Researchers propose new method for absolute calibration of multi-mode satellite navigation receiver delay
Friday, 02 July 2021 13:52
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Researchers from the National Time Service Center (NTSC) of the Chinese Academy of Sciences have proposed a new method to realize absolute calibration of multi-mode satellite navigation receiver delay.
The new method can be applied to fields like navigation positioning, satellite timing, and time transfer, increasing user positioning and timing accuracy.
The calibration of global navigation satellite system (GNSS) receiver delay poses a technology difficulty in the field of satellite navigation. The widely used relative calibration method can only obtain the delay difference between a tested receiver and a reference receiver.
However, fields like GNSS time offset monitoring, satellite timing technology and satellite-ground time synchronization need absolute calibration.
NTSC researchers used satellite simulator hardware and high-speed oscilloscope to completely calibrate all kinds of GNSS receiver delay, with the calibration accuracy better than 1.5ns(1σ).
An atomic clock provided reference frequency for all equipment. Testing Time-to-Code (TtC) by the oscilloscope was used to calibrate the simulator delay, and the channel delay could be calculated by the pseudorange, 1and PPS output delay measured by a time interval counter.
Week in images: 28 June - 02 July 2021
Friday, 02 July 2021 12:34 Write a comment
Week in images: 28 June - 02 July 2021
Discover our week through the lens
Image: Hubble sees a cluster of red, white, and blue
Friday, 02 July 2021 12:22 Write a comment
This image taken with the NASA/ESA Hubble Space Telescope depicts the open star cluster NGC 330, which lies around 180,000 light-years away inside the Small Magellanic Cloud. The cluster—which is in the constellation Tucana (the Toucan)—contains a multitude of stars, many of which are scattered across this striking image.
Because star clusters form from a single primordial cloud of gas and dust, all the stars they contain are roughly the same age. This makes them useful natural laboratories for astronomers to learn how stars form and evolve. This image uses observations from Hubble's Wide Field Camera 3 and incorporates data from two very different astronomical investigations. The first aimed to understand why stars in star clusters appear to evolve differently from stars elsewhere, a peculiarity first observed with Hubble. The second aimed to determine how large stars can be before they become doomed to end their lives in cataclysmic supernova explosions.
Hubble images show us something new about the universe.
NASA's self-driving Perseverance Mars rover 'takes the wheel'
Friday, 02 July 2021 11:51 Write a comment
NASA's newest six-wheeled robot on Mars, the Perseverance rover, is beginning an epic journey across a crater floor seeking signs of ancient life. That means the rover team is deeply engaged with planning navigation routes, drafting instructions to be beamed up, even donning special 3D glasses to help map their course.
But increasingly, the rover will take charge of the drive by itself, using a powerful auto-navigation system. Called AutoNav, this enhanced system makes 3D maps of the terrain ahead, identifies hazards, and plans a route around any obstacles without additional direction from controllers back on Earth.
"We have a capability called 'thinking while driving,'" said Vandi Verma, a senior engineer, rover planner, and driver at NASA's Jet Propulsion Laboratory in Southern California.
From atoms to planets, the longest-running Space Station experiment
Friday, 02 July 2021 08:56
First high-altitude drop test success for ExoMars parachute
Friday, 02 July 2021 08:19 Write a comment
After several weeks of bad weather and strong winds, the latest pair of high-altitude drop tests of the ExoMars parachutes took place in Kiruna, Sweden. The 15 m-wide first stage main parachute performed flawlessly at supersonic speeds, while the 35 m-wide second stage parachute experienced one minor damage, but decelerated the mock-up of the landing platform as expected.
Billionaire blast off: Richard Branson plans space trip ahead of rival Bezos
Friday, 02 July 2021 07:41 Write a comment
Call it a space race for billionaires: British mogul Richard Branson one-upped rival Jeff Bezos on Thursday, announcing that he too will blast beyond Earth's atmosphere - as many as nine days ahead of the Amazon founder.
With both tycoons having created space tourism companies and positioned themselves as leaders in the suborbital-flights-for-the-wealthy sector, the move signaled clear if n Perseverance Mars rover to use AutoNav in new self driving mode
Friday, 02 July 2021 07:41 Write a comment
NASA's newest six-wheeled robot on Mars, the Perseverance rover, is beginning an epic journey across a crater floor seeking signs of ancient life. That means the rover team is deeply engaged with planning navigation routes, drafting instructions to be beamed up, even donning special 3D glasses to help map their course.
But increasingly, the rover will take charge of the drive by itself, us Eye of ESA's asteroid mission
Friday, 02 July 2021 07:41 Write a comment
This is the main camera that ESA's Hera mission for planetary defence will be relying on to explore and manoeuvre around the Didymos asteroid system.
Hera - named after the Greek goddess of marriage - will be, along with NASA's Double Asteroid Redirect Test (DART) spacecraft, humankind's first probe to rendezvous with a binary asteroid system, a little understood class making up around 15% NASA offers $45M to solve risks for astronaut Lunar landing services
Friday, 02 July 2021 07:41 Write a comment
NASA is preparing to establish a regular cadence of trips to the Moon under Artemis. To help the agency fine-tune its approach, NASA will award firm fixed-price, milestone-based contracts of up to $45 million for commercial-led work under a broad agency announcement released Thursday.
NASA is seeking new work to mature designs and conduct technology and engineering risk-reduction tasks for Rogue Space and Orbital Assembly want to lease 2 Laura Orbot spacecraft
Friday, 02 July 2021 07:41 Write a comment
Rogue Space Systems Corporation announced the signing of a Letter of Intent by Orbital Assembly Corporation (OAC), the world's first large scale space construction company, to lease two Laura Orbital Robot (Orbots) spacecrafts for Orbital Assembly's P-STAR Mission to launch construction technologies for the first low gravity space hotel.
As part of the agreement, Rogue Space and Orbital As Trailblazing woman pilot, 82, to fly into space with Bezos
Friday, 02 July 2021 07:41 Write a comment
Barrier-breaking woman aviator Wally Funk, 82, will join Jeff Bezos this month on the first crewed spaceflight for the billionaire's company Blue Origin, the firm announced Thursday.
The trip is 60 years overdue for Funk, who was one of the Mercury 13 - the first women trained to fly to space from 1960-1961, but excluded because of their gender.
On July 20, she will become the oldest pe Physicists observationally confirm Hawking's black hole theorem for the first time
Friday, 02 July 2021 07:41 Write a comment
There are certain rules that even the most extreme objects in the universe must obey. A central law for black holes predicts that the area of their event horizons - the boundary beyond which nothing can ever escape - should never shrink. This law is Hawking's area theorem, named after physicist Stephen Hawking, who derived the theorem in 1971.
Fifty years later, physicists at MIT and elsew 'Lonely cloud' bigger than Milky Way found in a galaxy 'no-man's land' by UAH physics team
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A scientifically mysterious, isolated cloud bigger than the Milky Way has been found by a research team at The University of Alabama in Huntsville (UAH) in a "no-man's land" for galaxies.
The so-called orphan or lonely cloud is full of hot gas with temperatures of 10,000-10,000,000 degrees Kelvin (K) and a total mass 10 billion times the mass of the sun. That makes it larger than the mass Closing the gap on the missing lithium
Friday, 02 July 2021 07:41 Write a comment
There is a significant discrepancy between theoretical and observed amounts of lithium in our universe. This is known as the cosmological lithium problem, and it has plagued cosmologists for decades. Now, researchers have reduced this discrepancy by around 10%, thanks to a new experiment on the nuclear processes responsible for the creation of lithium. This research could point the way to a more