Cisco GainMaker Optoelectronic Node 1GHz with 65 86 MHz Split Installation Guide
Chapter 3 Balancing and Setup
2 Refer to the reverse system design print and inject the proper RF signal level into
the launch amplifier via the reverse injection test point. For the exact location of
the reverse injection test point, refer to the illustration in step 1.
The reverse system design print should specify a “design” reverse input level at
The reverse system design print should specify a “design” reverse input level at
the station’s reverse input port(s). You must inject the correct signal level into the
reverse injection test point using an RF test probe and a reverse sweep
transmitter or a CW signal generator. The reverse injection test point has 20 dB of
insertion loss (-20 dB injection point).
Note: To calculate the correct signal level to inject, you must first calculate the
Note: To calculate the correct signal level to inject, you must first calculate the
input level to the reverse amplifier module.
Example:
Example:
Specified port (station) input, per design = 19 dBmV
Injection test point loss = 20 dB
Port Input + Injection test point loss = Signal generator setting
19 dBmV + 20 dB = 39 dBmV
Set the signal generator output for + 39 dBmV. This signal, when injected
through the reverse injection point, is attenuated by 20 dB, simulating the 19
dBmV port input level specified per design.
Important:
If a CW signal generator is used, at least two carriers should be injected, one
at the low end and one at the high end of the reverse bandpass. In a reverse
system with a 5 MHz to 40 MHz bandpass, the low frequency carrier would
be in the 5 MHz to 10 MHz range, and the high frequency carrier would be in
the 35 MHz to 40 MHz range.
The amplitude of the signal generator output can be set higher or lower than
the level specified by the calculation above, but the difference between the
actual output level and the level calculated above must be known. If the
generator output is x dB higher (or lower) than the level calculated, then the
reference (desired) level received at the headend or hub should also be x dB
higher (or lower) than the original headend reference level.
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