For the configuration shown in Figure 2-1 to work, the fiber equivalent distance between transceiver A and transceiver B must be less than 4200 meters. As you can see in the calculation, there are still 1510 meters left for expansion in this configuration.
Be aware that the link from a 10BASE-T Module to a 10BASE-T Transceiver should not exceed the distances as defined in Table 2-3. In this example, the link cannot exceed 150 meters, using the 10BASE-T standard High Squelch mode and 22 gauge wire.
Table 2-3. Maximum Link Distance on Twisted Pair
Cable Gauge | Supports Link Distances Up To: |
| | |
Unshielded Twisted Pair: | High Squelch | Low Squelch |
10BASE-T | | |
| | |
22 (.6mm) | 150m | 200m |
| | |
24 (.5mm) | 125m | 150m |
| | |
Shielded Twisted Pair: | High Squelch | Low Squelch |
IBM Type 1 | | |
| | |
22 (.6mm) | 200m | 300m |
| | |
In areas of low noise, the Squelch level can be lowered to accept weaker signals. (Low Squelch does not conform to the 10BASE-T standard.) This allows the acceptable link distance to increase to 200 meters. The 10BASE-T standard limits link distance to approximately 200 meters (equivalent to 1 μsec of delay) on unshielded twisted pair.
10BASE-T signaling can also be used on shielded twisted pair even though the standard does not include shielded twisted pair in its specification. Since external noise does not affect signals on shielded twisted pair, there is no restriction in using the Low Squelch level. Using Low Squelch on shielded twisted pair allows link distances of up to 300 meters. Nevertheless, 3Com recommends that you always use the High Squelch setting except in situations where the link distance exceeds 200 meters.
2 - 10 ONline Ethernet 10BASE-T Module User’s Guide
