HP 8340B Manual page 72

4-15.
AMPLITUDE MODULATION TEST
Specification
Table 4-29. Amplitude Modulation Test Specifications
The
following specifications apply when the HP 8340B/41B are internally leveled, for waveforms
whose envelope peak
is
at least
1 dB below maximum specified
power
Unless noted, pulse modula¬
tion must be OFF; however, the HP 8340B/41B are capable
of simultaneous amplitude and pulse
modulation. See Section
III, Operation.
AM Depth: 0
to
90%
AM Sensitivity at 1
kHz rate and
30% depth:
100%/Volt
±
5%
AM Bandwidth relative to
a
1 kHz rate
at
30% depth:
DC
coupled,
3
dB point
2:100 kHz
AM Frequency Response
(Flatness) Relative to
a
1 kHz rate at
30%
depth,
DC to 10 kHz:
±0.20dB
Description
AM
sensitivity and accuracy is
determined by
simulating
a
modulation signal (i.e., setting the function
generator
to
a
dc voltage).
The unmodulated DUT RF output is
measured
using
a power
meter.
A
dc
voltage representing
±30%
modulation (±0.3
Vdc)
is
applied to the
DUT's AM
input.
The power
meter
indication should change by:
20 log (1
4-
(dc voltage
±
(0.05 times the
dc voltage)))
The sensitivity
and accuracy is
tested at several CW frequencies.
The AM frequency response and
bandwidth is
measured by down converting the
DUT's RF frequency
to an IF
frequency
within the range of the modulation analyzer. The
DUT
is amplitude modulated using
a
function generator. The
modulation analyzer
is
set to indicate
0 dB
at the
reference modulation
frequency of
1
kHz. The modulation frequency is
varied and
the
flatness
is indicated on the modulation
analyzer. The
modulating frequency
is then set to the bandwidth
specification (100 kHz) and the
modulation analyzer should indicate
> —3 dB.
This shows
that the actual
3
dB
point
will occur at
a
frequency
>100
kHz.
Finally,
the function generator output
level
is increased to obtain
>90%
modulation depth.
Equipment
Local Oscillator
........................
HP 8340A Opt.
001
or any HP
8341A/B'
Modulation Analyzer
............................................
HP 8901A
Function
Generator
.............................................
HP
3325A
Digital
Voltmeter
...............................................
HP 3455A
Amplifier
......................................................
HP 8447F
Power Meter
...................................................
HP 436A
Power Sensor
.................................................
HP 8485A
1
Usable
only with HP 8341B DUT
HP 8340B/41B
Performance Tests
4-71