Using MathWorks tools, LANL built and validated a rapid prototype of INFICOMM and applied the concept of modulated reflectance in a flexible communications demonstration system that could be modified for various implementations.
The team used MATLAB for front-end analysis of the demo system to determine the system’s power requirements and expected range. They relied on MATLAB for real-time control of the RF components and for demodulating the signal.
“Since the design stitches together packaged components and off-the-shelf vendor boards, it was essential to have MathWorks tools to control the mating of the components,” explains Briles.
The team verified that the system could transmit digital images by compressing still video images and using the Image Processing Toolbox to send a bit stream across the communication link. Using MATLAB, they then decompressed and displayed the images. They used the Signal Processing Toolbox to control the frequency and the MATLAB RS-232 serial port interface to control the carrier-wave signal source.
“With the Signal Processing Toolbox, I can control the frequency to a single kHz in the 2 to 3 GHz band and can also control the output power of the signal source via the RS-232 interface,” says Briles.
Next, the researchers used the Data Acquisition Toolbox to control the outgoing signal on a digital I/O board and MATLAB to control the filter/amplifier PCI card. They built the control by writing small C-language functions that they converted into MEX functions for interfacing with MATLAB.
“Instead of writing everything in C, I wrote a small function that controlled the card and used the MATLAB interface to call the function,” says Briles. “This lets me control the amplification of the return signal and its bandwidth.”
The researchers also used the Data Acquisition Toolbox to control a Measurement Computing analog/digital converter (ADC) board and digitize the reflected signal from the modulated reflector. The collected data was streamed into memory. Then they used the Communications System Toolbox™ to demodulate the frequency shift keying (FSK) modulation.
“Once the signal was on the ADC board, I knew that whatever demodulation was needed could be done in MATLAB,” says Briles. “Plus, MATLAB lets me investigate different modulation schemes, such as CDMA, more quickly than C code.”
LANL is approaching companies in various industries about using INFICOMM commercially, including oil companies for down-hole telemetry and communications companies for wireless LAN applications.