JPS58171158A - Transmitting system of data - Google Patents

Abstract

PURPOSE:To set up and release fall back operation automatically by turning the self-station to fall back status, informing the status to an opposite station and turning the opposite station also to the fall back status at the detection of deterioration of an error rate. CONSTITUTION:A digital signal is encoded by an encoder 1 and converted into an analog signal by a D/A converter 2. In the D/A converter 2, a value to be inputted is changed by the output of a level discriminator 25 for a subpilot signal from the opposite station. The output of the D/A converter 2 modulates carrier, and after adding a subpilot signal to the output, it is transmitted to the opposite station. The level of the subpilot signal is controlled by an error detector 15 in the self-station. A receiving signal from the opposite station is returned to a base band by a demodulator 10 and a digital signal is reproduced by an A/D converter 13 and a decoder 14. The A/D converter 13 is controlled by the output of the error detector 15.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention detects an error rate in a transmission path, automatically puts a transmitter and a receiver in a fallback state based on the detection result, and then releases the fallback state. The present invention relates to a data transmission method that can perform the following operations.

(Problems with the prior art) Using a modem, the transmitting side creates a multi-level analog signal from the digital signals of multiple channels, converts it into a modulated signal and sends it out, and the receiving side demodulates and reproduces it to produce a 9-level analog signal. In a transmission path for a communication system that decodes multiple channels of digital signals from analog signals, the state of the transmission path (SA
) deteriorates and the error rate deteriorates, a so-called fallback method is used to increase the S tolerance by reducing the number of channels of the digital signal to be transmitted and therefore the number of levels of the analog multilevel signal. Often used. Conventionally, fallbacks in transmitting and receiving devices have been implemented by detecting the deterioration of the error rate using a false error detector, displaying the detection result as an alarm, and visually checking this display to communicate with the game manually. In the past, operations were carried out by putting the system into a fallback state through manual operations, and when restoring the system, the same manual operations were used to restore the system.

FIG. 1 shows the configuration of a transmitter and a receiver in a conventional data transmission system. In the figure, 1 is an encoder, 2 is a digital-to-analog (D/A) converter, 3 is a low-pass p-wave converter, 4 is a modulator, 5 is an oscillator for generating signals, and 6 is a bandpass filter. 7 is a manual switch, and 8 is a fallback switch, which constitute a transmitter. Further, 9 is a band transducer, 10 is a demodulator, and 11 is a pilot signal extractor.

■ is a low-pass filter, 13 is an anaseg digital (A/D
) converter, 14 a decoder, 2 an error detector, 16 an alarm indicator, 17 a manual switch, and 18 a fallback switch, which form a receiving device.

Now, an explanation will be given of the operation when the transmitting apparatuses indicated by numbers 1 to 8 in FIG. 1 are on the transmitting side, and the receiving apparatuses indicated by numbers 9 to 18 are on the receiving side (playing game).

In a state where fallback is not performed, the binary digital signals of the three channels CH, -CH are input to the encoder 1 and encoded into an 8-value digital signal. The digital signal of 8[ is applied to the Meimu converter 2 and
The signal is converted into an analog signal of a value, and a baseband signal is extracted through a low-frequency wave transducer 3. The baseband signal is applied to the modulator 4, which modulates the carrier input from the oscillator 5 to generate a modulated wave signal.

The modulated wave signal is added with a carrier pilot signal, passes through a bandpass filter 6, and is sent to the opposing station as one channel of a frequency division multiplexed (FDM) signal.

On the receiving side, a signal of a desired channel is extracted from the input FDM signal through a band V wave generator 9 and applied to a demodulator 10. On the other hand, the pilot signal extractor 11 is a bandpass filter 9
A carrier is extracted from the output signal of and input to the demodulator IO. The demodulator 10 uses this carrier to convert the band F wave unit 9
demodulates the input signal from The demodulated signal is passed through a low-pass filter 12
The baseband signal is extracted. The extracted baseband signal is an 8-value analog signal.
The signal is added to the v'o converter 13 and converted into an 8-value digital signal. The 8-level digital signal is applied to a decoder 14 to generate 3-channel binary digital signals CH, ~C.
H, is decoded. The error detector 15 monitors the error rate in the binary digital signal of the decoder 14 and generates an alarm signal when the error rate becomes less than a predetermined value, and the alarm indicator 16 receives the alarm signal. At 9 o'clock, a predetermined warning display will be made.

Visually check the alarm display to prevent errors in the transmission line]
When it becomes clear that the rate has deteriorated, the receiving side manually contacts the game via another transmission line or other communication means such as a telephone, and both the sending and receiving sides operate manual switches 7.17. to operate the fallback switches 8 and 18, respectively. As a result, a fallback is performed, and on the transmitting side, only the digital signal of 2 channels CH, CH2 is encoded and transmitted as a 4-level analog signal, and on the receiving side, the resulting 4-level analog signal is demodulated. The digital signals of two channels CIh and C12 are decoded. When fallback is performed in this way, in the upper case, changing from an 8-value signal to a 4-value signal improves the Fi6 dB in the transmission path, thus preventing deterioration of the error rate. .

FIG. 2 shows signals of various parts in a conventional data transmission system. In the figure, (&) indicates the D/A converter output signal when there is no fallback, and it shows that an 8-value analog signal is generated corresponding to the 8-value digital signal 000 to 111 from the encoder. ing. This signal indicates that the timing pilot signal P becomes a rectangular tear volume with a constant period within the D/A converter. φ
) indicates the D/A converter output signal when there is a fallback, and the four-value digital signal from the encoder is 00 to 11.
It is shown that 41 analog signals are generated corresponding to . The superimposition of the timing pilot signal P in this case is the same as in the case without fallback.

(e) shows the spectrum of the FDM signal and each pilot signal. In the figure, an A IIi FDM signal is shown, B is a carrier pilot signal added in the modulator, and C is a timing pilot signal.

As described above, in conventional data transmission systems, fallback operations and recovery are performed manually based on warning displays indicating deterioration of the false alarm rate in the transmission path. Therefore, not only is it necessary to constantly monitor the alarm display, communicate with the game, and operate the fallback, but it also takes time to perform the fallback operation when an alarm occurs, and furthermore, Another means of communication had to be prepared for communication.

(Object of the Invention) The present invention is intended to solve the problems of the prior art, and its purpose is to generate an alarm signal when deterioration of the error rate in the transmission path is detected. By using this signal, the receiving device of the own station is switched to the fallback state, and the level of the pilot signal in the transmitting device of the own station is changed, thereby switching the transmitting device of the opposing station to the fallback state. Therefore, it is an object of the present invention to provide a system that allows a fallback operation to be automatically performed in a short time when an alarm occurs, and that does not require a separate communication means for the fall pack operation.

(Embodiment of the Invention) FIG. 3 shows the configuration of an embodiment of the data transmission system of the present invention. In this figure, the same parts as in Figure 1 are designated by the same numbers, and their operations are also similar. 21 is a coupler, n is an oscillator for generating a sub-pilot signal, and n is a level controller for controlling the signal level in the oscillator section, which are already explained in FIG. 1 and indicated by numbers 1 to 6 and 8. The transmitting device is configured together with the other parts. Mafc24 is a bandpass filter for extracting a sub-pilot signal, and Kuzu is a level determiner for determining the level of the extracted sub-pilot signal. The components already explained in FIG. 1 constitute a c#C receiving device. The transmitting device and receiving device in the wc3 diagram indicate the configuration of the same terminal station,
It is assumed that the game has exactly the same configuration.

In the state in which fallback is not performed in Fig. 3, the binary digital signals of the three channels cH1 to cH5 are converted from the eight-value analog signal through the encoder 1 = D/A converter 2 and low-pass filter 3. The modulator converts it into a baseband signal! generate a modulated wave signal at i;
The modulated wave signal is applied to the coupler 21, and the level of the sub-pilot signal is maintained at a constant level under the control of the level controller 23 when there is no fallback. The modulated wave signal to which the sub-pilot signal has been combined is sent to the opposing station via the band-pass transducer 6.

On the other hand, F containing the sub-pilot signal transmitted from the opposing station
The DM signal is applied to a demodulator 1o via a band V-wave unit 9, where it is demodulated, passed through a low-band F-wave unit ν, where it is converted into a baseband signal, and further passed through a KA/I) converter 13. 3 via decoder 14
The binary digital signals of channels CH, to cH3 are decoded. At this time, a sub-pilot signal is extracted from the FDM signal through a band pass filter 9, and is added to a level determiner to determine its level. If the level of the sub-pilot signal is normal, the level determiner will not generate an output.

Further, the error detector detects the error rate in the decoded output signal of the decoder 14, but does not generate an alarm signal when the error rate is less than a certain value.

Now, when the FDM signal sent from the game has deteriorated and the error rate of the decoded output signal of the decoder 14 exceeds a certain value, the error detector 15 generates an alarm signal and displays an alarm on the alarm indicator 16. At the same time, the 1 fallback switch 18 is operated. Fallback switch 18 controls v1 converter 13 to put it into a fallback state. Further, the alarm signal of the false alarm detector 15 is applied to the level controller section, which thereby changes the sub-pilot signal level of the oscillator n to a constant value indicating fallback. Game JC1? The level determiner detects a change in the sub-pilot signal level, generates an output from the level determiner section, operates the fallback switch on the transmitting side, and puts the D/A converter in the fallback state. As a result of this, the transmission path including the game transmitting device and the own station receiving device when transmitting from the game player enters a fallback state.

In addition, when a decrease in the error rate is detected in the opposing station and the receiving device is put into a fallback state, the sub-pilot signal in the FDM signal sent out is changed to a level indicating the fallback state. The level determination device detects h, generates an output, operates the fallback switch 8, and puts the D/A converter 2 in the fallback state. In this way, when transmitting from the local station, the transmission path including the local station transmitting device and the opposing station transmitting device enters a fallback state.

FIG. 4 shows the configuration of another embodiment of the data transmission system of the present invention. The embodiment of FIG. 4 differs from the embodiment shown in FIG. 3 in that coupler 211 oscillator n.

It lacks a level controller, a bandpass filter, and a level determiner 5, while a level controller 26 for the timing pilot signal. A bandpass filter extracts the timing pilot signal and a level determiner determines the level of the timing pilot signal.

In the embodiment shown in FIG. 4, when the false alarm detector 15 detects a deterioration of the false alarm rate in the own station, the fallback switch 18 is operated to put the receiving device in the fallback state, and the level controller 26 and D/
The level of the timing pilot signal added by the A converter 2 is changed from a normal state to a level indicating a fallback state, and an FDM signal is sent out. On the other hand, a timing pilot signal is extracted from the FDM signal that has passed through the band p wave generator 9 by a bandpass filter n, and its level is determined by a level judger. When the level changes from to a level indicating a fallback state, the level determiner generates an output signal, operates the fallback switch 8, and puts the transmitter in the fallback state.

In this way, in the case of the embodiment shown in FIG. 4 as well, when the error rate in the received signal of the local station is reduced, the receiving device of the local station is placed in the fallback state, and the timing pilot signal level of the transmitting device of the local station is changed. By changing the timing pilot level of the opposing station and placing the transmission device of the own station in the fallback state when the timing pilot level of the opposing station changes, it is possible to put the mutual transmission paths in the fallback state.

FIG. 5 shows the spectrum of the FDM signal and each pilot signal in the data transmission system of the present invention shown in FIGS. 3 and 4. In the same figure, A is an FDM signal,
B is a carrier pilot signal, which is the same as in FIG. cA and cB represent timing pilot signals, and as in the embodiment shown in FIG. 4, the levels thereof are changed, for example, between a normal state (CA) and a fallback state (CB). Furthermore, Dm and DB indicate sub-pilot signals, and as in the embodiment shown in FIG. There is.

(Effects of the Invention) As explained above, according to the data transmission system of the present invention, when deterioration of the error rate in the transmission path is detected, the receiving device of the own station is placed in a fallback state, and the change in the pilot signal level is By notifying the game player, detecting this in the game game, and putting the game transmitter in a fallback state, it is possible to automatically perform a fallback operation in a short time when the error rate deteriorates in the transmission path. This is advantageous because the fallback can be automatically canceled when the traffic rate improves, and no communication means is required at this time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a transmitting device and a receiving device in a conventional data transmission system, FIG. 2 is an explanatory diagram showing signals of each part in a conventional data transmission system, and FIGS. 3 and 4 are respectively in accordance with the present invention. FIG. 5 is an explanatory diagram showing the spectrum of the F'DM signal and each pilot signal in the data transmission method of the present invention. 1... Encoder, 2... Digital analog (D/A
) converter, 3... low-pass p-wave converter, 4... modulator, 5.
...Carrier oscillator, 6... Bandwidth transducer, 7... Manual switch, 8... Fallback switch, 9...
- Bandpass filter, lO... demodulator, 11... bimit signal extractor, n... low frequency wave filter, 13... analog digital (A/D) converter, 14... decoding vessel, 1
5... False detector, 16... Alarm indicator, 17...
・Manual switch, 18...Fallback switch,
21...Coupler, n...Sub-pilot oscillator, vane...Level fltlJll device, 24...Band pass filter, device...Level judger, 26...Level controller, γ・... Bandpass filter, Z... Level judger. Patent Applicant: Fujitsu Limited Representative Patent Attorney Hisashi Tamamushi Department 5 (3 others) 1st
Figure transmission use flower arranging diagram 3

Claims (1)

[Claims] In a data transmission system, the transmitting end encodes a multi-channel digital signal, converts it into a multi-value analog signal, sends it out to the transmission path, and the receiving end decodes the multi-value analog signal into a multi-channel digital signal. means for setting the receiving device at the local station to a fallback state and changing the pilot signal level added to the transmitted signal in the transmitting device at the local station when a deterioration in the error rate is detected; and a means for setting the receiving device of its own station to a fallback state when detected, and transmitting signals with both transmitting and receiving ends in a fallback state according to the error rate of the transmission path.
't is a data transmission method characterized by canceling a fallback state.