Ps Next (Power Sum Near End Crosstalk); Ps Acr-N (Power Sum Attenuation To Crosstalk Ratio, Near End); Acr-F (Attenuation To Crosstalk Ratio, Far End) - Fluke CableAnalyzer DTX-1500 Technical Reference Handbook

PS NEXT (Power Sum Near End Crosstalk)

PS NEXT results show how much each cable pair is affected
by the combined crosstalk from the other pairs. PS NEXT is
the difference (in dB) between the test signal and the
crosstalk from the other pairs received at the same end of
the cabling. The tester uses the NEXT values to calculate
PS NEXT. Higher PS NEXT values correspond to better
cabling performance.
PS NEXT results are typically a few dB lower (worse) than
worst-case NEXT results.
The 4 dB rule may apply to your PS NEXT results.
See page 3-13.
PS ACR-N (Power Sum Attenuation to Crosstalk
Ratio, Near End)
PS ACR-N is also known as PSACR.
PS ACR-N values indicate how the amplitude of signals
received from a far-end transmitter compares to the
combined amplitudes of crosstalk produced by near-end
transmissions on the other cable pairs. PS ACR-N is the
difference (in dB) between PS NEXT and attenuation
(insertion loss). The tester uses the PS NEXT and attenuation
results to calculate PS ACR-N values. Higher PS ACR-N values
mean received signals are much larger than the crosstalk
from all the other cable pairs. Higher PS ACR-N values
correspond to better cabling performance.
Note
Note
Certifying Twisted Pair Cabling
Twisted Pair Autotest Results
PS ACR-N is the difference (in dB) between each wire pair's
attenuation (insertion loss) and the combined crosstalk
received from the other pairs. The tester uses the PS NEXT
and attenuation values to calculate PS ACR-N values.
PS ACR-N results are typically a few dB lower (worse) than
worst-case ACR-N results.
The 4 dB rule may apply to your PS ACR-N results.
See page 3-13.

ACR-F (Attenuation to Crosstalk Ratio, Far End)

ACR-F is also known as ELFEXT.
While NEXT is measured at the same end as the signal
source, FEXT (far-end crosstalk) is measured at the far end.
Because all far-end crosstalk signals travel the same
distance, they experience the same amount of attenuation,
as shown in Figure 3-15. This means that all crosstalk signals
contribute equally to noise at the far end. This is different
from near-end crosstalk. At the near end, crosstalk
occurring closer to the source contributes more to noise
than crosstalk occurring farther from the source 
(Figure 3-21).
The 70 dB rule may apply to your ACR-F results.
See page 3-13.
Note
Note
Note
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