Questions tagged [radio-communication]

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

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6 votes
1 answer
125 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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1 vote
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Interactions between rocket exhaust and radio communications?

Rocket exhaust is bright in visible light, we can still see through it but when there's hot, glowing soot it's so bright that we think it's opaque, but it's not. See answers to How does the camera ...
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Does Russian mission control still use the callsign "Zarya", and how did that not conflict with the ISS module?

The Wikipedia page for the Salyut space station claims Initially, the space stations were to be named Zarya, the Russian word for 'Dawn'. However, as the launch of the first station in the ...
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What does "clearing of C-band spectrum" mean and why will it cost Intelsat a billion dollars?

From "Intelsat files for bankruptcy" One of the primary catalysts for restructuring the balance sheet now is Intelsat’s desire to participate in the accelerated clearing of C-band spectrum under ...
7 votes
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Curiosity / MRO UHF connection and weak signal modulation

In the case of MRO and Curiosity communications via UHF, an active feedback system was implemented in which Curiosity monitored the quality/SNR of the connection and commanded Curiosity to increase / ...
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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 ...
9 votes
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Why did Moon missions state their number in radio context?

I'm not sure if this still happens, so the question may be broader, but in the Apollo transcripts the astronauts would begin a call with something like "Houston, 13". I get that they may have been on ...
2 votes
1 answer
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UHF transceiver for cubesats network

I already asked things related to this topic. But this time I will try to divide it by points to make it more understandable. Features of my cubesats: Would have 8 cubesats 3U in Earth's orbit The ...
4 votes
1 answer
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Alternatives to the X-Band

is there any other band that can do something similar to what the x-band does? Any that require a smaller antenna and more electrical power?
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Why was Canberra able to listen to Voyager 2 but not talk to it?

The New York Times's When Voyager 2 Calls Home, Earth Soon Won’t Be Able to Answer explains that because Voyager 2's trajectory has taken it way below the ecliptic, of the three 70 meter dishes in the ...
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Why did Sputnik-1 transmit on both 20 and 40 MHz?

Wikipedia's Sputnik 1 and this answer to Why did Sputnik 1 have four antennas? say that Sputnik transmitted at both 20 and 40 MHz. Why two different frequencies? Why so far apart? It's worth noting ...
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2 votes
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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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How does SpaceX transmit the video feed from the first and second stage cameras back to Earth?

There appear to be at least 1 reasonably high-res (500+ px vertical res) live video stream being transmitted from both the SpaceX F9 first and upper stages all the way up into LEO throughout their ...
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What was the transmitting power of the Apollo astronauts' PLSS VHF radio transmitters?

I'm assuming many of you are familiar with Larry Baysinger. A radio amateur who independently detected and recorded the transmissions from the Apollo 11 EVA using a homemade antenna. Larry Baysinger ...
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4 votes
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What "gap" could have caused the Starliner instructions to be delayed?

The Starliner launch didn't go as planned today After being released by the rocket, Starliner was supposed to use its Orbital Maneuvering and Attitude Control engines to provide the thrust needed ...
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Possible interference in RF spectrum due to space-based internet

Multiple Commercial Operators plan to use satellite megaconstellations for providing internet coverage in near future. Is there a possibility of interference between RF spectrum already in use for ...
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Satellite Megaconstellations RF Spectrum usage for free(?)

As per my understanding, for terrestrial usage RF spectrum is auctioned by the governments before telecom operators can avail it for commercial purpose. Seems like a logical way to utilise limited ...
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Satellite Launch Aprroval: what is the role of ITU, FCC, and other international standards / regulators?

Seeking confirmation for the following assumption: Satellites used for non-communication applications (military surveillance, weather monitoring etc.) are launched without specific prior approval from ...
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Which radio communication protocol will Artemis voice communications likely use?

For want of a better term, is it possible crews will use 'non-digitally modulated' radio to communicate with earth? Apollo missions had very effective communication, with a ~2.5 second 'round trip' ...
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6 votes
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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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5 votes
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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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1 vote
1 answer
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Impact of having two antennas on link budget calculations

I'm working on link budget of a cubesat mission that needs to have two dipole antennas that are perpendicular to each other. I want to know if having two antennas affect the link budget? losses, and ...
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2 answers
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For 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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What's the "thump" I hear listening to Apollo 11 playback?

I've been listening to live playback of the Apollo 11 mission at https://apolloinrealtime.org/11/ Besides the expected static and hums, from time-to-time I hear a "thump", sometimes one, sometimes ...
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How large of an antenna would you need to connect to the ISS's WiFi network from Earth?

Supposing I wanted to connect to the ISS's WiFi network from the ground, how large of an antenna would I need to do so, and what kind? Would they need to increase the power on their end or use a ...
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What Soviet signals (if any) attempted to scramble communication and sabotage Apollo missions?

The NPR.org news item and audio podcast JoAnn Morgan: The Only Woman In The Firing Room During Apollo 11 features an excellent interview with JoAnn Morgan and other KSC personal. It's a short but ...
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What kind of transmitters and antennas do the Lightsail-2 ground stations use?

The cubesat Lightsail-2 has been deployed and has communicated with ground stations. See The Planetary Society's LightSail 2 Healthy as Mission Team Continues Spacecraft Checkouts, where it says: ...
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1 answer
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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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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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IRIS Transceiver for LEO Missions?

My professor really wants to know if the IRIS transceiver, which flew on MarCo, will be used in LEO. In fact so much that he doesn't accept "no" for an answer. I have searched for an example but found ...
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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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8 votes
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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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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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1 vote
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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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32 votes
4 answers
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Has any spacecraft ever had the ability to directly communicate with civilian air traffic control?

Should such a contingency become necessary, mission control centers have the ability to contact (e.g. by telephone) civilian or military air traffic control centers, even those located in other ...
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Why not send Voyager 3 and 4 following up the paths taken by Voyager 1 and 2 to re-transmit signals of later as they fly away from Earth?

Voyager 1 and Voyager 2 spacecrafts are on their journey out of solar system. They collected so much of important data that helped us understand our solar system. As these spacecrafts moving out of ...
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What is the lowest latency achievable in reliable Earth - Moon communications?

I know that radio waves travel at the speed of light in vacuum so the minimal latency to communicate between Earth and Moon would be about 1.25 second each way. This latency figure will then increase ...
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1 answer
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What kind of signal Voyager 1 is sending to us?

I was reading on wiki about Voyager 1 mission and I found very interesting! One thing I did not manage to find: what is the signal Voyager 1 is sending to us? Is it simply a sinewave or something more ...
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Data Rates and Radios with Satellites [closed]

I am new to using radios and was wondering why do data rates matter when you use a radio to pull info from somewhere else. Also what does it mean when a satellite sends a wide band signal. Thank you ...
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Which company provided communication equipment for Apollo missions in which Neil Armstrong was a part?

In July 1969, the Apollo mission transmitted Neil Armstrong’s first steps on the moon to millions around the world. Which famous company provided the entire communication equipment for the project?
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What is considered a good SNR for satellites?

When performing a link budget for satellite communications, a key component is defining an acceptable signal-to-noise-ratio in order to obtain the necessary bit-rate. How does one determine what the ...
1 vote
1 answer
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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) ...
2 votes
1 answer
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What is the lowest power signal that the DSN can detect?

It is said that the Deep Space Network can detect low-power signals sent from Voyager in the range of 10^-16 W. I can't seem to find any sources that indicate what the minimum power requirement of a ...
2 votes
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why do astronauts in the ISS still use wired microphones?

While I watched the DM-1 hatch opening, I noticed that astronauts use the wired microphone to talk to Huston. It was particularly strange seeing that even because during hatch opening, they were ...
2 votes
1 answer
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What are the trade-offs to use a radio relay orbiter also as a radar science instrument?

Any landed mission could benefit from having an orbiting radio relay satellite to help enhance its data rate to Earth. For polar landers on for example the Moon or Mercury it would be a necessity. For ...
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When scientific and engineering data are sent from space probes, are the signals repeated to minimize transmission error?

I would think that this would be the case. In any one transmission there will be a systematic error due to the fundamentals of the transmitter / receiver. Is there also a transient or stochastic error ...
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1 answer
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How many non-crewed deep-space destinations have had intentional broadcasts of music from Earth?

@Ingolifs's answer to the question What was the last message to Opportunity today (13 Feb '19)? quotes ArsTechnica's Opportunity did not answer NASA’s final call, and it’s now lost to us: Late ...
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4 votes
2 answers
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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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3 votes
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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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6 answers
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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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