1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
Intel Confidential
107
Worst-Case Cable for Jitter
Appendix C: Worst-Case Cable for Jitter
The cable used for the transmit jitter test is comprised of three sections: 2 120-ohm characteristic
impedance sections and 1 long CAT 5 100-ohm characteristic impedance section.
Note:
This cable is under development.
C.1
Constructing the 120-ohm Impedance Segments (L1
and L3)
It is recommended that a shielded 120-ohm impedance twisted-pair cable is used for construction.
(Shielded four-pair twisted pair 120-ohm cable is available from Alcatel [Alcatel 6806 GigaMatch
FTP 4P] and Belden [Belden YR44160 CM 4PR24 Shielded.)
1. Cut the cable (preferably, one of the cables mentioned above) to the lengths specified in the
IEEE 802.3ab specifications or this document.
2. Trim the outer insulating jacket and shield back about 1.5 inches.
3. Slide two four inch pieces of 3/8-inch or 1/2-inch diameter heat shrink tubing to the middle of
the cable. (Do not heat or shrink the tubing.)
4. Splice individual, insulated 1.5 inch pieces of 24 AWG CAT 5 wires at each end of each cable
on each of the eight conductors. (The wires in the shielded cables are too think to fit inside the
RJ-45 crimp-on connectors.)
5. Verify that the splices will not create a short on any of the twisted pair wires with each other.
Heat shrink or kapton tape can be should be used to insulate the splices.