Specifications

RADring
Installation & Operation Manual Token Ring Desing Considerations
3/11/98 12:26 Configuration Examples 6-15
Preventing Saturation of Optical Receivers
Optical receivers are optimized for operation at low optical power levels
(long cable runs). When the optical input power reaching the receiver is too
high, the receiver may saturate. Saturation causes pulse distortion, resulting
in very high bit error rate, high enough to disrupt data transmission. It is
therefore essential to prevent receiver saturation.
The dynamic range of the optical receivers used by the TFC is 20dB, and
their sensitivity is -32dBm. Therefore, the maximum optical input power
before saturation occurs is: -32dBm + 20dBm = -12dBm.
The saturation power is high enough to ensure that the TFC receiver will
never saturate when receiving the signal generated by another TFC, even
when operating with short 100/140 micron cable having a very low
attenuation.
6.6 Configuration Examples
1
2
TL-2/ED
1
2
TL-2/ED
1
2
3
4
TL-4/ASU
1
3
2
4
1
2
3
4
TL-4/U
1
3
2
4
1
2
3
4
TL-4/U
1
3
2
4
1
2
TL-2/F
TX
RX
TX
RX
CH1
CH2
1
2
TL-2/F
TX
RX
TX
RX
CH1
CH2
1
2
TL-2/F
TX
RX
TX
RX
CH1
CH2
TFR
TX
RX
TL-4/S
2
4
1
3
1
3
2
4
CH1 CH2
CML/NM
RESET
T
J
A
/
Figure 6-3 Stand alone hub - Passive lobes
Access Module Type Media Type Guaranteed lobe Distance (L)
4 Mbps 16 Mbps
TL-4/U type 3 100 m 70 - 80 m
TL-4/U level 4, 5 180 m 100 m
TL-4/S type 1 375 m 200 m
TL-4/CX 300 m 100 m