70 dB FEXT rule - DTX CableAnalyzer

  • The 70 dB rule applies to any TIA Perm. Link or ISO/IEC test limit containing the ACR-F measurement.
  • If at any frequency the FEXT is less than 70 dB, the ACR-F cannot fail at that frequency.
  • ACR-F is a calculation of FEXT minus the Insertion Loss.
  • On VERY RARE occasions, you may see "i" against the ACR-F summary result, meaning that the entire FEXT measurement was less than 70 dB for all pair combinations, so all of the ACR-F calculations are "ignored" or as the standards phrase it; "for information only".
  • This "i" will ressult in N/A appearing in the LinkWare Software and is nothing to be concerned about.
  • This was added in Version 2.74 Software.
  • Practically speaking, it will not turn an existing FAIL into a PASS or vice versa.