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Keysight Technologies
Solutions for Wideband Radar
and Satcom Measurements
Application Brief
Using wide bandwidth oscilloscopes to
directly measure and analyze X, Ku, and
Ka-band Radar and Satcom transmitter
outputs up to 62 GHz
Overview
A growing trend in Satellite communication (Satcom) and Radar systems
in the aerospace and defense market is the need for increased signal and
analysis bandwidth and processing gain. Satcom systems are being driven
by demands for increased data rates, while modern Radar systems require
more processing gain to improve range resolution, which in turn drives
wider modulation bandwidths. Modern Radar systems also employ more
complex pulse modulation signal formats to improve range resolution and
lower the probability of intercept and jamming. Many Radar and Satcom
systems operate at microwave frequencies (e.g., X, Ku and Ka bands), which
helps to support wider modulation bandwidths, increased capacity, and
also offers the benefit of smaller antennas.
In some cases, the wide bandwidths required exceed the intermediate
frequency (IF) bandwidths of commercially available RF spectrum analyz-
ers and vector (or FFT) signal analyzers. Coupled with the higher operating
frequencies, this creates a significant set of challenges for RF engineers
testing Radar and Satcom transmitters.
Problem
Quickly, accurately and cost-effectively measuring the performance of
RF/microwave transmitters in today's Radar and Satcom applications is
a challenging task. In some cases (e.g., to measure a Satcom transmit-
ter's Error Vector Magnitude (EVM)), the transmitter output can't always
be measured directly. Engineers often have to rely on custom-built down-
converter hardware to down-convert the RF/microwave frequencies to an IF
frequency that can then be measured with commercial off-the-shelf (COTS)
test equipment.
Unfortunately, the non-recurring engineering costs associated with
designing, building and testing the hardware can be counterproductive.
The down-converter hardware also adds its own RF impairments that can
mask the actual performance of the RF/microwave transmitter under test.
Moreover, distortion may occur that contributes to the overall EVM being
measured, making it difficult to discern how much EVM is from the actual
transmitter output. With no other available option, many RF engineers are
left with the measurement accuracy uncertainty that comes from this less
than ideal approach.
Solution
The wide-bandwidth oscilloscope allows RF of about 5 GHz enables it to be used as both
The answer to this dilemma lies in finding
engineers to directly measure and analyze an I/Q baseband and IF generator.
a solution that enables direct measure-
wideband Radar and Satcom transmitter
ment and analysis of the RF/microwave The PSG signal generator delivers high
outputs. With up to 33 GHz and 62 GHz
transmitter's output, without the need for quality test signals. Wideband IQ inputs
of analog bandwidth respectively, the
custom down-converter hardware. An ideal make it ideal for use with wideband Radar
90000 X-Series and 90000 Q-Series deliver
solution for this task is the wide-bandwidth and Satcom measurements. When the PSG
real-time measurement accuracy for direct
oscilloscope, which can directly measure and M8190A are combined, they provide
measurement of transmitter outputs--
and analyze X-, Ku- and Ka-band signals (up the flexibility necessary to create custom/
without the need for external down-conver-
to 62 GHz) from today's Radar and Satcom proprietary Radar signals and wideband
sion hardware. Time-domain analysis can be
transmitters. Using the wide-bandwidth modulated signals (e.g., QPSK and 16QAM)
performed to measure transmitter pulsed-RF
oscilloscope not only eliminates the time for Satcom applications. These signals can
characteristics (e.g., rise time, fall time and
and cost associated with use of custom be used for device under test (DUT) testing
pulse width).
down-converter hardware, but also relieves in the lab environment, without the need for
the engineer from having to deal with other The M8190A is a modular instrument pack- costly custom test equipment.
issues such as hardware calibration, correc- aged in the AXIe form factor. It is used to
tions for system impairments and uncertainty generate the wideband waveforms needed When used for component DUT testing, the
in measurement results. to test today's emerging Radar and Satcom M8190A generates wideband IQ signals that
systems. As a precision 1- or 2-channel are fed into the PSG's wideband IQ inputs.
Other aspects of wideband Radar and
AWG with a DAC resolution of 14 bits up The PSG then generates the microwave test
Satcom measurements that typically
to 8 GS/s and 12 bits up to 12 GS/s (2 to signal that will be used as DUT stimulus.
pose some level of difficulty for RF
4 bits more than what's currently available Next, the DUT's output is connected to
engineers include:
today), it offers excellent signal performance. the wide-bandwidth oscilloscope where