mmWave Design
utmost importance. While LFMCW and
FSK fulfill these requirements, LFMCW
needs multiple measurement cycles
and mathematical solution algorithms
to solve ambiguities, while FSK lacks in
range resolution. As a result, a technique
combining LFMCW and FSK into a
single waveform called multiple frequency
shift keying (MFSK) is of considerable
interest. MFSK was specifically
developed to serve radar development
for automotive applications and consists
of two or more transmit frequencies with
an intertwined frequency shift and with
a certain bandwidth and duration, as
shown in Figure 2 1.
As previously mentioned, pulsed
radars are also widely used in automotive
radar systems. Relative velocity can
be determined from consecutive pulses
using a coherent transmitter and receiver
to measure pulse-to-pulse phase variations
containing the Doppler frequency
that conveys relative velocity. For a
pulsed-Doppler (PD) radar, range is still
measured by signal propagation time. To
measure both range and relative velocity,
the pulse-repetition frequency is an
important parameter.
There are many tradeoffs to be
considered when deciding which
architecture and waveform modulation
technology delivers the necessary
performance while maintaining development
and production cost goals. These
requirements can be met with NI AWR
Design Environment, specifically Visual
System Simulator™ (VSS) system design
software that is dedicated to RF system
design and implementation, offering a
toolbox of commonly called-for simulation
technologies and radio block/signal
processing models, along with support
for user-developed coding.
VSS is an RF and wireless communications
and radar systems design
solution that provides the simulation
and detailed modeling of RF and digital
signal processing (DSP) components
necessary to accurately represent the
signal generation, transmission, antenna,
T/R switching, clutter, noise, jamming,
receiving, signal processing, and channel
model design challenges and analysis
requirements for today’s advanced
radar systems.
The VSS workspace example in
Figure 3 demonstrates a possible ACC
radar architecture, modulation scheme,
channel modeling and measurement
configuration. This workspace includes a
pulse-Doppler (PD) radar system design
with signal generator, RF transmitter,
antenna, clutters, RF receiver, moving
Figure 5: Sub-circuit defining transmit and receive antennas, channel, and target
with swept distance to radar (includes modeling of ground clutter).
Figure 6. Results of the simulation are shown in the system metrics graph.
Figure 7: Bosch mid range radar (MRR) bi-static, multi-modal radar featuring three
transmitters and four receivers, supporting a horizontal field of view 160m (±6°),
100m (±9°), and 60m (±10°) for the main antenna and 36 m (±25°), 12 m (±42°) for
the elevation antenna.
16 MW November - December 2017 www.mwee.com
