JPH0424668Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to an FM receiver, which receives an FM multiplex signal,
The present invention relates to an FM stereo receiver that receives FM stereo signals.

[Summary of the invention] In a synthesis device whose purpose is to synthesize an FM stereo signal and an FM multiplex signal, the FM stereo signal passed through a level limiting means and the FM multiplex signal are combined, and the level of the FM multiplex signal is detected. The FM demodulation output synthesis device operates so that when the FM multiplex signal level increases, the FM stereo signal decreases by controlling the signal obtained by the level limiting means.

[Prior art] FM broadcasting usually has a main signal with an audio signal band of 50Hz to 15KHz, and a main signal with an audio signal band of 23KHz to 53KHz.
Stereo modulation is performed using sub-signals having a band up to Hz. However, in order to further improve the usage efficiency of broadcasting power, a method is being considered in which an FM multiplex signal is placed in a band of 53KHz or above.For example, the SEA signal in the United States uses an FM modulation method with a subcarrier of 76KHz, and commercial music sources, etc. It is modulated. Therefore, to listen to the FM multiplex signal on an FM receiver, the FM
It must be demodulated by a multiple signal demodulator.

A conventional receiver compatible with FM multiplex broadcasting is shown in Fig. 3. In this type of FM multiplex receiver, an FM stereo demodulator converts stereo signals into
The multiplexed signal was demodulated using an FM multiplexed signal demodulator, and audio was output by selecting one of the signals using a switch.

That is, the stereo demodulator E and
In a receiver equipped with an FM multiplex demodulator F, the FM signal desired to be received from antenna A is transmitted to high frequency circuit B.
The signal is tuned and high-frequency amplified by the intermediate frequency circuit C, and then converted to an intermediate frequency and amplified by the intermediate frequency circuit C. Then, the intermediate frequency FM signal is detected by the FM detector D, and a composite signal is output.

This composite signal includes a main signal with a band of 50 Hz to 15 KHz, a sub signal with a band of 23 KHz to 53 KHz, and an FM multiplex signal with a band of 53 KHz and above.

The stereo demodulator E extracts the stereo left signal from the main signal and sub signal in the composite signal.
It outputs two signals: a channel audio signal and a right channel audio signal.

On the other hand, the FM multiplex demodulator F outputs an FM multiplex audio signal from the FM multiplex signal in the composite signal.

The two signals and the FM multiplexed audio signal are controlled to be distributed and outputted by the FM demodulation output control circuit G, and the distributed signals are audio amplified by the left and right channel low frequency amplifiers H and output to the speakers. Audio is output with I and J.

[Problem to be solved by the invention] However, in the FM multiplex receiver shown in Fig. 3,
The demodulated stereo signal and the multiplexed signal are simply selected by a switch and output as audio, and when one signal is being received, the content of the other signal is There was no structure or means in place to easily confirm whether the broadcast was being broadcast.

For this reason, for example, when receiving a multiplexed signal, there is a drawback that it is not possible to confirm what kind of stereo signal is being broadcast.

The purpose of this invention is to combine a stereo signal and an FM multiplex signal with an arbitrary amount of combination.
The purpose is to obtain a state in which two signals can be checked at the same time.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an FM demodulation means that demodulates a detected signal in which an FM multiplex received signal is detected and outputs a stereo signal and a multiplexed signal from the detected signal. and level detection means for detecting the level of the multiplexed signal from the FM demodulation means and outputting a detection signal according to the level, and based on the detection signal,
level control means for adjusting and controlling the level of the stereo signal from the FM demodulation means so as to be substantially inversely proportional to the level of the multiplexed signal; and combining the stereo signal from the level control means and the multiplexed signal at a predetermined synthesis ratio. and a signal combining means for obtaining a combined output signal.

Further, the apparatus is characterized in that it has a level setting means that can arbitrarily set the level of the multiplexed signal from the FM demodulation means to a predetermined level, and outputs the level to the level detection means and the signal synthesis means.

[Operation] The FM demodulation output synthesis device according to the present invention demodulates a detected signal obtained by detecting an FM multiplexed reception signal, and obtains a stereo signal and a multiplexed signal from the detected signal.

The level of this multiplexed signal can be set to any predetermined level.

Then, the level of the multiplexed signal is detected and a detection signal corresponding to the detected level is output, and based on this detection signal, the level of the stereo signal is adjusted and controlled so as to be substantially inversely proportional to the level of the multiplexed signal.

Further, the stereo signal from the level control means and the multiplexed signal are synthesized at a predetermined synthesis ratio, and a synthesized signal is output as audio.

As a result, the stereo signal level can be varied according to the settings of the predetermined multiplex signal level and synthesis ratio, and it becomes possible to selectively listen to the stereo signal and the multiplex signal.

[Example] Fig. 1 is a block diagram of an FM receiver having an FM demodulation output synthesis device of the present invention, and Fig. 2 is a block diagram of an FM receiver having an FM demodulation output synthesis device of the present invention.
FIG. 2 is a block diagram of an FM demodulation output synthesis device.

In Figure 1, 1 is an antenna, 2 is an RF circuit,
3 is an IF circuit, 4 is a DET circuit that demodulates the FM signal,
5 is a stereo demodulator that demodulates a stereo signal; 6 is a stereo demodulator that demodulates a stereo signal;
1 is a multiplex signal demodulator for demodulating an FM multiplex signal, 7 is an FM demodulation output synthesis device of the present invention, 8 is a two-channel AMP, and 9 and 10 are speakers.

Radio waves input from antenna 1 are sent to RF circuit 2
After being amplified, it is converted into an IF signal, which is further amplified by the IF circuit 3. The signal output from the IF circuit 3 is demodulated by an FM demodulator 4 and input to a stereo demodulator 5 and a multiple signal demodulator 6. In the stereo demodulator 5, the stereo L channel signal S _L
, the R channel signal S _R is outputted and inputted to the FM stereo synthesis device 7 , and the multiplexed signal demodulator 6 outputs a multiplex demodulated signal S _M and inputted to the FM stereo synthesis device 7 .

The stereo synthesizer 7 synthesizes the stereo L channel signal S _L and the multiplex demodulated signal S _M into an L channel output S _L ′, and also outputs the stereo R channel signal S _R
and the R channel signal that combines the multiplex demodulated signal S _M
S _R ′ is output, and both are input to the two-channel amplifier 8. The two-channel amplifier 8 amplifies the two input signals and drives the L-channel speaker 9 and the R-channel speaker 10.

FIG. 2 is a block diagram showing a detailed circuit configuration of the FM demodulation output synthesis device 7 of FIG. 1.

In FIG. 2, 11 and 21 are integrators 12 and 2.
2 is a variable attenuator controlled by the manual attenuators 14 and 23, level detectors 13 and 23 detect the signal level of the multiplexed signal S _M output from the manual attenuators 14 and 24;
15 and 25 combine the stereo signals S _L and S _R output from the variable attenuators 11 and 21, the multiplexed signal S _M output from the manual attenuators 14 and 24, and the signal output from the manual attenuators 14 and 24. It is a synthesizer.

Now, in such a configuration, the L channel signal S _L from the stereo demodulator is sent to the variable attenuator 1.
1, and the multiple demodulated signal S _M from the multiple signal demodulator is input to manual attenuators 14 and 24. The output from the manual attenuator 14 is sent to the combiner 1.
5 and is also input to the level detector 13 , and the output of the level detector 13 is given to the integrator 12 . As a result, the output of the integrator 12 can obtain a DC voltage corresponding to the level of the multiple demodulated signal output from the manual attenuator 14. Furthermore, the DC output from the integrator 12 is connected to a variable attenuator 11.
is controlled so that the stereo L channel signal S _L output from the variable attenuator 11 has a level that is inversely proportional to the level of the multiple demodulated signal output from the manual attenuator 14 . The synthesizer 15 synthesizes the stereo L channel signal S _L whose level has been controlled by the variable attenuator 11 in this manner and the multiplex demodulated signal S _M output from the manual attenuator 14, and outputs the L channel S _L '.

On the other hand, the stereo R channel signal S _R is input to the variable attenuator 21, and S _R ' can be obtained at the output of the synthesizer 25 in the same way.

Now, when there is no multiplex demodulated signal, the attenuation amount of the variable attenuators 11 and 21 is "0", and the input stereo signals S _L and S _R are left unchanged and the synthesizer 15 and
25 as S _L ′ and S _R ′. When the multiple demodulated signal S _M is input in this state, the attenuation amount of the variable attenuators 11 and 21 increases, and as a result, the stereo signals output from the combiners 15 and 25 decrease and the multiple demodulated signal S _M is synthesized. Vessels 15, 25
is output from.

If the multiplex demodulated signal S _M is in a signal state where the level fluctuates, the time constant of the integrator can be set to an arbitrary value to achieve a consistent synthesis.
It can be done in 5. Furthermore, the manual attenuators 14 and 24 can arbitrarily vary the synthesis ratio of the stereo signals S _L and S _R and the multiplex demodulated signal _SM in the synthesizers 15 and 25, and if the amount of attenuation is made infinite, The stereo signals S _L and S _R that are input independently to the input of the multiplex demodulated signal S _M are directly converted to S _L ′,
It is output as S _R ′, and if the attenuation amount is “0”, then
When the multiple demodulated signal S _M is input, the combiner 15,
It is possible to obtain only the multiplex demodulated signal S _M in the output signals S _L ′ and S _R ′ of 25.

[Effects of the invention] As explained above, according to the invention, it is possible to listen only to conventional stereo broadcasts, to listen only to FM multiplex broadcasts, and also to listen to only stereo broadcasts and FM multiplex broadcasts.
In addition to being able to listen to both multiplexed broadcasts at the same time with a desired combination ratio, the listener can also change the combination ratio for left and right channels separately by adjusting the two manual attenuators for the left and right channels.

Furthermore, since the average level of the synthesized output can be kept constant regardless of the synthesis ratio, there is no need to adjust the volume anew when the synthesis ratio is changed.

[Brief explanation of the drawing]

Figure 1 is a block diagram of an FM receiver equipped with the FM demodulation output synthesizer of the present invention, and Figure 2 is a block diagram of an FM receiver equipped with the FM demodulation output synthesizer of the present invention.
FIG. 2 is a block diagram of an FM demodulation output synthesis device. Third
The figure is a block diagram of a conventional FM multiplex receiver. 5... Stereo demodulator, 6... Multiple signal demodulator, 11, 21... Variable attenuator, 12, 2
2... Integrator, 13, 23... Level detector, 1
4,24...Manual attenuator, 15,25...
Synthesizer.

Claims (1)

[Claims for Utility Model Registration] FM demodulation means for demodulating a detected signal in which an FM multiplex received signal is detected and outputting a stereo signal and a multiplexed signal from the detected signal; and detecting the level of the multiplexed signal from the FM demodulation means. level detection means for outputting a detection signal according to the level; and level control for adjusting and controlling the level of the stereo signal from the FM demodulation means so as to be substantially inversely proportional to the level of the multiplexed signal, based on the detection signal. means for combining the stereo signal from the level control means and the multiplexed signal at a predetermined combination ratio to obtain a composite output signal, It is characterized by adjusting and controlling the signal level.
FM demodulation output synthesis device.