JPH02244834A - Method for testing optical signal reception equipment - Google Patents

Abstract

PURPOSE:To perform tests for plural optical links simultaneously, to compress testing man-hours, and to simplify the test by providing a photocoupler to divide the light output of an optical signal source into plural light output, the optical link to receive divided output from the photocoupler, and a comparator to compare digital output from the optical link. CONSTITUTION:An optical signal corresponding to a digital test signal is sent from the optical signal source 1, and is inputted to the photocoupler 4 via an optical fiber. The photocoupler 4 sends an inputted optical signal by dividing equally in parallel, and inputs them to the optical links 20-23, respectively in parallel. A digital signal from a reference optical link 20 is compared with the digital signals outputted from the optical links 21-23 to be tested, respectively at a comparison selector 5, and a comparison result is inputted to an optical link tester 3, and it is judged that the result is normal when it coincides with the output signal of the reference optical link 20, and it is judged as abnormal when noncoincidence is obtained. Thereby, it is possible to test the plural optical links simultaneously, and to compress the testing man-hours, and to simplify the test.

Description

[Detailed Description of the Invention] (Summary) This invention relates to a method for testing an optical signal receiving device that receives an optical signal and converts it into an electrical signal, with the aim of simultaneously testing multiple optical data links. an optical coupler that divides an optical output into a plurality of optical outputs, an optical link that receives each divided output from the optical coupler via an optical fiber, and a comparator that compares the digital output from the optical link; an optical link tester that tests and determines the output from the comparator, one of the optical links is used as a reference optical link whose normal operation has been confirmed in advance, and the remaining optical links are used as optical links to be tested, The comparator compares the outputs of the reference optical link and the remaining optical links under test, and the optical link tester determines the quality of the optical links under test.

[Industrial application field]

The present invention relates to a method for testing an optical signal receiving device such as an optical digital data link that receives an optical signal and converts it into an electrical signal.

An optical signal receiving device (hereinafter referred to as an optical link) such as an optical digital data link is a device that receives an optical signal emitted from an optical fiber and converts it into a corresponding electrical signal.

In recent years, compact and low-cost optical digital data links have been developed for the purpose of data transmission, but in order to supply these optical links at low cost, it is necessary to efficiently test the optical links after assembly. be.

[Conventional technology]

A conventional optical link testing method is shown in FIG. In the figure, 1 is an optical signal source, 2 is an optical link under test, and 3 is an optical link tester.

An optical signal source 1 is a random pattern generator of optical pulses, and an optical signal corresponding to a test data signal is sent to an optical link under test 2 through an optical fiber. The optical link under test 2 converts the optical signal received from the optical fiber into a digital electrical signal and sends it to the optical link tester 3. The optical link tester 3 checks whether the physical characteristics of the received digital signal are within the specifications and determines whether the optical link under test is good or bad.

Optical link tests include the error rate of data output, the presence or absence of clock output, and the presence or absence of optical signal disconnection alarms, but among these, the error rate test is the most important, and the test time is long. It may take some time.

[Problem to be solved by the invention]

In conventional optical link testing, a method is used in which one item is tested, and after all links have been tested, the next item is tested. In such a method, the test link must be replaced every time one optical link terminates.
Replacement man-hours increased costs, and as the number of optical links for testing increased, testing time also increased.

An object of the present invention is to test a plurality of these optical links at the same time, thereby reducing the number of testing steps and simplifying the testing.

[Means to solve the problem]

The principle configuration diagram of the test method of the present invention is shown in FIG.

In the figure, 1 is an optical signal source, 2 is an optical link under test, 3 is an optical link tester, 4 is an optical coupler, and 5 is a comparison selector. 21.
22 and 23 indicate optical links to be tested.

The optical signal source 1 and the optical coupler are connected by optical fibers, and the output terminal of the optical coupler 4 and the reference optical link 20 and the optical links under test 21, 22, 23 are connected by optical fibers. In addition, the output of the reference optical link 20 and the optical link under test 2
The comparison selector 5 compares the outputs of 1.22.23 and inputs the comparison results to the optical link tester 3.

The reference optical link 20 used is one that has been thoroughly tested in advance using the optical link tester 3 and has been determined to pass.

[Effect]

An optical signal corresponding to the digital test signal is sent out from an optical signal source 1 and input to an optical coupler 4 via an optical fiber.

The optical coupler 4 equally divides the input optical signal and sends it out in parallel. The divided optical signals are sent out in parallel through optical fibers to optical links 20, 21, 22, and 23, respectively.

The digital signal from the reference optical link 20, J:, and the digital signal output from the optical link under test 21, 22, 23 are compared by the comparison selector 5, and the comparison results are input to the optical link tester 3, If it is the same as the output signal of the reference optical link 20, it is determined to be good (5), and if it is not the same as the output of the reference optical link 20, it is determined to be defective.

Compare the output digital signals of the reference optical link 20 and the output digital signals of the optical links under test 21, 22, and 23, respectively, and if there are any signal omissions or deviations,
The optical link tester 3 can determine that the optical link under test has a signal error and select it. By separately performing a detailed test on the selected optical links to be tested using the optical link tester 3, it is possible to specify the nature of the defect.

〔Example〕

In FIG. 6 showing the second embodiment of the test method of the present invention, l is an optical signal source, 4 is an optical coupler, 20 is a reference optical link, 21, 22, 23 is an optical link under test, 51, 52゜53 is an EXOR gate, and 3 is an optical link tester.

The optical coupler 4 is a 1:4 optical coupler (star coupler) that optically divides the input amount into four parts and outputs the divided parts. In order to maintain this optical output, the output of the optical signal source 1 is made larger than before.
EXOR gates 51, 52, 53 input the output of the reference optical link 20 and the output of the optical links under test 21, 22, 23, respectively, and if it is a combination of mQZ@Qll or "l", '1', it is "0". ” and outputs “0”, “l” or “1”.

If the combination is "0", "1" is output. The optical link tester 3 determines that the signal is OK when the signal is O', and judges that the signal is defective or has an error when the signal is "1".

Now the digital input of the optical signal source 1 and the optical link 20゜21,
22. Comparison with the digital output of 23 is shown in the timing chart of FIG. ■.

(2) indicates the digital output of the optical links under test 21, 22.23; (2), (2), and (2) the comparative selection outputs of the ExOR gates 51, 52.53; (2) indicates the judgment signal of the optical link tester 3;

Since the output ■ of the reference optical link 20 is the same as the input signal ■ of the optical signal source l, the outputs ■, ■, ■ of the optical links under test 21, 22, 23 and the output ■ of the reference optical link 20 are the same. Check if there is BXOR gate 51゜52.5
3, and if the waveforms are the same, output "O',
If there is a discrepancy in even one pulse, it outputs “l”, so if ■, ■, and ■ are “0”, the optical link tester 3 determines that the optical link under test is normal, and If any of them detects "1", the optical link tester 3 holds that signal and determines that there is an abnormality in the corresponding optical link under test. In this case, since "1" is detected in the output of (2), it is determined that there is a code error in the optical link under test NCL2.

Note that in this example, a 1:4 optical star coupler is used.
Although one reference optical link and three optical links under test were divided and compared and determined, it is possible to simultaneously test even more optical links under test by using a 1:8 or 1:16 optical coupler. I can do it.

〔Effect of the invention〕

According to the present invention, since a plurality of optical links can be tested simultaneously, the number of testing steps can be reduced compared to the conventional method of connecting and testing optical links one by one. In addition, the number of man-hours required for tests that require a long time, such as code error rate tests, can be significantly reduced. Furthermore, if the logarithm of the optical coupler is increased, more optical links can be judged simultaneously, and the effect is even greater.

51, 52, 53 indicate EXOR gates, and ■～■
indicates the signal in the timing chart.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a circuit diagram of an embodiment, FIG. 3 is a timing chart of the embodiment, and FIG. 4 is a block diagram of a conventional example. In the figure, 1 is an optical signal source, 2 is an optical link, 3 is an optical link tester, 4 is an optical coupler, 5 is a comparator, 20 is a reference optical link, 21, 22, 23 are optical links under test, and input signals
■ Timing chart of the example Fig. 3

Claims (1)

[Claims] An optical signal receiving device that receives an optical signal and converts it into an electrical signal (
(optical link), an optical coupler (4) that divides the optical output of the optical signal source (1) into a plurality of optical outputs, and receives the divided outputs from the optical coupler (4) via optical fibers. A plurality of optical links (2), a comparator (5) that compares the outputs from the plurality of optical links (2), and an optical link tester (5) that tests and determines the outputs from the comparator (5). 3), one of the plurality of optical links (2) is used as a reference optical link (20) whose normal operation has been confirmed in advance, and the remaining optical links (21) and others are used as optical links under test. , the reference optical link (
20) and the remaining optical links to be tested (21) and others are compared by the comparator (5), and the outputs of the optical link tester (3) are compared.
) is used to determine the quality of the optical link under test (21).