1-109
Troubleshooting
RF Path Description (Frequency Generation, Level Control, and Modulation)
Generator, and is used to drive the pulse modulators on the A8 Output and A30 Modulation Filter.
The Burst Pulse signal is used by the digital modulation formats to synchronize the main RF path
and ensure maximum on/off level ratio.
The I and Q output signals are the main signals out of the A14 Baseband Generator. They are also
the digital modulation signals that go to the A13 I/Q Multiplexer, and are then routed to the I/Q
modulators on the A8 Output and A35 I/Q Modulator.
A13 I/Q Multiplexer
The A13 I/Q Multiplexer receives I/Q input signals from the A14 Baseband Generator, external I/Q
input signals from the front panel, and I/Q sense feedback signals from the I/Q modulators on the
A8 Output and A35 I/Q Modulator. The A13 I/Q Multiplexer inverts and routes the I and Q signals
to the rear panel, where these signals can be used to modulate external equipment. The A13 I/Q
Multiplexer also routes the main internal I and Q modulating signal into the I/Q modulators on the
A8 Output and A35 I/Q Modulator, which are used to modulate the main RF output.
The A13 I/Q Multiplexer has two identical paths in which to switch 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 on through more gain control circuitry, and finally out
to the A13 Output. I/Q signals are supplied simultaneously to the A8 Output or A35 I/Q Modulator,
and to both the inverted and non–inverted external jacks.
The EXT IN I and EXT IN Q signals enter the A13 I/Q Multiplexer, and can be switched into a 50 or
600 ohm input impedance.
An internal calibration source supplies the levels required to perform independent self tests. This
enables the firmware to check the A13 I/Q Multiplexer by setting known levels and reading the
various nodes without actually needing an I/Q signal.
An Offset Sense signal that comes in from the I/Q Modulators on the A8 Output and A35 I/Q
Modulator 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.
To Next Page
Loading...
Need help?
General
