Questions tagged [delay-doppler]
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Satellite Navigation: Measuring Velocity & Position
How is the position and velocity of a satellite measured from ground? Radar measurements could give us range and range rate which are scalar quantities (if I understand this correctly). But how could ...
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Calculating change to radio signal propagating around via satellite orbits
What is the best way to calculate either the time difference or frequency change for a radio signal in the following scenario?
60 satellites are in the same circular orbital path at 6 degree intervals....
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Analyse the Doppler effect in non-GEO satellites: calculation of Doppler shift ( frequency)
I want to compute the Doppler frequency for LEO/MEO/GEO satellites. For the calculation I am using the following equations:
$$V= \sqrt{(G \cdot \frac{M}{R+h})}$$ - satellite speed. Height dependent
$...
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What are the largest distances between two spacecraft that have been determined to a meter or so accuracy? How were these done?
This answer to Radio Telescope / DSN Node in L4 and/or L5 presents the challenge of implementing "very long" VLBI using the ~1 AU distance between Earth and a Sun-Earth triangular libration ...
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Radio coherent transponders are the foundation of deep space navigation, have optical analogues been used? If so, the furthest distance measured?
Coherent radio transponders receive a signal from Earth containing specially encoded modulation, amplify it and retransmit it back to Earth. Correlating the received signal with the transmitted signal ...
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What are the differences (if any) between the techniques of range-rate and delay-doppler measurements?
This answer to How does an onboard atomic clock help interplanetary navigation? says:
Range-Rate is the two-way measurement of signals broadcast from one location on Earth, received and retransmitted ...
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What was the first "bent pipe" or otherwise coherent transponder in deep space?
In this answer to On what basis is the information about the distance and velocity of the Voyager probes determined? in Astronomy SE I mentioned the term "bent pipe" transponder and also ...
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Has there ever been an instance of asteroid discovery by radar; seen first by radar rather than being observed after optical discovery?
In a discussion below this answer to Can we use something like RADAR to detect asteroids? I'm complaining that the answer is essentially wrong;
Yes, radar is one of the useful tools for detecting and ...
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How did LADEE and LDRC measure it's distance from Lunar orbit to Earth to 1 centimeter accuracy using optical communications?
The video Donald Cornwell plenary talk: NASA's Optical Communications Program: 2015 and Beyond was presented at SPIE Photonics West 2015. It's a great talk and worth the time.
LADEE had [the Laser ...
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Long delay-doppler measurements on deep space craft; couldn't optical measurements be made intermittently, mixed with contacts to other spacecraft?
In this comment below Will future deep space optical communications “ground stations” actually be in space, or on the ground? in response to a discussion about ground stations being used for tracking ...
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Has Same Beam Interference (SBI) been used or at least tested at Mars? Are there plans to use it in the next few years?
Question: Has Same Beam Interference (SBI) been used or at least tested at Mars? Are there plans to use it in the next few years? Considering that there's already some orbiters and landers and rovers ...
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How exactly does TDRSS provide tracking? (Tracking and Data Relay Satellite System)
This excellent answer to How does satellites know it is in apogee or perigee states:
The NASA Tracking and Data Relay Satellite System (TDRSS) adds to this a constellation of satellites in such a ...
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What does Cees Bassa's Doppler plot of Chandrayaan 2 show?
Cees Bassa's tweet shows a plot of received frequency versus time, with the Doppler shift of the Moon's center of mass subtracted. For a lunar orbit the resulting plot would show sinusoidal-like ...
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Farthest distance to a solar system object that's been determined by spacecraft transponder?
Bouncing radar off of Venus' surface has yielded a rich body of data about the planet. Based on Venus' aphelion and Earth's perihelion, we know then that the answer is at least 38 million kilometers ...
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Farthest distance to a solar system object that's been measured by radar?
Bouncing radar off of Venus' surface has yielded a rich body of data about the planet. Based on Venus' aphelion and Earth's perihelion, we know then that the answer is at least 38 million kilometers ...
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