JPS595892B2 - Code signal extraction circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit for extracting a code signal such as a cue signal when it is superimposed on an information signal such as an audio signal.

There is an adapter device shown in FIG. 1 that allows various games and learning to be played using a general television receiver and a VTR (magnetic recording/reproducing device). That is,
This adapter device includes a tape cassette 10 for questions,
It consists of an adapter 20 for answers, and the adapter 20
has an answer button (answer switch) 21, a correct answer indicator lamp 22, an incorrect answer indicator buzzer 23, a score counter 24, a speaker 25, a plug 26, and the like.

Then, as shown in FIG. 2, the plug 26 of the adapter 20
is connected to the earphone jack of the television receiver 2, and the cassette 10 is set in the VTRI.

When the cassette 10 is played back, appropriate sound effects and BG are output from the speaker 25 of the adapter 20 through the receiver 2.
M is played back, and on the screen of the receiver 2, for example, the third
As shown in the figure, a scene of four jet planes flying away is displayed, along with four sights. Therefore, as soon as one of the jet planes comes into sight, one of the answer buttons 21 is pressed with the same number as that one. At this time, the answer is a specified time limit (for example, 0.6 seconds) after the jet enters the sights.
If the answer is correct, the lamp 22 will be decremented to notify you of the correct answer, and the counter 24 will increase the score.

Even if the answer is correct, no action will be taken if the time limit has elapsed. Furthermore, in the case of incorrect answers or no answers,
When the buzzer 23 sounds, the score on the counter 24 is deducted. A number of such questions are then asked, and as the players continue to answer them, the final score is displayed on the counter 24 and the game ends.

Alternatively, for example, as shown in FIG. 4A or B, the question and answer are displayed on the screen of the receiver 2.

Therefore, before this question changes to the next question, the user presses the answer button 21 corresponding to the number that is considered to be the correct answer. Then, if the answer is correct, the lamp 22 lights up and the score on the counter 24 increases, but if the answer is incorrect, the buzzer 23 sounds, and if there is no answer, the buzzer 23 remains unchanged. However, in the case of an incorrect answer or no answer, the score on the counter 24 does not change. After a certain amount of time, the next question will be displayed and you can answer it in the same way.

Therefore, in this case, a game or learning is performed depending on the content of the problem. In order to be able to play games and study in this way, the force set 10 and the adapter 20 are configured as follows.

That is, FIG. 5 shows the recorded contents of the magnetic tape 11 of the force set 10. At the beginning of the tape 11,
Video and audio signals explaining how to play are recorded.

Next, in the video channel part, the two video signals to be played back as the problem are sequentially recorded, and in the audio channel part, there are sound effects corresponding to the problem and explanatory words if necessary. An audio signal Sa such as the following is recorded. In this case, the audio signal Sa includes a code signal Sc indicating information such as the answer to each question.
are frequency multiplexed.

That is, FIG. 6A shows an example of the code signal Sc.
This code signal Sc includes a cue mark signal Sm indicating the arrival of the code signal, a signal Sg indicating that the game content is the game explained in FIG. 3, and a time limit for an answer. It consists of a signal St and a signal Sk indicating the correct number, and these signals Sm-Sk are serially digitally encoded. Further, the time length of the code signal Sc for one problem is, for example, about 0.3 seconds. Then, as shown in FIG. 6B, such a code signal Sc is an AM signal Sh (carrier frequency is 7
．． 5KHz), and this AM signal Sh and audio signal S
a is frequency-multiplexed and recorded on the audio channel portion of the tape 11, as shown in FIG. Further, the adapter 20 is configured as shown in FIG. 8, for example.

That is, in the VTR1, the video signal and the multiplexed signal of the audio signal Sa and the AM signal Sh are reproduced from the power set 10 and supplied to the receiver 2, and the video signal is displayed on the receiver 2 as an image and is multiplexed. The signal is further supplied to the speaker 25 of the adapter 20 through the plug 26. The multiplexed signal is then supplied to a bandpass filter 27 to extract an AM signal Sh, this signal Sh is supplied to a demodulation circuit 28 to demodulate a code signal Sc, and this code signal Sc is supplied to a determination circuit 29. Along with
This determination circuit 29 is supplied with a signal indicating the answer from the answer button 21 .

In this way, in the judgment circuit 29, a judgment is made on the answer based on the code signal Sc, and the result is sent to the means 22.
~24, and the answer results are displayed. In this way, games and learning can be performed using the above-mentioned adapter device. In this case, the VTR 1 and receiver 2 may be completely ordinary ones, and there is no need for modification or special handling; simply plug the plug 26. Anyone can easily play games or study by simply connecting the receiver to the earphone jack of receiver 2.

However, for this purpose, as mentioned above, the code signal Sc
It is necessary to frequency multiplex the AM signal Sh with the audio signal Sa.
Since the frequency band is limited, the fidelity of the original sound deteriorates.

Therefore, the carrier frequency of the AM signal Sh is added to and mixed with the audio signal Sa as a combination of a plurality of frequencies, and the filter 27
Instead, a method may be considered in which the decoder determines the code signal Sc and the content of the code signal Sc from the combination of frequencies.

However, although this method does not limit the band of the audio signal Sa, the decoder must perform the above-described discrimination operation, which complicates its configuration and increases costs. In consideration of the above points, the present invention aims to provide a separation circuit that does not limit the band of the audio signal Sa and can extract the code signal Sc with a simple configuration.

An example of this will be explained below.

In the present invention, as shown in FIG.
A multiplexed signal obtained by time-division multiplexing the AM signal Sh at c with the audio signal Sa is received, and AM signal Sh from the multiplexed signal is received.
The code signal Sc is extracted using the frequency and time elements of the signal Sh.

That is, the AM signal Sh is set to a carrier frequency within the band of the audio signal Sa, for example 4KHz, and the audio signal Sa is left blank at the boundary of each problem, and the AM signal Sh is inserted into this blank part to generate the AM signal. The signal Sh is time-division multiplexed into the audio signal Sa, and this multiplexed signal Sj is recorded on the tape 11 of the power set 10, as explained with reference to FIG.

The duration time of each bit of the signal Sh, that is, the length of each bit of the signal Sc is, for example, 10 msec.
Then, the multiplexed signal Sj is reproduced in TRl, and the ninth
As shown in the figure, the level of the signal Sj is kept constant by being supplied to the plug 26 and further supplied to the AGC amplifier 31.
This constant level signal Sj is supplied to a narrowband bandpass filter 32, and an AM signal Sh (including audio signal components of the same frequency) is extracted.

For the sake of simplicity, in the following explanation, the audio signal Sa is
It is assumed that a signal having the frequency component of the signal Sh is not included.

Therefore, the AM signal Sh from the filter 32 is as shown in FIG. 6B. Furthermore, the AM signal Sh from the filter 32 is supplied to a rectifier circuit 33, and a positive half-cycle signal Sr is taken out, for example, as shown in FIG. As shown in FIG. 6D, this signal Si is supplied to a level discrimination circuit, for example, a Schmitt circuit 35, and as shown in FIG.
As shown in E, the signal Sc rising at a portion of the signal Si equal to or higher than the level Ei, that is, the code signal Sc is extracted.

Further, the signal Sg from the amplifier 31 is supplied to a narrowband band removal filter 42, and an audio signal Sa from which the AM signal Sh (including audio signal components of the same frequency) is removed is extracted. is sequentially supplied to the rectifying circuit 43, the integrating circuit 44, and the Schmitt circuit 45, where signal processing similar to that in the circuits 33 to 35 is performed, and the Schmitt circuit 45 outputs the audio signal Sa as shown in FIG. 6F. An output signal Ss corresponding to is extracted. In this case, since the AM signal Sh and the audio signal Sa are time-division multiplexed, the audio signal Sa must include a signal having the frequency component of the AM signal Sh.4 As shown in FIG. 6 E and F, Signals Sc and Ss do not overlap in time. Then, the signals Sc and Ss from the Schmitt circuits 35 and 45 are supplied to the set terminal S and the reset terminal R of the RS flip-flop circuit 36 which has priority on resetting, and as shown in FIG. Rising at bit, signal S
A signal Sf that falls at s is formed, and this signal Sf is supplied to the gate circuit (AND circuit) 37 as its flag signal, and the code signal Sc from the Schmitt circuit 35 is supplied to the gate circuit 37 as its input signal. Ru.

Therefore, the code signal Sc is taken out to the output terminal 38. On the other hand, when the audio signal Sa includes a signal having the frequency component of the AM signal Sh, the signal having the frequency component is extracted from the filter 32.

However, in order for a signal with such a frequency component to appear as a signal Sc from the Schmitt circuit 35, the signal must have a period corresponding to the time constant of the integrating circuit 34 and the threshold level Ei of the Schmitt circuit 35, that is, AM It must last for the duration of each bit in the signal Sh (for example, 10 ms), but in general music and speech,
In this way, a specific frequency component does not continue for a specific period of time, and therefore, even if the audio signal Sa contains a signal of the frequency component of the AM signal Sh, the signal "Sc" is not formed. Furthermore, even if the audio signal Sa contains a signal having the frequency component of the AM signal Sh for a considerable period of time, and thus the signal Sc is formed, general musical tones and voices include the frequency component of the AM signal Sh. Since it includes harmonic components,
A signal Ss is also generated simultaneously with the signal Sc, and this signal Ss causes the flip-flop circuit 36 to output the signal Sc.
It is set with priority.

Therefore, the flag signal Sf does not rise, so the terminal 3
8, the erroneous code signal Sc due to the audio signal Sa will not be extracted. Thus, according to the present invention, the code signal Sc can be reliably extracted.

Moreover, in that case, the band of the audio signal Sa is not limited, and therefore the fidelity of the original sound is not impaired. Also, the configuration is simple. In the above, when the signal Sh is the code signal Scl)5ゞ1゛, for example, it is 4KHz and 1
For example, in the case of an FM signal that becomes 5 KHz when the frequency is 01, the filters 32 and 42 are both band-pass filters, and the 4 KHz signal component is taken out from the filter 32, and the 5 KHz signal component is taken out from the filter 42. Then, the code signal Sc can be obtained from the flip-flop circuit 36 without providing the gate circuit 37.

Furthermore, in the above description, during the period of the signal Sh, the audio signal S
a is blank, but even if there is an audio signal Sa, the S/N as seen from the signal Sh only decreases, so this S
The audio signal Sa may be within the permissible decrease of /N.

Furthermore, the AM signal Sh supplied to the speaker 25 may be muted using the signal Sf.

[Brief explanation of drawings]

1 and 2 are perspective views of an example of a device in which the present invention can be used, FIGS. 3 to 7 are diagrams for explaining the same, FIG. 8 is a system diagram thereof, and FIG. 9 is a perspective view of an example of a device that can use the present invention. It is an example system diagram. 32, 42 are filters, 33, 43 are rectifier circuits, 34,
44 is an integrating circuit, 35 and 45 are Schmitt circuits, and 36 is an RS flip-flop circuit.

Claims (1)

[Claims] 1 A time-division multiplexed signal of a modulation signal modulated by a code signal and an information signal is supplied, and from this time-division multiplexed signal, a frequency component of the modulation signal corresponding to the frequency of the modulation signal is supplied. The first to take out the first signal
a second filter that extracts a second signal having a frequency component other than the first signal from the time division multiplexed signal; and a second filter that shapes the first and second filter outputs to generate the first and second signals. a circuit for generating a second pulsed signal;
and a bistable circuit that is set and reset by a second pulsed signal, and the first pulsed signal is gated by the output signal of the bistable circuit to extract the code signal. extraction circuit.