GPS World

Tag: TechDemoSat-1

  • Seen & Heard: March 2019

    Check out some GPS developments that have recently taken place around the world. (Click to enlarge; Map: iStock.com/nadla)

    Map: iStock.com/nadla

    1. When horses answer the call

    Taking a ride in a horse-drawn carriage delights many visitors to historic Charleston, South Carolina. Until now, city crews cleaning up the presents horses leave behind have relied on flag indicators left by carriage operators. Now the city is testing a new method. Carriage operators will send the exact location to equine sanitation crews using small GPS-enabled devices. When a horse or mule takes an on-street nature break, the guide presses a button, and the equine sanitation crew is notified of exactly where to go. When the cleanup is complete, the notification is deleted.

    2. Detecting rain over the ocean

    Despite a wide variety of monitored geophysical parameters, GNSS signals reflected off the Earth’s surface (GNSS reflectometry) have never been used to obtain rain information. A new study presents evidence that data from the U.K.’s TechDemoSat-1 potentially enables the GNSS-R technique to detect precipitation over oceans at low winds. The study — by scientists at the GFZ German Research Center for Geosciences at Potsdam — could serve as a starting point for developing a new GNSS reflectometry application, which might also be implemented for low-cost GNSS remote-sensing missions.

    Gamers around the world can now play with the Galileo constellation. Callisto for Android uses Galileo signals in a virtual maze game based on walking through a real-world location. Looking down on Earth as if from a spaceship, players use a Google Map display to traverse an area filled with randomly generated obstacles and collectibles. The project began as an entry to European Space Agency’s Galileo App Competition 2017–2018 and was one of three apps that made it to the finals. (Photo: Chocolateam)
    Click to enlarge. (Photo: Chocolateam)

    3. Gaming with Galileo

    Gamers around the world can now play with the Galileo constellation. Callisto for Android uses Galileo signals in a virtual maze game based on walking through a real-world location. Looking down on Earth as if from a spaceship, players use a Google Map display to traverse an area filled with randomly generated obstacles and collectibles. The project began as an entry to European Space Agency’s Galileo App Competition 2017–2018 and was one of three apps that made it to the finals.

    4. Guinness decision pending on world’s steepest street

    Dunedin, New Zealand, claims to have the world’s steepest street (Baldwin), a title officially challenged in January by the town of Harlech, Wales, when residents walked up and down the narrow, winding Ffordd Pen Llech carrying a GNSS surveying receiver. A total of 14 data points were recorded on the 330-meter-long road, which had an altitude accuracy of ±5 centimeters. New Zealand surveyor Richard Hemi said the GNSS method used by the Welsh group might not be accurate. Best accuracy is to survey from the center of the road — easy on Baldwin St. but much more difficult on a winding lane. The survey was sent to Guinness World Records, which will issue a decision this spring.

  • Using GNSS, new service maps wind speed over oceans

    The first global GNSS-reflectometry ocean-wind data service has been launched by Surrey Satellite Technology Ltd. (SSTL) with the National Oceanography Centre (NOC), and with support from the European Space Agency.

    The online data service, dubbed MERRBYS (Measurement of Earth Reflected Radio-navigation signals By Satellite), is free.

    Users can access measurements of wind taken by a specially designed GNSS receiver hosted on SSTL’s TechDemoSat-1 satellite, which collects signals reflected off the surface of the ocean. The service offers monthly maps of wind speed over the oceans.

    TechDemoSat-1 is also collecting GNSS reflections off land and polar regions, opening the door for new applications of this technology, such as soil moisture and ice measurements.

    TechDemoSat-1 was launched in 2014 and carried eight payloads from different U.K. organizations. On successful completion of the satellite’s original mission, a life extension now allows the GNSS reflectometry payload to be operated continuously.

    Onboard processed GNSS-R data is relayed to SSTL’s ground station in the U.K. and inverted for geophysical parameters using NOC retrieval algorithms for the estimation of near-surface ocean wind speed.

    Users have access to data from the past three years, and new data is added daily with a latency of 30 days. Users can also register for a fast service allowing retrieval of data with a shorter delay — currently 48 hours, but with a target of less than 24 hours as the service matures.

    Pilot demonstration

    The current service is a pilot demonstration showing the potential for a new source of wind and wave measurements from in orbit using a small satellite. In the future, a constellation of low-cost small satellites carrying enhanced instruments could provide measurements in near-real time to support weather and wave forecasting.

    The TechDemoSat-1 satellite and payload were supported by U.K. Centre for Earth Observation Instrumentation and the U.K. Space Agency, and sponsorship from European Space Agency has allowed the release of data.

    More than 50 international journal papers have been published based on the use of the TechDemoSat-1 GNSS-R data. GPS World first discussed the technology in a 1999 Innovation column by GPS World Leadership Award Winner Attila Komjathy, “GPS, a new tool for ocean science.”

    This was followed in 2007 by “Reflecting on GPS: Sensing land and ice from low Earth orbit” by Scott Gleason, a University of Surrey graduate detecting land and ice from orbit using one of the SSTL satellites; then in 2010 by “Friendly reflections: Monitoring water level with GNSS,” by Alejandro Egido and Marco Caparrini, which dealt with using reflections from water surfaces observed with receivers on the ground.

    SSTL also provided the same GNSS reflectometry instrument to the NASA CYGNSS mission, where eight small satellites are using this technique to probe and analyze hurricanes.