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CHAPTER 6: Cable Test Descriptions
3. Press ENTER. The test begins scanning immediately. (Press the arrow
keys to select another cable test standard.)
6.5.2 V
IEWING
ACR R
ESULTS
For each pair combination the ACR is displayed along with the frequency.
The attenuation value used is from the receive pair (for example, pair 3,6 of
12/36).
Press START (F1) to restart the test.
NOTE
Minimum ACR is not presently specified in most link test standards (such
as TIA TSB-67) or network standards (such as IEEE 802.3). ISO 11801
requires at least 4 dB of ACR at 100 MHz. Hub manufacturers recommend
a minimum of 5 dB for reliable data transmission.
6.6 Noise
Impulse Noise is non-repetitive electrical spikes or pulses caused by
external electromagnetic fields. It is one of the primary causes of
inconsistent performance on unshielded twisted-pair networks.
The Noise test counts noise impulses (spikes) greater in amplitude than a
minimum threshold on an idle twisted-pair cable segment and provides a
report of the results.
F1
F2
F3
F4