JPS6281137A - Pcm transmission system and its equipment - Google Patents

Abstract

PURPOSE:To obtain an excellent transmission performance even when a high frequency component and a low frequency component exist at the same time by controlling a differential coefficient at the calculation of a differential data in response to the result of discrimination of a level and a frequency of an analog original signal. CONSTITUTION:A digital differential data corresonding to a sequential difference of the analog original signal is calculated, the level and frequency of the analog original signal are discriminated substantially, the differential coefficient alpha in the calculation of the differential data is controlled variably in response to the result of discrimination to obtain a digital data, and the digital data is subject to data compression to obtain a digital transmission data to send the transmission data and discrimination information corresponding to the result of discrimination substantially. The transmission data and the discrimination information are received, the data expansion is applied and a received and sent data, the expanded data is subject to integration processing, the integration coefficient in the integration processing is controlled corresponding to the differnetial coefficient alpha at the transmission side based on the reception discrimination information and the result of integration is used for the conversion into an analog recovery signal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is based on PCM (pulse code mod
(pulse code modulation) transmission system and its device, in particular D PCM (dif'fcr
The present invention relates to a technology for improving DC component deviations during error correction in PCM transmission in a system that transmits difference data between samples, such as cntial PCM to differential PCM.

In this case, "transmission" is not limited to transmission via wireless or wired communication lines, but simply means transmission in a broad sense, including transmission through modulation/demodulation systems and recording/reproduction systems.
The term "transmission line" means a system including a communication/signal line, a modulation/demodulation system, a recording/reproduction system, etc., or a combination thereof.

[Conventional technology]

The DPCM transmission system is basically a system that cannot perform DC transmission. This is because only the difference value information of the original analog signal is transmitted, so if a transmission error occurs even once, that error will be permanently stored as a change in the DC value on the receiving side.

For example, a case will be described in which a transmission error occurs during DPCM transmission, cannot be corrected by so-called error correction processing, and error recovery is attempted by correction.

When a sine wave signal sw as shown in Fig. 7 is sampled at points A to D in the figure and transmitted as difference data, if the difference data at the BSC point is lost during the transmission process, a pre-hold is performed on the receiving side. The difference value is treated as zero and is received as points B' and C'' in the diagram.Next, if the correct difference data for point D is transmitted, the receiving side determines that the value is equal to point A. Difference data is added with point C' as a reference and received as point D'.Therefore, the received waveform becomes like the broken line in the figure, and the DC level shifts at the data missing part.As a result, the original signal Even if the signal is a sine wave signal centered at the zero level, the signal deviates from the center of the upper and lower limits of the dynamic range (centered at the zero level) of the reproduction system, resulting in a narrow effective dynamic range.

Another problem with DPCM transmission is that, especially during two-signal transmission where a high-frequency signal and a low-frequency signal exist simultaneously, the low-frequency signal drops to a lower bit level than the high-frequency signal. . If the low-frequency signal drops to a low bit level in this way, the low-frequency signal cannot be transmitted when there are few transmission bits. moreover,
Even when performing quasi-instantaneous companding on a PCM signal like this,
Since data is compressed by truncating lower bits on the transmitting side, low-frequency information is truncated, and low-frequency signals are no longer transmitted.

Here, PCM data, which is simply A/D (analog-digital) conversion of an analog signal, is linear PCM data.
A comparison will be made between the CM data and the above-mentioned DPCM data in the case of quasi-instantaneous companding. The PCM method for quasi-instantaneous companding of linear PCM data is Nl-PCM.
(nearinstantaneous P CM
~ quasi-instantaneous companding PCM). On the other hand, the PCM method for quasi-instantaneous companding of the DPCM data is
CM(dl('f'erent1al compand
lng PCM ~ differential quasi-instantaneous companding PCM). The S/N of N1-PCM is determined by the level of the original signal. On the other hand, in DPCM, the S/N is determined by the frequency and level of the original signal. therefore,
If the size of the original signal is smaller than the value corresponding to the transmission compression bit length, the S/N is the same for both N l-PCM and DC-PCM, but the original signal is If it is larger than the value corresponding to the bit length,
In N1-PCM and DC-PCM, S/
There is a difference in H. That is, at low frequencies, even if the amplitude of the original signal is large, the value of the DPCM data is small, and therefore, the loss of information when data is compressed is small, so the S/N of DC-PCM is good. However, this DC
- In PCM, when there is a reduction in information due to compression and the above-mentioned data loss, a deviation occurs due to the DC component. On the other hand, the value of linear PCM data simply corresponds to the amplitude of the original signal. Therefore, if the amplitude of the original signal is small, there will be less loss of information when compressing the data, and the S/N of Nl-PCM
will be good.

Furthermore, since this N1-PCM basically transmits linear PCM data, no DC deviation occurs.

[Problem that the invention seeks to solve]

An object of the present invention is to utilize compressed transmission of sequential difference data of an analog original signal, to substantially prevent adverse effects such as deviations in the DC component caused by transmission errors, and to eliminate high-frequency components and low-frequency components. It is an object of the present invention to provide a PCM transmission system and a device thereof, which make it possible to obtain good transmission characteristics even when PCM components simultaneously exist.

[Means for solving problems]

The first invention according to the present invention is an invention of a method, which calculates digital difference data corresponding to successive difference values of the analog original signal based on the analog original signal or a signal obtained from the analog original signal, and calculates the digital difference data corresponding to the sequential difference values of the analog original signal. Substantially determine the level and frequency of the analog original signal, and according to the determination result, variably control the difference coefficient in calculating the difference data to obtain digital data, and compress the digital data to obtain digital transmission data. and transmits the transmission data and discrimination information substantially corresponding to the discrimination result, receives the transmission data and discrimination information, expands the received transmission data, and performs integration processing on the expanded data. The PCM transmission system is also characterized in that the integration coefficient in the integration process is controlled in correspondence with the difference coefficient on the transmitting side based on reception discrimination information, and the integration result is used for conversion into an analog reproduction signal.

A second invention according to the present invention is an invention of a method that has the main part of the first invention as a main part and achieves the same object,
Obtaining linear data corresponding to the analog original signal and difference data corresponding to successive difference values of the analog original signal based on the analog original signal or a signal obtained from the analog original signal, and the values of these linear data and difference data. It is substantially determined whether or not the linear data exceeds both the predetermined value and the differential data value by comparing and determining, and according to the determination result, if the linear data exceeds both of the above, the differential data and the differential data are determined. If so, obtain compressed digital transmission data corresponding to the linear data, transmit the transmission data and discrimination information substantially corresponding to the discrimination result, and receive the transmission data and discrimination information. and expands the received transmission data, and based on the reception discrimination information, if linear data is selected on the transmitting side, the expanded data is used as is, or if differential data is selected on the transmitting side, the expanded data is expanded. This is a PCM transmission method characterized by integrating the received data and converting it into an analog reproduction signal.

Further, a third invention according to the present invention is an invention of a product directly used for implementing the method of the first invention, in which the analog original signal is sequentially converted from an analog original signal or a signal obtained from the analog original signal. a difference calculation means that calculates digital difference data corresponding to the difference value and makes the difference coefficient in the calculation variable; discrimination control means for discriminating the level and frequency of and variably controlling the difference coefficient of the difference calculation means according to the discrimination result; a data compression means for compressing the output data of the difference calculation means; and the data compression means. This PCM transmitting apparatus is characterized in that it comprises a transmitting means for substantially transmitting the output data of the PCM and the discrimination result of the discrimination control means to a transmission system.

The fourth invention according to the present invention is also an invention of a product directly used for carrying out the method of the first invention, and corresponds to the value of the analog original signal from an analog original signal or a signal obtained from the analog original signal. linear data detection means for obtaining linear data corresponding to the sequential difference values of the analog original signal from the analog original signal or a signal obtained from the analog original signal; and these linear data detection means and a determining means for determining whether or not the value of the linear data substantially exceeds both the predetermined value and the difference value based on the output of the difference detecting means; Based on this, and in accordance with the discrimination result of the discrimination means, if the value of the linear data substantially exceeds both the predetermined value and the difference value, the digital compression corresponding to the differential data, and if not, the digital compression corresponding to the linear data. PCM transmission characterized by comprising a compressed data generating means for obtaining data, and a transmitting means for substantially transmitting the output data of the compressed data generating means and the current determination result in the determination control means to a transmission system. It is a device.

And, the fifth invention according to the present invention is an invention of a product directly used for carrying out the method of the first invention, in which successive difference values are obtained by a difference coefficient that is variably controlled according to the level and frequency of the analog original signal. In a PCM receiving device for receiving and demodulating a transmission signal including transmission data consisting of digital difference data corresponding to the difference coefficient and discrimination information substantially corresponding to the difference coefficient, and obtaining information corresponding to the analog original signal. , a receiving means that receives these transmission data and discrimination information from the transmission system, and an integral value that calculates an integral value of the received transmission data received by this means and outputs it to the reproduction system, and an integral that makes the integral coefficient in the calculation variable. A PCM characterized in that it comprises a calculation means, and a coefficient control means for variably controlling the integral coefficient of the integral calculation means in correspondence with the difference coefficient on the transmitting side based on the reception discrimination information received by the reception means. It is a receiving device.

The sixth invention according to the present invention is also an invention of a product directly used for implementing the method of the first invention, in which linear data corresponding to an analog original signal is data compressed and successive differences of the analog original signal are obtained. digital transmission data in which one of compressed differential data corresponding to a value is sequentially selected; and discrimination information substantially corresponding to which of the compressed linear data and the compressed differential data is being transmitted. In a PCM receiving device for receiving and demodulating a transmission signal including a transmission signal and obtaining information corresponding to the analog original signal, a reception means for receiving the transmission data and discrimination information from a transmission system, and a reception transmission received by this means. A data decompression means for decompressing the data, and in response to the reception discrimination information received by the receiving means, if linear data is selected on the transmitting side, the output of the data decompression means is output as is to the reproduction system, and the data is transmitted. The PCM receiving apparatus is characterized in that it comprises a selective integration means for integrating the output of the data expansion means and outputting it to a reproduction system when differential data is selected on the side.

〔Example〕

Before specifically describing embodiments of the present invention, the principle of the present invention will first be explained.

In the case of DPCM transmission in which the complete difference of linear PCM data is obtained by sampling and digitizing an analog original signal, the data L
B (least 51gn1ficant bit~
(the least significant bit), and one transmission becomes impossible.

In such a case, if the difference coefficient α is reduced to less than 1 to form an incomplete difference, the data value becomes almost constant below the frequency fc. Since there is a correlation between this frequency tc and the value of the difference coefficient α, it is possible to transmit even low-frequency signals by controlling the value of the difference coefficient α according to the level and frequency of the original signal and changing the fcO value. Become. If the level of the original signal is very low and it can be sufficiently transmitted within a predetermined number of transmission bits using linear PCM data, the difference coefficient a may be set to 0, that is, linear PCM.

Furthermore, if the original signal is not a single low-frequency signal but includes a high-frequency signal or two or more signals with different frequencies, α can be controlled so that the frequency fC has a value close to the frequency of the high-frequency signal. Since the level of low frequency components does not decrease, no actual damage occurs. Therefore, if the difference coefficient α is controlled in accordance with the frequency and level of the original signal in consideration of these points, it becomes possible to perform good transmission of high frequency signals or two or more signals having different frequencies.

Therefore, in the present invention, the difference data used for companding transmission is not limited to normal complete difference data, that is, difference data when the difference coefficient α is 1, but the difference coefficient α is variably controlled under predetermined conditions. (Hereafter, for convenience of explanation,
This kind of differential data, including incomplete differential data and linear data, is called "variable differential data."
).

To obtain differential data from original sample data sampled and digitized at a predetermined sampling period, for example, as shown in FIG. The subtraction means 2 may subtract the original sample data from one sample before. For this subtraction, as shown in the figure, a multiplication means 3 for multiplying by a coefficient α is provided between the delay means 1 and the subtraction means 2. Multiply by the difference coefficient α. By variably controlling the multiplier α of this multiplication means 3,
The difference coefficient α as described above can be changed.

FIG. 4 shows the relationship between the value of the difference coefficient α and the obtained variable difference data. When the difference coefficient α is 1, it means that a normal difference, that is, a complete difference is taken, and as the output of the subtraction means 2, complete difference data is obtained as DPCMPCM data. When the difference coefficient α is O, it means that no difference is taken, and linear data corresponding to normal linear PCM data is obtained. When α is a value between O and 1 (0 × α × 1), incomplete difference data is obtained in which the difference data component and the linear data component are included in a ratio according to the value of α. When α is greater than 1 (1 × α)
In this case, the difference data component and the linear data component are included in a ratio according to the value of α, and in this case, incomplete difference data whose polarity is reversed with respect to the original data is obtained.

Therefore, in controlling the difference coefficient α when obtaining variable difference data, it is necessary to control the value of α so as to maintain the S/N during complete difference data transmission, which corresponds to when α is 1. becomes. That is, in terms of S/H, complete differential data is basically the best, followed by incomplete differential data and linear data. However, this relationship also changes depending on the frequency and signal level, and the S/N ratio obtained by any of the above three types of data may not change. Furthermore, when a transmission error occurs, there are problems with DC shift when correction is performed without being able to be processed by error correction, or when data compression is performed, as well as the problem of two-signal transmission that includes high-frequency signals and low-frequency signals at the same time. Regarding the problems that arise in this case, linear data yields the best results, followed by incomplete differential data and then complete differential data.

Therefore, in the present invention, the transmission PCM data generation method is switched and controlled according to the signal level and frequency, and overall a good S/N of 14 is achieved by utilizing differential PCM, while effectively solving the problems of complete differential PCM. so that it can be improved.

For a more concrete understanding, a case will be described in which complete difference data and linear data are selectively selected and subjected to quasi-instantaneous companding (in this case, intermediate incomplete difference data is not used).

In other words, ``Switching is performed depending on the frequency domain and level domain of the original signal, and in areas where there is a difference in S/N between the two, the one with a better S/N is selected, and in areas where the S/N of the two does not substantially change. , is transmitted using Nl-PCM, which is capable of transmitting DC components.

Therefore, in a band where the original signal level is higher than the level corresponding to the bit length of compressed data and the frequency is lower than a predetermined value (if the sampling frequency is fs, fs/12
(bands below), DC-PCM has lower S than N1-PCM.
/N is good, so DC-PCM data is transmitted. If the frequency of the original signal is high (band above fs/12) and the level of the original signal is lower than the value corresponding to the bit length of the compressed data, the accumulation of errors related to reception special transmission, that is, DC deviation. and good S/N in the high frequency range (f s / 6 to f s
/ When the level is large enough in the band 2, N1-PC
(M has a better S/N), N1-PCM data is transmitted.

For example, if the original sample data of IB bits is subjected to quasi-instantaneous companding processing that compresses it to 8 bits during transmission, the PCM data will be N1- If the data is PCM data and the original sample data to be subjected to quasi-instantaneous companding is complete differential data, it is DC-PCM data.

FIG. 5 shows the relationship between S/N and frequency.

Characteristic A shown by a solid line is a characteristic of DC-PCM, and characteristic B shown by a broken line is a characteristic of N1-PCM. The dynamic range of both of these is 16-bit linear P.
It is about 98 dB, which is the same as CM.

As shown in FIGS. 5(a) and 5(b), which show the effective bit length of differential data and linear data, respectively, when the original signal is in the frequency range of fs/2 to fs/6 and the maximum At the level (OdB), the differential data value is 17 bits, which is larger than the 16 bits of linear data. Therefore, if the bit length of compressed data is the same, DC-PCM is better than N1-PCM.
N will get worse.

In addition, when the original signal is in the frequency range of [s/6 to fs/12, as is clear from Fig. 5, DC-PCM and N1-P
When the S/N of CM is equal and that of DC-PCM is
There are cases where N is good. This means that in this region D
It is expected that the effective bit length of PCFv1 data and linear data will be the same.

In the frequency region lower than fs/12, DC-P
For CM, the S/
N gets better. In this frequency domain, when the level of the original signal is higher than the level corresponding to the bit length of compressed data, DC-PCM can obtain a better S/N. In this frequency domain, when the level of the original signal is below the level corresponding to the bit length of the compressed digit, the DC-PC
The S/N is the same for both M and N1-PCM.

Therefore, within the shaded area C in FIG. 5, DC-PCM data is transmitted, and for signal level and frequency areas outside area C,
If N1-PCM data is transmitted, good transmission characteristics can always be obtained.

The structure of an embodiment of the present invention based on such a principle is shown in FIGS. 1 and 2. FIG. 1 shows a transmitting device, and FIG. 2 shows a receiving device.

In the transmitter shown in FIG. 1, an analog original signal is input to the input terminal 11, and this analog signal is
The D converter 12 samples and digitizes the signal at a predetermined frequency. The output of this A/D converter 12 is given to a differentiator 13 and a block maximum value detector 14. The differentiator 13 sequentially obtains difference values for each sample of input original sample data. Block maximum value detector 1
4 detects the maximum absolute value of the samples within each data block consisting of a plurality of samples of original sample data. The output of the differentiator 13 is given to a block difference maximum value detector 15. Block difference maximum value detector 1
5c calculates the maximum absolute value of the difference data in each data block from the difference data output from the subtractor 13. The outputs of the block maximum value detector 14 and the block difference maximum value detection W15 are output to the discriminator 1B.
given to. The discriminator 16 determines whether the maximum (absolute) value of the linear data is a predetermined value (in this case -50d[ 3), and if so, by determining which of the maximum (absolute) values of both data is larger, the signal level and frequency of the original analog signal are substantially determined. Specifically, the determination by the discriminator 16 is to determine whether the original signal is within the shaded area C shown in FIG. It is determined that the area is within region C when the value is larger than . Then, the discriminator 1G outputs discrimination data indicating the discrimination result to the output terminal 17, and controls the switching means 18 according to the discrimination result. The switching means 1B switches and selects the output of the A/D converter 12 and the output of the differentiator 13, and supplies the selected output to the data compressor 19. switching means 18
When the discriminator 1G determines that it is within the region C, the output of the differentiator 13 is selected, and when the discriminator 1G determines that it is not within the region C, the output of the A/D converter 12 is selected.

In this case, the data compressor 19 encodes the input data using a quasi-instantaneous companding method, that is, performs data compression, and obtains compressed data and scale data based on human data and outputs them to output terminals 2o and 21, respectively. . In this quasi-instantaneous companding method, when the effective bit length of human-powered data exceeds the bit length of compressed data, the upper effective bit is output as compressed data and also indicates the bit position from which the compressed data was extracted. It outputs scale data. In this case, data compression processing is performed for each block, so when the effective bit length of the maximum (absolute) value data in a block exceeds the bit length of the compressed data, the maximum (absolute) value data is compressed for all data in the block. absolute)
The data at the bit position corresponding to the upper effective bit of the value data is used as compressed data, and the data indicating the bit position is used as scale data for the block. These compressed data and scale data become N1-PCM data when near data is selected by the switching means 18, and DC-PCM data when differential data is selected. The compressed data, scale data and discrimination data output from output terminals 20, 21 and 17 are
The signals are appropriately multiplexed by a time division multiplexing means (not shown) and sent to the transmission system. Of course, in this case, the signals may be sent to separate transmission paths without being multiplexed.

That is, in this transmitter, a plurality of pieces of sampling data are treated as one block, and the maximum (absolute) value of linear data and the maximum (absolute) value of difference data in the block are detected by the block maximum value detector 14 and the block difference detector 14, respectively. The rain is detected by the maximum value detector 15, and these rain detection values are sent to the discriminator I.
Distinguish with B. This discriminator 16, as mentioned earlier,
Depending on whether the linear data exceeds the predetermined value and is also larger than the differential data, the original signal
Determine whether or not it is within the range. The switching means 18 is switched according to the determination result, and when it is determined that it is within the region C, the difference data that is the output of the differentiator 13 is selected, and when it is determined that it is not, the difference data that is the output of the A/D converter 12 is selected. Select linear data. The selected data is compressed by the data compressor 19 according to the quasi-instantaneous companding method.

This data compressor 19 obtains compressed data and scale data indicating a compression scale factor for each block, and these compressed data and scale data are transmitted.

This transmission data also includes whether it was sent in N1-PCM or
In order to enable the receiving side to determine whether the data was sent using C-PCM, determination data that substantially indicates the determination result of the discriminator 16 is added.

In the receiving device shown in FIG.
Compressed data, scale data, and discrimination data transmitted and received from the transmitting device are input to 2 and 33, respectively. When these transmission data are multiplexed and transmitted, they are separated by appropriate separation means (not shown) and then input to these input terminals 31, 32 and 33. When the transmission data is transmitted via separate transmission paths without being multiplexed, the compressed data, scale data, and discrimination data are input as they are to the respective input terminals 31, 32, and 33, respectively. The compressed data and scale data are provided to a data decompressor 34 that follows a quasi-instantaneous companding method. The data decompressor 34 is
In this case, the compressed data is decoded using a quasi-instantaneous companding method, that is, data expanded, using the scale data, and the compressed data is bit-shifted according to the scale data and output. The output of this data expansion "JA 34 is given to an integrator 35 for demodulating the difference data. Also, the discrimination data given to the input terminal 33 is given to the switching means 3B. The switching means 36
It is configured as a changeover switch that responds to discrimination data,
Either the output of the data expander 34 or the output of the integrator 35 is switched and selected. The data selected by this switching means 3G is D/A (digital-analog)
The signal is supplied to a converter 37 and converted into an analog value.

An analog signal output from the D/A converter 37 is output via an output terminal 38 and is provided for reproduction.

That is, compressed data and scale data, which are transmission data, are led to the data decompressor 34 and are decompressed. The switching means 3B is controlled by the discrimination data, which is also transmission data, and the integrator 35 is controlled depending on whether linear data or differential data is selected on the transmitting side.
It is possible to switch whether to pass or not. In other words, when linear data is selected, N1-PCM transmission is performed, so the output of the data expander 34 is sent directly to the D/A converter 37.
When differential data is selected, since it is DC-PCM transmission, it is integrated by the integrator 35 and then converted to an analog value by the D/A converter 37, and the analog reproduction signal is converted to an analog value by the D/A converter 37. get.

In this case, for general music signals, speed signals, etc., the time to be transmitted in N1-PCM is relatively long, and DC-PCM transmission is performed for a long time without intervening N1-PCM transmission. It rarely lasts. and,
Even if an uncorrectable error occurs due to data loss during signal transmission and is corrected, the problem of DC component deviation will not occur during N1-PCM transmission. Also, DC-PCM
Even if a deviation occurs in the DC component due to an error or data compression during transmission, N1-P
By performing CM transmission, the deviation is substantially corrected. Therefore, there is virtually no problem of direct current deviation. Also, when 2 signals are input, N1
- There is no problem with the number of ships during PCM transmission, and PCM transmission can be performed without problems even with two-signal transmission.

In this way, the level and frequency of the original signal are determined by determining the absolute values of the linear data and difference data obtained from the original signal, and N1-PCM transmission and DC
- By combining PCM transmission, it is possible to widen the band with good S/N in highly efficient PCM transmission.

Moreover, in the high frequency range and low level range, N1-
Since it is PCM transmission, there is no difference in the DC component due to transmission errors, and furthermore, such high frequency and low level components appear frequently in general music signals, speech signals, etc. As a result, it is possible to effectively reduce direct current deviations in overall transmission.

Therefore, highly efficient PCM transmission can be performed, a high S/N ratio can be ensured, and the deviation of the DC component can be significantly reduced.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without substantially changing the gist thereof.

For example, in the above embodiment, the block difference maximum value detection 5t5 is provided on the output side of the difference device 13, and the difference device 13
Although the maximum value of the difference data for each block is detected from the difference data output from the A/D converter 12, a block difference maximum value detector is provided in parallel with the difference IHH on the output side of the A/D converter 12. A configuration may also be adopted in which the difference is calculated within the block difference maximum value detector.

In addition, in the same embodiment, N1-PCM and DC-PCM are selectively switched and transmitted depending on whether or not the area is inside area C in FIG. The complete differential data may be instantaneously compressed and transmitted. In such a case, the sender has a third
If a variable difference device having the configuration shown in the figure is provided, the difference coefficient can be variably controlled.

Furthermore, the discriminator may discriminate the frequency and level directly from the original signal, or may discriminate the frequency and level from another signal that reflects the frequency and level of the original signal.

〔Effect of the invention〕

According to the present invention, by using compressed transmission of sequential differential data of an analog original signal, problems such as deviation of the DC component are substantially solved, and in addition, high frequency range components and low frequency range components are simultaneously transmitted. It is possible to provide a PCM transmission method and its device that make it possible to obtain good transmission characteristics even when PCM exists.

[Brief explanation of drawings]

1 and 2 are block diagrams showing the configurations of a transmitting device and a receiving device, respectively, in an embodiment of the present invention, FIGS. 3 to 6 are diagrams for explaining the principle of the present invention, and FIG. FIG. 2 is a diagram for explaining problems with the conventional method. 12...A/D (analog-digital) converter, 13...Differentiator, 14...Block maximum value detector, 15...Block difference maximum value detector, 16...
Discriminator, 18, 3G...Switching means, 19...
・Data compressor, 34...Data decompressor, 35...
... Integrator, 37... D/A (digital-analog) converter. Applicant's agent Patent attorney Takehiko Suzue Susuke Samurai ku αΣ branch

Claims (1)

[Scope of Claims] (1) Based on the analog original signal or a signal obtained from the analog original signal, digital difference data corresponding to the successive difference values of the analog original signal is calculated, and the level of the analog original signal and The frequency is substantially determined, and the difference coefficient in calculating the difference data is variably controlled according to the determination result to obtain digital data, and the digital data is compressed to obtain digital transmission data, and the transmission data is and transmits discrimination information that substantially corresponds to the above discrimination result, receives these transmission data and discrimination information, expands the received transmission data, performs integration processing on the expanded data, and converts the received discrimination information into A PCM transmission system characterized in that an integral coefficient in the integral process is controlled based on the differential coefficient on the transmitting side, and the integral result is used for conversion into an analog reproduction signal. (2) Obtain linear data corresponding to the analog original signal and difference data corresponding to successive difference values of the analog original signal based on the analog original signal or a signal obtained from the analog original signal, and obtain the linear data and the difference data. Comparing and determining the data values to substantially determine whether the linear data exceeds both the predetermined value and the difference data value, and depending on the determination result, if the linear data exceeds both the above, the difference is determined. If the data is negative, obtain compressed digital transmission data that corresponds to the linear data, transmit the transmission data and discrimination information that substantially corresponds to the discrimination result, and then Receives information, expands the received transmission data, and based on the reception discrimination information, if linear data is selected on the sending side, the expanded data is left as is; if differential data is selected on the sending side, the expanded data is used as is. A PCM transmission method characterized in that the expanded data is integrated and converted into an analog playback signal. (3) a difference calculation means that calculates digital difference data corresponding to the sequential difference values of the analog original signal from the analog original signal or a signal obtained from the analog original signal, and makes the difference coefficient in the calculation variable; determination control for determining the level and frequency of the analog original signal based on the analog original signal or a signal obtained from the analog original signal, and variably controlling the difference coefficient of the difference calculation means according to the determination result; means, data compression means for compressing the output data of the difference calculation means, and transmission means for substantially transmitting the output data of the data compression means and the discrimination result of the discrimination control means to a transmission system. A PCM transmitting device characterized by: (4) Linear data detection means for obtaining linear data corresponding to the value of the analog original signal from the analog original signal or a signal obtained from the analog original signal, and from the analog original signal or the signal obtained from the analog original signal. difference detection means for obtaining difference data corresponding to the sequential difference values of the analog original signals; a discriminating means for discriminating whether or not the value exceeds the predetermined value; and a discriminating means for discriminating whether the value of the linear data is both a predetermined value and a differential value, based on the analog original signal or a signal obtained from the analog original signal, and according to the discriminating result of the discriminating means. a compressed data generating means for generating digital compressed data corresponding to differential data when the value substantially exceeds , and digital compressed data corresponding to linear data when not; and output data of the compressed data generating means and a determination result by the determination control means. 1. A PCM transmitting device comprising: transmitting means for substantially transmitting a PCM to a transmission system. (5) Transmission including transmission data consisting of digital difference data corresponding to successive difference values based on difference coefficients variably controlled according to the level and frequency of the analog original signal, and discrimination information substantially corresponding to the difference coefficients. Receive signal
In a PCM receiving device for demodulating and obtaining information corresponding to the analog original signal, there is provided a receiving means for receiving these transmission data and discrimination information from a transmission system, and an integral value of the received transmission data received by this means is calculated. and output it to the reproduction system, as well as an integral calculating means that makes the integral coefficient in the calculation variable, and an integral calculating means that corresponds to the difference coefficient on the transmitting side based on the reception discrimination information received by the receiving means. 1. A PCM receiving device comprising: coefficient control means for variably controlling an integral coefficient. (8) digital transmission data obtained by sequentially selecting one of data compressed linear data corresponding to an analog original signal and data compressed differential data corresponding to successive difference values of the analog original signal; In a PCM receiving device for receiving and demodulating a transmission signal including discrimination information substantially corresponding to whether compressed linear data or compressed differential data is being transmitted, and obtaining information corresponding to the analog original signal. , a receiving means for receiving the transmission data and discrimination information from the transmission system, a data decompression means for decompressing the received transmission data received by the means, and a transmitting side that responds to the reception discrimination information received by the receiving means. If linear data is selected on the transmitting side, the output of the data expansion means is output as is to the reproduction system, and if differential data is selected on the transmitting side, the output of the data expansion means is integrated and output to the reproduction system. What is claimed is: 1. A PCM receiving device comprising: selective integration means.