Installation guide

Troubleshooting
Block Descriptions for Option UNJ and Option 506
1-146
panel where these signals can then be used to modulate external equipment. Both inverted and non-inverted
signals are available at the rear panel. The A10 I/Q Multiplexer routes the main internal I and Q modulating
signal into the I/Q modulator on the A13 Output which is used to modulate the main RF output. These main
internal I and Q modulating signals can be either from the A7 Baseband Generator (Option 001 or Option
002) or supplied through the external I/Q inputs.
The A10 I/Q Multiplexer has two identical paths in which to switch the incoming I/Q signals. Each path has
individual gain control and can be switched to a summing node. The output of the summing node can be
switched to the EXT outputs and in addition continues on through more gain control circuitry and finally out
to the A13 Output. I/Q signals are supplied simultaneously to the A13 Output and to both the inverted and
non-inverted external jacks.
The I and Q inputs are 16-bit data generated in the A7 Baseband Generator (Option 001 or Option 002) either
by a waveform personality or by downloading externally. This data is converted to analog, filtered by the
I and Q DACs, filters on the A7 Baseband Generator (Option 001 or Option 002), and then goes to the A10 I/Q
Multiplexer.
The user, through the front panel, supplies the EXT IN I and EXT IN Q signals. These signals enter the A10
I/Q Multiplexer and can either be switched into a 50 or 600 ohm input impedance.
An internal calibration source supplies proper input levels in order to perform independent self tests. This
allows the firmware to check the A10 I/Q Multiplexer board by setting known levels and reading the various
nodes without actually needing an I/Q signal.
An Offset Sense signal comes in from the I/Q modulator on the A13 Output and is used to adjust for offsets
between the I and Q signals. The Offset Sense signal is compared to the I/Q signal output and the result is
used to control the amplitude; the feedback signal minimizes quadrature and gain errors.
The A10 I/Q Multiplexer also routes the Audio 1 and Audio 2 signals over to the Analog Modulation Block,
located on the A18 Reference, which enables the I (Audio 1) and Q (Audio 2) signals to be used as analog
modulation signals. These signals originate from either the I/Q signals supplied by the A7 Baseband
Generator (Option 001 or Option 002) or from the External I/Q inputs as selected by the A10 I/Q Multiplexer.