JPS5849050B2 - line correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line correction device that corrects signal distortion caused by a transmission line. The present invention relates to a line correction apparatus for use in a communication line network in which a partner station has a coexistence of apparatuses having a function of correcting signal fluctuations and apparatuses having no function of correcting signal fluctuations.

FIG. 1 is a block wiring diagram showing an example of the connection configuration of a conventional calligraphy and drawing transmission device to a communication line network. In the figure, 1 is a calligraphy and drawing transmission device, 2 is a transmission modulator of this calligraphy and drawing transmission device, and 3 is a calligraphy and drawing transmission device. The receiving demodulator 4 of the device 1 is a transmitting/receiving changeover switch that switches the receiving demodulator and the transmitting modulator 2 into a transmitting side 4a and a receiving side 4b according to transmission/reception.

The device shown in FIG. 1 is a device that allows calligraphy and drawings to be transmitted through a telephone line and at the same time allows the use of a telephone terminal by switching, and 5 is a network control device that enables half-duplex communication using the telephone line. It is.

However, even in the case of image transmission, the calling operation of dialing the destination station is performed by a telephone terminal, and when a call arrives at the called station, an automatic call detector detects the incoming call.

6 is an automatic incoming call detector of this network control device, and 1 is an incoming call connection that switches this automatic incoming call detector and the above-mentioned image transmission device 1 to the image transmission device side 7a and the automatic incoming call detector side 7b according to a signal. 8 is a telephone terminal; 9 is a telephone terminal and the above-mentioned incoming call connection switch 1 is connected to a calligraphy side 9a and a telephone side 9b according to a signal;
10 is a communication line network.

The conventional calligraphy/image transmission device is configured as described above. For example, when automatic reception of calligraphy/image transmission is performed, the transmission/reception changeover switch 4 is set to the receiving demodulator side 4b, and the incoming call connection switch 7 is set to automatically detect incoming calls. On the device side 7b, a telephone-image selection switch 9 is connected to the calligraphy side 9a.

When transmitting a calligraphy or drawing, the calling station switches the telephone one-print selection switch 9 to the telephone side 9b and calls the destination station by dialing.

At the called station, when there is an incoming call, the incoming call automatic detector 6 detects the incoming call and switches the incoming call connection switch 7 to the document/image transmission device side 7a.

After confirming this, the document/image transmission device 1 switches the transmission/reception changeover switch 4 to the transmission modulator side 4a, and transmits the called station identification signal.

This called station identification signal is a signal for informing the calling station that the called station is connected to the document/image transmission device, and is usually an audio frequency signal with a constant frequency.

After transmitting the called station identification signal for a certain period of time, the calligraphy transmission device 1
Then, the transmitter/receiver switch 4 is switched to the receiver/demodulator side 4b and waits for the next signal from the calling station.

Next, when the calling station confirms on the telephone terminal 8 that the called station identification signal has been sent, it switches the telephone one-stroke selection switch 9 to the calligraphy side 9a, and at the same time also switches the incoming call connection switch 7 to the calligraphy transmission device side. Switch to 7a.

When the callee station identification signal is confirmed, the calligraphy transmission device 1 switches the transmission changeover switch 4 to the transmission modulator side 4a, and after transmitting a test signal from the calling station side, starts transmitting the calligraphy transmission control signal.

Thereafter, both the calling station and the called station perform image transmission while controlling the transmission/reception changeover switch 4.

Calligraphy and drawings are transmitted and received through the communication line network 10 as described above, but depending on the communication line network 10, signal fluctuations may occur due to the line.

In other words, as will be explained in detail in a later section, calligraphy and drawing transmission is performed using a carrier wave phase modulation method, but the addition of phase fluctuations caused by the line and frequency fluctuations caused by the transmitter/receiver equipment tends to cause signal deterioration, which makes the transmission difficult. There was a drawback that the quality of the reproduced calligraphy and paintings deteriorated.

Furthermore, it is not economical to change the document and image transmission device itself of the terminal for correcting signal fluctuations caused by the communication line as described above, and compatibility with conventional devices is also a problem.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional technology. First, the signal fluctuations of the communication line are corrected by using a signal fluctuation correction device, and then the communication line It is an object of the present invention to provide a line correction device that can communicate with conventional devices as before by adding a function to select whether or not a person can connect to the network.

FIG. 2 is a block diagram showing one embodiment of the present invention, and numerals 1 to 10 are completely the same as the conventional device described above.

20 is a line correction device, 21 is a pilot signal oscillator that generates a pilot signal for signal fluctuation correction, 22 is an adder that mixes this pilot signal with a transmission signal, and 23 is a signal obtained by adding this pilot signal as a transmission signal (pilot A transmission signal selection switch selects either the signal addition side 23a) or the signal that is not added (pilot signal non-addition side 23b); 24 is a signal fluctuation correction device that corrects fluctuations in the received signal; 25 is a signal fluctuation correction device for correcting fluctuations in the received signal; A signal that has passed through the signal fluctuation correction device (signal fluctuation correction side 25a) or a signal that has not passed through this signal fluctuation correction device (signal fluctuation non-correction side 2)
5b) a received signal selection switch for selecting one of the following;
26 is a switch control device that controls the switching operations of the received signal selection switch and the transmission signal selection switch 22; 27 is a terminal-side hybrid circuit that branches the transmission signal;
28 is a line-side hybrid circuit that branches the received signal.

The transmission signal is transmitted from the transmission/reception changeover switch 4 to the terminal side hybrid circuit 27 to the transmission signal selection switch 23 and the adder 2.
2, supplied in parallel to the switch control device 26;

Operations related to the transmit signals supplied to the switch controller 26 will be described with reference to FIG. 3 in a later section.

In the line correction device 20 configured as described above, when performing automatic reception, when there is no communication, the transmission signal selection switch 23 is connected to the pilot signal addition side 23b1, and the reception signal selection switch 25 is connected to the signal fluctuation non-correction side 25b. .

When performing calligraphy transmission, the calligraphy transmission device 1 and the network control device 5
are connected in the same manner as in the conventional device described above.

When the called station detects an incoming call, it issues a called station identification signal using the same procedure as in the conventional device described above.

The transmission signal selection switch 23 selects the pilot signal addition side 2
3b, a pilot is always added to the transmission signal and the signal is sent from the line-side hybrid circuit 28 to the calling station.

The calling station sends the received called station identification signal to the switch control device 26 through the line-side hybrid circuit 28, and determines whether a pilot signal is included.

If a pilot signal is included, switch control device 2
6 sets the received signal selection switch 25 to the signal fluctuation correction side 25a.
If the pilot signal is not included in the called station identification signal, the switch control device 14 switches the transmission signal selection switch 23 to the pilot signal non-addition side 23a.

At this point, the switch selection of the line correction device 20 of the calling station is completed.

Subsequently, the called station identification signal is sent through the terminal-side hybrid circuit 27 to the document and image transmission device 1, and the document and image transmission device 1 transmits a test signal using the same means as the conventional device described above.

If the pilot signal is included in the called station identification signal,
Since the transmission signal selection switch 23 cannot be changed over, the pilot signal is always added to the test signal, and the test signal is sent out from the line-side hybrid circuit 28.

At the called station, the test signal passed through the line-side hybrid circuit 28 is sent to the switch control circuit 26.

If the pilot signal is included in the test signal, this indicates that the line correction device 20 is connected to both the calling station and the called station, so the received signal selection switch 2 of the called station is
5 is switched to the signal variation correction side 25a, and if the test signal does not include a pilot signal, the transmission signal selection switch 23 is switched to the pilot signal non-addition side 23a.

This completes the switch selection, and then signal communication for the document and image transmission procedure begins.

FIG. 3 is a block wiring diagram showing an example of the switch control device 26, and 23 to 25 shown as related are the second
It is exactly the same as the figure.

In the figure, reference numeral 30 denotes a called station identification signal detector I that detects a called identification signal.
A transmission signal from 7 is input.

31 is a flip-flop for selecting the transmitted signal of the called station; 32 is a delay circuit I using, for example, a monostable multi-by-break;
33 is an AND gate I, 34 is an OR gate, 35 is a pilot signal detector, and 36 is an output from a called station identification signal detector, into which the output signal from the line side hybrid circuit 28 is input.

31 is an AND gate (1), and 38 is a flip-flop for selecting a calling station transmission signal.

In the switch control device 26 configured as described above, the line correction device 20 in the calling station first receives the called station identification signal, and if the pilot signal is detected by the pilot signal detector 35, the received station Selection switch 25
is switched to the signal fluctuation correction side 25a.

When the called station identification signal detector 1136 detects the called station identification signal and determines that the own station is the calling station, the calling station transmission signal selection flip-flop 38 is reset.

Next, if the pilot signal is not included in the called station identification signal, the AND gate II 37 sets the flip-flop 38 for selecting the calling station transmission signal, and the OR gate 34 sets the transmission signal selection switch 23 to select the pilot signal. Switch to the non-addition side 23a.

The above is the switch control operation of the line correction device 20 at the calling station.

In the called station, when the called station identification signal is sent from the terminal side hybrid circuit 27 to the switch control device 26, the called station identification signal detector I30 detects it, and the line correction device 20 detects the called station identification signal. Know what to do as a side.

Subsequently, the flip-flop 31 for selecting the transmitted signal of the called station is reset, and at the same time, a detection signal is sent to the delay circuit I32.

Next, when it is detected that the pilot signal is not included in the test signal sent from the calling station, the AND gate I33 resets the called station transmission signal selection flip-flop 31, and the OR gate 34 selects the transmission signal. The selection switch 23 is switched to the pilot signal non-addition side 23a.

Delay circuit 32 delays the output after detecting the called station identification signal until such time as the test signal is expected to be received.

In addition, if a pilot signal is included in the test signal sent from the calling station, the received signal selection switch 25
is switched to the signal fluctuation correction side 25a.

The above is the switch control operation of the line correction device 20 at the called station.

As explained above, switching between the transmission signal selection switch 23 and the reception signal selection switch 25 by the switch control device 26 is performed as shown in Table 1.

FIG. 4 is a block diagram showing an example of the signal fluctuation correction device 24, and 21, 25, and 28 shown as related components are exactly the same as those shown in FIG. 2 above.

In FIG. 4, 40 is an internal oscillator for correction, 41 is a multiplier I that multiplies the output of this internal oscillator for correction and the output of the pilot signal oscillator 21, and 42 is a band that passes only one side band of the output of this multiplier I. The pass filter I, 43 is a band pass filter (2) that filters the input from the line side hybrid circuit 28, 44 is a multiplier (2), which multiplies the output of this band pass filter H by the output of the band pass filter 142, and 45 is a band pass filter (2) that filters the input from the line side hybrid circuit 28. The bandpass filter ■, 46, which passes only one side band of the output of the multiplier ■, is the line hybrid circuit 2 mentioned above.
Delay circuit ■ which delays the input of 8 for a certain period of time, 41 is a multiplier ■ which multiplies the output of this delay circuit ■ by the output of the band pass filter 45, and 48 passes only one side band of the output of this multiplier ■. The band pass filter (2), 49 multiplies this band pass filter (2) by the output of the correction internal oscillator 40. The multiplier (2), 50 is a reduced pass filter that passes only the one-sided signal/band of the output of this multiplier (2).

The operation of the signal fluctuation correction device 24 configured as described above will be described below.

First, the carrier angular frequency of the drawing transmission device 1 is ω.

It is assumed that information is transmitted by placing it on the phase of the carrier wave.

When the phase information is φ, the document and image transmission device 1 sends out a signal expressed by the following equation.

In the line correction device 20, the signals from the pilot signal oscillator 21 are added together by an adder 22.

If the angular frequency of the pilot signal is ω2, a signal expressed by the following equation is transmitted from the transmitting station.

After passing through the communication line 10, the signal received by the receiving side line correction device 20 is subject to phase fluctuations due to the line (referred to as θ) and fluctuations due to the transmitting/receiving device.

ω is the angular frequency that fluctuates depending on the transmitter and receiver.

Then, the received signal is expressed by the following equation.

On the other hand, the oscillation angular frequency ωi of the internal correction oscillator 40 is sufficiently higher than the carrier angular frequency ω (ωi>ω).

) has been selected.

The output of multiplier T41 is expressed by the following formula: Ru.

The band-pass filter I42 extracts the second term on the right side of (Equation 4), the band-pass filter 1143 extracts the second term on the right side of (Equation 3), and these two signals are multiplied by the multiplier 1144, as shown in the following equation. Become.

When the first term on the right side of (Equation 6) is extracted by the bandpass filter 135, the signal of the following equation is obtained.

On the other hand, the received signal expressed by (Equation 3) is processed by the delay circuit 46 as (
After being delayed by a time equal to the delay time required to obtain the signal 26), it is sent to the multiplier 147.

In the multiplier [47, the signal expressed by (Equation 3) and (26
) is performed.

The second term on the right side of (Equation 8) is extracted by bandpass filter IV48 to obtain the following equation.

The output of the correction internal oscillator 40 and (Formula 9
) is multiplied by the signal represented by the following equation.

Since ωi>ω0, if the first term on the right side of the above equation is extracted using the low-pass filter 50, a signal having the same information as the transmission signal in (Equation 1) can be extracted.

In the above embodiment, the line correction device 20 is placed between the document and image transmission device 1 and the network control device 5, but the line correction device 2
0 can also be placed between the network control device 5 and the communication line network 10.

Further, the line correction device 20 can be expected to perform similar operations not only for the document and drawing transmission device 1 but also for synchronous information transmission devices such as data communication devices and image communication devices.

Further, regarding the communication line network 10, similar operation can be expected not only for telephone line networks but also for data communication networks and leased line communication networks.

As explained above, by having the function of adding a pilot signal and correcting signal fluctuations, this invention increases the accuracy of communication information and is compatible with conventional communication line networks. This has the effect that it is sufficient to add an additional person to the line.

[Brief explanation of the drawing]

Fig. 1 is a block wiring diagram showing an example of the connection configuration of a conventional document and image transmission device to a communication line network, Fig. 2 is a block wiring diagram showing an embodiment of the present invention, and Fig. 3 is the constituent elements of the present invention. FIG. 4 is a block wiring diagram showing an embodiment of a switch control device which is a component of the present invention. FIG. In the figure, 1 is a document transmission device, 5 is a network control device, and 10 is a
2 is a communication line network, 20 is a line correction device, 21 is a pilot signal oscillator, 22 is an adder, 23 is a transmission signal selection switch, 24 is a signal fluctuation correction device, 25 is a reception signal selection switch, 26 is a switch control device, 27 9 is a hybrid circuit on the terminal side, and 28 is a hybrid circuit on the line side. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. In a line correction device connected to a communication device that transmits and receives signals through a communication line network, a pilot signal oscillator that generates a pilot signal, an adder that mixes this pilot signal with a transmission signal, and a communication device from a partner station a switch control device that determines whether or not a pilot signal is included in the received signal and controls switching of the transmitted and received signals based on the determination result;
A transmission signal selection switch that is controlled by this switch control device and switches between sending the above-mentioned adder output signal as a transmission signal or sending a signal that is not mixed with the pilot signal, and corrects signal fluctuations in the received signal from the other station. a received signal selection switch controlled by the switch control device to select between using the output signal of the signal fluctuation correcting device as the received signal or using a signal that does not pass through the signal fluctuation correcting device; A line correction device comprising a connection circuit for the communication line network side and the communication device side. 2 The connection circuit includes a terminal-side hybrid circuit provided on the communication device side and a line-side hybrid circuit provided on the communication line network side, and can be connected to either the transmitter or receiver by simply inserting it into a half-duplex line. 2. The line correction device according to claim 1, wherein the line correction device automatically determines whether to perform the operation.