Implementing An Increased Channel Load - Motorola GX2 EA1000C Series User Manual

Operation

Implementing an Increased Channel Load

Many systems operate under a reduced channel load with the capacity to add additional
channels as required. If the system initially operated with less than a full load (79 NTSC
channels from 52 through 550 MHz and 450 MHz of digital at –6 dBc from 550 through
1002 MHz) and you need to increase the channel load, you may have to decrease the RF
input level per channel accordingly in order to maintain an optimum drive level to the
laser. The controlling factor here is total power. For a full channel load, the minimum
input specification is +15 dBmV per analog channel and +9 dBmV per digital channel.
This equates to a minimum total power of 34.91 dBmV. Total power is calculated for
analog and digital channels separately because they are normally at different levels.
These total powers are calculated using the following formulas:
P = I + 10 x log
a a
P = I + 10 x log
d d
Where:
P = Total Power of Analog Channels
a
P = Total Power of Digital Channels
d
I = Analog Input Level Per Channel
a
I = Digital Input Level Per Channel
d
These powers must now be combined to yield a total power (P
However, the total analog power (P
added together. They must be added using power addition with the following formula:
P = 10 x log
t
10
The result of this formula should be within +/- 1dB of the minimum total power
specification. If it falls outside this window, change the input levels per channel and re-
calculate. Repeat this process until the answer falls within the +/- 1dB window.
To increase the channel load, you must perform one of the following procedures:
GX2 EA1000C*/* Multi-Wavelength DWDM 1550 nm Laser Transmitter • User Guide
589569-001-a
(# of analog channels)
10
(# of digital channels)
10
) and the total digital power (P
a
[10 + 10 ]
(P /10) (P /10)
a d
B
) that will drive the laser.
t
) cannot simply be
d
35