The BYU Synthetic Aperture Radar Systems
Links are to photos. An index to the entire set of photos can
be seen here.
The YINSAR hardware is housed in three rack-mount cases. The
system is controlled from a laptop connected through an RS-232
The top case contains
the computer subsystem. This subsystem includes two 500MHz A/D
cards, a 200MHz D/A card, a 6.25MHz timing card, and a custom interface
The next case contains the IF/RF hardware and power supplies. The
RF transceiver was built by Miteq. The
power amplifier and its
heat sink also take up a large portion of the box. This box
also contains power supplies,
a GPS receiver, and many subsystem interconnections.
The final case contains all of the motion measurement system, including
the Inertial Measurement Unit (IMU), the Omnistar
Differential GPS receiver will be in this box, and the Trimble
Kinematic GPS. These systems should allow 20cm accuracy in absolute
position and relative accuracy of a few millimeters per image.
YINSAR software can be divided into four basic parts: GUI and navigation,
control and communication, data collection, and processing. Each
of these software systems runs on a different platform.
The GUI and navigation software runs on the laptop. It receives
GPS data and system status and controls the system through the RS-232
port at 38.4kbps. This software was written in Microsoft Visual
Basic. This is the Graphical User Interface to the system and includes
such features as a map display for navigation, debugging displays,
and control panels.
The communication and control software runs on the COMM computer,
which is one side of a split backplane. This is a 133-MHz Pentium
system. The software collects and routes data between 5 serial streams,:
the IMU, the Trimble GPS, the Ashtech GPS, the laptop, and the SAR
computer. This computer also controls power supplies for all of
the components in the RF/IF box as well as for the YINSAR computer.
The data collection software runs on the SAR computer. This software
was written in C using the Microsoft Visual C++ compiler (version
2.0) with the Pharlap DOS-Extender, and runs under DOS. Commands
are received either through the RS-232 line from the COMM computer
or from the keyboard (in actual operation, no monitor or keyboard
The processing software runs on ECEn department and MERS lab workstations
(mostly HP and SGI workstations). This software system combines
components written by Doug Thompson specifically for YSAR and YINSAR
with components written by Charlie Werner of Gamma Remote Sensing
as a general SAR processing package. All of the SAR processing is
done in this post-processing stage. We have developed our own motion
compensation and autofocus code.