OPTICAL SYSTEMS DESIGN
DOC ID: 10111701
OSD9003/OSD9004 OPERATOR MANUAL
PAGE 11
2.5.4
SYSTEM SETTING RECOMMENDATIONS
The RF output power can be set to provide system unity gain if there is sufficient received optical
power. Table 6 shows what levels to expect in OSD9003/9004 system
TABLE 6: TYPICAL LEVELS FOR SINGLE CARRIER
Input RF
[dBm]
OSD9003
RF
Attenuator
[dB]
Tx Optical
Power
[dBm]
Optical
Attenuation
[dB]
Rx Optical
Power
[dBm]
OSD9004
RF
Attenuator
[dB]
Output RF
[dBm]
-10
0
+5.0
5.0
0
Auto
–26... –28
-10
0
+5.0
11
–6
Auto
–26... –28
-10
0
+5.0
17
–12
Auto
–26... –28
-10
0
+5.0
23
–18
Auto
–32... –34
-10
0
+5.0
26
–21
Auto
–38
-10
0
+5.0
26
–21
0
–38
-10
0
+5.0
23
–18
0
–32
-10
0
+5.0
20
–15
0
–26
-10
0
+5.0
17
–12
6
–26
-10
0
+5.0
14
–9
12
–26
-10
0
+5.0
11
–6
18
–27
-10
0
+5.0
8
–3
24
–27
-10
0
+5.0
5
0
30
–27
For best results, please note the following:
ALL
RF Fiber Optic Transmission Systems operate best if:
a.
Input carriers are as close as possible within each other, as this maximises the effective optical
power available to each carrier.
b.
The combined RF input spectrum is adjusted just below the onset of inter-modulation
distortion where the laser is still reasonably linear.
c.
It is important to have minimal optical reflections back to the laser diode. This is best ensured
by using only high quality, angle polished physical contact (SC/APC) optical connectors
which have a high optical return loss. Connectors must be clean and scratch free.
Similarly high quality splices (typically these are fusion splices) must be used to minimise
such reflections.
d.
The receiver's optical input is not overloaded with too much optical power, ie more than
+3dBm optical power, as this will cause saturation and subsequent intermodulation
distortion.
RF level figures in Table 6 are given for a single carrier. Suggested power levels per carrier for
multichannel operation are in Table 5.
