Specifications

8
Hardware configuration
The recommended method for making pulsed
residual measurements is to synchronously pulse
both paths to the phase detector. Using this
approach, the phase detector produces an output
during the pulse “ON” interval. This eliminates
several problems that occur when only the DUT
path is pulsed. Figure 2-5 shows the recommended
hardware configuration with one external pulse
modulator. Figure 2-6 shows the recommended
configuration with two external pulse modulators.
Both configurations assume that the source can-
not be pulsed, or that the AM noise of the source,
when pulsed internally, increases significantly
from its CW (non-pulsed) value, reducing the over-
all measurement noise floor to an unusable level.
As shown with Figures 2-5 and 2-6, the recom-
mended calibration method is “Derive From Single-
Sided Band Spur” to measure the phase detector
constant automatically (this technique is described
in the Agilent E5500 series user documentation).
The double-sided spur technique may also be used.
The spur frequency must be kept below PRF/4.
These techniques allow the phase detector constant
to be measured with the DUT configured into the
measurement.
A wide-band oscilloscope connected to the monitor
port of the 70420A is recommended as the quadra-
ture set and monitor device to see the phase tran-
sients that may be produced as a result of the pulse
modulation process.
Figure 2-5. Residual pulsed carrier measurement configuration
Figure 2-6. Residual pulsed carrier measurement configuration (alternate)
Pulse
Gen
Source
Splitter
Step
Attenuator
DUT
E5500
Input
Ref
Input
Phase
Shifter
16 dB Coupler
Amplifier
Cal Source
Pulse
Modulator
Pulse
Gen
Source
Pulse
Modulator
Splitter
Step
Attenuator
DUT
E5500
Input
Ref
Input
Phase
Shifter
16 dB Coupler
Amplifier
Cal Source
Pulse
Modulator