JP2002064588A - Digital transmission apparatus incorporating pattern generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital transmission that is not susceptible to the effect of the performance of a reception circuit section 2 and can conduct a DS3 transmission pulse mask test without the need for a '001' pattern generator 20 at the outside of the transmission apparatus. SOLUTION: A '001' pattern generating section 7 is incorporated to the digital transmission apparatus 1 and selection changeover section 6 supplies a pattern signal generated by the '001' pattern generating section 7 to a transmission circuit section 3 in the case of a DS3 transmission pulse mask test, the transmission signal generated by the transmission circuit section 3 is independently of the performance of the reception circuit section 2. Moreover, since no '001' pattern generator 20 required at the outside of the transmitter, the configuration of test measurement can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital transmission apparatus, and more particularly, to a test for a transmission pulse mask of a DS3 electrical interface standardized by ANSI standard without using an external pattern generator. The present invention relates to a transmission device that can perform the transmission.

[0002]

2. Description of the Related Art In recent years, transmission speeds of transmission devices for transmitting digital signals have been increasing. If the transmission speed increases, various factors such as the frequency characteristics of the transmission path through which signals are transmitted, as well as the response speed of the electronic elements inside the device, are required to respond to higher speeds. A sufficient test environment is required. In addition, even after the product has passed the design stage and has been commercialized, inspection tests have been conducted so that devices that do not satisfy the originally required performance characteristics are not shipped due to variations in the characteristics of each component used in the product. . Various standardizations have been made for various tests on such transmission devices.
DS3 (Digital signal configuration is 44.
The transmission pulse mask of the electrical interface (sending at 746 Mb / s) is measured by a continuous pattern of “001”.

FIG. 2 is a diagram showing a configuration example of an ANSI standard DS3 transmission pulse mask test measurement system when a conventional digital transmission device is measured. The test and measurement system shown in this example is a digital transmission device 1 capable of transmitting and receiving digital signals at a transmission speed of 44.746 Mb / s.
And a pulse mask measuring device 10 for measuring an input signal waveform.
And a “001” pattern generator 20 that generates a continuous pattern of “001” conforming to the ANSI standard.

First, the configuration and operation of a conventional digital transmission device 1 will be briefly described. The digital transmission device 1 includes a reception circuit unit 2, a transmission circuit unit 3, a frame termination unit 4, a frame generation unit 5, and a loop switch unit 8. The receiving circuit unit 2 receives a signal input from the outside, separates the signal into a data component (received data) and a clock component (received clock), and outputs the separated signal to the loop switch unit 8. The loop switch section 8 selectively switches between receiving the data and the received clock from the receiving circuit section 2 and outputting the data to the frame terminating section 4 or returning the data to the transmitting circuit section 3. The selection is determined by the operation mode of the digital transmission device 1.

First, if the operation mode is the "operation mode", the loop switch section 8 is switched to output the received data and the received clock from the receiving circuit section 2 to the frame terminating section 4, and the frame terminating section 4 The DS3 frame is detected by achieving frame synchronization based on the reception data and the reception clock supplied from the reception circuit unit 2. On the other hand, the transmission circuit unit 3 is connected to the frame generation unit 5 via the loop switch unit 8 at this time, receives the transmission clock signal and the transmission data from the frame generation unit 5, generates the transmission signal, and Send to Note that the transmission data generated by the frame generation unit 5 is obtained by inserting a DS3 frame into original data (information) to be transmitted from inside the device.

If the operation mode is the “test mode”, the loop switch section 8 switches so that the reception data and the reception clock output from the reception circuit section 2 are input to the transmission circuit section 3. Therefore, the transmission circuit unit 3 receives the reception data and the reception clock from the reception circuit unit 2 via the loop switch unit 8, generates a transmission signal, and sends the transmission signal to the outside.

A digital transmission device 1 having the above configuration
The operation of the test measurement for will be described. “001”
A continuous pattern of “001” (hereinafter, referred to as a pattern signal) supplied from the pattern generator 20 to the digital transmission device 1 and a transmission signal from the digital transmission device 1 to the pulse mask measuring device 10 are bipolar (transmission line codes). It is assumed that a unipolar (unipolar) pulse signal is used for the reception / transmission data and the reception / transmission clock in the digital transmission device 1. That is, when measuring the pulse mask of the transmission signal (44.746 Mb / s) transmitted by the transmission circuit unit 3 of the digital transmission apparatus 1 in accordance with the DS3 standard of the ANSI standard, first, the operation mode is set to the “test mode”. The output of the receiving circuit unit 2 is looped back to the input of the transmitting circuit unit 3 by the loop switch unit 8 to switch to form a loop. As a result, the pattern signal output from the “001” pattern generator 20 is input to the reception circuit unit 2 as a reception signal, and the reception circuit unit 2 outputs reception data and a reception clock from the pattern signal. In this case,
The reception data is a repetition code of “001”, and the reception clock is 44.746 MHz. The received data and the received clock are directly provided to the transmission circuit unit 3 as transmission data and a transmission clock by the loop switch unit 8, and the transmission circuit unit 3 generates a transmission signal based on the transmission data and the transmission clock. Pulse mask measuring instrument 1
Send to 0. The pulse mask measuring device 10 compares the waveform of the transmission signal from the transmission circuit unit 3 with a preset pulse mask, measures whether the waveform is within a predetermined reference range, and determines pass / fail. is there.

[0008]

However, in the above-described transmission pulse mask test of the conventional digital transmission device, there are the following problems. That is,
Since the transmission signal output from the transmission circuit unit 3 is generated based on the output from the reception circuit unit 2, the performance of the reception circuit unit 2 is directly reflected on the transmission pulse mask test result. Therefore, if the receiving circuit unit 2 cannot accurately extract a pattern consisting of a series of “001” as received data and gives another code string to the transmitting circuit unit 3, even if the transmitting circuit unit 3 is normal ( Even if it has the performance that meets the standard), it can no longer pass the transmission pulse mask test. That is, there is a problem that it is impossible to separate the transmission circuit unit 3 from other parts and perform a single performance test. In addition, the "001" pattern generator 20 had to be prepared externally as a test measurement configuration, and the test measurement configuration was complicated.

The present invention has been made in order to solve such a problem, and is not affected by the performance of the receiving circuit unit 2 and does not provide an external "001" pattern generator 20. It is another object of the present invention to provide a digital transmission apparatus capable of performing a DS3 transmission pulse mask test.

[0010]

According to a first aspect of the present invention, there is provided a digital transmission apparatus having a built-in pattern generator according to the present invention. In a digital transmission device including a transmission circuit unit that generates and outputs a transmission signal corresponding to a transmission line code form from data and a transmission clock based on an internal clock, a predetermined signal pattern is generated based on the transmission clock. A pattern generation unit, and a selection switching unit that receives the transmission data and the signal pattern supplied from the pattern generation unit, selects one of them, and outputs the selected one to the transmission circuit unit. And Further, the invention according to claim 2 is the invention according to claim 1.
A digital transmission device having a built-in pattern generator according to claim 1, wherein said digital transmission device is an ANSI standard DS.
3. The apparatus according to claim 3, wherein the pattern generation unit is “001”.
Is transmitted.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. FIG. 1 is a block diagram showing a configuration example of an ANSI standard DS3 transmission pulse mask test measurement system when a digital transmission device having a built-in pattern generator according to the present invention is measured. Note that the same reference numerals are given to the same functional blocks as those shown in FIG. 2 described above, and description thereof will be omitted.

The test and measurement system configuration shown in this example has four
It is only necessary to connect the pulse mask measuring device 10 for measuring the input signal waveform to the digital transmission apparatus 1 according to the present invention capable of transmitting and receiving digital signals at a transmission rate of 4.746 Mb / s, and the configuration becomes very simple. .

First, the configuration and operation of the digital transmission device 1 according to the present invention will be described. This digital transmission device 1 includes a receiving circuit unit 2, a transmitting circuit unit 3, a frame terminating unit 4, a frame generating unit 5, a selection switching unit (SE
L) 6 and a “001” pattern generator 7. The receiving circuit unit 2 and the frame terminating unit 4 are the same functional blocks as in the related art, and both the received data and the received clock are directly connected to each other. That is, since there is no loop switch configuration for returning a received signal and transmitting the signal, the signal is independent as a receiving system. On the other hand, the transmission system is also configured independently. The transmission clock from the frame generation unit 5 is supplied to the transmission circuit unit 3 and the “001” pattern generation unit 7, and the transmission clock from the frame generation unit 5 is supplied to one input terminal of the selection switching unit 6. The pattern signal from the “001” pattern generator 7 is supplied to the other input of the selector 6. Then, the output of the selection switch 6 is supplied to the transmission circuit unit 3. The pattern signal output from the “001” pattern generator 7 is a unipolar (unipolar) pulse signal, like the transmission data output from the frame generator 5.

The digital transmission apparatus 1 configured as above operates as follows. That is, the selection switch 6
One of the two inputs is selected according to the operation mode of the digital transmission device 1. First, when the operation mode is the “operation mode”, the selection switching unit 6 switches to select the transmission data from the frame generation unit 5 and outputs the transmission data from the frame generation unit 5 to the transmission circuit unit 3. If the operation mode is the “test mode”, the selection switch 6 switches to select the pattern signal from the “001” pattern generation unit 7 and transmits the pattern signal from the “001” pattern generation unit 7 to the transmission circuit unit. Output to 3.
In this way, the transmission circuit unit 3 receives the transmission clock from the frame generation unit 5 and transmits the transmission data from the frame generation unit 5 selectively output by the selection switch 6 or the transmission data from the “001” pattern generation unit 7. A continuous pattern (pattern signal) of “001” is given, and a transmission signal is generated based on these patterns and sent out.

Next, the operation of the test measurement for the digital transmission device 1 according to the present invention having the above configuration will be described. That is, in accordance with the DS3 standard of the ANSI standard, the transmission signal (4
4.746 Mb / s)
First, the operation mode of the digital transmission device 1 is set to the “test mode”, and the selection switching unit 6 is switched to the “001” pattern generation unit 7.
Is switched to supply the pattern signal from the transmission circuit unit 3 to the transmission circuit unit 3. At this time, the input to the receiving circuit unit 2 is “OPEN” (open) without any input, and the received data and the received clock of the receiving circuit unit 2 and the frame termination unit 4 are in an invalid state. However, since the test of the transmission system is tested here, the reception system may be separated.

In the state set as described above, the transmission circuit unit 3 transmits the transmission clock (4) from the frame generation unit 5.
4.746 MHz) and a pattern signal (repeated code of “001”) from the “001” pattern generator 7 to generate a transmission signal,
Send to 0. The pulse mask measuring device 10 checks the waveform of the transmission signal from the transmission circuit unit 3 against a preset pulse mask, measures whether the waveform is within a predetermined reference range, and determines pass / fail.

As described above, the digital transmission apparatus 1 incorporating the pattern generator according to the present invention has the “001” pattern generation section 7 incorporated therein. Since the pattern signal generated by the “001” pattern generation unit 7 is supplied to the transmission circuit unit 3, the transmission signal generated by the transmission circuit unit 3 can be independent of the performance of the reception circuit unit 2. . That is, if the determination result of the pulse mask measurement device 10 is rejected, it can be estimated that the transmission circuit unit 3 has a cause, and the accuracy of specifying the cause can be improved.

Further, a "001" pattern generator 2 is externally provided.
Since 0 is unnecessary, the test measurement configuration can be simplified. That is, the "001" pattern generator 20 provided outside needs not only a functional block for converting a pulse signal from a unipolar signal to a bipolar signal, but also an operation unit, a display unit, and a power supply circuit. On the other hand, the "001" pattern generator 7 incorporated in the present invention comprises only a circuit part which is the core of the "001" pattern generator 20. Therefore, the circuit scale of the "001" pattern generation unit 7 can be extremely small. Above, A
Although the present invention has been described by taking a transmission device conforming to DS3 of the NSI standard as an example, it is needless to say that the present invention can be applied to another device that has performed a loopback for testing a transmission circuit unit.

[0019]

As described above, the digital transmission apparatus incorporating the pattern generator according to the present invention can test only the transmission circuit section without being affected by the performance of the reception circuit section. Therefore, there is a remarkable effect that the performance of the transmission circuit unit alone can be checked. Further, the DS3 transmission pulse mask test can be performed without preparing an external "001" pattern generator.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a test and measurement system when a digital transmission device having a built-in pattern generator according to the present invention is a measurement target.

FIG. 2 is a diagram illustrating a configuration example of a test and measurement system when a conventional digital transmission device is to be measured.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Digital transmission apparatus 2 ... Receiving circuit part 3 ... Transmitting circuit part 4 ... Frame termination part 5 ... Frame generation part 6 ... Selection switching part (SEL) 7 ... " 001 "pattern generator 8 ... loop switch unit 10 ... pulse mask measuring device 20 ..." 001 "pattern generator

Claims (2)

[Claims] A digital circuit having a transmission circuit unit for generating and outputting a transmission signal corresponding to a transmission line code form from transmission data to be transmitted generated in a digital transmission apparatus and a transmission clock based on an internal clock. In the transmission device, a pattern generation unit that generates a predetermined signal pattern based on the transmission clock, and the transmission data and a signal pattern supplied from the pattern generation unit are input, and any one of the transmission data and the signal pattern is selected. A digital transmission device having a built-in pattern generator, comprising: a selection switching unit that outputs to a transmission circuit unit. 2. The pattern generator according to claim 1, wherein said digital transmission device is a device conforming to DS3 of the ANSI standard, and said pattern generation unit transmits a continuous pattern of "001". Digital transmission device with built-in device.