KR102289143B1 - Audio blending apparatus of fm bandwidth dab system - Google Patents

Abstract

The present invention provides a first signal delay detection circuit for detecting a first signal delay between a main broadcast signal and an extra broadcast signal input within an initial set time and applying the first signal delay to the extra broadcast signal; a signal delay monitoring circuit for determining whether a second signal delay due to a packet error of the main broadcast signal input from the first signal delay detection circuit occurs; a second signal delay detection circuit for detecting a second signal delay due to a packet error occurring during broadcasting and determining a delay type of the second signal delay according to the determination result of the signal delay monitoring circuit; a signal delay determining circuit for applying a second signal delay to any one of a main broadcast signal and an extra broadcast signal or setting a current frame to a signal interruption state according to a second signal delay and a delay type of the second signal delay detecting circuit; a voice motion detection circuit for outputting a voice motion coefficient so as to detect a signal interruption section of the main broadcast signal according to the signal interruption state set in the signal delay determining circuit; and a voice synthesizing circuit for synthesizing a main broadcasting signal and an extra broadcasting signal according to the voice motion coefficient output from the voice motion detection circuit.

Description

Audio synthesizer of FM band DAB system {AUDIO BLENDING APPARATUS OF FM BANDWIDTH DAB SYSTEM}

The present invention relates to an audio synthesizing apparatus for an FM band DAB system, and more particularly, to an audio synthesizing apparatus for an FM band DAB system that reduces signal disruption and reduces sound loss in digital audio broadcasting.

DAB (Digital Audio Broadcasting) is an audio broadcast that can transmit high-quality voice as well as text and graphics at the CD quality level.

In line with expectations for DAB and strong government intentions, the future broadcasting market is expected to rapidly shift from analog radio broadcasting (FM/AM) to DAB.

This means that DAB eliminates the white noise and noise generated by the existing analog radio broadcasting (FM/AM), and provides better sound quality (CD quality sound quality) and a higher number of channels (up to 5.1 channels) to reach consumers without noise. Because it has potential advantages.

Accordingly, the DAB market will grow bigger and bigger, and research on DAB has been conducted since 1990, and many broadcasting networks and products have been released to this day.

However, the conventional DAB system has a problem in that it cannot detect a signal interruption of less than 0.25 seconds, even though the listener should be able to listen to the same broadcast program seamlessly while continuously changing the frequency when moving through a vehicle. , there was a problem in that additional signal delay occurred during actual broadcasting and sound loss occurred due to stream breakage.

The background technology of the present invention is disclosed in Korean Patent Application Laid-Open No. 10-2002-0003195 (2002.01.10).

The present invention has been devised to solve the above problems, and an object of the present invention is to provide an audio synthesizing apparatus for an FM band DAB system, which reduces signal disruption and reduces sound loss in digital audio broadcasting.

Another object of the present invention is to provide an audio synthesizing apparatus for an FM band DAB system, capable of reducing undesired sound loss by detecting signal disruption of less than 0.25 seconds and synthesizing it with an extra broadcast signal in the corresponding signal disruption period. .

Another object of the present invention is that an extra broadcast signal delay occurs due to a fading phenomenon in a wireless environment. At this time, the sound interruption phenomenon is reduced by detecting the signal delay during initial reception and synthesizing the signal delay with the main broadcast signal. It is to provide an audio synthesis device of an FM band DAB system.

Another object of the present invention is to detect the time delay and then redetect the time delay and apply it to audio synthesis when a packet error occurs due to fading and service departure during digital audio broadcasting and additional signal delay occurs. To provide an audio synthesizing apparatus for an FM band DAB system, which enables a safer audio synthesizing system to be implemented in consideration of a wireless environment in which signal delay may change frequently during broadcasting.

Another object of the present invention is to detect a section in which the stream of the main broadcast signal is broken, set the main broadcast signal in the section as a signal interruption section, and replace it with an extra broadcast signal to compensate for sound loss in an FM band. It is to provide an audio synthesis device of the DAB system.

The audio synthesis apparatus of the FM band DAB system according to an aspect of the present invention detects a first signal delay between a main broadcast signal inputted within an initial set time and an extra broadcast signal, and applies the first signal delay to the extra broadcast signal. a first signal delay detection circuit to be applied; a signal delay monitoring circuit for determining whether a second signal delay due to a packet error of the main broadcast signal inputted from the first signal delay detection circuit occurs; a second signal delay detection circuit for detecting a second signal delay due to a packet error occurring during broadcasting and determining a delay type of the second signal delay according to the determination result of the signal delay monitoring circuit; According to the second signal delay and the delay type of the second signal delay detection circuit, the second signal delay is applied to any one of the main broadcast signal and the extra broadcast signal, or the current frame is set to a signal interruption state. signal delay discrimination circuit; a voice motion detection circuit for outputting a voice motion coefficient so as to detect a signal interruption section of the main broadcast signal according to the signal interruption state set by the signal delay determining circuit; and a voice synthesizing circuit for synthesizing the main broadcasting signal and the redundant broadcasting signal according to the voice motion coefficient output from the voice motion detection circuit.

In the present invention, the first signal delay detection circuit finds a position where the correlation value is maximum using a high-speed cross-correlation function between the main broadcast signal and the spare broadcast signal, and between the main broadcast signal and the spare broadcast signal. and detecting the first signal delay.

In the present invention, the first signal delay detection circuit divides each of the main broadcast signal and the extra signal within an initial set time into a plurality of blocks, and superimposes the blocks to apply the high-speed cross-correlation function. .

In the present invention, the signal delay monitoring circuit obtains the first signal delay through the mean square error method of the main broadcast signal and the extra broadcast signal, and the first signal delay obtained through the mean square error method and the Comparing the error value of the first signal delay input from the first signal delay detection circuit with a preset threshold, it is characterized in that it is determined whether the second signal delay appears according to the comparison result.

In the present invention, the signal delay monitoring circuit outputs a signal delay or not flag according to the magnitude of the error value with respect to the threshold, wherein the signal delay flag becomes 0 when the error value is less than the threshold value, When the error value is greater than the threshold value, it is characterized in that "1".

In the present invention, the second signal delay detection circuit is activated when the signal delay flag is "1", so that the delay type of the second signal delay due to packet loss is omnidirectional "1" through a bidirectional high-speed cross-correlation function. It is determined whether the signal delay is "2" or not, and if the signal delay flag is "1" and the second signal delay is "0", the delay type of the second signal delay is set to "3" characterized in that

In the present invention, the signal delay determining circuit applies the second signal delay to the main broadcast signal if the delay type is "1", and applies the second signal delay to the extra broadcast signal if the delay type is "2". It is characterized by applying a delay.

In the present invention, the signal delay determining circuit is characterized in that when the delay type is "3", a broken stream is included in the current frame of the main broadcast signal and the signal is set to a signal interruption state.

In the present invention, the voice motion detection circuit calculates the low-speed envelope and the high-speed envelope in units of samples using the absolute value of the main broadcast signal, and calculates the voice motion coefficient when the high-speed envelope is greater than the low-speed envelope. It is set to "1", and when the high-speed envelope is smaller than the low-speed envelope, the speech motion coefficient is set to "0" to detect the signal interruption section of the main broadcast signal.

In the present invention, the speech synthesis circuit synthesizes the main broadcast signal and the extra broadcast signal by using the speech synthesis coefficient.

In the present invention, the speech synthesis circuit is characterized in that when the speech motion coefficient is "0", the extra broadcast signal is synthesized in the signal interruption section of the main broadcast signal.

The present invention detects a signal disruption of less than 0.25 seconds and combines it with an extra broadcast signal in the corresponding signal disruption period to reduce unwanted sound loss.

In the present invention, an extra broadcast signal delay occurs due to a fading phenomenon in a wireless environment. In this case, the signal delay is detected during initial reception and the signal delay is synthesized into the main broadcast signal to reduce the interruption phenomenon.

According to the present invention, when a packet error occurs due to fading and service departure during digital audio broadcasting and additional signal delay occurs, the time delay is detected and then the time delay is detected again and applied to audio synthesis, thereby delaying the signal during broadcasting. It is possible to implement a safer audio synthesis system in consideration of this frequently changing wireless environment.

The present invention can correct the sound loss of the DAB system by detecting a section in which the stream of the main broadcast signal is broken, setting the main broadcast signal in the section as a signal interruption section, and replacing it with an extra broadcast signal.

1 is a block diagram of an audio synthesis apparatus of an FM band DAB system according to an embodiment of the present invention.

Hereinafter, an audio synthesis apparatus of an FM band DAB system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, definitions of these terms should be made based on the content throughout this specification.

1 is a block diagram of an audio synthesis apparatus of an FM band DAB system according to an embodiment of the present invention.

Referring to FIG. 1 , the audio synthesis apparatus of the FM band DAB system according to an embodiment of the present invention includes a demodulator 30 , a first signal delay detection circuit 40 , a signal delay monitoring circuit 50 , and a second signal delay It includes a detection circuit 60 , a signal delay discrimination circuit 70 , a voice motion detection circuit 80 , and a voice synthesis circuit 90 .

The demodulator 30 demodulates the broadcast signal. The broadcast signal is received through the antenna 10 , amplified through the amplifier 20 , and then input to the demodulator 30 . The demodulator 30 includes a first demodulator 31 and a second demodulator 32 .

The first demodulator 31 demodulates the main broadcast signal, which is a Digital Multimedia Broadcasting (DMB) signal, and then inputs the demodulated main broadcast signal to the first signal delay detection circuit 40 and the signal delay monitoring circuit 50, respectively. .

The second demodulator 32 demodulates an extra broadcast signal that is an FM (Frequency Modulation) signal, and then inputs the demodulated extra broadcast signal to the first signal delay detection circuit 40 and the signal delay monitoring circuit 50, respectively. do.

The first signal delay detection circuit 40 detects a first signal delay between the main broadcast signal and the extra broadcast signal input from the first demodulator 31 and the second demodulator 32, respectively, within an initial set time, and the first signal The delay is applied to the extra broadcast signal and input to the signal delay monitoring circuit 50 . Here, the initial setting time is initially set to 5 seconds after receiving the broadcast signal.

That is, the first signal delay detection circuit 40 converts the main broadcast signal input from the first demodulator 31 and the extra broadcast signal input from the second demodulator 32 within the initial 5 seconds using a high-speed cross-correlation function. The first signal delay between the main broadcast signal and the extra broadcast signal is detected by finding a position where the correlation value is maximized. In this case, if the fast cross-correlation function is applied to a broadcast signal having a length of 5 seconds, the size of the fast Fourier transform increases, resulting in a large amount of computation.

Accordingly, the first signal delay detection circuit 40 divides each of the main broadcast signal and the extra signal into a plurality of blocks to reduce the amount of computation, reduces the size of the fast Fourier transform, and superimposes the divided blocks to obtain a high-speed cross-correlation function. apply As a result, the total amount of calculation in the first signal delay detection circuit 40 can be greatly reduced, and the detection performance for the first signal delay is also improved.

In this case, the first signal delay detected by the first signal delay detection circuit 40 is input to the signal delay monitoring circuit 50 .

On the other hand, the first signal delay detection circuit 40 applies the first signal delay (signal delay detected through the fast Fourier transform) generated within the initial 5 seconds to the extra broadcast signal, and detects the main broadcast signal and the first signal delay. Each of the applied extra broadcast signals is input to the signal delay monitoring circuit 50 .

The signal delay monitoring circuit 50 detects the first signal delay using the mean square error technique for the main broadcast signal and the extra signal, and the first signal delay is detected by the first signal delay detection circuit 40 described above. It is compared with the first signal delay, and it is determined whether the stream is broken during broadcasting or a packet error signal delay, that is, a second signal delay occurs, according to the comparison result.

The signal delay monitoring circuit 50 determines whether a second signal delay due to a packet error of the main broadcast signal input from the first signal delay detection circuit 40 appears.

That is, the signal delay monitoring circuit 50 obtains the first time delay through the mean square error technique of the main broadcast signal and the extra broadcast signal (the extra broadcast signal to which the first signal delay is applied), and through the mean square error technique By comparing the detected first time delay with the first signal delay detected through the fast Fourier transform, and comparing the error value with a preset threshold value, it is determined whether the second signal delay appears according to the comparison result.

As a result of comparing the error value with the threshold value, if the error value is less than the threshold value, the signal delay monitoring circuit 50 sets the signal delay flag to "0", and if the error value is greater than the threshold value, the signal delay flag is set to "1".

Then, the signal delay monitoring circuit 50 inputs the main broadcast signal, the extra broadcast signal, and the signal delay flag (“0” or “1”) to the second signal delay detection circuit 60 . In this case, the main broadcast signal, the extra broadcast signal, and the signal delay flag are used in the second signal delay detection circuit 60 to detect the second signal delay due to a packet error occurring during broadcasting.

When the main broadcast signal, the extra broadcast signal, and the signal delay flag are input from the signal delay monitoring circuit 50 , the second signal delay detection circuit 60 determines the result of the signal delay monitoring circuit 50 during broadcasting. The second signal delay due to the generated packet error is detected and the delay type of the second signal delay is determined.

That is, the second signal delay detection circuit 60 is activated when the signal delay flag is "1", and when the signal delay flag is "0", the second signal delay and delay type are set to "0".

The activated second signal delay detection circuit 60 uses a bidirectional high-speed cross-correlation function to determine whether the delay type of the second signal delay due to packet loss is forward "1" and backward "2" do.

Here, the forward signal delay is a situation in which an extra broadcast signal inevitably has a signal delay due to packet loss of the main broadcast signal during broadcasting, and the backward signal delay is an extra signal delay in the main broadcast signal due to packet addition. situation that will occur.

On the other hand, the second signal delay detection circuit 60 sets the delay type to "3" by recognizing that the stream is broken during broadcasting when the signal delay flag is "1" and the second signal delay is "0".

Next, the second signal delay detection circuit 60 inputs the second signal delay and delay type to the signal delay determination circuit 70 as described above.

The signal delay determining circuit 70 applies the second signal delay to any one of the main broadcast signal and the extra broadcast signal or the current frame according to the second signal delay and the delay type input from the second signal delay detection circuit 60 . is set to the lost signal state.

That is, if the delay type is 1, the signal delay determining circuit 70 applies the second signal delay to the main broadcast signal, and if the delay type is 2, the second signal delay is applied to the extra broadcast signal. In particular, the delay type “3” indicates that a broken stream is included in the current frame of the main broadcast signal. Accordingly, if the delay type is “3”, the signal delay determining circuit 70 sets the current frame to a signal interruption state.

The voice motion detection circuit 80 outputs a voice motion coefficient so as to detect a signal interruption section of the main broadcast signal according to the signal interruption state set by the signal delay discrimination circuit 70 .

That is, the voice motion detection circuit 80 calculates the low-speed envelope and the high-speed envelope in units of samples by using the absolute value of the main broadcast signal to detect the signal interruption section of the main small signal. Then, the voice motion detection circuit 80 sets the voice motion coefficient to "1" if the low-speed envelope is greater than the high-speed envelope, while, if the low-speed envelope is smaller than the high-speed envelope, sets the voice motion coefficient to "" By setting it to 0", a signal interruption period is detected.

Here, the voice motion coefficient is used to synthesize the main broadcast signal and the extra broadcast signal.

The speech synthesis circuit 90 synthesizes the main broadcast signal and the extra broadcast signal according to the speech motion coefficient input from the speech motion detection circuit 80 , and inputs the synthesized broadcast signal to the amplifier 20 .

Here, an extra signal weighting coefficient is set in the speech synthesis circuit 90. The extra signal weighting coefficient is a value obtained by subtracting the speech motion coefficient from "1" and is used to determine whether or not broadcast signals are synthesized. That is, if the speech motion coefficient is "0", the extra signal weighting coefficient becomes "1", so the speech synthesis circuit 90 removes the main broadcast signal and outputs the extra broadcast signal. Accordingly, the extra broadcast signal is output instead of the main broadcast signal during the signal period section of the main broadcast signal.

In this way, the broadcast signal synthesized by the voice synthesis circuit 90 is input to the amplifier 100 and amplified, and the broadcast signal amplified by the amplifier 100 is output through the speaker 110 .

As described above, this embodiment detects a signal disruption of less than 0.25 seconds and combines it with an extra broadcast signal in the corresponding signal disruption period to reduce unwanted sound loss.

In addition, in this embodiment, an extra broadcast signal delay occurs due to the fading phenomenon of the wireless environment. At this time, the signal delay is detected during initial reception and the signal delay is synthesized into the main broadcast signal to reduce the interruption phenomenon. .

In addition, in the present embodiment, when a packet error occurs due to fading and service departure while digital audio broadcasting is in progress and additional signal delay occurs, the time delay is detected and then the time delay is detected again and applied to audio synthesis. It is possible to implement a safer audio synthesis system considering the wireless environment in which signal delay can change frequently.

In addition, this embodiment detects a section in which the stream of the main broadcast signal is broken, sets the main broadcast signal in the section as a signal interruption section, and replaces it with an extra broadcast signal, thereby correcting the sound loss of the DAB system.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary and those of ordinary skill in the art to which the art pertains are aware that various modifications and equivalent other embodiments are possible therefrom. will understand Accordingly, the true technical protection scope of the present invention should be defined by the following claims.

10: antenna
10,100: amplifier
30: demodulator
31: first demodulator
32: second demodulator
40: first signal delay detection circuit
50: signal delay monitoring circuit
60: second signal delay detection circuit
70: signal delay discrimination circuit
80: voice motion detection circuit
90: speech synthesis circuit
110: speaker

Claims (11)

a first signal delay detection circuit for detecting a first signal delay between the main broadcast signal and the extra broadcast signal input within an initial set time and applying the first signal delay to the extra broadcast signal;
a signal delay monitoring circuit for determining whether a second signal delay due to a packet error of the main broadcast signal inputted from the first signal delay detection circuit occurs;
a second signal delay detection circuit for detecting a second signal delay due to a packet error occurring during broadcasting and determining a delay type of the second signal delay according to the determination result of the signal delay monitoring circuit;
According to the second signal delay and the delay type of the second signal delay detection circuit, the second signal delay is applied to any one of the main broadcast signal and the extra broadcast signal, or the current frame is set to a signal interruption state. signal delay discrimination circuit;
a voice motion detection circuit for outputting a voice motion coefficient so as to detect a signal interruption section of the main broadcast signal according to the signal interruption state set by the signal delay determining circuit; and
and a voice synthesis circuit for synthesizing the main broadcasting signal and the extra broadcasting signal according to the voice motion coefficient output from the voice motion detection circuit;
The signal delay monitoring circuit obtains the first signal delay through the mean square error method of the main broadcast signal and the extra broadcast signal, and the first signal delay obtained through the mean square error method and the first signal delay The audio synthesis apparatus of the FM band DAB system, characterized in that by comparing the error value of the first signal delay input from the detection circuit with a preset threshold value, it is determined whether the second signal delay appears according to the comparison result. The method according to claim 1, wherein the first signal delay detection circuit finds a position where a correlation value is maximized between the main broadcast signal and the redundant broadcast signal using a high-speed cross-correlation function, and the main broadcast signal and the redundant broadcast signal An audio synthesis apparatus for an FM band DAB system, characterized in that detecting the first signal delay between signals. 3. The method of claim 2, wherein the first signal delay detection circuit divides each of the main broadcast signal and the extra signal within an initial set time into a plurality of blocks, and superimposes the blocks to apply the high-speed cross-correlation function. FM band DAB system audio synthesis device. delete The audio of claim 1, wherein the signal delay monitoring circuit compares the error value of the first signal delay with the preset threshold value and outputs a signal delay or not flag according to the comparison result. synthesis device. 6. The method of claim 5, wherein the second signal delay detection circuit is activated according to the signal delay flag, and determines whether the delay type of the second signal delay due to packet loss is forward or backward through a bidirectional high-speed cross-correlation function. The audio synthesis apparatus of the FM band DAB system, characterized in that it is determined whether the direction is in the direction, and a delay type of the second signal delay is set according to the signal delay flag and the second signal delay. The method of claim 6, wherein the signal delay determining circuit applies the second signal delay to the main broadcast signal or applies the second signal delay to the extra broadcast signal according to the delay type of the second signal delay. An audio synthesis device of the FM band DAB system, which is characterized. The FM band DAB according to claim 6, wherein the signal delay determining circuit sets that the broken stream is included in the current frame of the main broadcast signal and the signal is cut off according to the delay type of the second signal delay. The system's audio synthesizer. The method of claim 8, wherein the voice motion detection circuit calculates a low-speed envelope and a high-speed envelope in units of samples using the absolute value of the main broadcast signal, and compares the high-speed envelope with the low-speed envelope. According to the comparison result, the voice motion coefficient is set to “1”, and when the high-speed envelope is smaller than the low-speed envelope, the voice motion coefficient is set to “0” to detect the signal interruption section of the main broadcast signal. An audio synthesis device of the FM band DAB system, which is characterized. [10] The apparatus of claim 9, wherein the speech synthesis circuit synthesizes the main broadcast signal and the redundant broadcast signal using the speech synthesis coefficient. 11. The apparatus of claim 10, wherein the speech synthesis circuit synthesizes the extra broadcast signal in a signal interruption section of the main broadcast signal when the speech motion coefficient is "0".

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