JPS62194785A - Pcm voice multiplex method - Google Patents

Abstract

PURPOSE:To reduce a data error by converting a voice data into a 4-value level signal at 2-bit each, applying base band multiplex during the vertical blanking period and setting the 2-bit pattern to a pattern different from the adjacent bit pattern. CONSTITUTION:A PCM voice signal subject to base band multiplex is inputted to a shift register 5 during the vertical blanking period of a band compression video signal. The register 5 outputs the PCM voice signal at 2-bit each from output terminals Oa, Ob. A D/A converter 7 converts the 2-bit at input terminals ia, ib into a 4-value level signal analogically. An analog switch 8 outputs a band compression video signal of a clamp circuit at a period other than the vertical blanking period and outputs an output signal of the converter 7 during the vertical blanking period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention (e) relates to a PCM audio multiplexing method for baseband multiplexing a PCM audio signal during the vertical blanking period of a high-quality video signal with a reduced bandwidth of 1 mo.

[Conventional technology]

Conventionally, in order to perform high-definition television broadcasting using wideband high-definition video signals, the Japan Broadcasting Corporation (NHK) has developed a new band sub-line system, namely TCI (TimeComp).
A band compression method using multiple subsamples (resced integration) has been devised.

And the band compression method of TCI multiple subsampling method is as follows.
For example, the magazine ``Nikkei Electronics'' published by Nikkei McGraw-Hill on March 12, 1984, page 2.
As described on pages 116 to 116, this is a method in which a chrominance signal is temporally compressed and multiplexed with a luminance signal, and a sub-Nyquist sampling process is applied to perform band compression. This makes it possible to compress a high-definition video signal into a narrow band of about 8 MB2 for transmission.

In addition, it is thought that high-definition television broadcasting will be carried out by satellite8. In this case, the audio signal will be PCM modulated and A
It has been considered to time-division multiplex video signals in a B-mode or B-mode format.

In other words, when satellite broadcasting high-definition television broadcasting, the A mode voice period is 4-phase F during the vertical blanking period of the video signal.
It has been considered to time-division multiplex an audio signal into a high-quality video signal by applying SK modulation and RF switching.

3. A mode is a format that multiplexes 4-channel audio, and B mode is a format that multiplexes 2-channel audio with a wider band than A mode.

On the other hand, it was devised to record a high-quality video signal subjected to band compression processing using the TCI multiplex subsampling method, that is, a band compression: false image signal, on a recording medium such as a video disk. “Television Society Technical Report (TEH899-4) J”M dated 20th
USE system home video disc", during the vertical blanking period of the band-compressed video signal obtained by receiving high-definition television broadcasting, audio separation, etc.
The M audio signal is baseband multiplexed with a binary N1 (Z signal), and the band compressed video signal on which the PCM audio signal is time-division multiplexed by the baseband multiplexing is F''M modulated, and the band compressed video signal and the PCM audio signal are It is described that the same FM modulation is performed and recorded.

[Problem that the invention seeks to solve]

By the way, as mentioned above, if a PCM audio signal is baseband multiplexed with a binary NRZ signal, that is, a binary level signal, during the vertical blanking period of a band-compressed video signal,
Audio multiplexing of high-definition television broadcasting or 4-level signal based on 411'SK modulation is performed, so for example, one word of PCM audio obtained by receiving high-definition television broadcasting is baseband multiplexed and recorded. If the number of audio channels that can be multiplexed is reduced to 1/2 of the number of audio channels of the received high-definition television broadcast, and the audio multiplex format of the received high-definition television broadcast is A mode,
Only two of the four channels of audio can be recorded, and in B mode, only one of the two channels of audio can be recorded.

8. In the case of B mode, it is considered that the left and right channels of stereo audio are transmitted using 2-channel audio, so if baseband multiplexing is performed using a binary level signal and recorded, the received stereo audio will be This means that recording cannot be performed, and in fact, it is not possible to record a PCM audio signal in the B mode format.

And this invention provides P
When performing baseband multiplexing of CM audio signals, baseband multiplexing is performed using a method that minimizes the occurrence of data errors due to noise, etc., and allows for a larger amount of PCM signals to be multiplexed than when using binary level signals. is a technical issue.

[Means for solving the problems] This invention has been made with the above points in mind,
PCM that baseband multiplexes a PCM audio signal during the vertical blanking period of a high-quality video signal that has been subjected to band compression processing.
In the audio multiplexing method, the PCM audio signal is converted into a 4-level signal that changes 2 bits at a time to 4-level levels, and multiplexed in the vertical blanking period,
This is a PCM audio multiplexing method characterized in that the bit patterns of the bits are set to be different from each other and are set to a pattern that differs from the bit pattern of an adjacent level by l bits.

[Effect]

In the past, PCM audio was baseband multiplexed using a single word or a 4-level signal, and the amount of CM audio signal to be multiplexed was twice as much as when using a 2-level signal.
In addition, since the 2-bit bit pattern for each level of the 4-level level 1 direct code differs by only 1 bit from the bit pattern of the adjacent level, even if level fluctuations occur in the 4-level level signal due to noise etc., it will not be multiplexed. Bit errors in PCM audio signals are minimized.

〔Example〕

Next, the present invention will be explained in detail with reference to drawings showing embodiments thereof.

In Fig. 1, il+ is a video input terminal, and TC■
A high-definition video signal band-compressed by multiple sub-sampling band compression processing is input, and λ is a band-compressed video signal formed by reception of high-definition television broadcasting and audio separation. 121 is a capacitor for cutting a DC component connected to the input terminal m, and (3) is a clamp circuit connected to the capacitor 121, which reproduces the band compressed video signal via the capacitor 121 with DC current.

(41 is an audio input terminal, during the vertical blanking period of the band compressed video signal, the PCM audio signal to be baseband multiplexed, and the PCM audio signal of the high-definition television broadcast obtained by the audio separation are serially input. !
Reference numeral 51 denotes a shift register connected to the input terminal (41), which outputs each bit of the input PCM audio signal 2 bits at a time from upper and lower bit outputs 1 (Oa) and (Ob).

161 Lt Exclusive OR gate connected to shift register (6), (7) is upper and lower bit input terminal (i
-).

(1b), and has an input terminal (
1a) is connected to the output terminal (Oa), and the input terminal (1b) is connected to the gate +61, and the input terminal (i
a).

The 2 bits of (ib) are converted into an analog i1% signal which changes to a 4-level level based on the bit pattern of the 2-bits, and is output.

(8) is an analog switch that cuts and outputs the band compressed video signal of the clamp circuit (3) and the 4-level level signal of the converter (7), and only between the vertical blanking ribs of the band 1 compressed video signal. When the vertical blanking of the switching control input terminal (9) becomes high level or low level, the internal equivalent switch is set to contact (α) and contact (β).
It outputs the band 1 reduced video signal of the clamp circuit (31) during periods other than the vertical blanking period, and outputs the output frequency of the converter (7) between the vertical blanking intervals.00 is a multiplex signal output terminal to which the output signal of the switch (8) is input.

The DC component of the 1-band reduced video signal at the input terminal (1) is cut off by the capacitor 121, and then DC-regenerated by the clamp circuit (31) and input to the switch (8).

On the other hand, the PCM audio signal at the input terminal (4) is divided into 2 bits each by a shift register (61), and is divided into 2 bits (
The data is sequentially converted into data of A, B) and outputted from the output terminals (tea) and (Ob) of the shift register (61) as 2 bits each (A, B) or 1110 times.

By the way, the bit pattern of each 2 bits (A, B) is 2
Bits (0, 0), (0, I) from the smallest data content of the 2-bit data formed by bits (A, B).

It can be one of the four bars - (+, o), (+, +).

Then, each 2 bits (A, B) are input to the gate (6), and the output signal of the gate (6) is input to the input terminal (ib) of the converter (7). , 2 bits (A, H') consisting of the upper bit A of each 2 bits (A, H) and the lower bit B' converted by the lower bit B't-gate (6) will be input. , in this case 2 bits) The bit patterns of the four glazes (A, B) (o, o), (o, +
), (l, o), 2 bits for (1, t) (
The bit pattern of 813') is (0,0).

(o, l), (+, +), (+, O) respectively.

That is, each bit pattern of 2 bits (8B) is changed by the gate (61) to a bit pattern that differs by 1 bit from the bit pattern of 4 bits, and the 2 bits 1-(A, 13' ) is the converter (
71.

And the converter (7) has 2 bits each (A, H')
is converted into a 4-level signal that changes to a 4-level level depending on the data content of 2-bit data formed by each of the 2 bits.

Now, let's start with the 4-value levels from the lowest to the lowest. ,L,,L,.

If L3, converter (7) converts 2 bits (A
, H) with four different bit patterns (o, o),
(0,1).

2 bits (A) corresponding to (+, t), (+, o)
, B′) bit pattern (o, o), (o,
t), (+, o), (+, +), l, , ,
1. , .

L! , L3 are converted into four-value level signals, respectively.

In other words, the PCM that is serially input to the input terminal] 4)
Audio signal rooo++B 00111001001・
...'', then shift register (from 61, bit pattern (o, o), (o, +), (1, l),
(+, o), (o, +), (+, +),
(o, o).

(1,0), (0,I), ... 2 bits each (A
, B) are output sequentially, and at this time pn, bark, (
7], each 2. bit.

(A, B) are bit patterns (o, o), (o
, l), (+, o).

(z, +), (o, +), (t, o), (
o, o), (s, t), (o, +) are changed to (A, B') and inputted next,
The level of the four-value level signal output from the converter (7) changes as shown in Figure 2, and each level is L. - The bit pattern of 2 bits (A, B) for L3 becomes a bit pattern that differs from the bit pattern of the adjacent level by one bit. 2.942 [The 2 bits shown with the waveform of the 4-level signal of 1+ are the original 2 bits (
A, B).

Then, by switching the switch (8), the clamp circuit (3)
) During the vertical blanking period of the band compressed video signal output from the converter (7), the four-level signal from the converter (7) is output from the switch (8) to the output terminal
4 in the vertical blanking period of the band-compressed video signal.
A PCM audio signal is baseband multiplexed using a value level signal, and a band compressed video signal obtained by time division multiplexing the PCM audio signal is input.

Therefore, in the case of FIG. 1, the PCM audio signal is baseband multiplexed using a four-level signal, and in this case, the amount of PCM audio signals that can be multiplexed is twice that when two-level signals are used. For example, it is possible to baseband multiplex the received PCM audio signals of all channels in A and kl mode formats, and to record the signal at the output terminal αO on a video disc etc. I can do notes and peaks.

Also, each level L of the four-value level signal. -2 for Ll
The bit pattern of bits (A, B) or the bit pattern of two bits (AB) for adjacent levels differs by one bit (o, o), (o, +),
(+, t).

(l, 0), bit errors are suppressed as much as possible even if level fluctuations occur in the four-value level signal due to the influence of noise, occurrence of dropouts, etc.

That is, each level L. -L, 2 bits (A,
The bit pattern of H) is (o, o), (o, +
), (+, o).

(S, S), in this case, the bit pattern (0, +) for level L1 and the level L
The bit pattern (+,
0), the two bits have different patterns, so for example, due to the influence of noise, the level is L, or the level is L! If it fluctuates, a 2-bit bit error will occur.

However, as mentioned above, each level L. - Set the 2-bit (8B) bit pattern for L3 to a pattern that differs by one bit from the bit pattern for the adjacent level, and set the bit pattern rows (o, +), (+, t) for levels L l, L t. ), even if the level L1 changes to the level L2, only a 1-bit bit error will occur, and the number of bit errors that occur can be minimized.

Therefore, the occurrence of data errors is extremely low, and
Baseband multiplexing of one PCM voice word is performed using a method that doubles the amount of PCMt isophones that can be multiplexed than when using a value level voice.

3. Each level L. - 2 bits for L3 (813)
The combination of bit patterns may be other than those in the embodiment, for example, each level L in the embodiment. Of course, it is also possible to set a combination of bit patterns shifted by one bit pattern 't' for -L.

It goes without saying that the present invention can also be applied to a case where a high-quality video signal is band-compressed using a band-compression method other than the TCI multi-point sub-sampling method.

〔Effect of the invention〕

As described above, according to the PCM audio multiplexing method of the present invention, PCM single voice data is converted into a 4-level signal by 2 bits at a time, and is used in the vertical blanking period of a band-compressed high-definition: 1-level image signal. By setting the baseband multi-band pattern and the 2-bit bit pattern for each level to be a pattern that differs by only 1 bit from the bit pattern of the adjacent level, data errors due to noise etc. are suppressed, and binary The amount of PCM audio signals that can be multiplied by 4J can be increased compared to when level signals are used, and PCM audio signals can be baseband multiplexed using a technique with fewer data errors and a large amount of multiplexing.

[Brief explanation of drawings]

The drawings show a practical example of the PCM audio multiplexing method of the present invention, where Fig. fJ1 is a block diagram and Fig. 2 is a waveform diagram of a four-level signal. fl+...Video input terminal, 121...Capacitor, (
3)・Franz circuit, [4)...Audio input terminal, (6
)...shift register, (6)...exclusive ethical sum gate, (7)/1)/A converter, (8)...analog switch, (9)...switching 1 concave 1 input terminal, an
...Tazu f signal output terminal. Agent Patent Attorney Fuji 1) Ryotabe Figure 1 Figure 2

Claims (1)

[Claims] (1) PCM audio signal is baseband multiplexed during the vertical blanking period of high-quality video signal subjected to band compression processing
In the CM audio multiplexing method, the PCM audio signal is converted into a 4-level signal that changes to 4-level levels in 2-bit increments and multiplexed in the vertical blanking period, and the 2-bit bit patterns of each level are different from each other. A PCM audio multiplexing method characterized in that the PCM audio multiplexing method is characterized in that the bit pattern of an adjacent level is set to a pattern that differs by only one bit.