My question is how to design the loop_back without using 100 meter long
cable and still have the effect of 100 meter cable?
My idea is that using two short cables, 50cm, with resistors to
simulation attenuation of long cable shown below:
R1 : about
8.55 ohms to works as DC resistor for 100 m cable.
L1 (50 cm )
>--R1-------------------+ Because of
Characteristic imped. Z0 for cable is 100 ohms
| R2 // R3 =
100 ohms (to avoid reflection).
<---------------R2 +---+
L2 (50 cm) | R2/(R2+R3) =
attenuation of 100 m cable.
R3
|
----
/ / / (gnd)
Could somebody tell me if my idea is correct or not?
Thanks in advance.
John Lin
CAE of EDA dept, PC Engr.
Digital Equip. Corp. Taiwan
Email: [email protected]
TEL: 886-3-3900000 ext. 2565