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Questions tagged [delay-doppler]

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Understanding shape of DSN's 'kinky uplink protocol' keeping frequency in coherent transponder's optimum bandpass?

This tweet by deep space SDR enthusiast and amateur radio operator Edgar Kaiser @df2mz shows a squiggly tone from MRO. Mars Reconnaiscance Orbiter (MRO) X-band downlink. The signal shows this ...
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Was the Doppler shift of InSight's “tone” measured and plotted somewhere?

I watched a YouTube live broadcast from the InSight mission control area and saw lots of images of happy people cheering and jumping up and down, which is great! If it wasn't 4 AM where I was I might ...
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When two DSN stations are used in a VLBI measurement, how does a third station serve as a “relay” to tie-together observations?

Section 2.1 of the DESCANSO document 211 Wideband Very-Long Baseline Interferometry (from here, found here) says: The precision of a VLBI measurement improves with the length of the baseline. The ...
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Why are InSight's two RISE horns pointed slightly south of east, and north of west?

@karthikeyan's excellent answer links to The Rotation and Interior Structure Experiment on the InSight Mission to Mars (Folkner, W.M., Dehant, V., Le Maistre, S. et al. Space Sci Rev (2018) 214: 100. ...
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1answer
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How will InSight's RISE antennas end up pointed in the right direction?

The rendering of InSight shows the RISE antennas, the two microwave horns pointed just above the horizontal over each of the solar array paddles. If I understand correctly the experiment works when ...
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How many solar system bodies have had coherent radio transponders?

A transponder amplifies, (often) frequency-shifts, and rebroadcasts a received signal. Old-style telephone and TV distribution satellites in GEO used simple transponders to rebroadcast the uplinked ...
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45 views

Have any deep-space spacecraft supported same-band turnaround of Earth-based doppler measurements?

Table 1 of this document gives Spacecraft Transponder Turnaround Ratios that are supported by the Deep Space Network. These are the PLL controlled divide-by ratios that a spacecraft uses when ...
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230 views

How does a three-way doppler shift measurement work?

I was looking at this document who's name I can only speculate. Its title and designation includes: 810-005, Rev. E, 201, Rev. B, DSN Telecommunications Link, Design Handbook, 201, Rev. B, ...
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Is 2012 TC4 part of the Near-Earth Object Human Space Flight Accessible Targets Study?

This nifty answer describes and provides links to the data of the recovery of near earth object 2012 TC4, and the answer also shows the first actual image of the body for this pass. At apparent ...
6
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1answer
393 views

Why do radar maps of the surface of Venus have missing slices?

The visually opaque clouds of Venus still pass radio and some microwaves, and so powerful radar signals can be used to map the surface. This is probably done using some kind of delay-Doppler technique,...
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What can be learned from NASA's choice of Didymos B for the Double Asteroid Redirection Test

The NASA News item NASA’S First Asteroid Deflection Mission Enters Next Design Phase describes a test the kinetic impactor technique that could someday be used to adjust the orbit of an asteroid in ...
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Is delay-doppler radar imaging of NEO asteroids possible only if it spins fast enough?

Emily Lakdawalla's blog on the Planetary Society's page explains some of the basic principles in the delay-doppler radar imaging of asteroids, and other astronomical bodies by extension. Radar from a ...