Bob Rennard - Engineer on Original GPS, TeleNav Co-Founder; Q&A with GPSLodge
Bob Rennard, co-founder and CTO of TeleNav, the mobile phone navigation provider, was also one of the original engineers on the GPS system for the military when first developed. He took some time out of his day to answer some questions for GPSLodge about the early days of GPS and the recent news that the GPS system might not be performing well as a result of satellite issues. Clearly, the goals of the original team were not to have a tiny GPS chipset in every mobile phone sold today, so it's amazing to see the progress. See the Q&A below for more info on the history and how he landed at TeleNav.
GPSLodge: The first Block 1 Satellite was launched in 1978, with 10 total satellites launched right through 1985. When did you know that this new system was going to be a success and what was it like to see the results as these satellites were launched and the systems become functional?
Bob Rennard: Unfortunately, my tour of duty with the GPS program office ended just after the first USAF satellite was placed on orbit. Early testing at Yuma Proving Ground, Arizona employed a hybrid constellation of the 1977 Navy and 1978 USAF satellites with an array of synchronized ground transmitters that formed the 'inverted range'. During this testing, a Sylvania PATS tracker was used to provide ground truth for the testing. In short order, discrepancies between PATS and the GPS testing were determined to be due to a small mechanical error in the PATS that had never been noticed before, but that GPS detected. At that point, we knew GPS was going to be a success.
Continued after the jump.....
GPSLodge: Today the ability to render a user's location can be done by a tiny chip in a mobile phone, what was the first GPS receiver like and how big was it?
Bob Rennard: There were three competing families of user equipment under test at Yuma Proving Ground. These were: a) The Magnavox X multichannel receiver, Y multiplexed channel and Z prototype man-pack sets; b) the Texas Instruments High Dynamic User Equipment (HDUE), and c) the Rockwell/Collins high jamming tolerance receiver. You can readily find images of the Magnavox X-set on the web. It was packaged in three 19 inch wide chasses, a separate RF amplifier, and a control unit that was adapted from an aircraft inertial navigation system. The 'X-set' weighed close to 150 pounds, and so did the Texas Instruments and Collins airborne units . One of the more interesting things attempted during the Yuma Proving Ground testing was the automated landing of a C-141 Starlifter that carried multiple receivers under test. I am not sure what the first military use of GPS was, but clearly by Desert Shield the potential was realized, and by Desert Storm it was pervasively demonstrated.
GPSLodge: When you were first working on the project, these systems were designed for military use only. Did you or your team members ever envision that it would reach this level of popularity and scale? Did you have an idea that consumer products such as we have today would one day use GPS technology?
Bob Rennard: One of the selling points of GPS within the US Government was replacing a large collection of disparate military and civilian navigation and positioning systems that had less accuracy, were taxing to maintain, and individually had limited purpose. While prudent tacticians do not put all of their eggs into one basket, it was obvious that GPS could replace a lot of these systems achieving reduced cost and performance improvement. Early GPS receivers were bulky and costly, and used a mix of analog and digital signal processing. As technology matured, particularly high speed CMOS circuits, the need for analog circuitry almost completely disappeared. As CMOS density increased, GPS receivers shrunk following the tenets of Gordon Moore's Law. I do not think that anybody 30 years ago forecast that a GPS receiver's processing would become so compact that it would become buried in other circuitry such as the baseband processor of a mobile phone. This miniaturization and the Internet's spawning interest in digital maps lead to the current consumer demand for GPS-based products. It is fascinating how different facets of technology independently reach the level of maturity needed to make cool things happen from their synergy.
GPSLodge: What is your take on the recent discussions around the deterioration of the system and potential for it to lose accuracy or fail?
Bob Rennard: The Government Accountability Office (GAO) 09-325 report predicts that if the USAF does not take action to increase the frequency of satellite launches to meet forecast satellite failures due to old age there could be a reduction in satellite availability, and a concomitant reduction in GPS accuracy. Fox News and the UK Daily Mail have seized on this report, and are now causing some hysteria that hopefully the USAF can manage by continuing to launch Lockheed Martin block IIR satellites, and introducing Boeing block IIF satellites starting with the first highly delayed IIF launch scheduled for November, 2009. Hopefully nothing else will aggravate the USAF's ability to keep the constellation fully populated.
GPSLodge: From helping to invent the GPS system as we know it today, to TeleNav, how did you find yourself in the place to become a founder of the leading provider of mobile navigation applications?
Bob Rennard: The three founders of TeleNav had worked together in a captive startup with the mission of providing high-accuracy GPS correction information via satellite. This technology is currently used by precision farming companies such as a subsidiary of John Deere, but alas not using our approach. After that startup closed, we went our separate ways, but convened periodically to hear the others' ideas for forming another startup. In the summer of 1999, we became aware that Sprint would soon be offering WAP internet access on mobile phones, and that the FCC e911 mandate would result in location systems being deployed starting in 2001. Some phones already had sufficient processing power to consider building a mobile phone navigation application using the other two ingredients as enabling technologies. Our quest to be a pioneer in providing this capability was first realized in the summer of 2002 during a demonstration to Nextel. We reworked the application to make it more autonomous, and introduced it on the Nextel network in 2003.
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Posted by Scott Martin at July 31, 2009 11:33 AM