Design, implementation and testing of a digital baseband receiver for spread spectrum telesensing

Telesensing involves receiving data wirelessly from a remote sensor Generally, the sensor node is fixed and configured to transmit only or perform very basic reception Because of their low power consumption, telesensors can be powered by a battery for long periods of time without a measurement or transmission interruption This allows several nodes to be placed at strategic locations and creates a need to have all the individual data collected and processed at a centralized location Frequency Division Multiple Access (FDMA) provides robust data transmission from multiple telesensors to the same receiver at the cost of added bandwidth.

This thesis focuses on the digital recovery of spread spectrum data in an FDMA system A general digital spread spectrum receiver architecture is given(without transceiving capability) and each component is designed,implemented and tested m the receiver as a whole A sliding correlator with a threshold is used to synchronize the pseudonoise (PN) code used to encode the data with the incoming data System clocks are also recovered from the incoming data and distributed to the downstream modules The design is implemented in an FPGA and tested with favorable packet error rate results m an FDMA system The components of the digital receiver processor could be used in conjunction with a Costas Loop demodulator to provide CDMA for multiple sensors and its functionality and robustness are confirmed in this thesis This would fit into a complete CDMA, allowing the demodulator to discriminate between various sensors