The optical input power limits differ significantly between the two models. Strictly observe the following latest key specifications during testing:

DCA6201 Specifications

Test Sensitivity and Linear Measurement Range:

• NRZ: -8 to 0 dBm
• PAM4: -7 to -1 dBm

Maximum Trigger Input Peak-to-Peak Voltage: < 1.5 Vpp
Do not apply an electrical signal exceeding this limit.

DCA1065 Specifications

Test Sensitivity and Linear Measurement Range:

• PAM4: -5 to -1 dBm

Check the following two items:

1、Filter Setting

Check whether the Filter is configured correctly and make sure it has not been mistakenly set to a data rate intended for an electrical port.

2、External Signal

Confirm that the external signal is normal by checking whether the CDR has successfully locked.

If the eye diagram remains clearly abnormal and the issue is not related to the settings, please take a screenshot and contact FAE for further diagnosis.

Check the following three items:

① Confirm that no optical signal is entering the instrument.

② Confirm that the host computer is properly connected to the instrument.

③ Confirm that the instrument has been successfully switched to the correct data rate for the corresponding optical port.

If the calibration still fails after confirming all the above, please contact FAE for further assistance.

Please check the following items in sequence:

1、Mask Template Mismatch

Confirm that the selected Mask template matches the current test data rate. The name of the active template is displayed in the lower-left corner of the eye diagram.

2、Optical Input Power and Configuration

Confirm that the optical input power is within the linear range of -8 to -2 dBm and that the correct wavelength is selected.

3、Waveform Count

Check whether the Waveforms setting is configured correctly.

If the Margin measurement still shows a significant deviation after completing the above checks, perform a cross-check with another DCA under the same test conditions. After ruling out external environmental factors, contact FAE for further assistance.

There are two common causes:

1、Excessive Temperature Difference (Dark Current Recalibration Required)

If the current instrument temperature differs significantly from the temperature at which the previous dark current calibration was performed, the ER measurement may deviate. A temperature warning will appear below the eye diagram. It is recommended to set the temperature-difference warning threshold to 2–3°C under Calibration. If the warning appears, perform the dark current calibration again.

2、Incorrect ERCF Setting

Check whether the ERCF is correctly set for each data rate. The ERCF can be set to either a positive or negative value, but values beyond ±5% are not recommended.

If the ER measurement still shows a deviation after completing the above checks, perform a cross-check with another DCA under the same test conditions. After ruling out external environmental factors, contact FAE for further assistance.

Strictly observe the optical input power limits to prevent overload damage to internal components.

Optimal Linear Input Power Range: -8 dBm to -2 dBm (approximately -5 dBm recommended).

Damage Threshold: Input power above +7 dBm will cause permanent damage to the instrument. Do not exceed this limit.

Please troubleshoot the issue in the following three-step sequence:

1、Optical Port Contamination

Use a fiber inspection scope (FC/PC connector) to inspect the optical port. Contamination in the central optical transmission path may interfere with the signal and cause measurement errors. If contamination is found, clean it immediately with a fiber cleaning pen.

2、Incorrect Setting

Check whether the wavelength is set correctly in the host software. For example, if the signal under test is 1310 nm, make sure the wavelength has not been incorrectly set to 850 nm.

3、Adapter Damage

Visually inspect the fiber adapter in a well-lit environment. If the ceramic sleeve inside the adapter is cracked, replace the adapter.

If all the above checks are completed and no issues are found, but the problem persists after restarting the instrument, please contact Lianxun FAE for confirmation before returning the instrument for repair.

The default device IP address is 192.168.170.7 (port 8807). Configure the local computer's IP address as 192.168.170.X, then select LAN to establish a direct connection.