JPH11266229A - Data transmission equipment using spread spectrum communication - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Even if the error rate in the transmission path from the area where the required reception electric field is obtained to the vicinity of the use limit fluctuates, the image can be transmitted with an image corresponding to the change, and the use limit Provided is a data transmission device based on the SS communication method, which can be used stably even in the vicinity of a limit value. SOLUTION: This is a transmission device of a spread spectrum communication system for transmitting an image and a sound, and a measuring means (10, 1) for measuring a transmission state of a sound on a transmission path in real time.
1, 26, 27) and control means (8, 24) for controlling the image transmission state according to the situation when the sound transmission state measured by the measuring means deteriorates. is there.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission apparatus, and more particularly to a data transmission apparatus using a spread spectrum communication method applicable to transmission of images and sounds.

[0002]

2. Description of the Related Art As is well known, a spread spectrum communication system (hereinafter referred to as an SS communication system) differs from a conventional system in which communication is performed by a single signal modulation system in that a wireless transmission carrier is spread within a certain band. Since this is a digital transmission method, the error rate during playback of the received carrier is retransmitted and transmitted to the other party.The error rate in this case is the error rate of the entire carrier. It needs to be communicated or controlled with correlation.

The SS communication system is a system resistant to interference, and is a communication system that has recently attracted attention.

[0004]

However, it is a well-known fact that a data transmission device based on any communication method, for example, a wireless device, has a use limit before a radio wave reaches a limit. Below, how the user is notified of the limit has been reached, and at the same time, how the system will maintain its performance under these limit conditions will lead to a level evaluation as a product. FIG. 6 is an explanatory diagram showing the relationship between the reception electric field strength and the error rate of the analog radio and the digital radio. It is clear that the error rate of the communication electric field limit value of D is sharply reduced and becomes unusable compared to the analog radio A, and the SS communication method is also digital transmission, so that the above problem is included. I have.

The present invention solves the above-mentioned conventional problems. Even if an error rate in a transmission path from an area where a required reception electric field is obtained to a vicinity of a use limit fluctuates, the error rate is adjusted. It is an object of the present invention to provide a data transmission device based on the SS communication method, which can transmit an image in an image and can be used stably even at a limit value near a use limit.

[0006]

According to the present invention, there is provided a data transmission apparatus using an SS communication system, comprising: a measuring unit for measuring a voice transmission state in a transmission path in real time; and a voice transmission state measured by the measurement unit deteriorating. Then, there is provided control means for controlling the transmission state of the image according to the worsening situation.

According to the present invention, the image can be transmitted in an image corresponding to the fluctuation of the error rate in the transmission path, and even if the error rate is deteriorated, the image is not disturbed or the data cannot be transmitted. It is possible to prevent the received image on the receiving side from being interrupted, and to ensure the quality of the system.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The technical background of the present invention is as follows.

In general, when an image and a sound are transmitted simultaneously by a data transmission device based on the SS communication system, the data amount of the sound and the data amount of the image are different from each other in basic signal amount. The voice communication data is about 700 kbit. Here, assuming that the reception electric field is reduced and the error rate is deteriorated, an image having a large data amount is affected first in the process,
When the electric field strength of the audio signal is deteriorated, the error rate as data can always be maintained higher than the image signal from the data amount. Therefore, the error rate of the image can be predicted based on the error rate of the audio data, and even if the image cannot be communicated, the communication of the audio can be secured. Therefore, the control of the image communication can be performed from the audio data. The invention is based on this point.

Next, control of image communication using audio data will be described in more detail with reference to the drawings. FIG. 2 is an explanatory view showing a model of an error rate at the time of transmitting an image and a sound in a data transmission device based on the SS communication system, which is an object of the present invention. As is apparent from FIG. The voice signal error curve E _{1 with} respect to the received electric field can be sufficiently corrected for a voice having a very small volume.
The error rate shown in is always in good condition, it is possible to construct a system for controlling while watching the change in error rate of the image signal error curve E ₂ as an image the error rate monitor E. By controlling the frame rate of the image based on the change in the error rate of the audio based on the result of this monitoring, it is possible to narrow the band of the image data and reduce the error rate.

FIG. 3 is an explanatory view showing a model of a transmission band and an error rate in a data transmission device based on the SS communication system according to the present invention. FIG. is an explanatory view showing a model of an image frame rate and the error rate of the transmission due to low narrower the error rate, the in transmission band even lower reception field E _L even higher received field E _H 3, 4 When the error rate is getting worse like this, the image may change from a moving image to a still image state by narrowing the image data transmission band by lowering the image transmission frame rate according to the error rate prediction based on the audio data. Communication can be secured.

Here, the speech has a redundancy check (Cyclic
A redundancy check (hereinafter referred to as CRC) signal is superimposed to monitor the error rate at the electric field level. However, the error rate may be monitored by superimposing not only the CRC signal but also a signal in a unique format. The detection by the exemplified CRC signal is described in H.264. According to the error detection method according to the 223C international standard, 4-bit CRC X ⁴ + X ³ + X ² +1 12-bit CRC X ¹² + X ¹¹ + X ³ + X ² +1 20-bit CRC X ²⁰ + X ¹⁹ + X ⁶ + X ⁵ + X ³ +1 The error rate at the electric field level is detected from the voice by such an error detection method to change the frame rate of the image.

As described above, the frame rate is changed while estimating the error rate of an image based on a check signal such as a CRC signal. This estimation is performed as follows. Figure 5 is an explanatory diagram of the case where the electric field change in the data transmission device according to SS communication system to which the present invention to predict the rough error rate, real-time data D _R estimated prediction data level of the received electric field from give D _F, by which to vary equal, the intra-refresh period of the image processing to fix the image frame to a still image state when predicting a rapidly changing deeply as change points D _P of the data, the error rate , The transmission of image data is prioritized, and measures are taken to ensure the quality of the system.

The present invention has been made based on the above background, and an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of a data transmission apparatus using an SS communication system according to the present invention. In the figure, reference numeral 1 denotes an upper station for performing mutual communication, 2 denotes an antenna, and 3 denotes data transmission / reception. , A transmission / reception data multiplexing / demultiplexing unit, 5 a CRC adding unit, 6 a voice coding unit, 7 a voice input unit, 8
Is a video encoding unit, 9 is a video input unit, 10 is a CRC error rate calculation unit, 11 is a CRC error detection unit, 12 is an audio decoding unit, 13 is an audio output unit, 14 is a microphone, 15 is a camera, and 16 is It is a speaker. Reference numeral 17 denotes a lower station that performs bidirectional communication with the upper station 1, 18 denotes an antenna, 19 denotes an RF modem unit for transmitting and receiving data, 20 denotes a multiplexing / demultiplexing unit for transmitted / received data, 21 denotes a CRC adding unit, and 22 denotes a voice code. Kabe,
23 is an audio amplifier, 24 is a video decoder, 25 is a video output unit, 26 is a CRC error rate calculator, 27 is a CRC error detector, 28 is an audio decoder, 29 is an audio output unit, 3
0 is a microphone, 31 is a monitor, and 32 is a speaker.

Next, the operation will be described. First, the signal received by the antenna 2 is input to the RF modem unit 3 to control the transmission and reception of the SS signal, and the multiplexing / separating unit 4 separates the transmitted video / audio from the received video / audio. The error rate is detected by the CRC error detection unit 11 from the signal from the lower station 17, and when the error rate increases, the audio signal decoded by the audio decoding unit 12 is muted based on the CRC error detection data. The operation is performed, and a frame rate is instructed for the image based on the error rate detected by the CRC error rate calculator 10 as shown in FIG. With this instruction, when the error rate changes from a good state to a bad state,
The mode of the image processing data changes so that the image changes to a moving image, dropped frames, and still. A camera 15 is connected to the video encoding unit 8 as an external input, and encodes a video signal from the camera. At this time, based on error data from the CRC error rate calculation unit 10, control of the frame rate of the image is performed in the same manner as described above. I do. The coded data is converted into SS data by the multiplexing / demultiplexing unit 4 and transmitted from the RF modem unit.

An audio signal from the microphone 14 is encoded by an audio encoding unit 6, a CRC signal is added by a CRC adding unit 5, input to a multiplexing / demultiplexing unit 4 and multiplexed with the video signal, and is It is transmitted from the unit 3. C to be added to audio
The RC signal is received by the lower station 17, and the lower station 17 detects the error rate and uses it for applications such as a mute operation and an error rate display.

The radio signal transmitted from the upper station 1 is received by the antenna 18 of the lower station 17, input to the RF modem section 19, and separated into video data and audio data by the multiplexing / demultiplexing section 20. The audio is input to the audio decoding unit 28 and output from the speaker 32 via the audio output unit 29 as an audio signal. On the other hand, the audio mute operation is performed based on the error data of the audio signal input to the CRC error detection unit 27, and if the error rate increases, the audio notifying that the error rate has increased based on the data. Generate a signal or the like. The image data separated by the multiplexing / demultiplexing unit 20 is reproduced into a video signal by the video decoding unit 24, amplified by the video output unit 25, and reproduced as an image on the monitor 31. Based on the data from the CRC error detection unit 27 and the CRC error rate calculation unit 26, when the error rate increases, a display is provided on the monitor 31 to notify that the reception level has decreased and the image rate has decreased. The voice from the lower station 17 is input to the microphone 30 and amplified by the voice amplifying unit 23, converted into voice data by the voice coding unit 22, added with the CRC signal by the CRC adding unit 21, and added by the multiplexing / demultiplexing unit 20. The signal is converted into the SS transmission mode and transmitted, and the host station 1 receives it.

As described above, according to the present embodiment, when the transmission state of the transmission path deteriorates, the image may change from a moving image to a still image, but the image may be disturbed or data may not be transmitted. It is possible to prevent the received image on the receiving side from being interrupted and to ensure the quality of the system. In this case, the deterioration of the transmission line error rate is displayed on the image monitor to prevent the user from judging that the image changes from a moving image to a still image or the frame rate drops as other failures for the user. By doing so, the user can know that the change in the image frame is not a failure but that the system is working properly, and can also know the limit of use because the electric field strength is reduced. This notification can be given by voice, a simple signal sound, or voice by voice synthesis. Since such notification is performed on the receiving side, the transmitting side may not know what the receiving side looks like, but this problem is solved by sending the receiving state of the receiving side to the transmitting side. . Further, if the error rate becomes higher, the audio data itself cannot be communicated. Therefore, at that limit, the limit of communication incompatibility can be known by judging audio muting from the check signalized data.

[0019]

As described above, according to the present invention, even if the error rate in the transmission path fluctuates, it can be transmitted with an image corresponding to the fluctuation, and the error rate is degraded. In addition, there is an advantageous effect that it is possible to prevent the image from being disturbed or to interrupt the received image on the receiving side due to the failure to transmit data, thereby ensuring the quality of the system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a data transmission device using an SS communication system according to the present invention;

FIG. 2 is an explanatory diagram showing a model of an error rate at the time of transmitting an image and a sound in a data transmission device based on the SS communication method according to the present invention;

FIG. 3 is an explanatory diagram showing a model of a transmission band and an error rate in a data transmission device based on the SS communication method which is an object of the present invention.

FIG. 4 is an explanatory diagram showing a model of an image frame rate and an error rate of image transmission in a data transmission device based on the SS communication method according to the present invention;

FIG. 5 is an explanatory diagram of a case in which a rough error rate is predicted from a change in an electric field in a data transmission device based on the SS communication system according to the present invention;

FIG. 6 is an explanatory diagram showing a relationship between a received electric field strength and an error rate of an analog wireless device and a digital wireless device.

[Explanation of symbols]

 Reference Signs List 1 upper station 2, 18 antenna 3, 19 RF modem unit 4, 20 multiplexing / demultiplexing unit 5, 21 CRC adding unit 6, 22 audio encoding unit 7 audio input unit 8 video encoding unit 9 video input unit 10, 26 CRC Error rate calculation unit 11, 27 CRC error detection unit 12, 28 Audio decoding unit 13, 29 Audio output unit 14, 30 Microphone 15 Camera 16, 32 Speaker 17 Lower station 23 Audio amplification unit 24 Video decoding unit 25 Video output unit 31 monitor

Continuation of the front page (72) Inventor Masahiro Nomoto 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Matsushita Communication Industrial Co., Ltd.

Claims (11)

[Claims] 1. A transmission apparatus of a spread spectrum communication system for transmitting an image and a sound, comprising: a measuring unit for measuring a transmission state of the sound in a transmission path in real time; and a transmission state of the sound measured by the measuring unit. When it gets worse,
A data transmission apparatus using a spread spectrum communication system, comprising: a control unit that controls a transmission state of an image in accordance with the worsening situation. 2. A transmission apparatus of a spread spectrum communication system for transmitting an image and a voice, wherein a transmission side adds a check signal for judging an error rate to voice encoded data, and the reception side detects the check signal. Measuring means for measuring an error rate of data in a transmission path, and control means for controlling a transmission state of image transmission by the check signal in accordance with the error rate measured by the measuring means. A data transmission device using spread spectrum communication. 3. The frame rate control according to claim 1, wherein the control means performs a frame rate control to convert the image into a still image when the error rate is determined to be bad by the check signal and to convert the image into a moving image when the error rate is improved. 2. A data transmission apparatus according to the spread spectrum communication method described in 2. 4. The control means performs control to fix the image to a still image when the error rate is predicted by the check signal to be poor and the improvement cannot be expected or is predicted to worsen. A data transmission apparatus according to the spread spectrum communication method according to claim 2. 5. A transmission apparatus of a spread spectrum communication system for transmitting an image and a voice, wherein a transmission side adds a check signal for judging an error rate to voice encoded data, and the reception side detects the check signal. Measuring means for measuring an error rate of data, and changing an intra-refresh cycle of image processing while estimating the error rate by the check signal, thereby transmitting image data even if the error rate in the transmission path is deteriorated. A data transmission apparatus using a spread spectrum communication system, comprising: 6. A transmission apparatus of a spread spectrum communication system for transmitting an image and a voice, wherein a transmission side adds a check signal for judging an error rate to voice encoded data, and the reception side detects the check signal. Measuring means for measuring the error rate of data in the transmission path, and predicting the error rate in the future by the check signal,
A data transmission apparatus using a spread spectrum communication method, comprising: means for determining a frame rate of an image that can be transmitted based on the prediction, and changing a mode of the image processing data in advance so as to adapt to the frame rate. 7. The data transmission apparatus according to claim 6, further comprising means for displaying data of an error rate and a frame rate of a transmission path based on the check signal on an image monitor. 8. The apparatus according to claim 6, further comprising means for notifying a communication state of the transmission path by an audio signal from a device on the receiving side when an error rate of the transmission path based on the check signal is significantly deteriorated. A data transmission device according to the spread spectrum communication method described in the above. 9. An error rate when the error rate of the transmission path based on the check signal deteriorates and the image or audio signal transmitted by the other party is no longer reproduced is detected, and the error rate of the transmission path is determined by the detected error. 7. The data transmission apparatus according to claim 6, further comprising means for notifying the other party when the rate is reached. 10. The data transmission according to the spread spectrum communication method according to claim 6, further comprising means for operating the audio mute of the receiving-side device in accordance with the error rate of the transmission path based on the check signal. apparatus. 11. The data transmission apparatus according to claim 2, wherein the check signal is a CRC signal.