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Allowable range of core error (hardware design benchmark)

1. Crosstalk (NEXT/ELFEXT/PS ANEXT) - Complies with Level 2G/VI standards: the error is controlled within ± 1 dB of the standard limit. For example, the PS ANEXT limit for Cat 8 permanent links is 23.4 dB@2000  MHz， The error of the tester should be ≤ ± 1 dB, ensuring that the test margin is ≥ 2 dB.

2. Hardware redundancy design: In actual testing, the NEXT margin is usually 3-5 dB higher than the standard requirement. For example, the measured PS ANEXT of a Cat 8 jumper is 25 dB, and the tester displays 24-26 dB, far exceeding the standard limit.

Insertion Loss - Temperature Compensation Mechanism: 

Within the range of 0 ° C-45 ° C, for every 10 ° C increase in temperature, the copper cable resistance increases by about 4%. The tester controls the attenuation test error within ± 0.75 dB through a built-in algorithm. 

Calibration accuracy: After annual calibration, the attenuation error can be further reduced to ± 0.5 dB. 

For example, the measured attenuation of a 100 meter Cat 8 link is 19 dB, and the tester displays 18.5-19.5 dB, which meets TIA standards.

Return loss (RL) - calibrated error: 

After restoring the hardware reference value through the DSX-CAL calibration kit, the return loss error is ≤± 1 dB, which can increase the link margin by 1-2 dB. For example, the RL measured value of a Cat 8 jumper is 20 dB, and the tester displays 19-21 dB, which meets the standard requirements (≥ 12 dB) dB@2000  MHz）

Length measurement - segmented accuracy design:

0-150 meters: ± (0.3 meters+2%). For example, when testing a 100 meter link, the error range is ± 2.3 meters. 

150-800 meters: ± (0.3 meters+4%). For example, when testing a 200 meter link, the error range is ± 8.3 meters. 

NVP setting impact: If NVP is not set correctly (default 70%), the error may increase by an additional ± 30%. 

It is recommended to calibrate NVP using a known length cable (such as a 30 meter Cat 8 jumper), with an error margin of ≤± 2%.

Delay and Delay Deviation - Delay Test:

Accuracy up to ± 20 ns, suitable for timing sensitive applications such as 40GBASE-T.  

Delay deviation: Error ≤ ± 50 ns, ensuring synchronous transmission of multiple pairs of signals.

Flow resistance and PoE related parameters - Resistance imbalance test:

Error ≤± (0.5 Ω+1%), for example, when testing a 50 Ω link, the error range is ± 1 Ω to ensure the stability of 4PPOE power supply.  

PoE voltage measurement: error ≤ ± 2 V (DC/AC), in compliance with IEEE 802.3bt standard.

The core sources of errors and control measures

Environmental factors - Temperature: When the temperature exceeds the range of 0 ° C-45 ° C, the attenuation test error may increase by ± 1.5 dB.

It is recommended to test in an environment of 23 ° C ± 2 ° C, or enable the temperature compensation function of the tester (the error can be reduced to ± 0.5 dB).  

Humidity:>90% RH may lead to a decrease in insulation performance and an increase of ± 1 dB in NEXT testing error.

The core sources of errors and control measures

Hardware status and calibration - calibration cycle:

It is recommended to calibrate annually through an NVLAP certified laboratory to restore hardware benchmark values.

For example, the calibrated DSX-8000 can increase the return loss margin by 1-2 dB.

Test line loss:

 After every 5000 uses, the insertion loss of the DSX-CHA804S channel adapter may increase by 0.5 dB and needs to be replaced in a timely manner.

Industrial Environmental Interference Testing - Temperature Effects:

When testing the Cat 8 link at 35 ° C, the attenuation test error increased by 1.5 dB, and the tester displayed a margin of 4 dB, which was actually only 2.5 dB.

After enabling temperature compensation, the error is reduced to ± 0.5 dB and the displayed margin is 3.5 dB.

PoE power supply verification - DC resistance test:

The actual resistance of a certain link is 18 Ω (compliant with IEEE 802.3bt requirement ≤ 20 Ω), with a tester error of ± 1 Ω and a display of 17-19 Ω, ensuring power supply reliability.

The core sources of errors and control measures

Test standard matching:

Testing ISO links using TIA standards may mask issues, such as the PS ANEXT requirement for Class I being 2 dB stricter than TIA, and ensuring that the testing standards are consistent with the link level.

Test mode selection:

In dual ended testing mode, the crosstalk testing error is reduced by 30% compared to single ended mode, especially suitable for high-precision scenarios such as Cat 8/Class I/II.

Key measures for error control

Choose the appropriate testing mode:

Double ended testing: suitable for high-precision scenarios such as Cat 8/Class I/II, with an error reduction of 30% compared to single ended mode. -Automatic calibration: Run an internal calibration program before each test to compensate for the effects of test line and environmental fluctuations.

Optimize testing environment: - Temperature control: Test in an environment of 23 ° C ± 2 ° C, or use the DSX-REF-MOD reference module for temperature compensation. -Electromagnetic shielding: Keep away from interference sources such as motors and transformers to avoid an increase of ± 3 dB in crosstalk testing error.

Regular maintenance and verification: - Calibration records: Save calibration certificates to ensure that errors comply with TIA Level 2G/IEC Level VI standards.

Redundancy testing: Conducting 3 tests on critical links and taking the average can reduce length errors by 30%.

Industry standards and compliance

TIA-568-C.2: The accuracy of the tester is required to meet Level 2G, with an error range of - NEXT: ± 1 dB (1-2000 MHz) 

Attenuation: ± 0.75 dB (1-2000 MHz)。

ISO/IEC 11801: Class I/II requires testers to comply with Level VI with stricter error control (e.g. ACR-F margin needs to be at least 2 dB higher than the standard).

Calibration requirements: Annual calibration is a necessary condition for maintaining compliance, otherwise errors may exceed the allowable range of the standard.