JP3220277B2 - Measurement device for transmission signal of ISDN terminal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a transmission signal of an ISDN terminal for measuring the form of a signal pulse of the transmission signal of the ISDN terminal.

[0002]

2. Description of the Related Art CCITT recommendations I.I. At 430, IS
The specifications regarding the layer 1 of the basic user / network interface of the DN are defined. In this recommendation, a pulse waveform and a pulse amplitude of a transmission signal transmitted from a terminal device to a line are specified.

When it is determined whether a transmission signal conforms to this rule, a positive or negative single pulse is transmitted from the terminal device as a transmission signal, and the signal waveform is measured.
In order to transmit such a single pulse, it is necessary to transmit data on the B channel (information channel) from the terminal device.

For this reason, conventionally, a terminal device is connected to an ISDN to actually execute a communication operation with another terminal device, or a dedicated test device is connected to execute a communication operation on a trial basis. In addition, the transmission signal of the terminal device was observed with an oscilloscope or the like.

[0005] The method of actually communicating with a terminal device is ISD.
Since it requires N lines and other terminal devices and requires a line charge, it cannot be easily executed.

On the other hand, the method using a test apparatus requires the test apparatus to execute a normal communication operation on the terminal apparatus.
It must have a channel (control channel) call control function and a B channel data reception function. For this reason,
The cost of test equipment has increased, and signal measurement has required such expensive equipment.

When measuring a transmission signal, it is desirable that the transmission signal has a fixed pulse pattern. For this purpose, it is necessary to transmit data of a specific pattern from the terminal device. However, since many terminal devices cannot set the pattern of the transmission data arbitrarily, a constant pulse pattern cannot be obtained, and the measurement operation is difficult. Also, in the case of a terminal device that can arbitrarily set a pattern of transmission data,
The setting work was troublesome.

[0008]

As described above, conventionally,
There is a problem that the signal measurement of the transmission signal of the terminal device is not easy and the measurement cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for measuring a transmission signal of an ISDN terminal, which solves the above-mentioned problem and can easily measure the transmission signal and reduce the measurement cost.

[0010]

For this purpose, the present invention sets the terminal device to a loopback state in which the information channel data of the received signal is set as it is on the B channel of the transmission signal and transmitted in a loop-back manner. A signal in which constant pattern data is set in the B channel from the device is sent to the terminal device, and a signal returned from the terminal device is received.
The mode of the signal pulse is measured.

[0011]

Since positive and negative single pulses can be obtained in a fixed pulse pattern as a transmission signal of the terminal device, signal measurement is facilitated. Further, since the terminal device can output the transmission signal without executing the call control procedure, the call control function of the test device becomes unnecessary. This reduces the cost of the test equipment. In general, the terminal device is provided with the above-described loop pack function as a standard, so that it is possible to execute the signal measurement of the normal terminal device by the above method.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a test apparatus according to an embodiment of the present invention. In the figure, a connection terminal 1 is a terminal for connecting an ISDN terminal device. The load resistance switching unit 2 switches and connects three types of load resistance to the transmission line of the connected terminal device. The layer 1 control unit 3 has a function of a network termination device, and transmits and receives a predetermined frame signal to and from a terminal device. The bit pattern generation section 4 generates and outputs specific bit pattern data for testing.

The pulse measuring section 5 measures the form of the pulse signal of the transmission signal of the terminal device. The display unit 6
The waveform of the pulse signal, the measured value, and the result of determination as to whether the pulse signal conforms to the standard specifications are displayed on the screen. The operation unit 7 is used by an operator to execute various operations. The control unit 8 monitors and controls the above units.

With the above configuration, the test apparatus of the present embodiment
The mode of the signal pulse of the transmission signal of the terminal device for SDN is measured, and the signal pulse is transmitted according to CCITT Recommendation I.3. It is to determine whether the specification conforms to the specifications defined in 430.

When performing signal measurement, as shown in FIG. 2, the operator connects a terminal device to be measured to the connection terminal 1 of the test device (process 101). Then, the test apparatus is started. When the test apparatus is started, the operation of the layer 1 is started. As a result, transmission and reception of a predetermined frame signal between the connected terminal device and the test device starts (process 102).

Next, the operator specifies a load resistance value. This load resistance value is the value of the load resistance inserted into the transmission line of the terminal device. In the above recommendation, the specifications of the pulse signal in each state where the load resistance of the line is set to 5.6Ω, 50Ω and 400Ω are defined. The operator arbitrarily specifies a load resistance value to be measured by a predetermined operation. The test apparatus connects a load resistance having a specified value to the line (process 103).

Next, the operator sets the terminal device to a loopback state by a predetermined operation. This loopback is in accordance with CCITT recommendation I. 602 "Loopback 4"
(Process 104).

Then, the measuring operation of the test apparatus is started.
As a result, the test apparatus continuously transmits a frame signal in which the test data is set to the B channel to the terminal device. The test data in this case is, for example, “010101”.
.. "(Process 10
5).

The terminal device receives the frame signal transmitted from the test device from a receiving line. At this time, since the terminal device is set to the loopback state, as shown in FIG. 3, the B channel data of the received frame signal is set as it is in the B channel of the frame signal on the transmission side, and the transmission line Send it back to.

The test apparatus receives the frame signal transmitted from the terminal device. Then, the mode of the pulse signal such as the pulse waveform and pulse amplitude of the frame signal is measured (process 106). The above test data contains "010101
When a data pattern ".." is set, a positive and negative single pulse alternately appears in the frame signal at this time.

Then, the received pulse waveform, its measurement result, and recommendation I. The result of the determination as to whether or not the data conforms to the rule 430 is displayed (step 107).

As described above, in the present embodiment, the terminal device is set to the loopback state, the frame signal in which the test data is set in the B channel from the test device is transmitted to the terminal device, and the returned frame signal is transmitted. Is measured.

In this case, since data is transmitted from the terminal device to the B channel, a signal of positive and negative single pulses can be received. As the test data, for example, “010
By transmitting the specific pattern of “101...”, The single pulse can be obtained in a constant pulse pattern. This facilitates signal measurement.

Further, since the terminal device can output the above signal without executing the call control procedure, the call control function of the test device becomes unnecessary. As a result, the cost of the test apparatus is reduced, so that signal measurement can be performed with an inexpensive test apparatus.

In general, a terminal device conforms to CCITT Recommendation I.2. Since a loop pack function according to 602 is provided as a standard, a signal measurement of a normal terminal device can be performed by the above method.

In the above embodiment, the operator sets the terminal device to the loop-back state by manual operation. However, a command is sent from the test apparatus to the terminal device to automatically set the terminal device to the loop-back state. May be switched. In this case, it is conceivable to set the command information in the S bit of the layer 1 frame signal transmitted by the test apparatus and notify the terminal apparatus of the command information. The method of using the S bit is not yet specified in the standard recommendation, so that the S bit can be used effectively.

Further, in the above embodiment, the test apparatus
Although the connection with the terminal device is made at the S-point interface of the ISDN user / network interface, the connection with the terminal device may be made at the U-point interface via the network termination device. It is also conceivable to connect the terminal device with the primary group speed interface.

[0029]

As described above, according to the present invention, after the terminal device is set to the loopback state, the mode of the signal pulse transmitted from the test device to the terminal device and returned is measured. In addition, the signal measurement is facilitated, and it is not necessary to provide the test device with a call control function, and the cost of the device is reduced, so that the cost of signal measurement can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a test apparatus according to one embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of signal measurement.

FIG. 3 is an explanatory diagram of a loopback operation of a terminal device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Connection terminal 2 Load resistance switching part 3 Layer 1 control part 4 Bit pattern generation part 5 Pulse measurement part 6 Display part 7 Operation part 8 Control part

Claims (2)

(57) [Claims] 1. An ISDN for measuring a form of a signal pulse by receiving a transmission signal of an ISDN terminal device by a test device.
In the transmission signal measuring device of the terminal, a means for directly connecting the test device and the terminal device without passing through a network, a means for starting an operation of Layer 1, a means for connecting a load resistance, Means for setting the information channel data of the received signal as it is in the information channel of the transmission signal and setting a loopback state in which the signal is looped back; and Means for sending to the terminal device, means for receiving a signal returned from the terminal device and measuring the form of the signal pulse, and transmitting a signal in which specific pattern data is set in an information channel from the test device to the Transmitting to a terminal device, receiving a signal returned from the terminal device, and measuring a form of the signal pulse. An apparatus for measuring a transmission signal of an ISDN terminal. 2. The test apparatus sets command information in an S bit of a frame signal defined in layer 1 and notifies the terminal device of the command information, and the terminal device switches to the loopback state according to the command information. The apparatus for measuring a transmission signal of an ISDN terminal according to claim 1, wherein: