the two inputs _f1 and _f2 . Therefore, both of the above mixed output signals become a sine wave.

Moreover, when the L signal and the R signal are not in phase but out of phase, both the frequency deviation of the frequency modulation oscillator U ₃ and the frequency deviation of the bandpass filter U ₇ are
Assuming 5KHz, in bandpass filter U ₁₀ , L-R
In other words, a frequency deviation of 10KHz becomes harsh.
That is, the bandwidth that the bandpass filter U ₁₀ must cover must be large compared to the bandwidth that the bandpass filter U ₇ must cover. In order to cut a wide bandwidth sharply, _a high-precision bandpass filter is required. Better performance can be obtained when used with waveform U ₇ .

Next, one of the above modulated wave signals
Fs±Δ _(LR) is the main carrier frequency modulated oscillator U ₁₁
The main carrier wave of oscillation frequency Fm-p/q ( ₁ + ₂ ) is frequency modulated at Fm-p/q ( ₁ +
₂ ) Let ±ΔF{ _Fs± 〓 _(LR) }.

The other signal ( ₁ + ₂ ) ± Δ _{(L + R)} is guided to the p/q frequency converter U ₁₄ to convert the frequency converted signal p/q ( ₁ + ₂ ) ± p/q Δ _{(L +R
)} . Then, the frequency deviation Δ _(LR) on the difference signal side and the frequency deviation p/ on the sum signal side
Adjust the ratio of qΔ _(L+R) to the specified standard value.
Then, both output signals of the main carrier frequency modulation oscillator U ₁₁ and the p/q frequency converter U ₁₄ are guided again to the third frequency mixer U ₁₂ , and the sum frequency component signal Fm±p/qΔ _{( L+R)} ±Δ{ _Fs± 〓 _(LR
) } is extracted and transmitted from the output terminal 15.

Further, since it is necessary to stably maintain the carrier frequency of the signal outputted to the output terminal 15, an AFC circuit described below is provided for this purpose. In this case, the difference between the output frequency of the highly stable oscillator U ₁₈ of the standard main carrier (frequency Fm) and the output frequency at the terminal 15 is detected by the frequency difference detector U ₁₇ , and the oscillation frequency of the main carrier frequency modulation oscillator U ₁₁ is detected.
What is necessary is to frequency control Fm-p/q ( ₁ + ₂ ). Incidentally, the frequency difference detector U ₁₇ is configured by, for example, a discriminator and a low-pass filter having a center frequency equal to the difference in oscillation frequency between the highly stable oscillator U ₁₈ and the oscillator U ₁₁ .

Next, in another embodiment of the present invention shown in FIG. 3, the p/q frequency converter U ₁₄ in the case of FIG. A transducer U ₁₅ is interposed.

That is, in the case of FIG. 3, one of the output terminals of the second frequency mixer _U8 has the center frequency Fs= ₁
− ₂ second bandpass filters U ₁₀ , q/p frequency converter;
U ₁₅ , and a main carrier frequency modulation oscillator U ₁₁ ' having an oscillation frequency Fm-( ₁ + ₂ ) are successively connected to the third frequency mixer U ₁₂ . Also a second frequency mixer
The other output terminal of U ₈ is connected to a third frequency mixer via a third bandpass filter U ₁₃ with a center frequency of ₁ + ₂ .
Separately lined up with U ₁₂ .

In this case, the second bandpass filter U ₁₀
Difference signal from (LR) side signal Fs±Δ _(LR)
Convert the frequency at a constant ratio q/p to q/p・Fs±q/
As p・Δ _(LR) , the frequency deviation q/p・
Δ _(LR) and the frequency deviation of the sum signal side Δ _(L+R)
The ratio of This point differs from the above-mentioned embodiment, but other functions such as making the output signal a sine wave are substantially the same as those described above.

Next, in the case of FIG. 4, a 1/p first frequency divider is used instead of the p/q frequency converter U ₁₄ in the case of FIG.
U ₁₆ and 1/q second frequency divider U ₁₆ ′,
First, the bandpass filter is placed after the second bandpass filter _U10 ' whose center frequency is pFs=p( _{1-2 )} .
One output signal from U ₁₀ ′ i.e. pFs±Δ _(LR)
A 1/p first frequency divider U ₁₆ is connected to convert the frequency at a predetermined ratio of 1/p.

On the other hand, the third bandpass filter U13' whose center frequency is p( ₁ + ₂ ) is followed by the third bandpass filter _U13 '.
The other output signal from U ₁₃ ′ is converted to another predetermined ratio 1/q
It is connected to a second frequency divider U ₁₆ ' for frequency conversion.

In addition, corresponding to the above modification, each oscillation frequency of the frequency modulation oscillator U ₄ ′ that modulates the frequency with the right signal R and the frequency modulation oscillator U ₃ ′ that modulates the frequency with the left signal L is set to p ₁ , and the oscillation frequency from the oscillator U ₅ ′ is The frequency of the standard subcarrier to be oscillated is pFs, and the center frequency of the first bandpass filter _U7 ' is p( ₁ -
Fs).

Therefore, in the above case, the difference signal side, that is,
The signal side of pFs±Δ _(LR) is divided by 1/p, and the sum signal side, that is, the signal side of p( ₁ + ₂ ) ±Δ _(L+R) is divided by 1/p.
By dividing the frequency by q, the ratio of frequency deviations in both signals is adjusted to the standard value.

This point differs from the cases shown in Figures 2 and 3 above.
The other functions such as making the output signal a sine wave are substantially the same as described above.

Incidentally, both frequency dividers U ₁₆ and U ₁₆ ′ mentioned above are constructed by a combination of multiple flip-flop circuits, and the denominator is an odd number such as 1/3 or 1/5. In this case, a feedback circuit may be provided in a part of the circuit to delay the number of inversions of the flip-flop circuit by one time or an odd number of times.

Note that a combination of multiple flip-flop circuits as described above is a unit IC (one chip).
This makes it extremely easy to manufacture ICs.

Next, in the cases shown in Figs. 5 to 7, when making the subcarrier signal in the multiplexed output signal into a sine wave, the frequency mixer corresponding to the second frequency mixer _U8 is replaced with the fourth frequency mixer.
and a fifth frequency mixer U ₈ ′, U ₈ ″, and in order to set the ratio of both frequency deviations to a predetermined value, a p/q frequency converter U ₁₄ , q/p frequency converter
U ₅ and 1/p, 1/q frequency dividers U ₁₆ , U ₁₆ ′ are used, respectively.

In other words, the example in Fig. 5 is the fourth frequency mixer.
The output signals of a frequency modulation oscillator U ₃ frequency-modulated by the left signal L and a first bandpass filter U ₇ with a center frequency of ₁ −Fs are introduced into both input terminals of U _{8 ′} , and furthermore, this fourth frequency The output terminal of the mixer U ₈ ' is connected to a second bandpass filter U ₁₀ with a center frequency of Fs = ₁ - ₂ , and a main carrier frequency modulation oscillator U ₁₁ '' with an oscillation frequency of Fm - 2 (p/q) _1. and is connected to the third frequency mixer _U12 .

On the other hand, each output signal from both frequency modulation oscillators U ₃ and U ₄ , which frequency modulates with the left signal L and right signal R, is separately introduced into both input terminals of the fifth frequency mixer U ₈ ″. The output terminal of the frequency mixer _U8 '' is connected to a third bandpass filter with a center frequency of _2.1
It is separately connected to the third frequency mixer U ₁₂ through the U ₁₃ ″ and the p/q frequency converter U ₁₄ in sequence.

In the example shown in FIG. 5, the fourth frequency mixer _U12 of both input lines of the third frequency mixer U12
Signal Fs±Δ _(LR) transmitted on the output line side of U _{8 ′}
is a sine wave signal, and the subcarrier signal in the multiplexed output signal is a sine wave signal. Also, the frequency deviation Δ _(LR) on the difference signal side and the frequency deviation Δ ₍
To adjust the ratio of the sum signal side (main carrier wave) to the specified standard value, the frequency deviation Δ _{(L+ R
)} with the ratio p/q, p/q・Δ _(L+R)
This is done as follows.

Next, in the case of Fig. 6, the frequency mixer corresponding to the second frequency mixer U ₈ is composed of two frequency mixers U ₈ ′ and U ₈ ″, the fourth and fifth. is exactly the same as the case in Figure 5 above, but
The p/q frequency converter U ₁₄ in this example of Fig. 5
Instead, a q/p frequency converter _U15 is interposed in the signal line on the difference signal (LR) side. That is, the configuration is almost the same as the case shown in FIG. 3 described above in that the ratio of the frequency deviation in one output signal to the frequency deviation in the other output signal is set to a predetermined value.

Further, in correspondence with the above modification, the oscillation frequency of the main carrier frequency modulation oscillator _U11 is set to Fm- ₂₁ .

Next, in the case of FIG. 7, the second frequency mixer U ₈
The frequency mixer corresponding to the above is composed of two frequency mixers U ₈ ′ and U ₈ ″ as in the case of FIGS. 5 and 6, and the p/q frequency converter U ₁₄ in the case of FIG. Instead, a 1/p first frequency divider U ₁₆ and a 1/q second frequency divider U ₁₆ ' are used, i.e. the frequency deviation in one output signal and the frequency deviation in the other output signal are The configuration is almost the same as that of the example shown in FIG. 4 described above in that the ratio to the shift is set to a predetermined value.

Incidentally, components shown in FIGS. 3 to 7 that are the same or equivalent to those shown in FIG. 2 are designated by the same reference numerals as above.

As detailed above, according to the present invention, one signal input line in the second frequency mixer has a center frequency.
A first frequency mixer of ₁ -Fs is interposed, and this first bandpass filter selects the signal frequency and simultaneously removes the harmonics with respect to the center frequency. It oscillates with the excellent effect of making the subcarrier signal wave a sine wave.

Also, the frequency deviation Δ (L+R) due to the sum signal _(L+R) of frequency Fm and the difference signal (L−
When adjusting the ratio of the frequency deviation Δ _(LR) caused by
Furthermore, the multiplex signal generator as a whole can be easily configured and economical, and exhibits extremely excellent practical effects.

Furthermore, even if a q/p frequency converter is used instead of a p/q frequency converter, the frequency deviation ratio mentioned above can be adjusted to the standard value, which is an excellent method that can enrich the technology. be effective.

Furthermore, in addition to the above-mentioned effects, the left and right signals are not passed through the matrix circuit at the low frequency stage, but each signal is first guided to a frequency modulation oscillator where FM is applied, and the high frequency signal component is modulated by each signal. Then, these two signals are guided to a frequency mixer that mixes them at high frequency.The oscillation frequencies of both frequency modulation oscillators are set to the same frequency value, and the modulation characteristics of both are made to be the same. Improved signal separation,
Further, it exhibits an excellent effect in that there is no possibility of generation of crosstalk signal components.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional example, Fig. 2 is a block diagram of an FM-FM multiplex signal generator which is an embodiment of the present invention, and Figs. 3 to 7 show other embodiments of the same. FIG. 1... Input terminal for left signal L, 2... Input terminal for right signal R, 15... Output terminal, U ₃ , U ₃ ', U ₄ , U ₄ '... Frequency modulation oscillator, U ₅ , U ₅ '... Standard sub Carrier frequency oscillator, U ₆ ... first frequency mixer, U ₇ , U ₇ ′... first bandpass filter, U ₈ ... second frequency mixer, U ₈ ′... fourth frequency mixer, U ₈ ″... Fifth frequency mixer, U ₉ ,
_U17 ...Frequency difference detector, _U10 , _U10 '...Second bandpass filter, _U11 , _U11 ', _U11 '', _U11 ...Main carrier frequency modulation oscillator, _U12 ...Third frequency mixer, U ₁₃ /U ₁₃ ′,
_{U 13 ″ , _ _} U ₁₈ ...High stability oscillator.

Claims (1)

[Claims] 1. In a device for forming a stereo signal using the FM-FM system, a frequency modulation oscillator U ₄ with an oscillation frequency of ₁ that modulates the frequency with the right signal R and an oscillator U ₅ that oscillates a standard subcarrier FS are combined into a first frequency mixer U ₆ Connect this mixed output terminal to the center frequency
The oscillation frequency ₁ is connected to one input terminal of the second frequency mixer U ₈ via the first band filter U ₇ of 1 − FS = ₂ ( ₁ > ₂ > FS), and is frequency modulated with _the left signal L. frequency modulated oscillator
U ₃ is connected to the other input terminal of the second frequency mixer U ₈ , and further the second frequency mixer U ₈
One of the output terminals has the center frequency FS = ₁ - ₂
One output signal from this second band filter U ₁₀ is connected to a second band filter U ₁₀ with an oscillation frequency Fm.
−p/q( ₁ + ₂ ), and the output of this main carrier frequency modulation oscillator _{U 11 is} further guided to a third frequency mixer U ₁₂ , and the second frequency mixing The other output terminal of the filter U ₈ is a third band filter U ₁₃ with a center frequency of ₁ + ₂ , and the other output signal from the third band filter U ₁₃ is frequency-converted at a predetermined ratio p/q. The frequency converter U ₁₄ is connected to the third frequency mixer U ₁₂ in order to set the ratio of the frequency deviation in the one output signal to the frequency deviation in the other output signal to a predetermined value. Furthermore, from the output of the third frequency mixer U ₁₂ , only the sum frequency component is extracted, or a frequency mixer capable of extracting only the sum frequency component is used, and the output is separately provided for transmission. An FM-FM multiplex signal generator characterized by being installed in an aircraft, etc.