OPTICAL SYSTEMS DESIGN
DOC ID: 10111701
OSD9003/OSD9004 OPERATOR MANUAL
PAGE 10
The RF input level to the transmitter is adjusted for optimum Optical Modulation Index (OMI). The
input RF attenuator has a range of 31dB. It is important to set the attenuator so that the laser is working
with optimum modulation that will provide the best signal to noise ratio for the received signal. Table 5
provides a matrix of attenuator settings (RF Attn in dB) for the number of carrier channels whilst
showing the RF input range in dBm per carrier.
TABLE 5: ATTENUATOR SETTING MATRIX
RF Att.
(dB)
Number of Carriers
1
2
4
6
10
15
30
60
0
-10
–13
–16
–18
–20
–22
–25
–28
R
F
I
n
p
u
t
R
an
g
e
(d
B
m
/c
ar
ri
er
)
1
-9
-12
-15
-17
-19
-21
-24
-27
2
-8
-11
-14
-16
-18
-20
-23
-26
3
-7
-10
-13
-15
-17
-19
-22
-25
4
-6
-9
-12
-14
-16
-18
-21
-24
5
-5
-8
-11
-13
-15
-17
-20
-23
6
-4
-7
-10
-12
-14
-16
-19
-22
7
-3
-6
-9
-11
-13
-15
-18
-21
8
-2
-5
-8
-10
-12
-14
-17
-20
9
-1
-4
-7
-9
-11
-13
-16
-19
10
0
-3
-6
-8
-10
-12
-15
-18
11
+1
-2
-5
-7
-9
-11
-14
-17
12
+2
-1
-4
-6
-8
-10
-13
-16
13
+3
0
-3
-5
-7
-9
-12
-15
14
+4
+1
-2
-4
-6
-8
-11
-14
15
+5
+2
-1
-3
-5
-7
-10
-13
16
+6
+3
0
-2
-4
-6
-9
-12
17
+7
+4
+1
-1
-3
-5
-8
-11
18
+8
+5
+2
0
-2
-4
-7
-10
19
+9
+6
+3
+1
-1
-3
-6
-9
20
+10
+7
+4
+2
0
-2
-5
-8
21
+11
+8
+5
+3
+1
-1
-4
-7
22
+12
+9
+6
+4
+2
0
-3
-6
23
+13
+10
+7
+5
+3
+1
-2
-5
24
+14
+11
+8
+6
+4
+2
-1
-4
25
+15
+12
+9
+7
+5
+3
0
-3
26
+16
+13
+10
+8
+6
+4
+1
-2
27
+17
+14
+11
+9
+7
+5
+2
-1
28
+18
+15
+12
+10
+8
+6
+3
0
29
+19
+16
+13
+11
+9
+7
+4
+1
30
+20
+17
+14
+12
+10
+8
+5
+2
31
+21
+18
+15
+13
+11
+9
+6
+3
OSD9004 Settings
The OSD9004 receiver has one user adjustment available. The receiver attenuator can be set to the
required RF output power manually or alternatively can be set to automatic gain control by setting
switch 6 to the on position (up). In automatic gain control mode the unit maintains constant output level
over the optical range of 15dB.
