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ics. This system implements control algorithms
that accept operator inputs to
point the telescope to ground-based
objects of interest.
• Precision optics direct the light collected
by the telescope into a series of imaging
cameras. Aircraft engine vibration, structural
resonance, and other disturbances
can wreak havoc on the alignment of
these devices. To compensate for these
effects, an automatic alignment system is
incorporated. The goal is to stabilize the
imaging system so it can yield a clear, jitter-free
image for the system operators.
• Sensitive imaging cameras act as the
“eyes” of the electro-optical payload.
These devices provide high-resolution
daytime and nighttime video to real-time
image processing hardware.
• Sophisticated image-processing algorithms
that perform video enhancement, segmentation,
and feature extraction.
Together, these subsystems allow an operator
to identify and interrogate ground-based
objects with unprecedented capability. Figure 1
highlights some of the essential functions of
this system.
Boeing Subsystems
Boeing has chosen the Virtex-II Pro Platform
as a critical element in this programmable
system. The FPGA device and the supporting
chips connected to it execute the following
functions:
• High-speed image processing
• Digital-video scene generation
and storage
• Fiber-optic media conversion of
video data
• DVI display generation
• NTSC video generation
• Servo-control functions
• High-bandwidth data transfer
interfaces.
Embedded DSP
One reason Boeing chose the Virtex-II Pro
platform is that it incorporates three of the
most important elements for a modern,
embedded DSP device.
Aircraft Imaging System
Figure 1 – Essential
system functions
1. A high-performance, high-density,
programmable logic fabric – this capability
is the heart and soul of true parallel
processing. FPGA technology
lends itself very well to the repetitive,
systolic nature of our algorithms.
Embedded multipliers, SRL16 capabilities,
true dual-port Block RAM, and a
segmented routing architecture give us
key enabling technologies to produce
powerful designs.
2. A wealth of interface pins that can be
configured for different signaling standards
and easily integrated with devices
from other vendors – using a single
Xilinx chip, Boeing’s design team can
arrange a device with a PCI bus interface,
video encoder/decoder connections,
digital-video display outputs,
multiple SRAM interfaces, and a highspeed
digital-video input port. These
functions run in parallel, concurrently,
without the hassles of bus contention
and multi-processor scatter/gather issues.
The Virtex-II Pro multi-gigabit transceivers
(MGTs) raise the bar to another
level. MGTs are extremely useful for
the imaging camera interfaces. Boeing’s
design team can use a low-end Virtex-
II Pro device to serialize several parallel
digital video outputs. These serial outputs
are easily converted to fiber-optic
media. And because the data transfer is
point-to-point, designers can program
the serial transceivers with a userfriendly
data protocol.
Optical
Alignment
Servo-Control Systems
Image
Processing
3. An embedded IBM PowerPC 405
CPU – the point of using an FPGA
in many image-processing applications
is to unburden the host CPU
from simple, brute-force calculations.
With the embedded PowerPC CPU,
the host is left unimpeded to handle
the complex decision-making logic
that forms the brains of a system.
PowerPC Advantages
Many people might argue that it’s easy
enough to hook an FPGA to a PCI bus
interface – so why bother with the embedded
PowerPC CPU in the Virtex-II Pro
platform? For some applications, a PCI
interface is sufficient, but Boeing’s design
team has found many compelling reasons
to choose an embedded CPU:
• By using logic to accelerate the embedded
CPU, most of the residual backend
processing for our applications
requires only a modest amount of
compute power. We all like having
multi-GHz CPU power, but it is not
always necessary.
• The embedded PowerPC CPU consumes
a fraction of the power of a highend
CPU, while remaining directly
coupled to the logic fabric. In Boeing’s
business, it seems that Moore’s law does
not always apply. RISC CPUs for
embedded applications have not generally
kept pace with desktop systems in
terms of clock speed and performance.
Packaging and thermal dissipation con-
54 Xcell Journal Summer 2003