JPH06326735A - Modem with eye pattern signal monitor function and transmission system utilizing it - Google Patents

Abstract

PURPOSE:To monitor the demodulation state or line quality without use of a device such as an oscilloscope or a measurement device for line noise. CONSTITUTION:An eye pattern signal monitor function block 23 applies rotation/ parallel movement to an eye pattern signal outputted from a MODEM section 21, normalize the signal and calculates number of times of the variance of the phase and amplitude exceeding or less than a predetermined threshold level or the like and calculates line quality information representing the quality of line. A monitor control section 24 analyzes the line quality information outputted from the eye pattern monitor function block 23 and sends the result of analysis to an information collection distribution device 16 via a serial interface section 25 and displays the line quality information onto a display section 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modem device having a line status monitoring function and a transmission system using the modem device.

[0002]

2. Description of the Related Art A modem device has a function of converting data to be transmitted into a signal suitable for a band of a transmission line and transmitting the signal, and demodulating a received signal to reproduce the original data. It is used as a modulator / demodulator for data transmission between a host computer and a host computer, or between terminal devices. The modem device adds phase modulation, frequency modulation, etc. to the data to be transmitted and sends it to the transmission line.

Conventionally, there is a modem device provided with an output terminal for a demodulated signal (eye pattern signal) in order to monitor the demodulation state of a modem, and an oscilloscope or the like is connected to the output terminal to observe the eye pattern signal. I was checking the demodulation status of the modem.

[0004]

However, in the above-described modem device having an output terminal for the eye pattern signal, it is necessary to connect a waveform observing device such as an oscilloscope to the output terminal to observe the signal waveform. It was not possible to confirm the demodulation state with. In addition, as a matter of course, when a plurality of modems are connected to the network, the demodulation states of the plurality of modem devices cannot be collectively monitored.

Further, conventionally, in order to monitor the line state of the analog line to which the modem is connected, it is necessary to connect a measuring instrument for quantitatively measuring the line noise to the output terminal of the modem for measurement. It was not possible to monitor the condition of the line without measuring equipment.

An object of the present invention is to provide a modem device capable of monitoring the demodulation state and the line quality without using an oscilloscope or a line noise measuring device. Another object of the present invention is to provide a transmission system capable of comprehensively monitoring the demodulation states of a plurality of modem devices and the quality of the line to which each modem device is connected.

[0007]

FIG. 1A is an explanatory view of the principle of the first invention, and FIG. 1B is an explanatory view of the principle of the second invention.
FIG. 2 is an explanatory view of the principle of the third invention.

In a modem device which receives and demodulates a signal sent to an analog line to reproduce the original data and modulates data to be sent and sends it to the analog line,
Coordinate conversion means 1 of the modem device of the first invention (FIG. 1 (A))
In the reference), the coordinate data of the demodulated signal on the two-dimensional plane is rotated or translated and converted into coordinate data of a predetermined reference coordinate system.

The signal quality information calculating means 2 calculates line quality information indicating the line quality from the coordinate data converted by the coordinate converting means 1. The display means 3 displays the line quality information.

The modem device according to the second aspect of the present invention includes, in addition to the coordinate conversion means 1 and the line quality information calculation means 2, an output means 4 (FIG. 1B) for outputting the calculated line quality information to the outside.
See).

The transmission system of the third invention is the second system.
Of the present invention, and a network monitoring device 5 (see FIG. 2) that collects line quality information output from each modem device and monitors the line status of the entire network. ing.

[0012]

In the modem apparatus according to the first aspect of the invention, when the received signal is 4-phase PSK modulated, the coordinate data of each quadrant from the first quadrant to the fourth quadrant of the eye pattern signal is X,
Convert to coordinate data centered on the origin of the Y coordinate. By this coordinate conversion, the amplitude and phase error data of the eye pattern signal can be obtained directly from the coordinate data, so the line quality information indicating the line quality of the analog line through which the signal is transmitted is calculated from this coordinate data and the line quality information is displayed. To do.

Thus, the demodulation state or line quality of the modem device can be confirmed without connecting an oscilloscope or a line noise measuring device to the modem device. Further, in this case, since the amplitude and phase error components of the eye pattern signal are directly obtained by performing the coordinate conversion,
The processing can be simplified by obtaining the amplitude and phase errors.

Further, according to the second aspect of the present invention, by providing the line quality information output means, the line quality can be observed without using a dedicated measuring device. Furthermore, in the third invention, the network monitoring device 5 can determine the line quality of the entire network by collecting the line quality information of each modem.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a system configuration diagram of a transmission system in which a plurality of eye pattern signal monitoring function-equipped modem devices (hereinafter referred to as modems) according to the present invention are connected.

In the figure, the terminal devices 11a to 11c are connected to the host computer 15 via analog lines 13a to 13c, respectively.
13a to 13c are connected to the modems (MD) 12a to 12c with the eye pattern signal monitoring function according to the present invention, and the host computer 15 is also connected with the modems 14a to 14c with the eye pattern signal monitoring function. There is.

Further, the modems 14a to 14c are connected to an information collecting / distributing device 16 for sequentially designating the modems 14a to 14c and collecting the respective line quality information,
The line quality information collected by the information collecting / distributing device 16 is sent to the network monitoring dedicated device 17, and the network monitoring dedicated device 17 causes each of the analog lines 13a to 13c.
The line status of is monitored.

For example, the information collecting / distributing device 1 at regular intervals.
6 sequentially designates the modems 14a to 14c to instruct transmission of the line quality information, the designated modem 14i (14a
14c) outputs line quality information to the information collecting / distributing device 16 transmitted from its own device or a modem 11i on the terminal side (a modem on the terminal side corresponding to 14i) connected by an analog line.

The information collecting / distributing device 16 includes each modem 14a.
14c to collect the line quality information and send it to the network monitoring dedicated device 17. The network monitoring dedicated device 17 includes the modems 12a to 12c and 14a to 14c.
Based on the line quality information of c, the line state of the entire network is monitored to determine whether there is a fault.

Next, the configuration of the modem of the embodiment will be described with reference to the block diagram of FIG. In the figure, the modem unit 2
Reference numeral 1 includes an A / D conversion circuit, a demodulation circuit, etc., and outputs a demodulated signal (this is called an eye pattern signal) to an eye pattern signal monitoring function block.

Eye pattern signal monitoring function block 23
Calculates the number of times the phase variance and the amplitude value exceed or fall below a predetermined threshold value, the sum of the amplitude and phase powers, etc. by rotating, translating and normalizing the eye pattern signal output from the modem unit 21. Is performed to calculate line quality information including phase jitter indicating line quality, gain hit, gain drop, S / N, and the like.

The monitor control unit 24 analyzes the line quality information output from the eye pattern monitoring function block 23 to monitor the status of the main channel and DTE (host or terminal), and the analysis result is sent via the serial interface unit 25. And sends it to the information collecting and distributing device 16. Further, the monitor control unit 24 displays the line quality information output from the eye pattern signal monitoring function block 23 on the display unit 26 including a liquid crystal display or the like.

Backward channel modem unit 22
Collects information while demodulating the control information sent from the modem on the terminal side via the control channel (backward channel) and outputting the demodulated control information to the serial interface unit 25 having an interface function with the information collecting / distributing device 16. The control information sent from the distribution device 16 is modulated and output to the control channel.

In this embodiment, the line quality information is displayed on the display unit 26 of each modem. However, when the line quality information of each modem is managed by the information collecting / distributing device 16, the individual modems can be controlled. It is not necessary to provide a line quality information display function in.

Next, the eye pattern monitoring function block 23
The contents of the signal processing performed in step S1 will be described with reference to the flowchart of FIG. First, from the coordinate data on the two-dimensional plane corresponding to the eye pattern signal output from the modem unit 21 in step S1 of FIG.
It is determined which symbol (signal point) of the modulation method applied to the received signal corresponds to the eye pattern signal, and folding is performed on the X axis and the Y axis based on the determination result. For example,
When the eye pattern signal output from the modem unit 21 is a signal corresponding to the signal point in the third quadrant, the two-dimensional coordinate is folded back along the X axis and the Y axis to move the coordinate to the first quadrant.

In the next step S2, the coordinates after folding back on the X-axis or the Y-axis, or both the X-axis and the Y-axis are rotated by -45 ° about the origin, and further the X-axis is calculated in the step S3.
Translate in the axial direction ^by- (2) ^1/2 .

Now, the received signal is a 4-phase PS as shown in FIG.
It is assumed that the K-modulated signal indicates the amplitude in the X-axis direction and the phase in the Y-axis direction. The eye pattern signal monitoring function block 23 determines from the coordinate data (corresponding to the phase and the amplitude) of the eye pattern signal that the signal is in the third quadrant (-1,
If it is determined that the signal corresponds to -1), first the coordinate conversion that folds back on the X axis is performed to move the coordinates to the second quadrant (FIG. 6), and then the coordinate conversion that folds back on the Y axis is performed. Move the coordinates to the first quadrant (the same figure). Furthermore, −45
° Rotate the coordinates to move the coordinates on the X-axis (the same figure) and move the coordinates ^by- (2) ^1/2 in the X-axis direction to make the origin (0, 0) the center. Coordinate conversion to the coordinate system (see the figure).

As a result, the coordinate data of the eye pattern signal in the third quadrant can be converted into the coordinate data of the coordinate system centered on the origin (0,0). Similarly, when the eye pattern signal output from the modem unit 21 is a signal corresponding to the signal point in the fourth quadrant, the eye pattern signal is folded back along the X axis to move the coordinates to the first quadrant, and then -45 °. It is rotated, moved on the X axis, and further moved ^by- (2) ^1/2 in the X axis direction to be converted into coordinate data of a coordinate system centered on the origin (0, 0).

The coordinates of the eye pattern signal in each quadrant can be converted into coordinates centered on the origin (0, 0) by the processing of steps S1 to S3 described above. Here, the coordinate data of the eye pattern signal before performing the above-mentioned coordinate conversion processing is (x, y), and the coordinate data after being converted into the coordinate system centering on the origin (0, 0) is (X, Y). Then, when the amplitude and phase error components of the eye pattern signal are 0, that is, the coordinate data (x, y) of the eye pattern signal before conversion.
Is the same as the coordinate data of the signal point, the converted coordinate data (X, Y) is (0, 0). On the other hand, when the eye pattern signal includes amplitude and phase errors, the coordinate data (x, y) before conversion does not match the coordinate data of the signal point, and the coordinate data after conversion (X, Y). Does not become (0,0). At this time, the coordinate data (X, Y) after conversion indicates the amplitude and phase error of the demodulated signal.

That is, by applying the above-described coordinate conversion processing to the eye pattern signal, the amplitude and phase error components of the eye pattern signal can be directly taken out, and the processing for obtaining the error can be simplified.

When the amplitude and the phase error of the eye pattern signal are obtained in this way, the value obtained by adding the power Y ^{2 of the} phase error to the value of the previous Fj as the value of the present FJ in step S4 of FIG. Set. It should be noted that "0" is set as the initial value of FJ, and the value obtained by sequentially adding the power Y ² of the phase error is obtained as the phase error FJ by the processing of step S4.

Next, in step S5, it is determined whether or not the X coordinate after coordinate conversion, that is, the amplitude error is larger than a predetermined threshold value (4.5) ^1/2 . X> in the determination in step S5
When (4.5) ^1/2, the process proceeds to step S6 and the value of the counter GH that counts the number of gain hits is incremented by "1". Note that when the amplitude value of the X coordinate exceeds a predetermined threshold value in the positive direction, it is called a gain hit, and when it falls below the predetermined threshold value in the negative direction, it is called a gain drop.

The X coordinate is (4.5) ^{1/2 by} the determination in step S5.
If it is equal to or smaller than (X ≦ X (4.5) ^1/2 ), the process proceeds to step S7 and the X coordinate after coordinate conversion is − (4.5).
Determine whether it is less than ^1/2 . If the X coordinate is smaller than − (4.5) ^{1/2 in} this determination, the process proceeds to step S8 and the value of the counter DO that counts the number of dropouts is incremented by “1”.

By these processes, the X coordinate is (4.5) ^1/2
When it is larger, the counter GH is incremented and the number of gain hits is counted up. When the X coordinate is smaller ^than- (4.5) ^1/2 , the counter DO is incremented and the number of gain drops is counted up.

Further, in step S9, a value obtained by adding the power X ² of the present X coordinate and the power Y ^{2 of the} Y coordinate to the value of the previous SN is set as SN. Note that "0" is set as the initial value of SN, and in the process of step S9, a value obtained by sequentially adding the power X ^{2 of the} amplitude error and the power Y ^{2 of the} phase error is set as SN.

If the above processing is performed n times, ar
ctan (FJ ÷ n) ^1/2 is calculated to obtain the average phase fluctuation (jitter) n times. Similarly, log (SN ÷ n) ^1/2 is calculated to obtain an average signal-to-noise ratio S / N of n times.

In this embodiment, when the amplitude and phase error of the signal demodulated by each modem device is obtained, the coordinates of the eye pattern signal on the two-dimensional plane are coordinate-converted and normalized to obtain the eye pattern signal. It is possible to obtain the phase and amplitude errors included in the signal by simple signal processing.

Further, by calculating and displaying the phase jitter and S / N indicating the quality of the line from the phase and amplitude errors and the error data thereof, the waveform observation device such as an oscilloscope or the line quality is quantitatively displayed on the modem. It is possible to check the demodulation status of the modem and the line quality without connecting a measuring device for measuring to.

Further, each modem device is provided with a function of outputting a line quality signal to the outside, and from the information collecting and distributing device 16 and the information collecting and distributing device 16 which collects the line quality information outputted from each modem device on the network. By providing the network monitoring dedicated device 17 for monitoring the state of each line based on the output line quality information, it becomes possible to comprehensively monitor the line state of the entire network and the presence / absence of a failure.

In this embodiment, the information collecting device 16 for collecting the line quality information output from each modem device and the network monitoring dedicated device 17 are provided separately, but the functions of both are realized by one device. May be.

[0041]

According to the present invention, a measuring device or the like for measuring line noise is provided in each modem by providing an eye pattern signal monitoring function for obtaining amplitude and phase error from an eye pattern signal to obtain line quality information. The demodulation status and line status of the modem can be monitored without using it. Further, when the amplitude and phase errors included in the eye pattern signal are obtained, the coordinate data of the eye pattern signal is converted into the coordinate data of the predetermined reference coordinate system, so that the signal processing for obtaining the phase and amplitude error can be simplified. . Furthermore, it is possible to grasp the line state of the entire network by collecting line quality information of a plurality of modem devices having an eye pattern signal monitoring function and providing a monitoring device for monitoring the respective line states.

[Brief description of drawings]

FIG. 1A is an explanatory diagram of the principle of the first invention, and FIG. 1B is an explanatory diagram of the principle of the second invention.

FIG. 2 is an explanatory view of the principle of the third invention.

FIG. 3 is a system configuration diagram of a transmission system according to an embodiment of the present invention.

FIG. 4 is a block configuration diagram of a modem device according to an embodiment of the present invention.

FIG. 5 is a flowchart showing the processing contents of an eye pattern monitoring function block.

FIG. 6 is an explanatory diagram of coordinate conversion.

[Explanation of symbols]

 1 coordinate conversion means 2 line quality information calculation means 3 display means 4 output means 5 network monitoring device

Claims (6)

[Claims] 1. A modem device for receiving a signal sent to an analog line, demodulating it to original data, modulating the data to be sent, and sending it to an analog line. Coordinates of the demodulated signal on a two-dimensional plane. Coordinate conversion means for rotating or translating data to convert into coordinate data of a predetermined reference coordinate system, and line quality information calculation means for obtaining line quality information indicating line quality from the coordinate data converted by the coordinate conversion means. And a display device for displaying the line quality information, the modem device with an eye pattern signal monitoring function. 2. The modem device with an eye pattern signal monitoring function according to claim 1, further comprising output means for outputting the line quality information to the outside. 3. A modem device for receiving a signal sent to an analog line, demodulating it to original data, modulating the data to be sent, and sending it to an analog line. Coordinates of the demodulated signal on a two-dimensional plane. Coordinate conversion means for rotating or translating data to convert into coordinate data of a predetermined reference coordinate system, and line quality information calculation means for obtaining line quality information indicating line quality from the coordinate data converted by the coordinate conversion means. A modem device with an eye pattern signal monitoring function, comprising: and an output unit that outputs the line quality information calculated by the line quality information to the outside. 4. The eye pattern signal monitoring function according to claim 1, wherein the coordinate conversion means converts the demodulated signal into coordinate data of a coordinate system centered on the origin of two-dimensional coordinates. Modem device. 5. A transmission system in which a plurality of modem devices for receiving a signal sent to an analog line, demodulating it to original data and modulating data to be sent and sending it to an analog line are connected to a network, Coordinate conversion means for converting coordinate data of a demodulated signal on a two-dimensional plane into coordinate data of a predetermined reference coordinate system by rotating or moving in parallel, and line quality is indicated from the coordinate data converted by the coordinate conversion means. A plurality of modem devices having line quality information calculating means for obtaining line quality information, and an output means for outputting the line quality information to the outside, and line quality information output from each of the modem devices is collected to collect network-wide information. A transmission system comprising a network monitoring device for monitoring the line status. 6. The transmission system according to claim 5, wherein the modem device has a display unit for displaying the line quality information.