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Operating Information
2–14
AM700 Audio Measurement Set Service Manual
Input Range and Auto. The gain range for the analog inputs defaults to Auto
enabled to provide auto ranging on the applied signal. This avoids possible
overloading of the A/D converters and is the recommended setting for normal
operation. When you know the amplitude of the signal being measured, you may
choose to make a manual gain setting. Follow these steps when changing the
input range setting:
1. Turn off the Auto enabling (check goes away) by touching the Auto soft key.
2. Make the new gain range setting by either rotating the large control knob to
the new setting and again touching the soft key or make a direct keypad
entry of the new number and press enter.
The gain range steps of the AM700 have fixed upper limits for each range,
therefore when a number is entered that is not exactly one of the available range
numbers, the gain switches to the next highest valid setting above the number
you entered.
Input gain range settings are also available as menu choices from within the
applications that make measurements on analog signals. From within a running
application you may make the change and observe the effects on the signal.
Digital Input Connector Selection. The Digital Main Input connector selection
choices are: Front-panel XLR connector (the most common selection and made
by default), the Rear-panel BNC, and the Rear-panel Optical connector. An
internal connection to the AES generator is also available. Touching the selection
soft key associated with the digital generator choices advances the selection box
through the list.
Measurement Channel Assignment. A pull-down menu (see Figure 2–12) is used
to individually assign the signal to the two measurement channels of the AM700.
The same range of signals input choices is available for both Channel 1 and
Channel 2, and the channels may have the same signal applied to each as well. If
you wish both inputs to be obtained from the same type of generator (High
Resolution, High Bandwidth, or Digital Main), the fast selection soft keys along
the lower right of the screen may be used (see Figure 2–12). (These choices are
also available within the Main menu for the applications with the Input menu
displayed.) With a single touch of the choice both measurement channels may be
set simultaneously to the A and B High Resolution generator, the A and B High
Bandwidth generator, or the Digital Main Inputs.
If you want to use the digital generator or the digital reference signal as inputs to
the measurement channels, select the appropriate one instead of the analog high
bandwidth or analog high resolution route. The most common selections (and the
default connections) are the Analog A high resolution input connected to
measurement Channel 1 and the Analog B high resolution input connected to
measurement Channel 2.