JP2551963B2 - Pre-emphasis method - Google Patents

Description

Detailed Description [Table of Contents] Outline Industrial field of application Conventional technology (Fig. 4, Fig. 5, Fig. 7) Problem to be solved by the invention (Fig. 6) Means (Fig. 1) Operation Embodiment (Figs. 2 and 3) Effect of the invention [Outline] In a pre-emphasis system in which a local station transmitter and a local station receiver of a modem are connected to perform a loopback test, the deterioration amount A deterioration amount calculating means (4) for calculating, a holding means (6) for holding a setting request value (A ′) of the fixed equalizer on the transmission side for the previous training signal, and the deterioration amount calculating means (4).
The determination means (5) for outputting the optimum set value of the fixed equalizer of the transmission unit based on the output of the above and the set value of the fixed equalizer of the partner station (PE3), and the determination result of the determination means (5) are Setting request held by the holding means (6), the first comparing means for comparing whether or not the setting value (PE3) of the fixed equalizer of the partner station is equal, and the judgment result of the judging means (5). The comparing means having a second comparing means for comparing whether or not the value (A ') is equal to the value (A'), and the determination result when the training signal is received are not equal to the set value (PE3) of the fixed equalizer of the partner transmitting unit. When the setting request value (A) is updated and the judgment result is equal to the setting value (PE3) of the fixed equalizer of the partner transmission section and the judgment result is not equal to the previous setting request value, training is performed.
The determination means (5) determines to end the training when the determination result and the set value (PE3) of the fixed equalizer of the partner transmission unit are equal, and the determination result and the previous determination request value (A ') are equal. It is characterized by controlling.

[Industrial applications]

The present invention relates to a pre-emphasis system, and more particularly to a system capable of accurately detecting the convergence of a fixed equalizer of a modem during a self-loopback training test of the modem.

[Conventional technology]

For example, as shown in FIG. 4 (a), when data is transmitted and received between the terminal devices 21 and 22, each terminal device
High-speed modems 31, 32 are provided in 21, 22, and data is transmitted and received.

Prior to data transmission, this modem is trained to set its built-in fixed equalizer according to the deterioration state of the line. Now, when data is transmitted from the terminal device 21 to the terminal device 22, the terminal device 21 to the modem 31
To the modem 32, and then the modem 32 is trained for a certain period of time to train the modem 32 on the receiving side. After the training is completed, the data transmission permission signal CS is sent from the modem 31 to the terminal device 21 as a response to the transmission request signal RS. In the modem 32 on the receiving side, the automatic equalizer is pulled in by the training signal to correct the line distortion. At this time, the modem 32 on the receiving side calculates the optimum setting value of the automatic equalizer by observing the state of the transmitting side of the modem 31 and the line state, and sends the result to the modem 22 on the transmitting side to obtain the optimum value. Set as fixed equalizer value.

[Problems to be Solved by the Invention]

When testing the modem at the time of development or at the installation site, do not train with the other station as shown in Fig. 4 (a), and test the modem 30 with its own station as shown in Fig. 4 (b). I have something to do. At the time of this test, the line simulator 23 is connected between the transmitter and the receiver of the modem 30 of the own station 20, and the transmitter transmits the set value of the fixed equalizer of the transmitter and the training signal to the line simulator 23. Input to the receiver via.

In this case, although the deterioration state in the line simulator 23 is constant, there is a problem that the determination on the receiving side is not constant and the training state is permanent, as described below.

As shown in FIG. 5, the reception unit 34 of the modem 30 includes a deterioration amount calculation unit 35 and a determination unit 36, and the transmission unit of the own station can be used according to the deterioration amount and the set value of the fixed equalizer of the partner station. The determination unit 36 determines the set value of the fixed equalizer to the transmission unit of the partner station to be transmitted,
Training is continued until it becomes equal to the previous judgment result. In FIG. 5, PE1 is the set value of the fixed equalizer of the transmitter 33 of the own station, PE2 is the set value of the fixed equalizer required by the transmitter of the partner station, and PE3 is the fixed equalizer of the partner station. The setting value, PE4, is the setting request value from the partner station to the local station transmitter. CEQ0 to CEQ2 are three types of deterioration amounts of the signal of the partner station transmitting unit and the line, and are calculated by the deterioration amount calculating unit 35.

When the modem is subjected to the loopback test, the PE1 to PE4 are all zero, the output of the deterioration amount calculation unit 35 is all zero, and the determination results are all zero, as shown in the initial state of FIG. In this initial state, the first training signal is sent from the transmitter 33 to the receiver 34 via a simulator not shown in FIG. In this training signal, PE1 and PE2 are present as modulated. And the first
During the reception of the second training signal, the deterioration amount calculation unit 35 determines that the deterioration amount is “101” (this is not a numerical value but CEQ0, CEQ
Since three types of states of 1 and CEQ2 are calculated), the result determination unit 36 outputs the determination result A = X.

Before the second training signal is transmitted, the determination results A and PE4, that is, B after the first training signal is received are set to be transmitted to the transmitter 33, and as a result PE1 is "0.
0 "and PE2 are" X ", but PE3 and PE4 are in the state after receiving the first training signal, and PE3 is" 0 ".
0 "and PE4 are also" 00 ". When the second training is performed in such a state, the deterioration amount calculation unit 35 displays “110”.
And the determination unit 36 outputs A = “Y”. After receiving the second training signal, PE3 and PE4 are in the second
PE1 and PE2 "00" and "X" before starting the second training
Becomes

Before the third training signal is transmitted, the determination result A and PE4 after the second training signal is received are set in the transmitter 33, and PE1 and PE2 become “X” and “Y”.
PE3 and PE4 = PE3 after receiving the second training signal
“00” and PE4 = “X”. When the third training is performed in this state, the deterioration amount calculation unit 35 calculates “100” and the determination unit 36 outputs A = “X”. And the third
PE3 and PE4 after receiving the third training signal become “X” and “Y” of PE1 and PE2 before sending the third training signal.

Before the fourth training signal is transmitted, the determination result A and PE4 after the third training signal is received are set in the transmitter 33, and PE1 and PE2 become “Y” and “X”.
However, PE3 and PE4 are
PE3 = “X” and PE4 = “Y”. When the fourth training is performed in this state, the deterioration amount calculation unit 35
Then, the determination unit 36 outputs A = “Y”. And the PE that was in the state after receiving the third training signal
3 and PE4 are PE1 and PE2 before sending the 4th training signal
“Y” and “X”.

Before the fifth training signal is transmitted, the determination result A and PE4 after the fourth training signal is received are set in the transmitter 33, and PE1 and PE2 become “X” and “Y”, but PE3 And PE4 are PE after receiving the 4th training signal
3 = “Y”, PE4 = “X”. When the fifth training is performed in this state, the deterioration amount calculation unit 35 displays “100”.
And the determination unit 36 outputs A = “X”. And PE3 and P which were in the state after receiving the 4th training signal
E4 becomes “X” and “Y” of PE1 and PE2 before the fifth training signal transmission.

As is clear from FIG. 7, the state after the third training signal reception is A = PE3, and the fixed equalizer settings in the modem have converged,
As shown in the fourth time, the fifth time, ...
The values of X and X are output alternately, and training is repeated forever.

For example, as shown in FIGS. 6A to 6C, n-1 to n
The + 1st training is performed, and the output of the determination unit 36 alternately outputs X and Y even though the training has converged, and the training is repeated forever. In FIG. 6, B is PE4 and (Y → X) is X after receiving the training signal.

Therefore, it is an object of the present invention to provide a pre-emphasis system that prevents endless training even when the modem is converged, which occurs in the case of the local loopback test as described above.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, the receiving unit 3 of the modem 1 having the transmitting unit 2 and the receiving unit 3 is provided.
In addition, the deterioration amount calculation unit 4, the determination unit 5, the holding unit 6, the comparison unit 7,
8 is provided. The deterioration amount calculation unit 4 operates in the same manner as the deterioration amount calculation unit 35 shown in FIGS. 5 and 6. The holding unit 6 holds the previous judgment result A ′ by the judging unit 5. The comparison unit 7 determines whether the determination result of the determination unit 5 is equal to PE3, and the comparison unit 8 determines whether the determination result of the determination unit 5 is equal to the previous determination result A '. Then, the determination unit 5 (1) sends the determination result A every time the training signal is received and when the determination result is not equal to PE3, updates PE2. (2) The determination result = PE3 and the determination result and the previous time If the determination results A ′ of 1 are not equal, re-training is requested.

[Action]

Therefore, in the state where the modem does not converge, the determination result is not equal to PE3, so the determination result A is sent to the transmitting unit 2 and the training is continued. If the modem converges, the judgment result = PE3, and since the judgment result A this time is the same as the judgment result A ′ of the previous time, the training will be ended, and the training as described above will not be repeated forever. .

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG. 2 is a configuration diagram of an embodiment of the present invention, and FIG. 3 is an operation explanatory diagram thereof.

In the figure, the same parts as in FIG. 1 indicate the same parts, 9 is a microprocessor, 10 is a fixed equalizer, 11 is a training signal demodulator, 12 is a fixed equalizer, 13 is a training signal output part, 14 Is a microprocessor, 15 is a line simulator, and 16 is a modem tester.

The microprocessor 9 controls the receiving unit 3 of the modem 1, and sets the coefficient of the fixed equalizer 10 and PE1 (the current transmitting unit 2 of the own station) present in the training signal.
(Set value of fixed equalizer of), PE2 (set value of fixed equalizer required for transmission of partner station), and calculate the amount of deterioration of fixed equalizer 12 of transmitter 1 and line Or PE3
From the deterioration amount, the optimum value of the transmission unit (the transmission unit 2 in the self-loopback test, the transmission unit of the partner station in the normal case) is output as the determination result A, the set value of the fixed equalizer. Yes, the deterioration amount calculation unit 4, the determination unit 5, the holding unit 6, the comparison unit 7,
Eight. Here, the holding unit 6 holds the previous judgment result A ′, and the judgment unit 5 updates the judgment result A when the judgment result is not equal to PE3 after the training is received, and the judgment result A = PE3 and A ≠ A '
In the case of, it is determined to request retraining.

The training signal demodulator 11 demodulates the transmitted training signal.

The training signal output unit 13 outputs the training signal of the modem, and modulates PE1 and PE2.

The microprocessor 14 controls the transmission unit 2 of the modem 1, outputs PE1 and PE2, controls the training signal output unit 13 and controls coefficient setting of the fixed equalizer 12. .

The line simulator 15 pseudo-sets the state of deterioration of the line when performing a loopback test on the own station.

The modem tester 16 performs control when testing the modem 1.

 Next, the operation of the present invention will be described.

(1) When the operator touches the test start key of the modem tester 16 when performing a loopback test of the modem,
The modem tester 16 instructs the MPUs 9 and 14 to set the initial state, and as a result, as shown in the initial state of FIG.
All of E4 are all zero, and the output of the deterioration amount calculation unit 4 and the determination result of the determination unit 5 are all zero. The determination result is held in the holding unit 6. After entering such an initial state, the modem tester 16 outputs a training start instruction signal such as an RS signal to the MPU 14. As a result, the MPU 14 causes the training signal output unit 13 to output the first training signal. At this time, the fact that PE1 and PE2 are all zero is modulated and input in this training signal, and this is sent from the transmission unit 2 to the reception unit 3 via the line simulator 15. Then, during the first reception of the training signal, the deterioration amount calculation unit 4 causes the fixed equalizer 12 on the transmission side to
Since the deterioration amount “101” (state of CQE0 to CQE2 as described above) is calculated based on the setting state of the above and the line deterioration amount by the line simulator, this and PE3 (that is, the fixed equalizer 1
The determination unit 5 outputs the determination result = “X” based on the set value PE1) of 2. The determination result “X” is compared with PE3 by the comparison unit 7. At this time, PE3 is “00” and does not match “X”, so MPU9 requests MPU14 to send the training signal. Then, the determination result “X” is set in the holding unit 6, and this determination result is set as A, and A = “X” and PE4 =
Send "00" to MPU14.

(2) MP before sending the second training signal
U14 sets PE1 to "00" and PE2 to "X". At this time with PE3
PE4 is in a state after receiving the first training signal P
E3 is "00" and PE4 is also "00". When the second training is performed in this state, the deterioration amount calculation unit 4 returns to “11.
Then, the determination unit 5 outputs A = “Y”. And after receiving the second training signal, PE3 and PE4 are the second
PE1 and PE2 "00" and "X" before starting the second training
Becomes However, even after the second training signal is received, the determination result ≠ PE3 “00”, so MPU9 requests the MPU14 to send the training signal, sets the determination result “Y” in the holding unit 6, and outputs this determination result. As A, A = “Y”
And PE4 = "X" are sent to MPU14.

(3) MP before sending the third training signal
U14 sets PE1 to “X” and PE2 to “Y”. At this time with PE3
PE4 is PE3 = "0 after receiving the second training signal"
0 ”and PE4 =“ X ”. When the third training is performed in this state, the deterioration amount calculation unit 4 calculates “100” and the determination unit 5 outputs the determination result “X”. And the third
After receiving the third training signal, PE3 and PE4 become "X" and "Y" of PE1 and PE2 before the start of the third training. Thereby, the comparison unit 7 reports the determination result = PE3 to the determination unit 5. However, at this time, "Y", which is the result of the previous training, that is, the second training, is set in the holding unit 6, and the setting request value A to the fixed equalizer 12 for the transmitting unit 2 based on the previous determination is set. Since ′ = “Y” is not equal to the present determination result “X”, the MPU 14 is requested to send the fourth training signal. However, at this time, PE3 = judgment result, which indicates that the fixed equalizer of the modem is in the converged state, so A is not changed and A = “Y”
Is sent. At this time, PE4 = “Y”.

(4) Therefore, the MPU 14 sets PE1 and PE2 to “Y” before transmitting the fourth training signal. At this time, PE3 and PE4 are
PE3 = “X” and PE4 = “Y”. When the fourth training is performed in this state, the deterioration amount calculation unit 4 displays “01
Then, the determination unit 5 outputs the determination result “Y”.
After receiving the 4th training signal, PE3 and PE4
Is "Y" of PE1 and PE2 before the start of the 4th training,
It becomes "Y". Accordingly, the comparison unit 7 determines the determination result = PE3. At this time, the holding unit 6 stores the previous A, that is, A ′ =
Since “Y” is held, the comparison unit 8 makes the determination result = A ′.
To judge. This shows that the modem is in the converged state and the fixed equalizer setting of the modem is in the optimum state according to the line condition, so the MPU9 reports this to the modem tester 16 and turns on the training end lamp, for example. The test completion is reported to the operator by, for example, displaying this on the display unit of the modem tester 16.

In this way, the end of training can be detected immediately.

In the above description, an example using a line simulator and a modem tester has been described, but the present invention is not limited to these, and an actual line may be used, or a terminal device to which a modem is connected is used. You can also test it. Further, it is of course possible to perform the comparison with only one comparison unit.

〔The invention's effect〕

According to the present invention, this occurs during the local loopback test. The problem of repeated training forever can be solved by simple means.

[Brief description of drawings]

 FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a configuration diagram of an embodiment of the present invention, FIG. 3 is a diagram illustrating the operation of the present invention, FIG. FIG. 6 is an explanatory diagram of a station loopback test, FIG. 6 is a diagram illustrating problems in the local station loopback test, and FIG. 7 is an operation explanatory diagram of the local station loopback test. 1 ... Modem, 2 ... Transmission unit 3 ... Reception unit, 4 ... Degradation amount calculation unit 5 ... Determination unit, 6 ... Holding unit 7 ... Comparison unit, 8 ... Comparison unit 9 ... Microprocessor 10 …… Fixed equalizer 11 …… Training signal demodulator 12 …… Fixed equalizer 13 …… Training signal output unit 14 …… Microprocessor 15 …… Line simulator 16 …… Modem tester

Claims (1)

(57) [Claims] 1. A pre-emphasis system in which a local transmitter and a local receiver of a modem are connected to perform a loopback test, and a deterioration amount calculation means (4) for calculating a deterioration amount and a transmitter side for a previous training signal. Holding means (6) for holding the setting request value (A ') of the fixed equalizer, and a transmitter based on the output of the deterioration amount calculating means (4) and the setting value (PE3) of the fixed equalizer of the partner station. Determining means (5) for outputting the optimum set value of the fixed equalizer, and whether the judgment result of the judging means (5) is equal to the set value (PE3) of the fixed equalizer of the partner station. It has first comparing means for comparing and second comparing means for comparing whether or not the determination result of the determining means (5) is equal to the setting request value (A ′) held by the holding means (6). The comparison result and the judgment result when the training signal is received are If the setting value (PE3) of the equalizer is not equal, the setting request value (A) is updated, and the judgment result and the setting value (PE3) of the fixed equalizer of the partner transmitter are equal and the judgment result and the previous setting. Training is performed when the required values are not equal, and the training ends when the determination result and the set value (PE3) of the fixed equalizer of the partner transmission unit are equal, and the determination result and the previous determination request value (A ′) are equal. The pre-emphasis method is characterized in that the determination control is performed by the determination means (5).