KR920004944Y1 - Sound multiplex demodulation circuit of 12/nicam common using - Google Patents

Abstract

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Description

A2 / NiCam common multiple voice circuit

1 is a baseband characteristic diagram of the A2 / NiCam system.

2 is an RF signal spectrum when broadcasting A2 / NiCam system.

3 is a frequency shift diagram of an A2 / NiCam broadcasting 0.11 MHz oscillator.

* Explanation of symbols for main parts of the drawings

2: tuner 14: mixer 1

15: oscillation unit 23: matrix

31: switching block 40: video processing unit

50: sub-channel signal extraction unit 60: A2 broadcast processing unit

70: Nicam broadcast processor SW1, SW2: switch

The present invention relates to an A2 / Nicam common voice multiple demodulation circuit capable of receiving both A2 broadcast and Nicam broadcast, which are compatible in Europe, and are particularly suitable for PAL B / G broadcasting. This technology is applicable to VCR.

Voice multiple stereo broadcasting in Europe (limited to PAL B / G broadcast areas) is available in two ways: two-carrier (A2) system and Nicam (Near Instantaneously Companded Audio Multiplex) system.

The Nicam system is currently being piloted and the Nicam system is being recruited in Sweden, Norway, Finland, Denmark and Spain, and the Nicam system is gradually spreading.

Therefore, in a special area and situation in Europe, a common voice multiple stereo demodulation circuit is required to receive both the conventional voice multiple stereo broadcast A2 system and the new Nicam system.

In other words, it should be able to receive voice multiple stereo broadcasting regardless of A2 system or Nicam system.

Therefore, the present invention is to provide A2 / Nicam common voice multiple demodulation circuit for receiving both A2 system and Nicam system with different voice multiple stereo broadcasting in PAL B / G area. When receiving, the video signal processing is the same and the main channel audio carriers among the audio signals are the same, but only the subchannel audio carriers are different from each other, so that the subchannel audio carriers can be received during A2 broadcasting or Nicam broadcasting.

To this end, the present invention extracts a subchannel frequency by shifting the subchannel audio carrier during A2 broadcasting or Nicam broadcasting, and then applies the extracted subchannel frequency to the A2 broadcasting processor and the Nicam broadcasting processor to output the subchannel audio signal. In case of A2 broadcasting, the audio signal output of the Nicam broadcast processor is cut off, and in case of Nicam broadcasting, the audio signal output of the A2 broadcasting processor is cut off.

The present invention as described above is described in detail based on the accompanying drawings.

The present invention is a video processing unit 40 for processing the intermediate frequency (IF) signal output from the tuner 2 under the control of the microcomputer (1) and outputs the video signal, and the intermediate frequency (IF) of the tuner (2) A SiF detector 8 for detecting a signal as a SiF signal, a 5.5 MHz filter 9 for filtering a main channel audio carrier among SiF signals of the SiF detector 8, and a main channel audio carrier for the 5.5 MHz filter 9 A2 / Nicam broadcasting receiver having an FM detector 10 for FM detection and applying to the matrix 23 as a main channel audio signal, wherein the SiF signal of the SiF detector 8 is band-passed and the subchannel audio is received. A subchannel signal extractor 50 for detecting a carrier and frequency shifting the subchannel audio carrier to output a subchannel audio carrier of a single frequency in A2 broadcast and Nicam broadcast; and a subchannel signal extractor 50 Channel audio carrier subchannel An A2 broadcast processor 60 for converting the video signal into a matrix 23, AM-detecting the subchannel audio signal, and outputting a broadcast state determination signal and an A2 broadcast detection signal, and the subchannel signal extractor 50; Nicam converts the subchannel audio carriers into subchannel audio signals and applies them to the switching block 31 to which the main channel audio signal of the FM detector 10 is applied, and detects the subchannel audio signals and outputs a Nicam broadcast detection signal. Connected to an output side of the broadcast processor 70 and the matrix 23 and the switching block 31 and switched by the A2 broadcast detection signal of the A2 broadcast processor 60 and the Nicam broadcast detection signal of the Nicam broadcast processor 70. The switches SW1 and SW2 are connected and configured.

Here, the subchannel signal extractor 50 includes a bandpass filter 11 for band-passing the subchannel audio carriers of the A2 broadcast and the Nicam broadcast detected by the SiF detector 8, and the subchannel of the bandpass filter 11. 5.74 MHz filter 12 and 5.850 MHz filter 13 for filtering audio carriers, and subchannel audio carriers passing through the filters 12 and 13 are mixed with the oscillation frequency of the 0.11 MHz oscillator 15 to shift the frequency. A mixer 14, a 5.850 MHz peaking unit 16 which increases a gain of 5.850 MHz among the frequency shifted frequencies of the mixer 14, and a single channel subcarrier frequency of the 5.850 MHz peaking unit 16. The 5.850 MHz filter 17 is applied to the A2 broadcast processor 60 and the Nicam broadcast processor 70 by filtering the 5.850 MHz.

The A2 broadcast processor 60 performs FM detection on the subchannel audio carriers of the subchannel signal extraction unit 50 and applies them to the matrix 23. Among the subchannel audio signals of the FM detector 18, the A2 broadcast processor 60 54.7 KHz band pass filter 19 for passing only the pilot carrier, AM detector 20 for AM detecting the pilot carrier of the band pass filter 19, and pilot signal of the AM detector 20 are discriminated. The broadcast state discrimination unit 21 for applying the broadcast state discrimination signal to the matrix 23 and the broadcast state discrimination signal from the broadcast state discrimination unit 21 to detect and apply the A2 broadcast detection signal to the switch SW2. The A2 detector 22 is connected and configured.

In addition, the Nicam broadcast processor 70 performs a phase demodulator 25 for demodulating the subchannel audio carriers of the subchannel signal extractor 50, and a digital sound data and a clock of the phase demodulator 25. Nicam decoder 25, a digital analog converter 26 for converting the digital audio signal of the Nicam decoder 25 into an analog signal, and a low pass through the analog audio signal of the digital analog converter 26 for a switching block 31 Low-pass filter (29) (30) to be applied to the signal, a mode display unit (27) for discriminating and displaying the Nicam broadcast mode of the Nicam decoder (25), and a Nicam broadcast mode signal from the mode display unit (27) By connecting the Nicam detector 28 to apply the Nicam broadcast detection signal to the switch (SW1).

That is, in the present invention, in the audio signal output of A2 broadcasting or Nicam broadcasting, the main channel audio signal output follows a general audio processing method, but the subchannel audio signal is mixed with a predetermined frequency to shift the frequency, and the common frequency is extracted from the subchannel signal. The audio signal is extracted from the unit 50 and outputs an audio signal through each of the A2 broadcast processor 60 and the Nicam broadcast processor 70, while the A2 broadcast processor 60 operates to cut off the audio signal of the Nicam broadcast processor 70. When the Nicam broadcast processing unit 70 operates, the audio signal of the A2 broadcast processing unit 60 is blocked.

The baseband characteristics of the A2 and Nicam broadcasting systems are shown in FIG. 2, and the RF signal spectrum of each broadcast is as shown in FIG. 3. The A2 broadcast subchannel carriers, 5.74 MHz and the Nicam broadcast subchannel carriers, The frequency shift shown by mixing 5.850 MHz by the oscillation frequency of 0.11 MHz is shown in FIG.

Such an effect in the present invention will be described in detail based on one embodiment circuit diagram.

When the user selects a channel by pressing a key, the microcomputer 1 recognizes this and supplies the PLL data to the tuner 2 so that the tuner 2 converts the RF signal into an intermediate frequency (IF), which causes the ViF SAW filter (3) and the like. ViF SAW filter 7 is applied.

The signal passing through the ViF SAW filter (3) is applied to the video amplifier / detector (4), amplified and detected, and then applied to the SiF trap (5) as a composite video signal, and 5.5 in the SiF trap (5). By trapping audio intermediate frequencies of MHz, 5.74 MHz, and 5.85 MHz, only the video intermediate frequency signal is applied to the video processor 6, thereby outputting the final video signal.

In this case, the video processing unit 40 which separates the video intermediate frequency (ViF) signal from the intermediate frequency (IF) signal output from the tuner 2 and outputs the video signal as a video signal is used in common when receiving A2 broadcast and Nicam broadcast. This is because the video specifications are the same in A2 and Nicam.

The intermediate frequency IF signal output from the tuner 2 is applied to the SiF detector 8 after passing through the SiF SAW filter 7 to detect the voice intermediate frequency SiF.

At this time, in the A2 broadcast or the Nicam broadcast, the main channel audio carriers are all at 5.5 MHz, as shown in the baseband characteristics shown in FIG. 2, so that the main channel audio carriers detected by the SiF detector 8 are 5.5 MHz filters (9). After passing through to filter the main channel audio carrier and then applied to the FM detector 10, the FM detector 10 detects the FM and outputs the main channel audio signal, and the main channel audio signal output from the FM detector 10 Is applied to the matrix 23.

That is, the main channel audio carrier of the voice intermediate frequency output from the SiF detector 8 is applied to the matrix 23 as the main channel audio signal through the 5.5 MHz filter 9 and the EM detector 10.

Then, the voice intermediate frequency (SiF) signal detected by the SiF detector 8 is applied to the 5.74 MHz filter 12 and the 5.850 MHz filter 13 through the band pass filter 11.

In this case, the band pass characteristic of the band pass filter 11 should have a characteristic capable of passing both 5.74 MHz and 5.850 MHz described above because the subchannel carrier of A2 broadcast is at 5.74 MHz and the subchannel carrier of Nicam broadcast is at 5.850 MHz. do.

Therefore, both the A2 and Nicam subchannel audio carriers are applied to the 5.74 MHz filter 12 and the 5.850 MHz filter 13 through the band pass filter 11, and thus the mixer 14 passes through the 5.850 MHz filter 13. A 5.850 MHz A2 broadcast subchannel carrier is applied, or a 5.74 MHz Nicam broadcast subchannel audio carrier with a total of 5.74 MHz filters 12 is applied.

As such, the subchannel audio carriers of 5.850 MHz and 5.74 MHz are applied to the mixer 14 according to A2 broadcast and Nicam broadcast, which are mixed with the 0.11 MHz oscillation frequency of the oscillator 15 to shift the frequency as shown in FIG. Will happen.

That is, when receiving any of the A2 broadcast or the Nicam broadcast, the subchannel audio carrier of 5.7 MHz or 5.850 MHz is applied to the mixer 14, which is mixed with the 0.11 MHz oscillation frequency of the oscillator 15 to be the same frequency as in FIG. The output frequency of the mixer 14 is increased through the 5.850 MHz peaking unit 16, and the gain for the audio carrier of 5.850 MHz is increased, which is again the 5.850 MHz subchannel through the 5.850 MHz filter 17. Only audio carriers will be output.

At this time, the 5.850MHz filter 17 outputs 5.850MHz, which is the same as the original subchannel audio carrier in the case of Nicam broadcasting, but converts the original 5.74MHz subchannel audio carrier to 5.850MHz in the case of A2 broadcasting.

That is, the 5.850 MHz subchannel audio carrier is output to the output side of the subchannel signal extracting unit 50 regardless of A2 broadcast or Nicam broadcast.

The subchannel audio carrier output from the 5.850 MHz filter 17 of the subchannel signal extraction unit 50 is a subchannel audio signal through the FM detector 18 in the case of A2 broadcasting. 19).

At this time, when the sub-channel audio carrier output from the 5.850 MHz filter 17 is A2 broadcast, it is applied to the phase demodulator 24 of the Nicam broadcast processing unit 70. However, the Nicam broadcast and A2 broadcast are not shown in the table shown in FIG. Likewise, the left and right audio outputs through the low pass filter 29 and 30 of the Nicam broadcast processing unit 70 cause noise to be output due to the different broadcasting systems.

On the other hand, the sub-channel audio signal output from the FM detector 18 of the A2 broadcast processor 60 is applied to the matrix 23 while passing only the pilot carrier (recognition signal) through the 54.7 KHz band pass filter 19. Since the pilot signal passing through the 54.7 KHz band pass filter 19 is AM modulated, the AM signal is detected by the AM detector 20 and then applied to the broadcast state discrimination unit 21 to provide the current broadcast state (bilingual broadcast (Bi). -L) or stereo broadcast) and the broadcast state discrimination signal from the broadcast state determiner 21 is applied to the matrix 23 to matrix the left and right audio signals of the A2 broadcast system according to the broadcast state. Will be printed.

The broadcast state determination signal of the broadcast state determination unit 21 is input to the A2 detector 22 to display a mode high level in both modes regardless of bilingual broadcast (Bi-L) or stereo broadcast during A2 broadcast. The driver 32 recognizes that the broadcast system currently being received is an A2 broadcast system, and at the same time turns off the switch SW2 to block the noise output when the Nicam broadcast processing unit 70 receives the A2 broadcast. .

However, in the case of the Nicam system voice multi-stereo broadcasting other than the A2 broadcasting system as described above, the subchannel audio carrier passing through the 5.850 MHz filter 17 of the subchannel signal extraction unit 50 is a phase demodulation unit 24 of the Nicam broadcasting processing unit 70. ) To apply the digital sound data and clock to the Nicam decoder 25.

The Nicam decorator 25 recognizes the current broadcast condition and controls the mode display unit 27, while converting the digital sound data and clock into the digital analog converter 26 to convert the analog signal into a low pass filter 29 (30) to output the Nicam digital left and right sounds.

At this time, the audio output from the matrix 23 during Nicam broadcasting outputs the audio signal of the main channel, and the output of the Nicam left and right audio signals passed through the FM sound output and the low pass filter 29 and 30 of the main channel is output. Is applied to the switching block 31.

In the mode display unit 27, the Nicam broadcast is mono 1, mono 2 or stereo broadcast, and the display 32 is driven to the user by driving the display 32 and is simultaneously applied to the Nicam detector 28, and the Nicam detector 28 is Nicam. Regardless of whether the broadcast is mono 1, mono 2, or stereo, high level output is output even when only one mode is input, informing the user whether the current broadcast is Nicam, and the high level output of the Nicam detector 28 is connected to the switch (SW1). By applying the " off " switch SW1, the audio signal output of the A2 broadcast processing unit 60 output from the matrix 23 is cut off.

In addition, the Nicam left and right audio signal outputs passed through the low pass filters 29 and 30 are applied to the switching block 31 together with the FM sound output of the FM detector 18. In the switching block 31, an external switching control signal is output. Will output only two of them.

That is, in the case of Nicam broadcasting, the audio signals applied to the switching block 31 are two types of digital sound left and right and one type of FM sound, so the switching block 31 outputs only two of them by an external switching control signal. .

At this time, since the A2 detector 22 is a Nicam broadcast, the left and right audio signals selected by the external switching control are output from the switching block 31 by outputting a low level and turning the switch SW2 on.

Meanwhile, even when the 5.850 MHz peaking unit 16 and the 5.850 MHz filter 17 of the present invention are used as the 5.74 MHz peaking unit and the 5.74 MHz filter, respectively, the same operation is performed without any influence on the A2 and Nicam broadcasting reception of the present invention. .

As described above, the present invention enables the reception of both A2 and Nicam broadcasts in the PAL B / G broadcasting area, and therefore, it is possible to broadcast by A2 broadcasting system or Nicam broadcasting system in the PAL B / G broadcasting area. All audio signals can be received irrespective of the scope of the present invention, which makes it possible to use a wide range of devices regardless of the region, especially under special regions such as in Europe.

Claims (4)

A video processor 40 for processing an intermediate frequency (IF) signal output from the tuner 2 under the control of the microcomputer 1 and outputting the video signal as a video signal, and an intermediate frequency (IF) signal of the tuner 2. FM detection of the SiF detector 8 for detecting the signal, the 5.5 MHz filter 9 for filtering the main channel audio carrier among the SiF signals of the SiF detector 8, and the main channel audio carrier of the 5.5 MHz (9) In the A2 / Nicam broadcast receiver provided with the FM detector 10 which applies the main channel audio signal to the matrix 23, the SiF signal of the SiF detector 8 is band-passed to detect the subchannel audio carrier. the sub channel by frequency shifting the audio carrier a ₂ broadcasts and Nicam conveyed during subchannel audio carrier of the sub-channel signal extraction unit 50 for output to the sub-channel audio carrier of a single frequency, the sub-channel signal extraction unit 50, Detect the subchannel An A2 broadcast processor 60 for converting an ocarrier into a subchannel audio signal, applying the same to the matrix 23, AM detecting the subchannel audio signal, and outputting a broadcast state discrimination signal and an A2 broadcast detection signal; The subchannel audio carrier of the extractor 50 is converted to a subchannel audio signal and applied to the switching block 31 to which the main channel audio signal of the FM detector 10 is applied, and the subchannel audio signal is detected to detect the Nicam broadcast. Nicam broadcast processing unit 70 for outputting a signal, and A2 broadcast detection signal of A2 broadcast processing unit 60 and Nicam broadcast detection unit 70 connected to an output side of the matrix 23 and the switching block 31. A multiplex demodulation circuit for common A2 / Nicam, comprising a switch SW1 (SW2) switched by a signal. The subchannel signal extraction unit 50 of claim 1, further comprising: a band pass filter 11 for band-passing the A2 broadcast and the Nicam broadcast subchannel audio carrier detected by the SiF detector 8, and the band filter 11; A 5.74 MHz filter 12 and a 5.850 MHz filter 13 for filtering the sub channel audio carriers of the subchannel audio carrier, and a sub channel audio carrier passing through the filters 12 and 13 with the oscillation frequency of the 0.11 MHz oscillator 15. A mixer 14 for mixing and frequency shifting, a 5.850 MHz peaking unit 16 for increasing a gain of 5.850 MHz among the frequency shifted frequencies of the mixer 14, and the subchannel audio of the 5.850 MHz peaking unit 16; A multi-modal demodulation circuit for A2 / Nicam, characterized in that a 5.850 MHz filter (17) for filtering a single 5.850 MHz of carrier frequencies to be applied to the A2 broadcast processor (60) and the Nicam broadcast processor (70). The FM detector 18 of claim 1, wherein the A2 broadcast processor 60 FM-detects the subchannel audio carriers of the subchannel signal extractor 50 to the matrix 23, and the FM detector 18. A 54.7 KHz band pass filter 19 for passing only pilot carriers among the subchannel audio signals of the sub-channel audio signal, an AM detector 20 for AM detecting the pilot carriers of the band pass filter 19, and an AM detector 20 The broadcast state discrimination unit 21 for discriminating the pilot signal and applying the broadcast state discrimination signal to the matrix 23 and the broadcast state discrimination signal of the broadcast state discrimination unit 21 are detected to switch the A2 broadcast detection signal. A2 / Nicam common multiple demodulation circuit characterized by connecting and configuring the A2 detector 22 to be applied to SW2) 2. The apparatus of claim 1, wherein the Nicam broadcast processor (70) includes a phase demodulator (25) for demodulating the subchannel audio carriers of the subchannel signal extractor (50), and digital sound data of the phase demodulator (25). The Nicam decorator 25 which encodes a clock, the digital analog converter 26 which converts the digital audio signal of the Nicam decorator 25 into an analog signal, and the analog audio signal of the digital analog converter 26 Low pass filters 29 and 30 for low pass to apply the switching block 31, a mode display unit 27 for discriminating and displaying the Nicam broadcast mode of the Nicam decoder 25, and the mode display unit 27 And a Nicam detector 28 for detecting a Nicam broadcast mode signal and applying a Nicam broadcast detection signal to a switch SW1.