The 2026 is a multisource signal generator offering as
standard two signal sources in one instrument. Up to three
sources may be fitted, each of which is a fully functional
modulated signal generator. Each source can either be routed
to its own individual RF output or switched to the input of
an RF combiner network before being fed to a separate
combined RF output. All sources cover the frequency range 10
kHz to 2.4 GHz. An additional RF input is provided to enable
the output from an external RF signal generator to be
combined with the signals from up to two internal sources.
Each signal source can be controlled independently in
frequency and level, and each has its own amplitude,
frequency, phase, FSK and pulse modulation capability. All
parameters can be entered from the front-panel keyboard and
a rotary control can be used to adjust most settings. The
instrument includes a GPIB interface which allows remote
control of all standard signal generator functions except
the supply switch.
The instrument is provided with built-in tests specifically
for use with two or three combined sources such as for
amplifier and receiver intermodulation tests and receiver
The sources may be locked together, offset in frequency
(additionally with a harmonic or sub-harmonic relationship)
as well as level.
Microprocessor control ensures that the instrument is
flexible and easy to use and allows programming by the
General Purpose Interface Bus (GPIB) or RS-232 serial bus.
The GPIB is designed to IEEE Standard 488.2 and is a means
of sending commands to an instrument, via a data bus, from a
remote controller or personal computer. The instrument can
therefore be used manually or as part of a fully automated
Main features Operation
Selection of parameters on the screen may involve one or
more of the numeric, hard or menu selection keys or the
rotary control knob. Parameters may be set to specific
values by numeric key entry, while values may be varied in
steps of any size using the [ ^ ][ ΰ ] keys or altered by
moving the control knob, set to a particular sensitivity.
The display is a dot matrix liquid crystal panel, with
backlighting. Display contrast and brightness may be varied
to accommodate differing lighting conditions and the setting
saved in memory.
Carrier frequency is either selected directly via the
keyboard or remotely via the interfaces. Frequency
resolution is 1 Hz across the complete frequency range of 10
kHz to 2.4 GHz. A series of carrier frequencies can be
stored in non-volatile memory for recall when required.
Peak RF output levels from each signal source of up to +24
dBm can be set up to 1.2 GHz (+20 dBm up to 2.4 GHz) by
direct keyboard entry with a resolution of 0.1 dB down to
-137 dBm. The peak output level from the combiner is +4 dBm
up to 1.2 GHz (0 dBm up to 2.4 GHz). RF ON/OFF keys are
provided to disable each individual output as well as the
A choice of level units is available to the user and
provision is made for the conversion of units (for example,
dBm to μΥ) by a simple keypress.
An electronic trip protects each independent signal source
output against reverse power of up to 50 W. This prevents
damage to output circuits when RF transmitter or DC power
supply is accidentally applied to an RF OUTPUT connector.
To facilitate testing of receiver squelch systems, an
attenuator hold function allows control of the RF output
without introducing RF level drop-outs from the step attenuator.
Comprehensive amplitude, frequency and phase modulations are
available. Pulse modulation can be applied to the carrier
from an external pulse source. The instrument also produces
FSK modulated outputs. An internal modulation oscillator is
provided, having a frequency range of
0.01 Hz to 20 kHz. Sine, triangle and square waveforms are
available. The oscillator is capable of generating one or
two modulation tones simultaneously in one modulation
channel. A BNC connector on the front panel offers access to
the internal LF signal as well as providing an input for
external modulation signals to be combined with the internal
signals. These sources can be combined to give a number of
modulation modes. The pulse modulation can be used in
combination with the other forms of modulation.
The frequency modulation range provides a 1 dB bandwidth of
typically 100 kHz and provides FM deviation of 0 to 100 kHz.
AC or DC coupled FM can be selected. Phase modulation is
provided with a 3 dB bandwidth of 10 kHz and deviation range
of 0 to 10 radians.
Amplitude modulation with a 1 dB bandwidth of typically 30
kHz and with modulation depths of up to 99.9% is available
with a resolution of 0.1%. Pulse modulation is available as
standard with typical rise and fall times of less than 10 μs
and 40 dB on/off ratio.
The instrument also accepts one or two logic level inputs to
produce a 2-level or 4-level FSK modulated output. The
required FM deviation is set by keyboard entry.
The external input voltage required for specified modulation
is 1 Υ RMS (1.414 Υ peak). To accommodate other signal
levels, Automatic Level Control (ALC) can be selected which
provides correctly calibrated modulation for inputs between
0.75 and 1.25 Υ RMS.
A modulation ON/OFF soft key simplifies the testing of
All major parameters can be incremented or decremented in
step sizes entered via keyboard entry or remotely. If no
step size is entered for a parameter, the steps are preset
to 1 kHz for carrier frequency, 1 kHz for modulation
oscillator, 1 kHz for FM deviation, 0.1% for AM depth, 0.01
rad for ΦM and 1 dB for output level.
In addition, the rotary control knob can be used to vary the
parameter with the sensitivity of the knob being changed by
means of the [x 10] and [^10] keys.
Control knob operation can be assigned for the adjustment of
one parameter, while another parameter is adjusted by the
increment and decrement keys. By this means two parameters,
for example carrier frequency and RF level, can be adjusted
The sweep capability of the instrument allows comprehensive
testing of systems. Four parameters are used to specify
sweep; start, stop, step size and time per step, all of
which may be specified by the user. The sweep can be paused
at any time and the frequency and level manually altered.
During the sweep the RF level can be altered using the
rotary control. Sweep triggering can be single shot or
continuous and can be initiated directly or on the detection
of a trigger. The triggering signal may either be programmed
or from a TTL signal applied to the rear-panel TRIGGER 1
input. When frequency coupling is enabled, the coupled
sources will track with the swept source.
The instrument provides both non-volatile and volatile
memory for storing instrument settings.
The non-volatile memory provides 100 full instrument
settings and 100 settings of carrier frequency only. The
volatile memory (RAM) also provides 100 instrument settings.
Any one of the non-volatile instrument settings can be
selected as the power-up setting for the instrument.
To prevent accidental interference with the contents of
internal memories, internal data is protected.
A GPIB interface is fitted so that all functions are
controllable via the interface bus which is designed to the
IEEE Standard 488.2. The instrument can function both as
talker and listener.
The instrument also has an RS-232 interface which uses the
common GPIB command set to control the instrument and also
allow new software upgrades or applications to be downloaded
into the instrument.
All alignment data is digitally derived. Realignment can be
undertaken, without removing covers, by protected
front-panel functions or via the GPIB interface.
With an SSB phase noise performance of typically -121 dBc/Hz
at 20 kHz offset from a 1 GHz carrier, these instruments can
be used for both in-channel and adjacent channel receiver
measurements. Harmonically-related signals and non-harmonics
are typically better than -30 dBc and -60 dBc respectively.
This instrument has a recommended two-year calibration
interval after which it should be returned for recalibration
(for addresses refer to ‘International Service Centers’
section at end of manual).