JP2002344513A - Digital communication system receiver, computer program therefor and record medium recording the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital receiver which does not generate noises even when it receives a packet containing uncorrectable error data. SOLUTION: In a digital communication system which sequentially transmits digital data by a packet, a receiver 1 comprises data converting means 12, 14, 15 and an error detection means 13. When the error detection means 13 has detected that the packet at a certain point of time is an unnecessary packet containing the digital data having an error, the data converting means 12, 14, 15 analog-convert the digital data of the packet received just before the unnecessary packet in place of the digital packet of the unnecessary packet, or output a signal obtained by analog-converting the digital data of the packet received just before the unnecessary packet in place of a signal obtained by analog- converting the digital data of the unnecessary packet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus optimal for a digital communication system for transmitting an original analog signal such as an audio signal in a digital format, a computer program therefor, and a recording medium recording the same.

[0002]

2. Description of the Related Art When an analog signal such as voice is transmitted in a digital format, an error may occur in data on a communication channel. When such data is received and reproduced, annoying noise is output. I will. To prevent this,
Conventionally, the receiving side is provided with an error correction and error detection function. However, when an error of a correctable level or more occurs, there is a problem that noise is still output. These problems can be improved by adopting advanced error correction technology, but for that purpose, data must be added for error correction, which increases the data amount and complicates the complicated processing involved. The problem of need arises.

On the other hand, in digital communication, a packet communication system for dividing data into packets in a predetermined unit and transmitting the divided data is generally used. In this system, basically, in order to process data in packet units, packets having the same destination address are sequentially received and arranged, and after performing processing for reproducing the original digital data, the data is converted to analog data. It needs to be converted to a format and played.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed to solve such a problem, and the present invention generates noise even when a packet containing digital data that cannot be corrected is received. It is an object of the present invention to provide a receiving device that does not have the above, a computer program and a recording medium therefor.

[0005]

To achieve the above object, according to the present invention, there is provided a receiving apparatus in a digital communication system for sequentially transmitting digital data obtained by digitizing an analog signal by a packet, Error detection means for detecting whether there is an error in the digital data contained in the packet, and when the error detection means does not detect an error in the data contained in the packet, while converting the data contained in the packet to analog, When the error detecting means detects that the packet at a certain time is an unnecessary packet including digital data having an error, instead of the digital data of the unnecessary packet, the packet received immediately before the unnecessary packet is replaced with the digital data of the unnecessary packet. Data conversion means for converting digital data into analog data. That the receiving device, to provide.

In order to achieve the above object, a second aspect of the present invention is a receiving apparatus in a digital communication system for sequentially transmitting digital data obtained by digitizing an analog signal by packets, which is included in the packets. Error detecting means for detecting whether or not there is an error in the digital data; and when the error detecting means does not detect an error in the data contained in the packet, the data contained in the packet is converted into an analog signal. When it is detected that the packet at a certain time is an unnecessary packet including digital data having an error,
Data conversion means for outputting a signal obtained by converting the digital data of the packet received immediately before the unnecessary packet into an analog signal instead of a signal obtained by converting the digital data of the unnecessary packet into analog data. A receiving device is provided.

According to a third aspect of the present invention, the error detecting means includes:
When detecting that the packet contains digital data having a correctable error, a means for performing error correction processing on the digital data is provided.

The invention according to a fourth aspect is characterized in that the data conversion means performs a process for generating a discontinuous point when performing a process of replacing the digital data of the unnecessary packet.

According to a fifth aspect of the present invention, in the receiving apparatus according to any one of the first to fourth aspects, the digital communication system includes a communication mode requiring real-time processing.

According to a sixth aspect of the present invention, a computer used for a receiving device in a digital communication system for sequentially transmitting digital data obtained by digitizing an analog signal in packets by using a packet determines whether or not the digital data included in the packet contains an error. Error detection means for detecting
When the error detecting means does not detect an error in the data included in the packet, the data included in the packet is converted into an analog signal, and the error detecting means determines that the packet at a certain point in time contains digital data having an error. When detecting that the packet is a packet, instead of the digital data of the unnecessary packet, a program that causes the digital data of the packet received immediately before the unnecessary packet to be converted into an analog signal. provide.

According to a seventh aspect of the present invention, a computer used in a receiving apparatus in a digital communication system for sequentially transmitting digital data obtained by digitizing an analog signal by packets is used to determine whether there is an error in the digital data contained in the packets. Error detection means for detecting
When the error detecting means does not detect an error in the data included in the packet, the data included in the packet is converted into an analog signal, and the error detecting means determines that the packet at a certain point in time contains digital data having an error. When detecting that the packet is a packet, data for outputting a signal obtained by converting the digital data of the packet received immediately before the unnecessary packet into analog instead of the signal obtained by converting the digital data of the unnecessary packet into analog. A program characterized in that it functions as a conversion unit.

[0012] The invention according to claim 8 is characterized in that the data conversion means performs a process for generating a discontinuous point when performing a process of replacing the digital data of the unnecessary packet.

A ninth aspect of the present invention is the program according to any one of the sixth to eighth aspects, wherein the digital communication system includes a communication mode that requires real-time processing.

According to a tenth aspect of the present invention, there is provided a computer-readable recording medium storing the above-mentioned program.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and operation of one embodiment of a digital communication receiving apparatus according to the present invention will be described below. FIG. 1 is a diagram showing a basic configuration of one embodiment of a digital communication receiving apparatus according to the present invention. In the figure, a transmitting side digitizes an analog audio signal, converts the digital signal into a packet, and sequentially transmits the packet to a receiving side. The receiving apparatus 1 that receives a packet transmitted from the transmitting side wirelessly or via a wire includes a receiving unit 11, a data processing unit 12, an error detecting unit 13, a memory 14,
An analog (D / A) converter 15. Hereinafter, an outline of the operation of the receiving device 1 will be described.

The receiving section 11 takes out a packet containing the address of the receiving apparatus 1 in a header portion from a transmission line (not shown), reproduces a packet sequence in which the taken out packets are arranged in a correct order, and outputs it. The packet sequence reproduced by the receiving unit 11 is transmitted to the data processing unit 12 and the error detecting unit 13.
Sent to Therefore, the data processing unit 12 creates digital data from the received packet sequence, performs error correction as needed, and writes the output to the D / A conversion unit 15. Further, the error detection unit 13 determines whether or not there is an error in the data of each packet in the packet sequence output from the reception unit 11 and notifies the digital processing unit 12 of the determination result.

The memory 14 operates to receive a packet from the receiving unit 11, store the packet for a time corresponding to one packet length, and then read out the packet to the data processing unit 12. The digital data output from the data processing unit 12 is converted into an analog signal by the D / A conversion unit 15 and provided to the outside as an output of the receiving device 1.

With such a configuration, the receiving apparatus 1 shown in FIG.
When the error detection unit 13 detects that the received packet contains an error, the error detection unit 13 performs analog conversion using the digital data of the packet received immediately before, instead of the digital data of the packet. This can prevent packets containing errors from being reproduced,
Generation of noise is prevented. At this time, the data processing unit 1
2 preferably processes packet data used in place of an error-containing packet so that a discontinuous portion does not occur in an analog signal reproduced from the receiving device 1.

Hereinafter, the receiving apparatus 1 will be described with reference to FIGS.
Will be described in detail for the case where a packet received at a certain point in time is reproduced as an analog signal two packet times later. Here, the k-th packet is referred to as a packet (k). First, on the transmitting side, an audio signal having an analog waveform shown in FIG. 2A is digitized. Here, data obtained by analog / digital conversion of the parts A, B and C obtained by dividing the original sound by vertical lines are sequentially transmitted from the transmitting side to the receiving apparatus 1 by packet (n), packet (n + 1), and packet (n + 2). Suppose you came.

At a certain time t, the packet (n) is
, The packet (n) is confirmed to be error-free by the error detection unit 13, and the packet (n) is stored in the memory 14. Therefore, at that time t
At time point t + 1 one packet time after
1, when the receiving unit 11 receives the packet (n + 1), the received packet (n + 1) is
2 and the error detection unit 13, and the error detection unit 13 checks in step 22 whether the data of the packet (n + 1) includes an error. As a result of the inspection, when the error detection unit 13 determines that the packet (n + 1) does not include an error, the determination result is notified to the data processing unit 12. In response to this, the data processing unit 12
4, the data of the packet (n) is read out and written to the D / A conversion unit 15, and the packet (n +
The data of 1) is stored (step 23).

Next, at time t + 2, which is one packet time later than time t + 1, the receiving unit 11 sends the packet (n +
2) (step 24), the error detection unit 13 determines whether there is an error in the data of the packet (n + 2). When it is determined that the data does not have an error, the error detection unit 13 sends the determination result to the data processing unit 12 Notify to In response to this, the data processing unit 12 reads the data of the packet (n + 1) from the memory 14, writes the data of the packet (n + 2) to the D / A conversion unit 15, and writes the data of the packet (n + 2) to the memory 14 (step 25). In parallel with this, the D / A converter 15
Converts the data of the packet (n) into an analog signal and reproduces it.

Thereafter, at time t + 3, which is one packet time later than time t + 2, the receiving unit 11 receives the packet (n + 3) in step 26, and thereafter, similarly, an uncorrectable error is detected in the data of the received packet. When there is no data, the data of the packet one packet time earlier is read out from the memory 14 and written into the D / A converter 15, and is reproduced as an analog audio signal one packet later.

However, when it is determined in step 22 that there is an error in the data of the packet (n + 1), in step 27, the error detecting unit 13 sets the packet (n + 1)
It is determined whether or not the data can be reproduced as correct data, that is, whether or not error correction is possible. As a result of the determination in step 27, when the error detection unit 13 determines that error correction is possible, in step 28, the error detection unit 13 corrects an error in the data of the packet (n + 1). Therefore, the data processing unit 12 determines in step 23 that the memory 1
4, the packet (n) is read out and written to the D / A converter 15, and the error-corrected packet (n + 1) is read out.
Is written into the memory 14. Hereafter, as explained above,
Steps 24, 25 and 26 are performed.

However, when the error detector 13 determines that the data of the packet (n + 1) received at time t + 1 is uncorrectable (step 27), the data processor 12 includes an error in step 29. The data of the missing packet (n) is read out from the memory 14 and D / A
The data is written into the conversion unit 15, and then, at step 30, the reception unit 11 receives the packet (n + 2) at time t + 2.

The packet (n +) received at time t + 2
When the error detection unit 13 determines that the data in 2) has no error, the data processing unit 12 replaces the data of the packet (n + 1) in the memory 14 with the data of the packet (n) in step 31. At this time, if the data is simply replaced, as shown in FIG.
Discontinuities 2 ₁ and 2 ₂ occur in the output from the A conversion unit 15 and noise occurs. Therefore, the data processing unit 12
When replacing the data of the packet (n + 1) with the data of the packet (n), an analog waveform having no discontinuity as shown in (c) of FIG. Process the data and use the processed data in step 3
In 2, the packet (n + 2) is written to the memory 14 while writing to the D / A converter 15. In parallel with this, the D / A converter 15 converts the data of the packet (n) written in step 29 into an analog signal.

At the next time point t + 3, the receiving unit 11 receives the packet (n + 3) (step 33), and when the error detecting unit 13 determines that the data of the packet (n + 3) has no error, the data processing unit 12 The data of the packet (n + 2) is read from 14 and written into the D / A converter 15. In parallel with this, the written packet (n +
The data of 2) is reproduced at time t + 3. Since then
Operations similar to those described in steps 21 to 33 are repeated.

The data processing unit 12 which performs the above-described operation
The error detection unit 13 can be easily realized by appropriately programming a commonly used microcomputer, and it is not necessary to prepare special hardware.

As described above, one embodiment of the digital voice communication receiver according to the present invention has been described, but the present invention is not limited to such an embodiment. For example,
In the description so far, the data processing unit 12 has the error detection unit 1
3, the digital data of the packet containing the error is replaced with the digital data of the packet containing no error. Instead of the replacement in the digital domain, the output from the D / A converter 15 is performed. The analog signal to be performed may be replaced.

Further, the present invention is suitable for application to a communication mode such as voice transmission or moving image transmission which requires chapter reception of data without delay, that is, a communication mode which requires real-time processing. is there. Among them, it is suitable to be applied to a communication mode in which an error easily occurs during transmission, such as wireless communication.

In addition, in the above embodiment, as shown in step 28 of FIG. 3, if an error contained in the packet data can be corrected, error correction is performed. Thus, since the error detection unit 13 performs only error detection and does not perform error correction, the cost of the receiving apparatus can be reduced.

[0031]

As can be understood from the above description of one embodiment of the digital communication receiving apparatus according to the present invention, the present invention has the following advantages. (2) Even if the state of the communication path is bad and the packets cannot be error-corrected continuously, the receiving apparatus only remains silent. It does not generate harsh noise, and (3) is particularly suitable for communication requiring real-time processing, particularly, a communication mode in which an error is likely to occur during transmission, such as wireless communication.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing one embodiment of a receiving apparatus for a digital voice communication system according to the present invention.

2A is a diagram illustrating packets sequentially received by a receiving unit 11 in FIG. 1; FIGS. 2B and 2C are diagrams illustrating analog signals output from a D / A converting unit 15 in FIG. 1; It is a figure which shows a signal waveform, (b) is a waveform which has a discontinuous part, (c)
Indicates a smoothly connected waveform.

FIG. 3 is a flowchart showing a packet processing procedure in the receiving device 1 of FIG. 1;

Continued on front page F-term (reference) 5K014 AA01 BA05 EA00 FA00 FA06 HA05 5K030 GA04 GA18 HA08 HB01 HB12 KA19 MB04 5K034 AA10 AA18 BB06 CC05 FF13 HH01 HH02 HH09 HH62

Claims (10)

[Claims] 1. A receiving apparatus in a digital communication system for sequentially transmitting digital data obtained by digitizing an analog signal in packets by an error detecting means for detecting whether or not an error exists in digital data included in the packet. When the error detecting means does not detect an error in the data included in the packet, the data included in the packet is converted into an analog signal, and the error detecting means includes digital data in which the packet at a certain time has an error. A data conversion unit for converting, when detecting that the packet is an unnecessary packet, the digital data of the packet received immediately before the unnecessary packet, in place of the digital data of the unnecessary packet, into analog conversion. apparatus. 2. A receiving apparatus in a digital communication system for sequentially transmitting digital data obtained by digitizing an analog signal by packets in an error detecting means for detecting whether or not digital data included in the packets has an error. When the error detecting means does not detect an error in the data included in the packet, the data included in the packet is converted to analog, and the error detecting means converts the digital data in which the packet at a certain point has an error. When it is detected that the unnecessary packet includes unnecessary packets, a signal obtained by converting the digital data of the packet received immediately before the unnecessary packet into analog is output instead of the signal obtained by converting the digital data of the unnecessary packet into analog. And a data conversion unit that performs the conversion. 3. The receiving apparatus according to claim 1, wherein the error detection unit detects an error in the digital data when the error detection unit detects that the packet includes digital data having a correctable error. Receiving means for performing the following. 4. The method according to claim 1, wherein said data converting means performs processing for generating a discontinuous point when performing processing for replacing digital data of said unnecessary packet.
3. The receiving device according to any one of 3. 5. The digital communication system includes a communication mode requiring real-time processing,
The receiving device according to claim 1. 6. A computer for use in a receiving apparatus in a digital communication system for sequentially transmitting digital data obtained by digitizing an analog signal by packets in an error detection method for detecting whether or not digital data included in the packets has an error. Means for converting the data contained in the packet to analog when the error detecting means does not detect an error in the data contained in the packet; When detecting that the packet is an unnecessary packet including data, in place of the digital data of the unnecessary packet, a function of converting the digital data of the packet received immediately before the unnecessary packet into analog data is provided. Program to do. 7. A computer for use in a receiving apparatus in a digital communication system for sequentially transmitting digital data obtained by digitizing an analog signal in packets by using a computer to detect whether or not an error exists in digital data included in the packet. Means for converting the data contained in the packet to analog when the error detecting means does not detect an error in the data contained in the packet; When an unnecessary packet including data is detected, a signal obtained by converting the digital data of the packet received immediately before the unnecessary packet into an analog signal instead of the signal obtained by converting the digital data of the unnecessary packet into analog is used. Function as data conversion means for outputting Program characterized. 8. The reception according to claim 6, wherein the data conversion unit performs a process for generating a discontinuous point when performing a process of replacing the digital data of the unnecessary packet. apparatus. 9. The receiving device according to claim 6, wherein the digital communication system includes a communication mode requiring real-time processing. 10. A computer-readable recording medium in which the program according to claim 6 is recorded.