Frequency Division Multiplexing for a Multi-Sensor Wireless Telemetry System
Introduction
The problem of encoding multiple input signals into a finite bandwidth space is one that is common in engineering problems today. It is found in communication system encoding schemes from cell phones to cable TV. The problem is that the system needs to carry several independent signals over a single communications medium. Some examples of data encoding for these data communication problems include time division multiplexing (i.e. telephone lines), code division multiplexing (cell phones), statistical multiplexing (internet), and frequency division multiplexing (cable TV).
We have designed a wireless telemetry system that utilizes frequency division multiplexing (FDM) to encode several input sensor values onto a single analog channel for transmission. By using a single transmitter, we can simplify design and reduce bandwidth consumption and power costs. We have encoded three-axis accelerometer data using our technique. Direct digital synthesis (DDS) was utilized to convert three separate ten bit number intro three orthogonal frequencies. A linear combination of these orthogonal signals was FM modulated into the commercial FM band. We also have developed a decoding scheme which reconstructs the original input levels.
Link: http://instruct1.cit.cornell.edu/courses/e...6/476Final.html
Introduction
The problem of encoding multiple input signals into a finite bandwidth space is one that is common in engineering problems today. It is found in communication system encoding schemes from cell phones to cable TV. The problem is that the system needs to carry several independent signals over a single communications medium. Some examples of data encoding for these data communication problems include time division multiplexing (i.e. telephone lines), code division multiplexing (cell phones), statistical multiplexing (internet), and frequency division multiplexing (cable TV).
We have designed a wireless telemetry system that utilizes frequency division multiplexing (FDM) to encode several input sensor values onto a single analog channel for transmission. By using a single transmitter, we can simplify design and reduce bandwidth consumption and power costs. We have encoded three-axis accelerometer data using our technique. Direct digital synthesis (DDS) was utilized to convert three separate ten bit number intro three orthogonal frequencies. A linear combination of these orthogonal signals was FM modulated into the commercial FM band. We also have developed a decoding scheme which reconstructs the original input levels.
Link: http://instruct1.cit.cornell.edu/courses/e...6/476Final.html