JPH0740736B2 - MUSE audio information modulator - Google Patents

Description

The present invention relates to an audio information modulator for MUSE type television broadcasting.

2. Description of the Related Art Currently, the MUSE system is planned as one of new television broadcasting services using broadcasting satellites.

In this MUSE system, an analog audio signal, which has been conventionally transmitted by an image signal and a frequency division multiplexing system, is digitized and then transmitted by an image signal and a time division multiplexing system.

That is, on the transmitting side, after the analog signal is digitized by pulse code modulation, it is time-axis compressed to about 1/16 and transmitted in a burst form within the vertical blanking period between each field, while the receiving side In the above, the time-axis-compressed burst digital signal is expanded in the time-axis to restore a continuous audio signal and then converted into an analog signal.

Further, in the MUSE system, the image signal is sent out as an FM modulated wave, and the time-axis-compressed digital audio signal is a differential carrier wave (RF carrier) used for FM modulation of the image signal.
It is transmitted as a phase-modulated signal. Therefore, a data pair obtained by differentially modulating a continuous 2-bit voice data pair is called a symbol, and the concept of this symbol is used to MUSE.
The transmission format of the system is specified.

That is, the transmission format of the MUSE system is defined by the line number and the transmission sample number, as shown in FIG.
Each line corresponds to one horizontal scanning period of the image signal, and each transmission sample consists of one symbol.

The first field of image information starting from the 44th line and ending at the 576th line, and the maximum of 112 starting from the 605th line
During the vertical blanking period existing between the second field of the image information which passes through the fifth line and ends with the next fifth line, 37 lines of audio information are transmitted. Further, 38 lines of audio information are transmitted within the vertical blanking period existing between the second field and the next first field of the image information. 480 transmission samples are assigned to one line of each audio information area.

The first and second fields of image information are composed of control signals associated with the image signal, and the audio information area is composed of control signals associated with the audio signal.

The size of the audio information area is alternately set to 37 lines and 38 lines for the purpose of synchronizing all signal systems including video signals. Similarly, from the viewpoint of synchronization, there are two types of transmission formats for each audio information area: a leap field that appears periodically once every 15 fields and a non-leap field that appears 14 times in between. .

The transmission formats of the non-leap field and the leap field are as shown in FIG. 2 and FIG.
The first and the 604th) are the same, and all other lines are exactly the same.

That is, both non-leap fields and leap fields
Each line except the last line starts from transmission sample number 1.
Guard signal period G1 up to 18, transmission symbol number (RIS signal) period of transmission sample number 19, transmission sample number 2
Voice signal period from 0 to 475 and transmission sample number 476
It consists of the guard signal period G2 from 1 to 480.

During the guard signal period G1, symbols of the last transmission sample number 480 of the preceding line are continuously transmitted. However, in the first line (6 or 568) of each burst, the last transmission sample number 4 of the last line (43 or 604) of the preceding burst
Eighty symbols are transmitted continuously.

During the guard signal period G2, the symbols of the final transmission sample number 475 of the audio signal on that line are continuously transmitted.

Further, during the RIS signal period, the same symbol as the symbol of the final transmission sample number 475 of the voice signal on the preceding line is transmitted. However, in the first line (6 or 568) of each burst, the final transmission sample number 459 or 45 of the audio signal on the last line (43 or 604) of the preceding burst.
The same symbol as the 5th symbol is transmitted.

In the case of the non-leap field, the audio signal of the final line 43 or 604 ends at the transmission sample number 459, and the R signal is transmitted during the period from the transmission sample number 460 to 475. In the guard period G2, the same symbols as the symbols of the final transmission sample number 459 of the audio signal on that line are continuously transmitted.

In the case of a leap field, the final line 43 or 604
Sound signal ends at the transmission sample number 455, and the R signal is transmitted during the period from the transmission sample number 456 to 475. During the guard signal period G2, the same symbols as the symbols of the final transmission sample number 455 of the voice signal on that line are continuously transmitted.

The symbol sequence of the R signal inserted in the last line corresponds to 0 continuous data or 1 continuous data depending on whether the subsequent field is a non-leap field or a leap field. Sent out.
As described above, since the leap field appears periodically every 15 fields, 16 symbol strings corresponding to one continuous data are transmitted in the R signal period of the 14th non-leap field. , In the other non-leap field and leap field R signal periods, a symbol sequence corresponding to 0 continuous data is transmitted.

In the transmission format described above, the field frequency is
This is for 60 / 1.001Hz. Field frequency is 60
In the case of Hz, the number of R signals transmitted is 32 symbols in the non-leap field and 36 symbols in the leap field.
The other points are the same as when the field frequency is 60 / 1.001.

A configuration as shown in FIG. 12 has been proposed as the MUSE-type audio information modulator.

The analog audio signal supplied to the input terminal IN is BS-II PCM.
After being converted into a PCM signal by the encoder 1, it is time-axis compressed by the time-axis compression 2 to about 1/16. A control signal including a guard signal G, a RIS signal, and an R signal is added in the control signal adding circuit 3 to the time-base compressed audio PCM signal. The serial / parallel conversion circuit 4 converts the audio information to which the control signal is added into a serial bit pair into a parallel bit pair. This parallel bit pair is differentially modulated in the differential modulation circuit 5, and then in the 4-phase phase modulation circuit 6, RF
Used for carrier modulation. The differential 4-phase phase modulated wave is
It is supplied to the antenna system from the output terminal OUT.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The voice information modulator is configured to differentially modulate voice information composed of a time-axis-compressed voice signal and a related control signal, and therefore differential modulation can be performed at high speed. However, there is a problem in that the differential modulation circuit becomes expensive because it becomes necessary.

Configuration of the Invention Means for Solving the Problems An audio signal modulating apparatus of the present invention is one in which a pulse code modulated audio signal is differentially modulated before time axis compression, and the differential modulation output is time axis compression. By adding a symbol of a control signal to time-compressed audio information, a low-speed and inexpensive differential modulation circuit can be used.

That is, the present invention has been made based on the knowledge that it is possible to differentially modulate only an audio signal independently of a control signal even in a differential modulation method in which modulation corresponding to the context of a signal is performed. Therefore, the cost of the modulation circuit can be reduced.

Hereinafter, the operation of the present invention will be described in detail with reference to Examples.

Embodiment 1 FIG. 1 is a block diagram showing the configuration of a MUSE type audio information modulation circuit according to an embodiment of the present invention.

This audio information modulator has a BS-II PCM encoder 11
A serial / parallel conversion circuit 12, a differential modulation circuit 13, a time axis compression / control signal addition circuit 14, and a four-phase phase modulation circuit 15.

The analog audio signal supplied to the input terminal IN is BS-II P
In the CM encoder 11, it is converted into a digital audio signal. The digital audio signal is immediately converted into a parallel bit pair by the serial / parallel conversion circuit 12, and then differentially modulated by the differential modulation circuit 13 to be converted into a symbol (P, Q) sequence.

Symbol (P, Q) sequence is time axis compression / control signal addition circuit 1
In 4, the control signal is added while being compressed on the time axis,
It is used to modulate the RF carrier in a 4-phase phase modulation circuit. RF carrier modulated by symbol train is output terminal OUT
Supplied to the antenna system.

As shown in FIG. 2, the differential modulation circuit 13 is composed of a mo-dulo4 addition circuit and a delay circuit for one symbol.

Data bit pair Dn (D ₁ , D ₂ ) and immediately preceding symbol S
Modulo4 addition is performed on _n-1 (P ', Q') to generate a new symbol S _n (P, Q).

That is, the relationship between the data bit pair D _n (D ₁ , D ₂ ), the immediately preceding symbol S _n-1 (P ′, Q ′) and the new symbol S _n (P, Q) is as shown in FIG. Becomes However, the symbols are expressed in Gray code, and "0" = (0,0), "1" = (0,1) "2" = (1,0), "3" = (1,1) Is.

The symbol sequence differentially modulated in this way is demodulated in four phases on the receiving side, and then, as shown in FIG.
By the differential demodulation circuit consisting of the subtraction circuit for lo4 and the delay circuit for one symbol, the original data bit pair D _n (D ₁ , D ₂ ) is restored while following the algorithm shown in FIG.

FIG. 6 is a block diagram showing the configuration of the time axis compression / control signal adding circuit 14 of FIG.

This time axis compression / control signal adding circuit is a serial / parallel conversion circuit 21, a latch circuit 22, a RAM 23 and a parallel / serial conversion circuit 24 involved in time axis compression for a P signal sequence in a symbol sequence.
P signal system composed of P, Q, and a Q signal system composed of a serial / parallel conversion circuit 31, a latch circuit 32, a RAM 33, and a parallel / serial conversion circuit 34, which are involved in time axis compression for the Q signal sequence in the symbol sequence. Timing control circuit common to both signal systems 35
And an address generation circuit 36, and a gate and flip-flop group 37 configured for each of the P and Q signal systems.

The P signal sequence in the symbol sequence is shifted in the serial / parallel conversion circuit 21 in synchronization with the low-speed clock signal CKL supplied from the timing control circuit 35, and the 8-bit parallel P signal sequence is obtained.
It is converted into a signal string and is temporarily written in the RAM 23 via the latch circuit 22. Similarly, the Q signal sequence in the symbol sequence is also serial /
In the parallel conversion circuit 31, it is shifted in synchronization with the low-speed clock signal CKL and converted into an 8-bit parallel Q signal string,
It is temporarily written in the RAM 33 via the latch circuit 32. RAM23 above
Writing to 33 and 33 is continuously performed word by word at a predetermined cycle.

During the vertical blanking period, high-speed reading in word units is performed from the RAMs 23 and 33 in a period of about 1/16 of the writing period by interposing the writing between the RAMs 23 and 33 in word units. However, if there is a conflict between the writing and the reading, the reading is prioritized, and the writing of one word is performed after the reading of one word is completed.

In this way, the 1-word P signal string read from the RAM 23 is synchronized with the high-speed clock signal CKH at the parallel / serial conversion circuit 24, which is approximately 16 times as fast as the clock signal CKL supplied from the timing control circuit 35. Then shifted, 16
It becomes a serial p signal train which is time-axis compressed to one half and is supplied to one input terminal of the exclusive OR gate EX1. Similarly, the 1-word Q signal sequence read from the RAM 33 is also shifted in the parallel / serial conversion circuit 34 in synchronization with the high-speed clock signal CKH, and serial q is time-axis compressed to 1/16.
The signal string is supplied to one input terminal of the exclusive OR gate EX2.

Exclusive OR gates EX1 and EX2 from the timing control circuit 35
Control signal insertion signal A supplied to the other input terminal of
Is always held at a logic low except during the transmission period of the R signal composed of 16 consecutive data pairs (1,1). Therefore, if both the p and q signals of the voice signal and control signal (G1, G2, RIS signal and R signal other than the data pair (1,1)) are low, the low signal is exclusive, and if the p and q signals are high, the high signal is exclusive. Logical OR gate EX
Output from 1, EX2. That is, the audio information other than the R signal of the data (1,1) is directly subjected to the exclusive OR gate EX1, EX1.
It passes through EX2 and is supplied to one input terminal of AND gates A1 and A2.

The preamble insertion signal B supplied from the timing control circuit 35 to the other input terminals of the AND gates A1 and A2 has a period of 6 lines 6 to 43 lines, as shown in FIG.
It rises high only for the period of 568 to 604 lines. Therefore, the AND gates A1 and A2 are exclusive OR gates EX1 and E
The audio information consisting of the audio signal and the control signal supplied from X2 is passed as it is.

The signal supplied to the other input terminal of the AND gates A1 and A2 rises to low except during the audio information transmission period, and the clamp level (preamble) of FIG. 9 consisting of continuous symbols (0,0) is transmitted. To be done.

This clamp level (preamble) is applied to the image information by transmitting the non-phase modulated wave corresponding to the symbol (0,0) at the frequency corresponding to the intermediate value between the highest gradation and the lowest gradation of the image signal. It provides a clamp level and a preamble for audio information.

During the period of the guard signal G2 from the transmission sample number 476th to 480th of each line, the timing control circuit 35
From the parallel / serial conversion circuits 24 and 34 to the shift inhibit signal (IN
H) is supplied and the shift of each parallel / series circuit is prohibited. Therefore, over the period of the guard signal G2, five symbols identical to the symbol of the final voice signal of the transmission sample number 475 are continuously transmitted.

From the timing control circuit 35 to the parallel / serial converter circuit 24, the guard signal G1 and the RIS signal of the transmission sample numbers 1 to 19 on the next line are continuously transmitted.
And 34 continue to be provided with the shift inhibit signal (INH), and the shift of each parallel / series circuit is still inhibited. Therefore,
Over the guard signal G1 and RIS signal transmission period, the same symbol as the 480th symbol transmitted on the preceding line,
That is, 19 symbols identical to the symbol of the final voice signal of the transmission sample number 475 are continuously transmitted.

However, in the first line (line 6 or 568) of each audio information field, the 480th symbol of the last transmission sample number of the last line (line 43 or 604) of the preceding field (this is described later) 19 symbols which are the same as the symbol of the final transmission sample number 459 or 455 of the audio signal) are continuously transmitted.

Next, a method of transmitting the R signal will be described.

[I] When sending an R signal consisting of a series of data pairs (1, 1).

In the field immediately before the leap field, when the transmission of the R signal consisting of 16 consecutive data pairs (1,1) is started, the shift inhibit signal INH supplied from the timing control circuit 35 causes the parallel / serial conversion circuit. 24 and 34 shifts are prohibited. As a result, the exclusive OR gates EX1 and EX2
One of the input terminals has a parallel / series conversion circuit 24
And 34 continuously supply the symbols (p ₄₅₉ , q ₄₅₉ ) of the speech signal of the transmission sample number 459. In sync with this,
As shown in the waveform diagram of FIG. 8, the R signal insertion signal A is alternated between high and low in the transmission sample period.

If the symbol (p ₄₅₉ , q ₄₅₉ ) is (0,0) as shown in the top row of the table in FIG. 8, the transmission sample number 4
At 60, the R signal insertion signal A rises to high (1), so that the symbol (1, 1) becomes the exclusive OR gate E.
Output from X1 and EX2 and flip with AND gates A1 and A2
After passing through the flops FF1 and FF2, it is sent to the receiving side as a symbol (p ₄₆₀ , q ₄₆₀ ) of the transmission sample number 460.

In the next transmission sample number 461, R signal insertion signal A
By falling to low (0), the symbol (0,
0) is output from the exclusive OR gates EX1 and EX2, passes through AND gates A1 and A2 and flip-flops FF1 and FF2, and is sent to the receiving side as a symbol (p ₄₆₁ , q ₄₆₁ ) of the transmission sample number 461. It

In the next transmission sample number 462, the R signal insertion signal A
By rising high again, the symbol (1,1)
Is output from the exclusive OR gates EX1 and EX2, and is sent to the receiving side as a symbol (p ₄₆₂ , q ₄₆₂ ) of the transmission sample number 462.

Thus, as shown in the uppermost row of the table of FIG. 8, symbols (0,0) and (1,1) are alternately transmitted to the receiving side, and the final transmission sample number 475 of the R signal transmission period is 475. Then, the symbol (0,0) of the transmission sample number 459 immediately before the R signal transmission period
Return to.

As can be seen by referring to the fourth row from the bottom and the bottom row in the table of FIG. 5, as the symbol (0,0) and the symbol (1,1) alternate, the data (1,1 ) Is played continuously.

If the symbol (p ₄₅₉ , q ₄₅₉ ) is (0,1) as shown in the second row of the table of FIG. 8, the next symbol is (p ₄₆₀ , q ₄₆₀ ) is inverted to (1,0), and at the next symbol (p ₄₆₁ , q ₄₆₁ ), the symbol inversion to return to (0,1) is repeated, and the final symbol (p _475, q _475), the flow returns to just before the symbol R signal insertion period (p _459, q _459).

As can be seen by referring to the third and second rows from the bottom in the table of FIG. 5, as the symbol (0,1) and the symbol (1,0) alternate, the data (1, 1) is played continuously.

Assuming that the symbol (p ₄₅₉ , q ₄₅₉ ) is (1,0) as shown in the third row of the table of FIG. 8, the next symbol becomes (p ₄₆₀ , q ₄₆₀ ) is inverted to (0,1), and at the next symbol (p ₄₆₁ , q ₄₆₁ ), the symbol inversion to return to (1,0) is repeated, and the final symbol (p _475, q _475), the flow returns to just before the symbol R signal insertion period (p _459, q _459).

As can be seen by referring to the second and third rows from the bottom in the table of FIG. 5, as the symbol (1,0) and the symbol (0,1) alternate, the data (1, 1) is played continuously.

Assuming that the symbol (p ₄₅₉ , q ₄₅₉ ) is (1,1) as shown in the fourth row of the table of FIG. 8, the next symbol becomes (p ₄₆₀ , q ₄₆₀ ) is inverted to (0,0), and at the next symbol (p ₄₆₁ , q ₄₆₁ ), the symbol inversion to return to (1,1) is repeated, and the final symbol (p _475, q _475), the flow returns to just before the symbol R signal insertion period (p _459, q _459).

As is clear by referring to the bottom row and the fourth row from the bottom in the table of FIG. 5, as the symbol (1,1) and the symbol (0,0) alternate, the data (1, 1) is played continuously.

When the signal A supplied to the other input terminals of the exclusive OR gates EX1 and EX2 falls to low at the start of the guard period from the next transmission sample number 476, the final symbol (p ₄₇₅ , q ₄₇₅ ) is continuously transmitted as it is, and the first line 6 or 56 of the next leap field is transmitted.
Further, 19 (p ₄₇₅ , q ₄₇₅ ) are continuously transmitted from 8 transmission sample numbers 1 to 19, and the receiving side receives the last symbol (p ₄₅₉ , q ₄₅₉ ) of the preceding non-leap field voice signal.
The phase of is saved.

[II] When sending an R signal consisting of 16 or 20 consecutive data pairs (0,0).

In this case, as described above, transmission sample numbers 460 to 475 for non-leap fields and transmission sample numbers 456 to 4 for leap fields.
Up to the 75th, the timing control circuit 35 supplies the shift prohibiting signal (INH) to the parallel / serial conversion circuits 24 and 34, and raises the signal A supplied to the exclusive OR gates EX1 and EX2 to low.

As a result, 16 identical symbols held in the parallel / serial conversion circuits 24 and 34 are continuously transmitted in the non-leap field and 20 identical symbols are continuously transmitted in the leap field. On the receiving side, as is clear by referring to the first to fourth stages in the table of FIG. 5, a continuous data pair (0,0) is reproduced with the continuation of arbitrary symbols. .

In this way, the insertion of the R signal that continuously transmits a predetermined number of symbols corresponding to the data pair (1,1) and (0,0) is prohibited by the shift operation of the parallel / serial conversion circuit and exclusive. This can be easily realized by installing the logical OR gates EX1 and EX2 and alternating the A signal supplied to the other input terminal of these exclusive OR gates for each symbol or lowering it to low.

The configuration for creating and adding the control signal symbol by using a part of the time axis compression circuit for the voice symbol has been illustrated above, but the circuit independent of such time axis compression creates the control signal symbol. The configuration may be such that the addition is performed.

EFFECTS OF THE INVENTION As described in detail above, the MUSE-type audio modulator according to the present invention differentially modulates the pulse code-modulated audio signal before time-axis compression, and outputs the differential modulation output on the time-axis basis. Since the time-axis-compressed audio information is created by adding the control signal symbol to the compressed one, it is possible to use a low-speed and inexpensive differential modulation circuit.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of a MUSE type audio modulator according to an embodiment of the present invention, FIG. 2 is a functional block diagram showing the configuration of the differential modulation circuit of FIG. 1, and FIG. Second
4 is a conceptual diagram for explaining the operation of the differential modulation circuit shown in FIG.
FIG. 6 is a functional block diagram showing the configuration of the differential demodulation circuit on the receiving side, FIG. 5 is a conceptual diagram for explaining the operation of the differential demodulation circuit of FIG. 4, and FIG. 6 is the time axis compression of FIG.・ A circuit diagram illustrating the configuration of the control signal adding circuit 14, FIGS. 7 and 8 are signal timing diagrams for explaining the operation of the circuit of FIG. 6, and FIGS. 9 to 11 are MUSE type transmissions. A format diagram and FIG. 12 are functional block diagrams showing the configuration of a conventional voice modulator. 11 …… BS-II encoder, 12 …… Series / parallel conversion circuit,
13 …… Differential modulation circuit, 14 …… Time axis compression / control signal addition circuit, 15 …… 4-phase phase modulation circuit, 21,31 …… Series / parallel conversion circuit, 22,32 …… Latch circuit, 23, 33 ... RAM, 34 ... Parallel / serial conversion circuit, 35 ... Timing control circuit, 36 ... Address generation circuit, 37 ... Gate and flip-flop circuit.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Yoshimichi Otsuka 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the Japan Broadcasting Corporation Broadcasting Technology Laboratory (72) Inventor Yoshinori Izumi 1-10 Kinuta, Setagaya-ku, Tokyo No. 11 Broadcasting Technology Laboratory of Japan Broadcasting Corporation (72) Inventor Seiichi Koshi 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside Broadcasting Technology Laboratory of Japan Broadcasting Corporation

Claims (1)

[Claims] 1. Modulation means for pulse code modulating an analog voice signal, differential modulation means for converting a pulse code modulated voice signal into a voice symbol sequence, and time axis compression means for time axis compressing these voice symbol sequences. MUSE, which further comprises: addition means for adding the guard signal, the introduction symbol signal and the R signal to the time-axis-compressed voice symbol sequence, and the modulation means for performing the four-phase phase modulation on the output of the addition means. System audio information modulator.