Agilent
8645A Agile Signal Generator
252 kHz to 2060 MHz
Data Sheet
Combining frequency agility
with high performance
Performance signal generator series —
a commitment to cost-effective solutions
2
The 8645A agile signal generator is
a 252 kHz to 2060 MHz synthesized
generator that combines high
performance with frequency agility.
With this combination, test both
stringent RF performance and fast
hopping capability of frequency agile
radios and surveillance receivers. In
addition, the 8645A can simulate a
complex environment to test for
susceptibility to interference or
provide a fast-switching stimulus
for decreasing production test time.
In the past, testing secure
communications receivers required
two separate pieces of equipment.
Measurements such as sensitivity and
distortion were done one frequency
at a time with a generator of high
spectral purity and modulation
capability. Another generator that
switched frequency quickly, or another
radio was used to functionally test
the dynamic or agile portion of the
radio. Now the 8645A offers both
high performance and fast hopping
so you can test both static and agile
operations of the receiver with just
one calibrated signal generator.
Quality measurements
begin with a quality source
Signal generator performance
must be better than receiver
design, or you end up measuring
the source rather than the receiver.
The 8645A offers high performance
for in-channel and adjacent
channel measurements, both in
static and agile operation. For
example, an adjacent channel
signal must have low phase noise
and spurs at the channel offset or
the receiver’s signal will be masked.
The 8645A specifies <–127 dBc
phase noise and <–100 dBc
spurious amplitudes at a 20 kHz
offset from the carrier. Typical
performance is even better.
As an in-channel signal generator,
low FM distortion and residual
FM become essential. The 8645A
specifies less than 1 to 6% of FM
distortion for deviations up to
20 MHz, and less than 1 to 4 Hz
residual FM for carrier frequencies
from 0.25 to 2060 MHz.
For traditional receiver
measurements the 8645A offers
the performance you need for
even the most stringent receiver
specifications. Add frequency
agility without sacrificing high
performance specifications and
you have one generator for testing
both static and agile operation.
Modulation while hopping
For receiver measurements, the
8645A offers simultaneous FM,
AM and pulse modulation. Whether
in fast hop mode or doing static
receiver measurements, the
carrier can be either internally
or externally modulated. The
8645A has a digitally generated
0.1 Hz to 400 kHz audio source. Or
you can use external FM with up
to 20 MHz deviation and 10 MHz
rates. In fast hop mode, maximum
deviation is 3.5 MHz with rates
up to 10 MHz. AM is available
with up to 100 kHz rates and
99% depth. Pulse modulation
allows a 35 dB on/off ratio with
100 nsec rise/fall times.
Testing frequency
agile radios
Testing frequency agile radios
in design and manufacturing
requires two sets of capabilities.
High performance is needed for
traditional measurements such
as sensitivity and distortion.
Frequency agility is needed for
testing hopping characteristics.
The 8645A provides both of these
in one generator. Because spectral
purity and accurate modulation
is available under both static
and dynamic operation, you can
make fundamental tests such
as sensitivity while hopping the
radio. Selectable FM deviations
from 1 Hz to 20 MHz with rates
up to 10 MHz lets you test either
voice quality or high-speed
data reception. Built-in control
capabilities allow the 8645A to
synchronize with a transmitter,
or directly to the receiver. Key
parameters such as hop rate, dwell
time, amplitude and frequency
can be modified precisely either
in real time, from the front
panel, or over GPIB.
The 8645A agile signal generator
brings all the pieces together
Courtesy of ITT Aerospace/Optical Division
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Specified agile performance
In the past, to get agility in a
generator, you had to give up
performance such as phase noise,
spurious levels and amplitude
range. With the 8645A you can
maintain signal performance while
switching frequencies as fast as
15 µsec from 128 to 2060 MHz.
Typical frequency accuracy is 1 Hz
per MHz and amplitude accuracy
is better than ±1 dB. Extending
the range down to 8 MHz increases
switching speed to 85 µ sec. Below
8 MHz it is 500 µ sec. For a full
test of the receiver, you can enter
2400 unique frequencies and
specify unique sequences of up
to 4000 frequency settings. Key
performance parameters such as
phase noise, spurious, amplitude
accuracy, and modulation
remain high quality and are
completely specified.
Complete control
of frequency hopping
The 8645A offers flexible control
of frequency switching. You can
input parameters from the front
panel, with GPIB or using TTL
connectors from the rear panel.
Extensive hopped frequency
simulations can be entered into
the nonvolatile memory from the
front panel. Your system is up
and running quickly without
needing a special interface. To
activate a hopped sequence, you
just push a button. Or you can
enter in the data with a computer
using HPSL (Hewlett-Packard
Systems Language) and start the
sequence with a single command.
Either way, you can precisely
control hop rate, dwell time,
frequency, amplitude and
modulation. For real-time control,
the rear panel accepts TTL
inputs for triggering, dwell time
and frequency selection. With
this choice of control, you can
customize use of the 8645A for
any test application.
Frequency sweeping
To find the amplitude response
of frequency-sensitive devices,
the 8645A can sweep even
wide frequency ranges without
surrendering to long sweep times
and slow display updates. To
stimulate IF passband circuits or
filters, spans up to 40 MHz can
be swept with a phase continuous
output in only 10 msec. Much
wider spans of more than 1 GHz
can be covered in less than
100 msec with a stepped output
of up to 1000 points. In either
sweep mode, up to three markers
can be set to highlight points on
the response.
Testing surveillance
receivers
Surveillance receivers are
designed to detect and identify
a wide variety of transmissions.
The 8645A can benefit designers
of surveillance hardware with a
calibrated nonclassified source
that can simulate many fixed and
agile transmitters. The 8645A
signal generator can operate
from 252 kHz to 2060 MHz with
FM, AM, and pulse modulation.
Hop rates as fast as 50,000
changes per second and dwell
times as short as 6.4 (sec per
frequency allow receiver testing
for transmitters now and into
the future.
Courtesy of Rockwell International
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The 8645A agile signal
generator is the first member of
the performance signal generator
series. Using innovative design
and manufacturing, this series
offers benefits such as selectable
performance, greater reliability,
modular support strategy, and an
easier programming language.
Analyzing receiver
vulnerability
Using the 8645A, you can exercise
your receiver’s susceptibility to
various RF signal environments.
Complete control of frequency,
amplitude, modulation and
hop parameters lets you fully
characterize performance. Adjust
the amplitude at the input to
the receiver to determine its
performance in the presence of
jamming. Combine frequency
and amplitude modulation to
evaluate propagation losses or
transmitter velocity shifts. Use
the white Gaussian noise output of
the internal modulation oscillator
to create a static or agile jamming
signal to evaluate minimum
signal detection. Or vary the hop
frequency, hop rate, dwell time
power or FM deviation to test the
receiver’s susceptibility to loss of
synchronization. With the 8645A,
you can start with a nominal signal
and stretch every parameter to
test the receiver’s limits.
Optimize your purchase
and your measurements
The performance signal generator
series offers cost-effective choices
when you buy it and when you
use it. Purchase as many options
as you need to meet your most
stringent requirements. An
internally modular design means
Performance signal generator series—
a commitment to cost effective solutions
Courtesy of AEL Industries, Inc.
For example, phase noise
and spurious products can be
decreased by allowing a slower
switching speed. Also, very wide
FM deviations can be selected by
giving up some spectral purity.
With the performance signal
generator series, you buy only
what you need and optimize for
each application.
the particular configuration you
need doesn’t come with extra
hardware that adds to the price.
On your bench, you can optimize
the particular capability that is
most important to the test.
You select the performance
you need at the front panel by
pressing a mode key.
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