JPS6053937B2 - Signal relay transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for relaying and transmitting data signals sent and received using an analog transmission system and control signals using various frequencies using a digital transmission line.

300Hz to 3.4KHz as a data communication system
Currently, systems using analog transmission lines for the purpose of transmitting broadband audio signals are widely used.

2. Description of the Related Art In data communications using analog transmission lines such as telephone lines, various control signals are used to reliably transmit and receive target data signals. There are two methods: one uses logical binary information as a control signal, and the other uses various frequencies as a control signal, such as in a 6-minute or 3-minute machine of a facsimile terminal. As an example of the latter, 3
At the facsimile terminal of the splitter, the image signal as a data signal is AM-PM-■S using a carrier frequency of 2100Hz.
It is transmitted using B method, but the control signal is 462Hz,
1100Hz, 1300Hz, 1650Hz, 1850
Frequencies such as Hz are used, and control information is exchanged between terminals using these frequencies and their durations. Now, generally speaking, when a telephone line is used as an analog transmission line,
It is well known that when the distance between terminals is long and the communication time is long, such as with facsimile terminals in 3-minute or 6-minute mode, the charges for the relay network become very expensive.
As a means of economically providing communication between data terminals such as facsimile terminals with the above characteristics, digital transmission lines, which are relatively cheaper than analog transmission lines, are used as relay transmission lines, and analog transmission lines and digital A method has already been proposed in which a storage/product conversion device is introduced between the transmission line and the transmission line.

An example of such a conventional method will be described below. FIG. 1 shows that an analog transmission line 3 and a storage/conversion device digital transmission line 5 are connected between a transmitting terminal 1 and a receiving terminal 2. The storage conversion device 4 is a storage device 6
, a central processing unit 7, a terminal interface device 8, a trunk line interface device 9, and an input/output control device 10. In the figure, the terminals are classified into transmitting terminals and receiving terminals, but this is for explanation and the same terminal may switch from transmitting to receiving mode or from receiving to transmitting mode.

Next, communication between facsimile terminals using the system shown in FIG. 1 will be described as an example. However, the transmitting terminal 1 is assumed to be a transmitter of a facsimile terminal, and the receiving terminal 2 is assumed to be a receiver of a facsimile terminal. In the storage/conversion device 4 that accommodates the analog transmission line 3 to which the transmitting terminal 1 is connected, the central processing unit 7 sequentially controls the terminal interface device 8 via the input/output control device 10, thereby providing various control functions. The sending terminal 1 is notified of the completion of image signal reception preparation by a procedure using frequencies. Thereafter, the transmitting terminal 1 sends the image signal to the storage/conversion device 4 using the analog transmission line 3 using a predetermined modulation method. The image signal on the analog transmission line 3 is sampled into a binary digital signal by the terminal interface device 8,
Generally, a redundant signal included in a facsimile image signal is subjected to suppression processing and then stored in the storage device 6. When the central processing unit 7 receives all the image signals from the transmitting terminal 1, it issues a command to the terminal interface device 8 to transmit the corresponding frequency in order to notify the transmitting terminal 1 of the control frequency that indicates completion of image signal reception. After the redundancy suppression process has been applied, the image signals stored in the storage device 6 are sent via the input/output control device 10 and the relay line interface device 9 to the digital transmission line 5 as a relay line under the control of the central processing unit 7. and sent to the storage/conversion device 4 on the side where the receiving terminal 2 is accommodated.

In general, a high-speed digital line of about 48 Kb/s is used in a system using a storage/conversion device in order to efficiently transfer image signals from a large number of terminals. Now, on the side of the storage/conversion device 4 that accommodates the receiving terminal 2, the redundancy suppressed image signal from the digital transmission line 5 is sent to the relay line interface device 9, input/output, under the control of the central processing unit 7. It is stored in the storage device 6 via the control device 10. Thereafter, the central processing unit 7 starts up the receiving terminal 2 by monitoring and controlling the terminal interface device 8 that accommodates the analog transmission line 3 to which the receiving terminal 2 is connected, and also performs various control operations from the receiving terminal 2. The frequency is monitored to detect whether the receiving terminal 2 is ready to receive the image signal. Thereafter, the redundancy suppressed image signals in the storage device 6 are sequentially transferred to the terminal interface device 8 via the input/output control device 10. Terminal interface device 8
adds a redundancy signal to the redundancy suppressed image signal sent from the central processing unit 7 side to return it to the original image signal, and then
The image signal is placed on the analog transmission line 3 based on a predetermined carrier frequency and modulation method, and is sent to the receiving terminal 2. After completing the predetermined full-picture signal processing, the storage/conversion device 4 also performs frequency detection processing corresponding to the confirmation control signal in order to monitor whether the receiving terminal has normally received the picture signal. In terminal communication using the storage/conversion method described above with a configuration example and its operation, the target data signal from the perspective of the transmitting terminal is stored in the storage device in the storage/conversion device and then transferred. In addition to the disadvantage that it is not immediately clear whether or not the delivery is being delivered to the receiving terminal, it generally requires a large amount of hardware, such as a storage device, a central processing unit, a terminal interface device, and an interface circuit for a high-speed trunk line. It also has the disadvantage that it requires a winter program to control the system and a high-speed digital relay line, making the system uneconomical unless it accommodates a large number of terminals.

The purpose of the present invention is to solve the above-mentioned drawbacks associated with the storage/conversion method, and to solve the above-mentioned drawbacks associated with the storage/conversion method. A digital transmission line with a speed that does not cause quality deterioration due to data signal transmission is used for the relay line, and when various control frequencies are being detected on the analog transmission line, codes corresponding to each frequency are sent to the digital transmission line. and the receiving side of the digital transmission line. The system is characterized in that while the identification flag bit indicates that it is a control signal, the corresponding frequency is generated in accordance with the contents of the code and sent to the analog transmission line,
The purpose is to economically provide data communications using various frequencies as control signals on a real-time basis, at a standard level, and economically.

The present invention will be explained in detail below using the figures. FIG. 2 shows an example of a communication system embodying the present invention, focusing on the transmission of data signals and control signals from the transmitting terminal 1 to the receiving terminal 2.

Of the line connection devices that connect the analog transmission line 3 and the digital transmission line 5 used as a relay line, the transmission terminal 1
A reception control device 20 accommodating the analog transmission line 3 to which the 2
Demodulation sampling circuit 2 for sampling into a value digital data signal
1. Frequency detection and identification circuit 22 that detects and identifies various frequencies transmitted on analog transmission lines as control signals for transmitting data signals, and outputs predetermined signals corresponding to each frequency during detection; While there is a control signal encoding circuit 23 that generates a binary code for identifying the output signals from the circuit 22, and an output signal from the demodulation sampling circuit 21 or the control signal encoding circuit 23, Consists of an identification flag generation circuit 24 that generates flag bits for identifying them, sends the binary signal output from each circuit to the digital transmission line 5, and also constantly generates synchronization bits necessary for the digital synchronous transmission system. be done. On the other hand, among the line connection devices, the transmission control device 25 that accommodates the analog transmission line 3 to which the receiving terminal 2 is connected synchronizes from the binary digital information sent from the digital transmission line 5 as a relay line. By extracting the used bits, a synchronization relationship in the transmission method is established, and the identification flag generation circuit 24 of the reception control device 20 identifies the inserted flag bits to determine whether the transmitted information is a general data signal. If it is a data signal, it activates the digital-to-analog conversion circuit 27 described below and passes the received digital signal, and if it is a control signal, it is sent to the control signal decoding circuit 28, which will also be described later. An identification flag detection control circuit 2 having functions such as activating the system and passing the received binary digital code.
6. Digital-to-analog conversion circuit 27 that sends the digital signal to the analog transmission line 3 to which the receiving terminal 2 is connected using a predetermined carrier frequency and modulation method, and creates a predetermined frequency generation signal from the code indicating the control signal. and a control signal decoding circuit 2 that starts a control frequency generation circuit 29, which will be described later.
8, and a control frequency generation circuit 29 that generates a control frequency.

Note that the control frequency generation circuit 29 is prepared for the required control frequencies. On the other hand, FIG. 3 shows an example of a transmission format on a digital transmission line.

This example uses an octet structure, and shows two octets of a continuous bit group. Among these, Fl
, F2, etc. are bits for octet synchronous transmission, and a pattern such as 1010... is used, for example. On the other hand, Cl, C2, etc. are identification flag bits, and the subsequent 6-bit signals (S1-1 to S1-6, S2-1 to S2
-6, etc.) is used to display whether the content is a data signal or a control signal. As mentioned above, F
1, Cl, F2, C2, etc. are generated by the identification flag generation circuit 24 and removed after identification processing by the identification flag detection control circuit 26. Furthermore, signal bits S1-1 to S1-6, S2-
In the case of general data, 6 bits such as 1 and S2-6 are created by the demodulation sampling circuit 21, and are transmitted to the digital-to-analog conversion circuit 27 after passing through each of the above-mentioned circuits, and in the case of control signals. is created by the control signal encoding circuit 23 and transmitted to the control signal decoding circuit 28 after passing through each circuit. Next, the operation will be described with attention to the flow of control signals and data signals from the transmitting terminal 1 to the receiving terminal 2 using FIGS. 2 and 3.

First, a predetermined frequency for a control signal is created by the transmitting terminal 1 and sent to the receiving control device 20 on the analog transmission line 3. In this case, when the frequency detection and identification circuit 22 in the reception control device 20 detects the corresponding control signal frequency, it connects the signal line to the control signal encoding circuit 23 that has been allocated in advance corresponding to that frequency to "゜1". , and maintains this state during detection. In this state, the control signal encoding circuit 23 converts the binary digital code ( (in this embodiment, within 6 bits), starts the identification flag generation circuit 24, and supplies the created digital code.When the identification flag generation circuit 24 receives activation from the control signal encoding circuit 23, Cl,C2 shown in
For example, the identification flag bits such as
6, place it on positions such as S2-1 to S2-6. That is, while detecting the control signal frequency from the transmitting terminal 1, the reception control device 20 sends a code corresponding to the frequency and a flag bit indicating the control signal to the digital transmission line 5. On the other hand, on the transmission control device 25 side, the identification flag detection control circuit 26 always maintains octet synchronization as shown in FIG.
, C2, etc., and monitor the identification flag bits such as ゜゜1.
In the case of ', the control signal decoding circuit 8 is activated and the subsequent bits such as S1-1 to S1-6 and S2-1 to S2-6 are delivered.

When the control signal decoding circuit 28 is activated, it sequentially decodes the transferred signals S1-1 to S1-6, S2-1 to S2-6, etc., and based on the output results, the control signal decoding circuit 28 decodes the received signals S1-1 to S1-6, S2-1 to S2-6, etc. in advance. This state is maintained as long as the promised predetermined control frequency generation circuit 29 is activated and the decoded output result remains the same. When the control frequency generating circuit 29 receives activation, it generates a predetermined control signal frequency assigned to each circuit, sends it to the analog transmission line 3 to which the receiving terminal 2 is connected, and while receiving activation, the control frequency generating circuit 29 generates a predetermined control signal frequency assigned to each circuit. Continue transmitting frequencies. As can be seen from the above description, the control signal frequency sent from the transmitting terminal 1 is relayed to the receiving terminal 2 on an instant basis. Next, the flow of data signals will be explained.

Data from the transmitting terminal 1 is sent to the reception control device 20 using the analog transmission line 3 based on a predetermined carrier frequency and modulation method.
will be sent to. In this case, the demodulation/sampling circuit 21 activates the identification flag generation circuit 24, demodulates the modulated data signal, samples it, converts it into a binary digital signal, and delivers it. During this state, the identification flag generation circuit 24 sets the identification flag bits such as Cl, C2, etc. in FIG. Sequentially S1-1~
The signals are placed in positions such as S1-6, S2-1 to S2-6, and sent out to the digital transmission line 5. Correspondingly, the identification flag detection control circuit 26 of the transmission control device 25 activates the digital-to-analog conversion circuit 27 when the identification flag bits such as Cl, C2, etc. in each quintet are 6'0 bits. The transmitted bits of S1-1 to S1-6, S2-1 to S2-6, etc. are delivered sequentially. When the digital transmission line-to-analog conversion circuit 27 receives activation from the identification flag detection circuit 26, it receives signals S1-1 to S1-6, S2-1 to S
An original signal waveform is created from a binary digital signal such as 2-6, and this signal is sent to a receiving terminal using a predetermined carrier wave and modulation method. 2 is connected to the analog transmission line 3. That is, as for data signals, similarly to the transmission of control signals, data signals from the transmitting terminal 1 are transmitted to the receiving terminal 2 on an immediate basis. Here, in this embodiment, the speed of the digital transmission line as a relay line between the reception control device 20 as a line connection device and the transmission control device 25 will be described using a three-minute facsimile terminal as an example.

The maximum image signal frequency to be transmitted by an analog scanning 3-minute facsimile terminal is approximately 2.5 KHz, and when a telephone line is used as an analog transmission line, the frequency ranges from 300 Hz to 3.5 KHz.
One channel of 4KHz band is required. However, in the case of facsimile communication, if the signal is sampled at about three times the maximum image signal frequency or more, transmitted, and reproduced, no deterioration in image quality will occur. Therefore, the speed of the digital transmission line is 12
．． If approximately 8 Kb/s is used, the sampling rate in this embodiment is 9.6 Kb/s, which is 3.0 Kb/s of the highest image signal frequency.
84 times can be secured, and image quality deterioration due to relay transmission does not occur. On the other hand, in order to transmit the signal within one channel of a telephone line as it is using a digital transmission line, 64Kb/s is used.
lines are required.

Therefore, if the relay line speed is set to 12.8 Kb/s as in this embodiment, a signal path for communication between facsimile terminals for five lines will be provided within one telephone channel using a 64 Kb/s digital transmission line. be able to. For ease of explanation, the flow of signals is limited to the direction from the sending terminal to the receiving terminal, but if signals in the opposite direction are used together in data communication, a line connection that combines a receiving control circuit and a sending control circuit is used. The device may be configured and the relay transmission line may be a full-duplex line.

Further, in the above description of the embodiment of the present invention, signals between the transmitting terminal and the receiving terminal are directly communicated between the terminals via the line connection device.

However, when data signals are transmitted over analog transmission lines, the carrier frequency may be the same as that for control signals. When such terminal-to-terminal communication is carried out using a line connection device, signals other than control signals, such as data Signals or voice signals, control signals that indicate the transition from communication using link back tones, ringing tones, and busy tones to communication using control signals in telephone exchange lines.For example, monitoring a specific frequency that is predefined as a communication start signal. A control signal communication start confirmation circuit for monitoring and confirming the start of communication, and a control signal communication end signal indicating the end of communication using the control signal, which is also predefined, for example, a control signal communication end signal for monitoring and confirming a specific frequency. Just add a confirmation circuit. In this case, the control signal communication start confirmation circuit connects the analog transmission line 3 to the frequency detection identification circuit 2 at the time when the predetermined frequency signal is detected.
Connect to 2.

Thereafter, when the control signal communication end confirmation circuit detects a predetermined frequency indicating the end of communication using the control signal, the analog transmission line is transferred from the frequency detection identification circuit 22 to the demodulation sampling circuit 2.
Switch to side 1. By using such a circuit, data communication according to the invention becomes even more reliable. As explained above, the present invention employs a method in which various control signals and data signals exchanged between terminals are detected and encoded, and then immediately relayed and reproduced and transmitted. Therefore, the terminal side can communicate on an instant basis. In addition, the line connection device can be configured with a circuit with a small amount of hardware, and there is no need to use a high-speed line for the relay transmission line, so there are advantages such as the ability to configure an economical communication system.

j Note that in the present invention, an example is shown in which various frequency detections are used as control signals, but since communication on an instantaneous basis is possible, it is also possible to relay ordinary audio signals in a similar manner.

In this case, an audio-to-digital conversion circuit and a digital-to-audio conversion circuit may be added.

[Brief explanation of the drawing]

Fig. 1 is a connection block diagram of a conventional communication system using a storage/conversion device, Fig. 2 is a connection block diagram of a communication system showing an embodiment of the present invention, and Fig. 3 is a connection block diagram of a conventional communication system using a storage/conversion device. This is an example of a wire transmission format. 1... Sending terminal, 2... Receiving terminal, 3
...Analog transmission line, 4...Storage and conversion device, 5...Digital transmission line, 6...
...Storage device, 7...Central processing unit, 8...
...Terminal interface device, 9...Relay line interface device, 10...Input/output control device, 20...Reception control device, 21...Demodulation sampling Circuit, 22... Frequency detection identification circuit, 23
... Control signal encoding circuit, 24 ... Identification flag generation circuit, 25 ... Transmission control device, 26 ...
... Identification flag detection control circuit, 27 ... Digital-to-analog conversion circuit, 28 ... Control signal decoding circuit, 29 ... Control frequency generation circuit.

Claims (1)

[Claims] 1. An identification flag generation circuit that identifies a control signal and a data signal on an analog transmission line and generates flag bits corresponding to each, and an identification flag generation circuit that detects the control signal on the analog transmission line and controls the signal. A frequency detection identification circuit and a control signal encoding circuit that generate a binary signal according to the type of signal, and a demodulation sampling circuit that demodulates and samples a data signal on an analog transmission line to generate a binary signal. a reception control device having;
an identification flag detection control circuit that identifies flag bits on a digital transmission line and separates the transmitted signal into a binary signal corresponding to a control signal and a binary signal corresponding to a data signal; A transmission control comprising a control signal decoding circuit and a control frequency generation circuit that reproduce a control signal from a corresponding binary signal, and a digital-to-analog conversion circuit that reproduces a data signal from a binary signal corresponding to the data signal. 1. A signal relay transmission system, comprising: a device for relaying information transmitted in an analog transmission system using a digital transmission line, and then reproducing the information in the original analog transmission system on an instantaneous basis. . 2. An identification flag generation circuit that identifies control signals and data signals on an analog transmission line and generates flag bits corresponding to each; A frequency detection identification circuit and a control signal encoding circuit that generate binary signals; a demodulation sampling circuit that demodulates and samples data signals on an analog transmission line to generate a binary signal; a control signal communication start confirmation circuit that detects a control signal communication start signal and connects the analog transmission line to the frequency detection identification circuit; and a control signal communication start confirmation circuit that detects a control signal communication end signal on the analog transmission line and connects the analog transmission line to the frequency detection identification circuit. A reception control circuit having a control signal communication end confirmation circuit for switching from the identification circuit to the demodulation sampling circuit, and a reception control circuit that identifies the flag bit on the digital transmission line and converts the transmitted signal into a binary signal and data corresponding to the control signal. an identification flag detection control circuit that separates the signal into a binary signal corresponding to the control signal; a control signal decoding circuit and control frequency generation circuit that reproduces the control signal from the binary signal corresponding to the control signal; and the data signal. a transmission control device having a digital-to-analog conversion circuit for reproducing a data signal from a binary signal corresponding to A signal relay transmission method characterized by reproducing information from an analog transmission method on an instantaneous basis.