Semight-SUPPORT-FAQ-Semight Instruments

Q&A

Common Problem

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？Q

The Er of the sampling oscilloscope dca4201 is unstable or the equipment of competitive products is quite different

A

Before use, it needs to heat the engine for more than 15 minutes to make the equipment reach thermal balance, and then conduct dark current calibration. At this time, the ER brush value is stable; In addition, if there is still a gap between ER and competitive products at this time, ercf compensation can be made. The method is: measure configure measurement - set the corresponding ercf compensation
？Q

Can the new generation of sampling oscilloscope dca4201 be connected with network cable?

A

No, the first generation only supports USB connection
？Q

Sampling oscilloscope dca4201 generation driver can't be installed successfully?

A

Confirm the computer system. If the win10 system needs to disable digital signature, install the driver according to the manual. After the installation is successful, connect the device and see Holly 10g in the device manager
？Q

Why is the jitRMS of the module products tested by the sampling oscilloscope too large, or other indicators are poor?

A

a. Bert's high-frequency signal and trigger cable are not plugged properly --- check the cable connection
b. The inside of the optical port flange interface is dirty, or the optical fiber is dirty --- clean the port
c. The optical power is not in the proper range --- generally, the optical power is in the range of - 3 ~ - 6dbm, and better test results can be obtained by increasing the optical power
d. If a single end is used, whether it is matched at differential termination -- both ends of Bert and clamp need to be matched with 50 ohms
？Q

Why does the ER test result of the sampling oscilloscope have a large deviation and is unstable (especially for a large Er of 1.25g or 2.5G, more than 10)?

A

Possible causes and solutions:
a. When the DCA was just started, the test was started when there was no thermal balance. The device was affected by the temperature rise, and level1 and level0 changed violently. Please start the test 15-20 minutes after the machine is started and the machine reaches the thermal balance;
b. Before the test, please calibrate dark to get a more stable Er value;
c. If the ER is still different after the above operations are completed, perform ercf compensation and align the ER test results of the calibration oscilloscope;
？Q

Why is the eye chart of the sampling oscilloscope so poor that it is easy to be dazzled?

A

a. Check the optical power, and the best use range is - 3 ~ - 6dbm
b. Eliminate that the trigger jitter is too large, cross verify and replace a bit error detector
？Q

Why is there a big difference between the optical power read by the sampling oscilloscope DCA and the actual optical power?

A

a. Check whether there is dirt inside the fiber inlet flange
b. Whether the smooth flange ceramic is broken
c. Whether optical power compensation is added inside the GUI
？Q

Why does the sampling oscilloscope have no eye chart?

A

a. Check incoming light -- check optical power
b. Check whether the modulation signal of the bit error meter is on
c. Check whether trigger is abnormal
In the above three steps, DCA of other brands can be used to verify the cross verification of optical path and high-frequency signal.
？Q

How to use sampling oscilloscope DCA? Description of specific operation steps.

A

a. Warm up the engine for 15 minutes before use
b. Connect the external trigger to the trig of DCA and connect the optical signal to the optical port (optical power recommendation - 3 to - 6)
c. Open the GUI to connect the device, and the first time it is connected will take a long time (it needs to read the internal information of the device)
d. Select the channel and rate. Note that dark current calibration must be performed after changing the channel or reopening the GUI
e. Add appropriate waveforms and appropriate mask template, check the test item on the left for normal test

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