JPH08251554A - Method and device for speech transmission - Google Patents

Abstract

PURPOSE: To transmit a speech signal through simple circuit constitution without narrowing down the occupation frequency band of a video signal by encoding the speech pulses, superposing them on the front or back porch part of the video signal, and transmitting them. CONSTITUTION: An adder 13 superposes the PAM-coded speech signal (d) from a sampling circuit 12 on, for example, the back porch part of the video signal (a) synchronized with a horizontal synchronizing signal (c) and sends them out to a modulator 14. The modulator 14 imposes specific modulation on the video signal (e) to generate a high frequency signal and sends it out from an antenna 15. The high frequency signal received by the antenna of a reception- side device is selected by a tuner, and sent to an intermediate-frequency circuit after high frequency amplification. The intermediate frequency circuit outputs the video signal which has the speech signal superposed to a pulse extracting circuit and a monitor display part and the horizontal synchronizing signal to the pulse extracting circuit. The pulse extracting circuit extracts the PAM-coded speech signal at the back port part from the video signal according to the horizontal synchronizing signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio transmission method and device for transmitting an audio signal such as a television signal together with a video signal linked with the audio signal.

[0002]

2. Description of the Related Art A signal for transmitting an audio signal together with a video signal interlocked with the audio signal, for example, an NTSC television signal adopted in Japan, uses a 4.5 MHz carrier as the audio signal for the video signal. The signal modulated by the FM is created, superposed, and modulated for transmission.

Therefore, in addition to the video signal processing circuit,
On the transmitting side, a circuit that creates a 4.5 MHz FM modulated wave,
Since the receiving side needs an audio intermediate frequency circuit that extracts the audio signal from the video signal and amplifies and demodulates it, the circuit scale becomes large on both the transmitting and receiving sides, and the frequency bandwidth for transmitting the video signal is narrowed by the audio signal. There was a problem that it ended up.

[0004]

As described above, in the case of a signal that handles an audio signal together with a video signal, such as a conventional television signal, a circuit for superimposing the audio signal on the video signal on the transmitting side and a signal on the receiving side. The circuit configuration for extracting the audio signal superimposed on the video signal becomes complicated, and the audio signal narrows the transmission frequency bandwidth of the video signal, so that the allocated frequency band is effectively used. There was a problem that I could not do it.

The present invention has been made in view of the above situation, and an object thereof is to transmit an audio signal with a simple circuit configuration and without narrowing the occupied frequency band of a video signal. Another object of the present invention is to provide a simple voice transmission method and apparatus.

[0006]

That is, according to the present invention, on the transmitting side, an audio signal is sampled and pulsed in synchronization with a horizontal synchronizing signal in a video signal and superposed on a front porch portion or a back porch portion of the video signal. The audio signal pulse superimposed on the front porch portion or the back porch portion of the video signal is extracted and analogized and output on the receiving side.

[0007]

By doing so, the circuit structure for transmitting and receiving the audio signal can be greatly simplified, and the occupied frequency band of the video signal is not narrowed by the audio signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an apparatus for transmitting and receiving television signals will be described below with reference to the drawings. FIG. 1 shows a circuit configuration of a transmission side device. An analog audio signal b to be transmitted is passed through a low pass filter (LPF) 11 at a specific frequency, for example, about 7.8 [k].
After the high frequency component of [Hz] or higher is removed, it is supplied to the sampling circuit 12.

The sampling circuit 12 samples the audio signal in synchronism with a horizontal synchronizing signal c given from the outside and applies a PAM (pulse amplitude modulation) signal d.
Is sent to the adder 13.

A video signal a synchronized with the horizontal synchronizing signal c is also input to the adder 13. Adder 1
3 superimposes the PAM-converted audio signal d from the sampling circuit 12 on the back porch portion of the video signal a,
The signal is sent to the modulator 14.

In the modulator 14, a predetermined modulation is applied to the video signal e on which the audio signal sent from the adder 13 is superimposed to obtain a high frequency signal, which is transmitted from the antenna 15. FIG. 2 shows a circuit configuration of a receiving side device which receives and reproduces the high frequency signal transmitted by the circuit of FIG. 1 described above. The high frequency signal received by the antenna 16 is tuned by the tuner 17 and high frequency amplified. It is later sent to the intermediate frequency circuit 18.

The intermediate frequency circuit 18 converts the input signal into an intermediate frequency signal, and further performs processing such as video detection and sync separation to process the video signal f on which the audio signal is superimposed on the pulse extraction circuit 19 and the monitor. The horizontal synchronizing signal g is output to the display unit 20 and to the pulse extracting circuit 19.

The monitor display section 20 reproduces and displays an image based on the image signal f from the intermediate frequency circuit 18. At this time, the audio signal is superposed on the image signal f, but the back porch portion. Therefore, it does not affect the image.

The pulse extraction circuit 19 is a PAM-converted audio signal of the back porch portion based on the horizontal synchronizing signal g from the intermediate frequency circuit 18 with respect to the video signal f on which the audio signal from the intermediate frequency circuit 18 is superimposed. Extract h. The audio signal h obtained by the pulse extraction circuit 19 is converted into an analog audio signal i by removing a high frequency component through a low-pass filter (LPF) 21, and then is appropriately amplified by an audio amplification circuit 22. It is amplified and then output loudly by the speaker 23.

With the circuit configuration as described above, the operation is as follows. That is, in the transmitting side device, as shown in FIG.
When an analog audio signal b having a waveform as shown in (2) is input, this audio signal b is passed through the low-pass filter 11 to a frequency half that of the horizontal synchronizing signal, for example, about 7.8 [kHz] or more in the NTSC system. The high frequency component of is cut and supplied to the sampling circuit 12.

The sampling circuit 12 samples the audio signal in synchronization with the horizontal synchronizing signal c shown in FIG. 3C to obtain the PAM-converted audio signal d as shown in FIG. This is sent to the adder 13.

This adder 13 has a sampling circuit 1 at the back porch portion of the video signal a as shown in FIG.
By superimposing the PAM audio signal d from No. 2 in FIG.
A video signal e as shown in (1) is obtained, which is modulated by the modulator 14 into a predetermined high frequency signal and transmitted from the antenna 15.

On the other hand, in the receiving side device, the high frequency signal received by the antenna 16 and tuned by the tuner 17 is sent to the intermediate frequency circuit 18, where it undergoes processing such as intermediate frequency conversion, video detection and the like. A video signal f on which an audio signal as shown in 1) is superimposed is obtained and output to the pulse extraction circuit 19 and the monitor display unit 20.

Further, at this time, the intermediate frequency circuit 18 extracts the horizontal synchronizing signal g shown in FIG. 4 (2) by the sync separation processing, and at the same time sends it to the pulse extracting circuit 19. The pulse extraction circuit 19 uses the PAM-converted audio signal h as shown in FIG. 4C based on the timing of the horizontal synchronizing signal g with respect to the video signal f on which the audio signal from the intermediate frequency circuit 18 is superimposed.
When the high frequency component of this audio signal h is cut through the low pass filter 21, an analog audio signal i as shown in FIG. 4 (4) can be obtained. Then, the analog audio signal i is amplified by the audio amplifier circuit 22 and then amplified by the loudspeaker 23, whereby audio reproduction is realized.

In the above embodiment, the audio signal is superposed on the back porch portion of the video signal, but it goes without saying that it may be the front porch portion. Further, in the above embodiment, an example in which the audio signal is converted into PAM and superimposed on the video signal is shown, but the present invention is not limited to this, and other modulation such as PWM (pulse width modulation) and PCM (pulse code modulation). It is also possible to adopt a method.

[0021]

As described above, according to the present invention, the circuit configuration for transmitting and receiving audio signals can be greatly simplified, and the audio signals can narrow the occupied frequency band of the video signals. It is possible to provide an audio transmission method and device capable of effectively using an occupied frequency band to which a video signal is allocated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a transmission side apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of a receiving side apparatus according to the embodiment.

FIG. 3 is a diagram for explaining the operation according to the embodiment.

FIG. 4 is a view for explaining the operation according to the embodiment.

[Explanation of symbols]

 11, 21 ... Low-pass filter (LPF) 12 ... Sampling circuit 13 ... Adder 14 ... Modulator 15 ... (Transmission) antenna 16 ... (Reception) antenna 17 ... Tuner 18 ... Intermediate frequency circuit 19 ... Pulse extraction circuit 20 ... Monitor display unit 22 ... Audio amplification circuit 23 ... Speaker

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04N 7/085

Claims (5)

[Claims] 1. A transmitting side samples an audio signal in synchronism with a horizontal synchronizing signal in a video signal to pulse it, superimposes it on a front porch portion or a back porch portion of the video signal, and transmits it. An audio transmission method characterized in that an audio signal pulse superimposed on a front porch portion or a back porch portion of a video signal is extracted, converted into an analog signal, and output. 2. A transmitter for sampling an audio signal in synchronism with a horizontal synchronizing signal in a video signal, converting it into a pulse, and superimposing it on a front porch portion or a back porch portion of the video signal for transmission, and a transmitter for transmitting from this transmitter. An audio transmission system, comprising: a receiver for receiving the received video signal, extracting the audio signal pulse superimposed on the front porch portion or the back porch portion thereof, converting the signal into an analog signal, and outputting the analog signal. 3. An audio signal is sampled and pulsed in synchronism with a horizontal synchronizing signal in the video signal, superposed on a front porch portion or a back porch portion of the video signal and transmitted, while the transmitted video signal is A transmitting / receiving device, which receives, extracts a voice signal pulse superimposed on a front porch portion or a back porch portion thereof, converts the voice signal pulse into an analog signal, and outputs the analog signal. 4. A transmitting apparatus, wherein an audio signal is sampled and pulsed in synchronism with a horizontal synchronizing signal in a video signal, and the audio signal is superimposed on a front porch portion or a back porch portion of the video signal and transmitted. 5. A receiving device, which receives a transmitted video signal, extracts a voice signal pulse superimposed on a front porch portion or a back porch portion thereof, converts the voice signal pulse into an analog signal, and outputs the analog signal.