Links are to photos. An index to the entire set of photos can be seen here.

Hardware

The YINSAR hardware is housed in three rack-mount cases. The system is controlled from a laptop connected through an RS-232 serial line.

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 card.

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.

Software

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 is attached).

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.