There’s something I’ve been wanting to write about since the ION-GNSS conference a few weeks ago. However, a nasty cold, a 10-day trip to Europe (INTERGEO conference), and some jet lag have kept me from it until now.
Normally, my column following a webinar is dedicated to Q&A follow-up from the webinar. However, immediately following the April 22 webinar, I traveled to Phoenix, Arizona, to attend the ACSM/GITA conference, which I wrote about earlier this month.
It’s been a tough couple of weeks for SBAS (Satellite-Based Augmentation System), namely the USA’s WAAS program and India’s GAGAN program. WAAS and GAGAN have taken big hits recently that threaten the integrity of the programs. Both events were totally unexpected and are causing disruptions of GPS correction services.
After reviewing current performance of WAAS, EGNOS, and MSAS, the authors present expected future performance, including the benefits of GPS L5. They evaluate the impact of the Indian GAGAN and Russian SDCM systems on global coverage and examine southward expansions for the original three SBASs. Finally, a look at the impact of a second constellation of navigation satellites and the performance for a user taking advantage of two core constellations.
Deterministic risk modeling, the basis of the Efficient Market Hypothesis (EMH) at the core of modern quantitative finance, is known to be fundamentally flawed, but its elegance and convenience has blinded researchers to growing evidence of its weaknesses. The near-complete acceptance of the EMH led to models that dramatically accentuate its flaws, which in turn led to absurd but eagerly accepted conclusions for loan-default risk. These models proved dramatically vulnerable to changes in the housing market in 2007–2008 and led directly to the ensuing crash.
Few precise-positioning users have employed Loran in a professional sense, although maybe you have in your personal life if you’re a airplane pilot or a mariner. Then again, if you’ve flown as an airline passenger or cruised onboard a ship, you’ve benefited from the back-up to GPS that Loran provides. That back-up is about to go away. As attention and resources shift away from Loran, they focuses more intensely on GPS augmentations, specifically differential GPS (DGPS) and satellite-based augmentation systems (SBAS) such as WAAS and EGNOS.
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