NEWS & ARTICLES

T-1 Install Cable for Use At and Beyond the Premise Demarc

September 2001

First to develop a modular plug compatible T-1 cable for Central Office switching, Quabbin now introduces DataMax® T Line P/N 9719 for T-1 signaling and installation at and within the user premise network. This cable enables true T-1 signaling in the “last mile” of a commercial T-1 installation. Installers may now confidently extend T-1 transmission and signaling provided by the local Telco to customer's CSU/DSU devices.

T-1 cabling and signaling, developed for the Telco Central Office “T-Carrier” system, is not widely understood at the user or premise end of the network. Since most contractors and installers are not familiar with T-1 requirements, they often use the wrong cabling and connections when extending T-1 circuitry into and within the LAN. Using UTP category cabling, POS (point of sale) cable, or cable with the wrong impedance results in T-1 transmission problems. Worse, unshielded cable enables T-1 signaling to interfere with 10Base-T Ethernet protocols.

Quabbin's P/N 9719 cable will transmit a T-1 pulse (defined by ANSI specification T1.403) at distances up to and exceeding 300 feet and is easily terminated to space-saving modular connectors.  In larger campus type installations, these cables may also be bundled together without creating any damaging inter-cable (alien) T-1 signal crosstalk.

This two pair cable uses 22 AWG conductors insulated with a 2-layer composite insulation. When the outer insulation layer is removed, the inner one will fit into either a shielded or unshielded modular plug for an efficient IDC crimp termination. Details on termination to either shielded or unshielded modular connectors are available.

Each pair has an isolated tape shield and drain wire for termination ease. The cable's impedance is nominally 100 Ohms, has a 15 pF/ft capacitance, 71% velocity of propagation, and provides minimal T-1 signal distortion. The attenuation at 772 KHz is -0.5 dB/100 Ft with return loss > 30 dB through 3.5 MHz. An oval flame-retardant jacket provides both an NEC and CEC riser rating.

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