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system to raise the sampling rate of the file. This ensures the generation
of low adjacent channel power and low spectral noise density.
The dual channel ARB is suited for the generation of both narrow
band and wideband signals, including WCDMA signals, without the
use of switched reconstruction filters. Combining a large ARB memory
with the smaller file size required to define a waveform allows the
ARB to store up to 180 waveforms. Alternatively the whole of the
memory can be devoted to a single file. One such file would store over
1.5 seconds of a 3GPP WCDMA waveform signal. The use of interpolation
techniques ensures that when narrow band systems are simulated
the waveform
generator can still operate at a high sample rate
without requiring excessively large amounts of data to be loaded or
restricting the repetition time. The library waveforms are structured
in a directory form to ease their selection and the optimization of the
user's
generator. The modulation waveforms can be simply changed
by selection from a file list with the changeover between waveforms
occurring in a few milliseconds rather than the many seconds
required in more traditional waveform
generators. The file name can
be determined by the user to convey a useful description of the contents
of the file.
Real Time Baseband Generator
Fitted internally, the optional Real Time Baseband, RTBB, generates
baseband signals (I and Q) that modulate an RF source in real time
to produce generic FSK, PSK and QAM signals at rates up to
2 Msymbols/sec. The RTBB generates or inputs a set of modulation
symbols, modulates them with the chosen scheme, filters them using
an appropriate channel filter, and then converts the digital stream to
analogue I and Q for the I/Q vector modulator. The source of the
symbol data is very flexible. The symbol data can originate from a
variety of internal or external sources. Internal data source choices
include a PRBS
generator, an internal pattern
generator or internal
memory storage of user downloaded symbols. External real-time
symbol data can be input in serial or parallel format via an industry
standard Low Voltage Differential Signalling (LVDS) interface.
Digitized I/Q data, available from sources such as basestation simulators,
can be input via the LVDS interface as an alternative to external
parallel or serial symbol data. Streaming digitized I/Q data samples
are available as an output via the LVDS interface from internally
generated symbols for testing D/A convertors.
Synchronized clock, RF Burst, RF Burst Attenuation control and
marker output signal facilities are available for both internal and
external data generation.
An important feature necessary to support GSM signal generation is
the ability to frequency hop between channels. The RTBB option
provides frequency hopping by re-mixing the I and Q data at baseband.
The resultant I and Q vectors then modulate the core synthesizer
frequency thus producing a new RF frequency at the output of
the signal
generator. This method ensures that synchronization is
maintained between the IQ data and the hop trigger. In addition,
because the main synthesizer hardware remains unchanged, frequency
stabilization is nearly instantaneous.
®
The 3410 series is supplied with a free copy of ®, a software
package to aid the creation and download of files to the ARB and
RTBB options.
® is a Windows based software utility that enables a user to
set up a modulation scheme and then create an ARB file using modulation
templates. The resulting file may be saved on a PC or downloaded
into the ARB. User-defined configurations can also be saved.
Consequently, it is possible to load previously saved setups to regenerate
the ARB files quickly and easily. The capabilities of ®
include:-
Generic Modulation Types
PSK, FSK, MSK, QAM modulation types
Nyquist, Root Nyquist and Gaussian filters
PRBS, fixed pattern and user defined data sources
IQ errors - residual carrier, IQ imbalance, quadrature offset
Multi-carrier
Also included are 2G, 2.5G and 3G cellular TDMA and CDMA digital
standards along with WLAN and other cordless phone standards.
In addition, ®includes a utility that allows user-defined
waveforms, created using software simulation tools such as
MATLAB, to be converted and packaged into a form that can be
downloaded into the 3410 Series ARB.
12345® is continually updated to include new modulation capabilities
and facilities. The latest version is available for download at
www.aeroflex.com/IQCreator.
Options to have an instrument's ARB pre-loaded with a suite of example
waveform files are available. A selection of waveforms from each
of the standards, or just waveforms relevant to the user's applications,
can be chosen. Although only available at the time of order, all the
waveforms are available within IQCreator should any of the files be
deleted then required in the future.
I/Q Outputs
Single ended baseband I/Q outputs are available as standard.
Differential I/Q outputs, combined with comprehensive voltage bias
and offset facilities, are optionally available to simplify component and
module testing.
Pulse Modulator
An optional pulse modulator allows the generation of fast rise time RF
signals with on/off ratios that meet the most demanding radar and
ECM/ECCM test applications.
Remote Control
The 3410 series include both fast GPIB and Ethernet remote control
interfaces for flexibility in production environments. RS-232 control
is also provided for use in legacy ATE systems.
The protocol and syntax of the GPIB commands have been designed
in accordance with IEEE 488.2 to simplify program generation. Plug
and play drivers are available that include a virtual front panel for
remote instrument supervision and debug.
Frequency Standard
The 3410 series includes a high stability OCXO as standard. The
inclusion of a main input power standby mode maintains the oscillator
at working temperature while the rest of the instrument is powered
down. Time to full specification working is thereby minimized
for equipment facilities held on standby.
