During the test campaign of the EPOC (Early Proof-Of-Concept) in the frame of the AALECS (Authentic and Accurate Location Experimentation with the Commercial Service) project, magicGNSS reference products have been broadcast in the Galileo E6 signals.

Orbit and clock predictions have been generated 2-3 days in advance of each test by magicODTS using data gathered by the IGS MGEX network (http://igs.org/mgex/). This high-accuracy (HA) data is then sent to GMS and uploaded to the IOV satellites for broadcast during test slots (see figure below).

The E6-B signal has been tracked both with SCE (Spreading Code Encryption) enabled and disabled. During tests broadcast products are gathered and authenticated via TESLA-based NMA and/or SCE. Then, a high-precision data-authenticated PVT solution is computed by means of magicPPP.

The aim of the test campaign has been to evaluate the E6 data transmission performance, and prove that the system is capable of providing authentication and HA positioning/timing services. Several static and kinematic tests have been conducted from mid-July to late-September 2014. The figure below shows performance of a static PVT with SCE enabled: an RMS below 40 cm in the horizontal plane is achieved, including the convergence period.

Some of the IGS stations placed in Japan are providing data after the magnitude 9.0 earthquake that hit Japan on March 11th, 2011. We have processed data from those stations with magicGNSS, to evaluate the site displacements due to the earthquake and its aftershocks. They are shown in the following graphic:

The pre- and post-earthquake coordinates have been computed with static PPP (GPS only, as most of the sites do not provide GLONASS data) using 1 day of data (March 10th and 15th, 2011, respectively).

Note that due to the aftershocks, the coordinates on March 15th may not be considered truly static, yet the results are considered very illustrative of the magnitude of the event.
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A 9.0-magnitude earthquake hit Japan on Friday March 11th, 2011 at 05:46 UTC. The epicenter was reported to be 130 kilometers (81 mi) off the east coast of the Oshika Peninsula, Tōhoku.

The National Astronomical Observatory in Mizusawa hosts a GNSS station which belongs to the IGS network. This station, labeled mizu, is located at around 140 km (87 mi) northwest of the epicenter, and provided GPS and GLONASS data at 1-sec rate until 06:00 UTC.

The following plots show the displacements of the mizu antenna coordinates during the earthquake, computed with magicGNSS’ GPS+GLONASS kinematic PPP. In both plots the positions are computed every second.

The IGS data from the mizu station for March 11th, 2011 used to compute the above plots have been made public in magicGNSS, so you can log into your account and process them yourself right now.



As explained in the previous entry of this blog, the ODTS algorithm inside magicGNSS is able to calculate precise station coordinates. Another technique that is becoming increasingly propular to calculate receiver coordinates is Precise-Point-Positioning (PPP).

The main difference between ODTS and PPP is that ODTS is a multi-station global solution that calculates also satellite orbits and clocks, and PPP is a single-station technique where satellite orbits and clocks are solved beforehand using an independent software (or are fixed to IGS solutions). ODTS is based on a batch least-squares algorithm whereas PPP is normally based on a sequential filter that solves for the user reciever coordinates, clock, tropo, and phase ambiguities.

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