Inter-Relay Communications - GE L30 Instruction Manual

2.4 SPECIFICATIONS
ETHERNET SWITCH FIBER OPTIC PORTS
Maximum fiber segment length calculation:
The maximum fiber segment length between two adjacent
switches or between a switch and a device is calculated as fol-
lows. First, calculate the optical power budget (OPB) of each
device using the manufacturer's data sheets.
OPB
2
where OPB = optical power budget, P
and P = receiver sensitivity.
R
The worst case optical power budget (OPB
lated by taking the lower of the two calculated power budgets, sub-
tracting 1 dB for LED aging, and then subtracting the total insertion
loss. The total insertion loss is calculated by multiplying the num-
ber of connectors in each single fiber path by 0.5 dB. For example,
with a single fiber cable between the two devices, there will be a
minimum of two connections in either transmit or receive fiber
paths for a total insertion loss of 1db for either direction:
Total insertion loss
The worst-case optical power budget between two type 2T or 2S
modules using a single fiber cable is:
OPB = OPB 1 dB (LED aging) –
WORST
10dB 1dB 1dB
– – =
To calculate the maximum fiber length, divide the worst-case opti-
cal power budget by the cable attenuation per unit distance speci-
fied in the manufacturer data sheets. For example, typical
attenuation for 62.5/125 μm glass fiber optic cable is approxi-
mately 2.8 dB per km. In our example, this would result in the fol-
lowing maximum fiber length:
Maximum fiber length
The customer must use the attenuation specified within the manu-
facturer data sheets for accurate calculation of the maximum fiber
length.
SHIELDED TWISTED-PAIR INTERFACE OPTIONS
INTERFACE TYPE
RS422
G.703
RS422 distance is based on transmitter power
and does not take into consideration the clock
NOTE
source provided by the user.
2-24
P P
= –
( ) ( )
T MIN R MIN
= transmitter output power,
T
) is then calcu-
WORST
×
= number of connectors 0.5 dB
×
2 0.5 dB 1.0 dB
= =
– total insertion loss
8dB
OPB (in dB)
WORST
= ------------------------------------------------------ -
cable loss (in dB/km)
8 dB
= -------------------------- - = 2.8km
2.8 dB/km
TYPICAL DISTANCE
1200 m
100 m
L30 Line Current Differential System
2 PRODUCT DESCRIPTION
ETHERNET SWITCH 10/100BASE-T PORTS
Connector type: RJ45
MAXIMUM 10 MBPS ETHERNET SEGMENT LENGTHS
Unshielded twisted pair: 100 m (328 ft.)
Shielded twisted pair: 150 m (492 ft.)
MAXIMUM STANDARD FAST ETHERNET SEGMENT LENGTHS
10Base-T (CAT 3, 4, 5 UTP): 100 m (328 ft.)
100Base-TX (CAT 5 UTP):100 m (328 ft.)
Shielded twisted pair: 150 m (492 ft.)

2.4.9 INTER-RELAY COMMUNICATIONS

LINK POWER BUDGET
EMITTER, TRANSMIT
FIBER TYPE POWER
820 nm LED, –20 dBm
Multimode
1300 nm LED, –21 dBm
Multimode
1300 nm ELED, –23 dBm
Singlemode
1300 nm Laser, –1 dBm
Singlemode
1550 nm Laser, +5 dBm
Singlemode
These power budgets are calculated from the
manufacturer's worst-case transmitter power
NOTE
and worst case receiver sensitivity.
RECEIVED POWER
SENSITIVITY BUDGET
–30 dBm 10 dB
–30 dBm 9 dB
–32 dBm 9 dB
–30 dBm 29 dB
–30 dBm 35 dB
GE Multilin