New place for our GAP1 files

June 10th, 2013 by Ricardo Píriz

We have now a new ftp address on the GMV server for the RINEX measurement files coming from our GAP1 station. The files can now be downloaded with the following login information:

  • server: ftp.gmv.es
  • user: magicgnssro
  • password: R0gnss06

We are storing hourly files at a 1-second rate and daily files at a 30-second rate. The files can be accessed on a web browser through the following URLs (examples):

ftp://magicgnssro:R0gnss06@ftp.gmv.es/gap1161j.13d.Z (hourly file)

ftp://magicgnssro:R0gnss06@ftp.gmv.es/gap11610.13d.Z (daily file)

Files are kept on the server for the last 45 days, older files are also available upon request.

GAP1 station now contributing to IGS’ MGEX

July 30th, 2012 by Ricardo Píriz

Our GAP1 station is now contributing GPS+GLO data to the IGS’ MGEX experiment (RINEX files and real-time stream). RINEX files are available on the following ftp servers: CDDIS (USA), BKG (Germany), IGN (France). Hourly high-rate files are also available at GMV’s ftp server as usual (see below). A new GAP1 station log is also available. Galileo data is not yet ready due to unavailability of the required receiver firmware.

  • Daily files (@ 30 sec):

ftp://cddis.gsfc.nasa.gov/gnss/data/campaign/mgex/daily/rinex2/

ftp://igs.bkg.bund.de/MGEX/obs

ftp://igs.ign.fr/pub/igs/data/campaign/mgex/daily/rinex2

  • Hourly files (@ 30 sec):

ftp://cddis.gsfc.nasa.gov/gnss/data/campaign/mgex/hourly/rinex2/

ftp://igs.bkg.bund.de/MGEX/nrt

ftp://igs.ign.fr/pub/igs/data/campaign/mgex/hourly/rinex2

  • High-rate files (@ 1 sec):

ftp://cddis.gsfc.nasa.gov/gnss/data/campaign/mgex/highrate/rinex2/

ftp://igs.bkg.bund.de/MGEX/highrate

ftp://igs.ign.fr/pub/igs/data/campaign/mgex/highrate/rinex2

  • Hourly high-rate files (@ 1 sec); example:

ftp://ftp.gmv.es/incoming/gap1212m.12d.Z (only available for the last week or so)

Navigation messages have been discontinued, we recommend using daily “brdc” files from IGS:

GPS; example:

ftp://cddis.gsfc.nasa.gov/gps/data/daily/2012/212/12n/brdc2120.12n.Z

ftp://igs.bkg.bund.de/IGS/BRDC/2012/212/brdc2120.12n.Z

GLONASS; example:

ftp://cddis.gsfc.nasa.gov/gps/data/daily/2012/212/12g/brdc2120.12g.Z

ftp://igs.bkg.bund.de/IGS/BRDC/2012/212/brdc2120.12g.Z

New app for clock synchronization via GPS

September 29th, 2011 by Ricardo Píriz

Time transfer via satellite is nowadays the primary means to synchronize distant atomic clocks on ground. Clock synchronization is fundamental for example for maintaining UTC (Universal Time Coordinated), the official  scale by which the world regulates clocks and time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose.

Each national Timing Laboratory contributing to UTC keeps its own independent timescale, normally based on a very stable, temperature controlled, atomic clock or set of clocks. Then, all contributing timescales are inter-compared and combined in order to create an even more stable, international timescale (UTC).

But how to compare clocks located on different continents? One possibility is to use satellites that are in simultaneous view from the different laboratories. Enters GPS. By connecting each clock to a GPS receiver, in such a way that the measurements to the satellites are time-stamped by the external atomic clock instead of the internal receiver clock, and combining satellite measurements (RINEX files) from all these timing receivers in a sophisticated algorithm, it is possible to solve for all the system unknowns (satellite orbits, atmospheric delays, etc.) and compute the relative offsets of all ground clocks involved. This is precisely what the ODTS algorithm (Orbit Determination and Time Synchronization) within magicGNSS does. Read the rest of this entry »

Japan earthquake – IGS site displacements observed with magicGNSS

March 17th, 2011 by Álvaro Mozo

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.
Read the rest of this entry »

The Japan earthquake observed by GPS and GLONASS

March 15th, 2011 by Álvaro Mozo

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.