Due to inherent imbalances in balanced twisted-pair cabling and components, differential mode signals traveling along balanced twisted-pairs can be partly converted to common mode signals and common mode signals traveling along a balanced twisted-pairs can be partly converted to differential mode signals. This mechanism is referred to as mode conversion. There are multiple mode conversion parameters within a twisted-pair and between twisted-pairs that can manifest as additional sources of alien crosstalk between channels.
TSB-1197 “Mode Conversion Parameters for Balanced Twisted Pair Cabling” was developed by the TIA TR-42.7 Copper Cabling Subcommittee and published in September, 2014. TSB-1197 presents models that explain the effects of mode conversion parameters within a pair (TCL,LCL, TCTL, and LCTL), mode conversion parameters between pairs (NEXTdc , NEXTcd, FEXTdc, and FEXTcd), and other common mode parameters (NEXTcc, FEXTcc, ILcc, and RLcc) on alien crosstalk between channels. In addition, this bulletin provides an assessment of mode conversion parameters for category 6A UTP cabling and components and includes methods that may be used to evaluate these parameters. These models are provided to help cabling professionals better understand noise coupling mechanisms in balanced twisted-pair cabling (including alien crosstalk and other sources of external noise); it not the intent of this bulletin to specify performance recommendations for these parameters.
TSB-140 Content
- Mode Conversion Parameters
- Modeling Results