The Unger Model is an empirical standard model for near-end crosstalk (NEXT) power spectra as experienced by communication systems over unshielded twisted pair (UTP). Twisted pair cables are usually grouped together in a binder where they experience crosstalk. Based on empirical observations, Unger proposed that, at the 1% worst case, the NEXT power spectra | H N E X T ( f ) | 2 {\displaystyle |H_{\mathrm {NEXT} }(f)|^{2}} , due to a single disturber, can be bounded by
10 log ( | H N E X T ( f ) | 2 ) = { − 66 + 6 log ( f ) dB , if f < 20 kHz ; − 50.5 + 15 log ( f ) dB , if f ≥ 20 kHz . {\displaystyle 10\log(|H_{\mathrm {NEXT} }(f)|^{2})={\begin{cases}-66+6\log(f)\,{\text{dB}},&{\text{if }}f<20\,{\text{kHz}};\\-50.5+15\log(f)\,{\text{dB}},&{\text{if }}f\geq 20\,{\text{kHz}}.\end{cases}}}
while the NEXT power spectra due to 49 disturbers (full binder) can be bounded by
10 log ( | H N E X T ( f ) | 2 ) = { − 59.2 + 4 log ( f ) dB , if f < 20 kHz ; − 42.2 + 14 log ( f ) dB , if f ≥ 20 kHz . {\displaystyle 10\log(|H_{\mathrm {NEXT} }(f)|^{2})={\begin{cases}-59.2+4\log(f)\,{\text{dB}},&{\text{if }}f<20\,{\text{kHz}};\\-42.2+14\log(f)\,{\text{dB}},&{\text{if }}f\geq 20\,{\text{kHz}}.\end{cases}}}
References
See also Digital subscriber line