Cisco Cisco 1 GHz GainMaker Amplifier インストールガイド
Balancing the Reverse Path
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In the example shown above, 19 dBmV + 20 dB = 39 dBmV. Therefore, you would set
the signal generator output for + 39 dBmV.
the signal generator output for + 39 dBmV.
Important:
When using a CW signal generator, inject at least two carriers, 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 should be in the 5 MHz to 10 MHz
range and the high frequency carrier should be in the 35 MHz to 40 MHz range.
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 should be in the 5 MHz to 10 MHz
range and the high frequency carrier should 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.
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.
The station reverse input pad values are selected during the reverse system
design and are based on the need to minimize variations in return path losses for
the various reverse inputs. Do not permanently alter the values of the reverse
input pads without consulting a system designer.
design and are based on the need to minimize variations in return path losses for
the various reverse inputs. Do not permanently alter the values of the reverse
input pads without consulting a system designer.
In the 1.2 GHz GainMaker System Amplifier, the reverse input comes after the
reverse injection point in the reverse path. Temporarily replacing the design
value reverse input pad on the port being balanced with a 0 dB pad allows the
reverse injection level and the receive levels at the monitoring end to remain
constant from amplifier to amplifier and from port to port.
reverse injection point in the reverse path. Temporarily replacing the design
value reverse input pad on the port being balanced with a 0 dB pad allows the
reverse injection level and the receive levels at the monitoring end to remain
constant from amplifier to amplifier and from port to port.
An alternative to this method is to expect a receive level that is x dB lower than
normal, where x is the value of the reverse input pad on the port being balanced,
which you noted earlier in the reverse path balancing procedure.
normal, where x is the value of the reverse input pad on the port being balanced,
which you noted earlier in the reverse path balancing procedure.
High Gain Dual Pad Values
While most system design prints should specify a design value reverse input pad for
each port, the following chart provides guidelines for minimum reverse input pad
values that should be installed for the High Gain Dual with an Auxiliary Signal
Director (other than a jumper) installed in the amplifier module.
each port, the following chart provides guidelines for minimum reverse input pad
values that should be installed for the High Gain Dual with an Auxiliary Signal
Director (other than a jumper) installed in the amplifier module.
Signal Director
Tap Leg
Thru Leg
Splitter
4.0 dB
4.0 dB
DC-8
8.5 dB
2.0 dB
DC-12
12.5 dB
1.5 dB
The 1.2 GHz GainMaker amplifier signal director creates loss in the forward path
only. To equalize forward and reverse path losses, these minimum pad values are
recommended on the associated reverse input ports.
only. To equalize forward and reverse path losses, these minimum pad values are
recommended on the associated reverse input ports.
Note: Design print values may be greater than the minimum recommended reverse
input port pad values listed above.
input port pad values listed above.