Evaluating the Navigation Potential of the NTSC Analog Television Broadcast Signal

Ryan J. Eggert and John F. Raquet

Abstract:	The accuracy and worldwide availability of the Global Positioning System (GPS) make it a highly valuable system for navigation and precise positioning. Unfortunately, many situations arise in which GPS may not be adequate, such as urban navigation. This research evaluates the navigation potential of the National Television System Committee (NTSC) broadcast signal using a time-difference-of-arrival (TDOA) algorithm. TDOA measurements were made using NTSC broadcast signals collected from low and high multipath environments. These measurements were then used to evaluate the severity and dynamic effects of NTSC broadcast multipath signals. Three data reduction algorithms were developed–one that modifies the classical cross-correlation TDOA approach, and two that difference the signals’ time-of-arrival at each receiver. Each algorithm was evaluated for consistency and accuracy in each environment. Also, multipath mitigation was demonstrated using a locally fabricated antenna. TDOA measurement errors ranging from 1 to 200 meters, with typical errors between 10 and 40 meters. Multipath was shown to be the dominant error source. However, errors due to the particular hardware configuration used in this research were also significant. Simple multipath mitigation techniques were able to reduce these errors, and analyses of the received waveforms provide the foundation for developing additional active multipath mitigation techniques. Simulations using eight television station locations near Dayton, Ohio reveal 40 meter position accuracy with the typical range errors found in this research. Extreme measurement errors from high multipath areas reduced this accuracy to 100 meters. Additionally, using the same transmitter geometry, simulation results showed that TDOA measurement accuracies of 5 to 10 meters were required to provide position estimates with 10 meter accuracy–the accuracy of readily available single frequency GPS receivers.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	2436 - 2446
Cite this article:	Eggert, Ryan J., Raquet, John F., "Evaluating the Navigation Potential of the NTSC Analog Television Broadcast Signal," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 2436-2446.
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