GPS World, January 2013

expert advice Andrei Shkel reprised his paper entitled Precision Navigation Timing and Targeting enabled by Microtechnology Are we there yet Gravity Tom Murphy of the University of California San Diego gave a fascinating paper of fundamental importance to understanding gravity by laser ranging to retroreflectors left on the moon by various Apollo and Russian missions A highly contrived initialism for the project is APOLLO for Apache Point Laser Observatory identified the massive security threat represented by millions of smart phone and tablet users who can store millions of bytes of information such as maps of sensitive locations Lunar Laser Ranging Operation The work is a product of a seven university research center consortium The system of APOLLO for measuring the range of the moon relative to the earth at Apache Point is a marvel of experimental ingenuity and advanced instrumentation in collecting the few photons that get back from the laser shots at the moon Laser light is caught by the retroreflectors and returned to the telescope at Apache Point A very sensitive gravimeter system at the observatory enables compensation for the Earths crustal motions and orbital deviations are compensated Precisions of a few millimeters in range to these devices on the moon are achieved almost good enough to be useful in testing the Strong Equivalence Principle of General Relativity From an engineering point of view the timing motion compensation detection sensitivity a few photons per shot and several other features of the system are truly impressive and the potential for improving our understanding of general relativity so called dark matter or energy and more are exciting aspects of this work To have much better precision through placing laser transceivers on the moon to increase the number of reflected transponder photons in the samples would appear to be quite valuable and relatively simple NASA missions for future work even though the data may eventually be sufficient to enable theoretical advancements without such added signal to noise benefit This paper was an example of excellent engineering in the service of important science Vulnerabilities and Limitations Charles Schue of UrsaNav gave a very detailed and comprehensive paper on wide area timing navigation and data using low frequency technology He provided data for timing location and data transmission over distances greater than 125 nautical Mmiles eLoran He made the point and showed examples to demonstrate that the technology for these systems exists today is highly affordable and can represent a major strengthening of the nations critical infrastructure The systems and hardware he presented are very attractive and seemingly very mature Schue was preaching to the choir as far as I can tell there is in the PNT community no controversy about the need for eLoran Further there is a sense of disappointment and wonder that so little money was saved at the expense of great risk to our critical PNT infrastructure particularly in view of the vulnerability to jamming and spoofing of GPS and the other GNSS systems for civil use a vulnerability analysis which informed the balance two of the papers in this summary report Spoofing Dennis Akos presented data on spoofing tests conducted at Lulea Sweden near a low density commercial airport with limited road traffic and a restricted Swedish Air Force weapons test area and in Kaohsiung Taiwan near a very busy airport with dense roadway traffic The incidence of radio frequency interference RFI in the latter case was great and in the former case negligible until the team introduced their jamming and spoofing equipment In both cases a simple automatic gain control AGC monitoring design which was computationally efficient was able to detect and measure the RFI from the jammer spoofer Using all commercial off the shelf COTS hardware the jammer was identified and located with time ofarrival and power difference of arrival The researchers showed that using a controlled reception pattern antenna CRPA like the Stanford four element CRPA and all COTS equipment jammers could be indentified and located efficiently through AGC processing A large amount of detailed data were presented with screen shots and plots of the effects of the jamming on the receivers Proof of Location Logan Scott of LS Consulting gave a paper on proof of location He projected the need for location proof in several applications ranging from system control and data acquisition intrusions that would affect industrial control systems to bogus Mayday calls the response to which is very expensive and he provided many examples of data security applications He also provided several schemes ranging from cryptographic GPS RF signal structures to the use of overlapping systems like Galileo and GPS to enable verification of location Scott identified the massive security threat represented by millions of smart phone and tablet users who can store millions of bytes of information such as maps of sensitive locations An authorized user of such a map GNSSScott GPS World January 2013 www gpsworld com 16