TX RX Systems Inc. Manual 7-9487-3 05/05/11 Page 24
1) Press the DOWN ARROW button on the front
panel to scroll through the menu choices until
you reach the ATTENUATORS menu.
2) With the ATTENUATORS menu displayed
press the ENTER button to step down to the
RESERVE GAIN sub-menu.
3) Press the ENTER button again to advance to
the RESERVE GAIN adjustment screen. The
current value will now be displayed. Use the UP
and DOWN ARROW buttons to set it to the
desired value. The attenuation setting works in
a forward loop fashion, starting at 0 and
increasing to 15.5, a button press after 15.5
returns the setting back to 0.
4) After setting the correct value press the ENTER
button to return back to the ATTENUATORS
menu. This will save your setting choice. Then
pressing the CANCEL button while at the
ATTENUATORS menu will return you to the
default display.
Setting Distribution Attenuation (MCU Only)
The control unit to receiver cable loss can be deter-
mined from the cable manufacturers specifications.
For your system these values will be fixed once the
cable type is chosen and cut to length. Typically 2
to 3 dB of distribution attenuation is usually
required to achieve unity gain. Use the attenuation
values shown in
Table 6
to set the distribution
attenuation to the correct value.
ADJUSTMENT PROCEDURE
The factory default attenuation setting for receiver
multicoupler distribution is 1.0 dB. This is the initial
settings that is programmed into your system when
you first turn it on. You will need to adjust this value
to optimize your system. This is done through soft-
ware interface via the menu select buttons. Your
setting will be stored in system memory until you
change it again even if the equipment is powered
down. The receiver multicoupler distribution atten-
uation is adjustable from 0.0 to 3.0 dB in 0.5 dB
increments. To adjust the multicoupler attenuation
perform the following;
1) Press the DOWN ARROW button on the front
panel to scroll through the menu choices until
you reach the ATTENUATORS menu.
2) With the ATTENUATORS menu displayed
press the ENTER button to step down to the
RESERVE GAIN sub-menu.
3) Press the UP ARROW button to move to the
DISTRIBUTION sub-menu.
4) Press the ENTER button again to advance to
the DISTRIBUTION adjustment screen. The
current distribution value will now be displayed.
Use the UP and DOWN ARROW buttons to set
the distribution to the desired value. The attenu-
ation setting works in a forward loop fashion,
starting at 0.0 and increasing to 3.0, a button
press after 3 returns the setting back to 0.
5) After setting the distribution value press the
ENTER button to return back to the ATTENUA-
TORS menu. This will save your setting choice.
Then pressing the CANCEL button while at the
ATTENUATORS menu will return you to the
default display.
SPECTRUM ANALYSIS
Obtaining good sensitivity requires an understand-
ing of the levels applied to the receiver. A receiver,
like any electronic device, has a dynamic range of
operation. As long as this dynamic range is main-
tained, the specifications of the receiver are main-
tained. When the levels applied to the receiver
exceed this range, the sensitivity, intermodulation
rejection, as well as the adjacent channel selectiv-
ity will deteriorate. To properly perform a Spectrum
Analysis, a spectrum analyzer must be connected
to the output of the multicoupler as if it were a
receiver, essentially monitoring what the receiver
sees.
Set distribution
attenuation to
for cable / distribu-
tion losses of
3 dB
1 dB
2 dB
2 dB
1 dB *
3 dB
0 dB
more than 3 dB
* factory default setting
Table 6
: Distribution attenuation settings.
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