Non-GPS Methods of Geolocation

Abstract : JASON was asked to conduct a brainstorming session on the problem of precision (that is, at GPS-like accuracy) geolocation of ground elements by means other than use of GPS satellite transmissions in the usual way. This is important because GPS transmissions are weak and easily jammed, so it may be possible for enemy forces to deny conventional GPS use. We had no briefings on this subject, and (aside from the conventional idea of pseudolites) we are not aware of other work going on in this area. Our work was also limited by the very short time available for this project in the Winter Study, and so we furnish a rather brief report. Our general conclusion is that there are several perfectly practicable schemes for non-GPS geolocation, although more detailed investigation is needed to sort out the various advantages and disadvantages. If DARPA is interested, further studies on the best schemes could be carried out in the Summer Study.