Questions tagged [radio-communication]

Using radio wavelengths to communicate between multiple spacecraft or between a spacecraft and the Earth.

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12
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2answers
4k views

How to calculate data rate of Voyager 1?

I've read the following passage in the answer to the Quora question How can Voyager send a signal strong enough for us to receive, in spite of its enormous distance from us? And how can it have the ...
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5answers
848 views

Why doesn't thermal radio emission from a DSN “hot dish” completely swamp the benefits of a cold LNA?

The 70 meter DSN dishes are often used to receive the weakest signals, and so their receiver LNAs have cryogenic front-ends in an assembly that also contains a LHe refrigerator and vacuum system. If I ...
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6answers
857 views

Hijacked space data, notable instances of recovering images or other goodies from someone else's space mission?

These are images taken by a Chinese cubesat in lunar orbit, taken again by a Dutch radio telescope. The original of this GIF was tweeted here and I've reconstructed it because I don't know how to ...
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619 views

What is the highest non-optical frequency used or tested for use in deep space communication?

For dish antennas used to transmit a signal over large distances, the on-axis gain scales as $D^2/ \lambda^2$ or $D^2 f^2 / c^2$ where $\lambda$ and $f$ are the wavelength or frequency and $c$ is the ...
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1answer
889 views

Has DSS-43 ever been used in high power mode (>>20 kW) for an emergency situation?

This answer notes that while most Deep Space Network transmitters are 20 kW of power or less, one dish (DSS-43 in Canberra) is equipped with a transmitter capable of 400 kW. As described in 101, 70-m ...
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1answer
414 views

How does the Satellite Networked Open Ground Station operate? How is it used?

SatNOGS, the Satellite Networked Open Ground Station (mentioned in this answer) appears to be a distribution of independently maintained amateur DIY satellite receiving ground stations, linked by a ...
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China, UAE and US all sending missions to Mars in 2020 (Summer of L̶o̶v̶e Mars); how far apart are their frequencies?

Gizmodo's Second failure of ExoMars parachute test throws schedule in jeopardy says: ExoMars 2020 is due to launch during a narrow window open between July 25th to August 13th 2020, during which ...
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1answer
344 views

Will there be “Near Space” Ka-band allocations for TESS?

update: More information in Phys.org's news item TESS mission to discover new planets moves toward launch, including a video of the telescope array's final assembly. Also see GSFC's TESS page. The ...
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3answers
696 views

Why have four parabolas on a ground-side array instead of just a single large one

An article on RT: Russia to stop ferrying US astronauts to ISS from April 2019, is accompanied by a photo of a ground-side radio array consisting of four separate parabolas merged into one pointable ...
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1answer
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Why is TESS' high gain antenna made of undulating BLACK fabric rather than metal?

above: from Facebook, then annotated. There is an excellent review of the design of the TESS spacecraft in G. R. Richter et al. Journal of Astronomical Telescopes, ...
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1answer
501 views

Have deep-space spacecraft always used some form of spread-spectrum for data downlink?

tl;dr: Question: Have deep-space spacecraft always use some form of spread-spectrum for data downlink? note: I'm looking for some insight into why, and any possible exceptions, not just a "yes" or "...
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1answer
210 views

Are the Voyager spacecrafts' X-band TWTAs currently set to high or low transmit power? How often were they changed?

In this answer I discuss that the Voyager spacecraft can be commanded to use either high or low power to transmit to Earth on X-band. Question: Are the Voyager spacecrafts' X-band Traveling Wave Tube ...
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3answers
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How much RF transmit power does DSN need to send commands to Voyager?

I recently looked up how weak the Voyager signals are when they get to Earth from the 22 W transmitters (as of September 2013, it was roughly -245 dBm). But that got me wondering how many watts of ...
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3answers
701 views

What are the prospects for comms with cubesats using “normal” internet connections?

Can a cubesat in orbit be operated like a R/C airplane in real time? edit: if the link here and the end aren't clear, I'm interested in the ease and convenience of access, the frequency of possible ...
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505 views

Which satellites can hear emergency signals from Scott Kelley's watch?

In this July 2018 tweet by Cdr. Scott Kelley, with the north face of Mt. Everest over his shoulder, he mentions his "Emergency" watch. I've searched and then found the Hodinkee.com article ...
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425 views

Does man send any signal to attract aliens?

Does man send any signal (such as electromagnetic radiation) to space to attract aliens?
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1answer
342 views

Deep Space Network time budgets per spacecraft - is such statistics available?

Is statistics available about time consumed by different spacecraft for communication wint NASA Deep Space Network (DSN)? It would be interesting to compare which space missions are more downlink-...
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1answer
865 views

Why such a large observed doppler shift from Apollo 17 orbiting the moon?

Following the links in this comment by @Uwe I've found some interesting sources of information on Ham (amateur) radio operators trying to listen in on Apollo transmissions. One of them is Sven Grahn's ...
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2answers
449 views

Why is the operating temperature for the Voyagers' receiver noise calculation about 1550K?

In line 10 of Table 5.2 of DESCANSO IV - Voyager Telecommunications it shows a value of the uplink receiver noise spectral density of -166.7 dBm/Hz, which is 196.7 dBW/Hz which is 2.1E-20 Watts/Hz = $...
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278 views

Could multimode (polymer) optical fiber Gigabit Ethernet be a better choice than WiFi inside future satellites?

In this answer the recent question Are and should satellites use wireless communication internally, rather than cables? it is stated that: This is actually an open research area and despite ...
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1answer
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If a MarCO-type CubeSat were in orbit around Bennu, what kind of power would it need to communicate with the Deep Space Network?

This is a follow-up question to: What is the lowest power signal that the DSN can detect? Essentially, I have determined that the asteroid Bennu (ranging from 25 to 350 million kilometers from Earth) ...
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2answers
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How would the Voyagers finally die if allowed to transmit to the bitter end?

According to this answer and this question the Voyagers will run out of power to "operate a single instrument" in 2025 for Voyager 2 and a little longer for Voyager 1. It is purported to be the end of ...
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2answers
164 views

What does it take to upgrade a radio antenna to receive from the surface of Mars?

All the discussion about receiving transmissions from Mars rovers got me thinking, what determines the capability of a radio antenna, and what goes into adding the capability of listening to a Mars ...
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How did NASA prevent third parties from spoofing Apollo communications?

The Apollo crews transmitted footage to Earth using SSTV, a ham radio technique that amateurs and pirates can use to send similar messages around the world. Did NASA have any technical ...
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1answer
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Why were there beeps punctuating the voice communications during missions such as Apollo?

Voice communication between ground and spacecraft during missions such as Apollo seemed to be always punctuated by beeps. What was the origin of these beeps? Were they some sort of unavoidable ...
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1answer
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When is a phased array antenna not a phased array?

This question is inspired by an answer to this question, where it is stated that: The real power of phased arrays is their ability to be steered electronically. This set me wondering about the ...
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0answers
543 views

Can anything at Mars speak 900 MHz ZigBee besides Ingenuity helicopter and Perseverance rover?

Interest is piqued by What could be strong arguments against Ingenuity following Perseverance at a safe distance when the flight test program has been a success? Question: Can anything at Mars ...
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1answer
769 views

Why does NASA use higher frequencies even though they have worse Free Space Path Loss (FSPL)?

Looking at the Formula for FSPL we see that it increases with Frequency. Why is X-Band used for Deep Space Communications instead of lower bands like S-Band? Is it a question of data-rates? Is the ...
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319 views

What radio frequencies were used by the Soviet space program circa 1961? (“Lost Cosmonaut” recording)

The recent Joe Scott video The Mysterious "Lost Cosmonaut" Recording | Random Thursday describes radio recording said to have been made by the Judica Cordiglia brothers from Italy in the early 1960's. ...
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1answer
144 views

How does an onboard atomic clock help interplanetary navigation?

On 2019 June 22, JPL will launch and test the accuracy of an onboard atomic clock. Its FAQ says that it will improve interplanetary navigation because for the ship to determine its position, instead ...
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1answer
312 views

Power and frequency units used in Deep Space Network XML data?

NASA's Deep Space Network activity can be viewed conveniently at https://eyes.nasa.gov/dsn/dsn.html but if you would like data in a more raw XML form, it can be accessed as described in this answer ...
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Encryption in radio system

We know that radio waves are used in communication with rockets, space crafts and satellites. Now, radio system basically consists of transmitter and receiver. If there is frequency match between ...
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1answer
955 views

Why has the Earth's motion carried it out of view of Pioneer 11's antenna?

According to The Pioneer Missions, my emphasis, The Pioneer 11 Mission ended on 30 September 1995, when the last transmission from the spacecraft was received. There have been no communications ...
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1answer
199 views

The appearance of TESS' dish seems to be evolving, what will be the final configuration?

The question Why is TESS' high gain antenna made of undulating BLACK fabric rather than metal? has had three bounties, and is probably the recipient of this sites longest answer. My personal pet ...
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3answers
295 views

Did New Horizons use its smaller medium-gain antenna for most/all downlinking of Pluto and Arrokoth flyby data?

Brian May's New Horizons video (below) was released at about the same time that the New Horizons spacecraft passed 2014 MU69 Arrokoth and includes a lot of technically meaningful graphics. One item ...
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1answer
473 views

What are the main sources of radio noise & interference limiting deep space data rates and availability?

Let's call "radio" anything electromagnetic below 300 GHz (1 millimeter), unless there is a compelling reason to do otherwise. The question How well can Voyager 1 separate Earth signals from Solar ...
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1answer
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Was “I have the farts, again” broadcast from the Moon to the whole world?

The BBC News article Apollo in 50 numbers: Medicine and health says: When Apollo 16 commander John Young walked on the Moon, he shared his feelings on the new diet with his companion Charlie Duke. ...
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4answers
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How many stations could one hear with an AM/FM radio in front of the ISS' cupola window?

Propagation of AM and FM radio signals up into the sky would behave differently than propagation along the surface of the Earth. As a Gedankenexperiment, if you were on the ISS and had an AM/FM radio ...
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1answer
836 views

How is a space probe's antenna directed toward Earth?

I wonder how is it possible to direct the probe's antenna from enormous distances (like Pluto) toward the Earth. Because if even an extremely small inclination in antenna direction emerge, it will ...
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1answer
101 views

Are NASA (and ESA?) deep space spacecraft now generally able to store and forward messages between themselves?

There are discussions under the current answer to Will Curiosity and the Mars 2020 rover be able to communicate with each other via a Mars orbiter? about the feasibility of MRO receiving a message ...
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2answers
216 views

How can one know that Chang'e-4 was in “locked to the Queqiao” from this SDR spectrogram?

Deep space SDR enthusiast and amateur radio operator Edgar Kaiser @df2mz's 28-Dec-2018 tweet says: Chang'e 4 in lunar orbit last night on 8479.77 MHz. The spacecraft seems to be locked to the ...
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1answer
429 views

Why are there so many waveguide feeds (?) near the focus of Cassini's dish antenna?

Cassini has quite a complex Radio Science Subsystem. Accorting to that article (and confirmed in Wikipedia): Cassini is the only deep space mission to transmit to Earth at three radio wavelengths (...
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2answers
454 views

How does this strangely-shaped horn at Honeysuckle Creek Tracking Station work?

After reading the BBC article Australia to create national space agency and clicking around to identify the dish antenna shown in the photo in the article, I came across an image of an interesting ...
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0answers
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How many total hours had Arecibo transmitted a signal?

Update: Sadly, parts of the dish have collapsed, several cables have snapped, and the Arecibo radio telescope is now decommissioned and demolition has been recommended because it is now too unsafe to ...
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1answer
312 views

Is the recently discovered VLF-induced radiation barrier in any way important or useful?

There are several popular news articles that refer to this video, who's notes point to the NASA news item NASA's Van Allen Probes Spot Man-Made Barrier Shrouding Earth which points to the ...
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Can I transmit signals from a wristwatch to geostationary orbit?

In comments below this answer to the question Which satellites can hear emergency signals from Scott Kelley's watch? we are (or at least I am) trying to figure out definitively if a wristwatch can ...
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How long did the plasma blackouts of Perseverance's signals to MRO and direct-to-Earth last during its seven minutes of terror?

Congratulations to NASA JPL and the Perseverance Team and everyone else who participated and contributed in some way! Watching the live feed of the EDL seven minutes of terror I heard there was a ...
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1answer
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How will “InSight's onboard communications gear perform a radio-science experiment to shed further light on Mars' innards?” (Space.com)

The Space.com article How NASA Mars Lander's 'Steampunk' Claw Will Work (Video) says: InSight's mission aims to provide a detailed look at Mars' interior structure and composition. The lander ...
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1answer
964 views

What did Sputnik-1 sound like? Did it use multiple tones?

Radio transmissions from Sputnik-1 could be heard on short wave radios around the world. Questions: A carrier signal only would not be particularly audible to an AM radio listener, was it modulated ...
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1answer
260 views

Juno RF power output

What is the RF Power Output from Juno into its Parabolic dish, and the RF radiated out from the dish and the eventual power received say at the dish in Canberra which obviously then would need to be ...