Questions tagged [radio-communication]
Using radio wavelengths to communicate between multiple spacecraft or between a spacecraft and the Earth.
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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 ...
2
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0answers
43 views
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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3answers
186 views
Hijacked space data, notable instances of recovering images or other goodies from someone else's space mission?
The original of this GIF was tweeted here and I've reconstructed it because I don't know how to post it here (How to show this particular tweeted (GIF?) in a question? - trouble downloading). These ...
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55 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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2answers
81 views
Did New Horizons use its smaller medium-gain antenna for most/all downlinking of Pluto and Ultima Thule flyby data?
Brian May's New Horizons video (below) was released at about the same time that the New Horizions spacecraft passed 2014 MU69 Ultima Thule and includes a lot of technically meaningful graphics.
One ...
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1answer
2k views
What is carrier lock and bit lock?
I'm not sure if this question belongs here or in Amateur Radio, but during the acquisition of signal from New Horizons on New Year's Day, I heard the controllers call out "carrier lock", "symbol lock",...
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From where do all the space agencies receive signals from scientific spacecraft from launch to deep space?
The ISRO web page Ground Segment says:
SRO Telemetry Tracking and Command Network (ISTRAC) will be providing support of the TTC ground stations, communications network between ground stations and ...
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Are Hayabusa-2's high gain antenna disks electrically point-able?
Writing this answer I realized that Hayabusa-2 has two very similar looking circular flat disks that serve as it's high gain antennas. One is dedicated to X-band (7-8 GHz) and the other to Ka-band (32 ...
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4answers
6k views
Is Quantum Entanglement technology possible for interplanetary communication in future to achieve low real-time latency?
There is a small debate over the comment session in NASA Lands InSight on Mars video uploaded by JPL. The 1 minute and a half video is about the essential part of InSight's EDL event cropped out from ...
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1answer
183 views
Does Mars Reconnaissance Orbiter require “reprogramming” when handling communications for newer spacecraft or landers?
While I was going through the question What happens to Insight's parachute? I learned of the role of the Mars Reconnaissance Orbiter to provide reliable communication between other Mars spacecraft and/...
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1answer
149 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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1answer
50 views
Function and nature of the RHC/LCH pair of cables to New Horizons's dish antenna secondary mirror?
Spaceflight 101's New Horizons Spacecraft Overview is full of interesting information and shows this RF Comm System Block Diagram. The thin (red) lines to the dish antenna area are coaxial cables and ...
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1answer
46 views
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
396 views
Is two-way communication really required to use BeiDou GNSS?
The BBC's How China's GPS 'rival' Beidou is plotting to go global mentions a scenario where end-users can send signals to other Earth locations using BeiDou and later says:
But despite its ...
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1answer
117 views
How does this antenna work, with both a feed horn and hyperbolic secondary in front of the dish?
Scrolling through the Roscosmos twitter feed I saw this image of a dish antenna in a recent tweet. Google translate shows that the post says:
Новый измерительный пункт будет построен на Сахалине ...
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1answer
69 views
Which is stronger per Hz, radio signals from a Mars spacecraft, or Mars' blackbody radiation?
It just occurred to me that while Mars is cold from a human's perspective, from a radio engineer's perspective it's still kind-of hot.
When even the largest DSN antennas are pointed at Mars to ...
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3answers
347 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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2answers
264 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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1answer
54 views
Is it practical for HF skywave propagation to be utilized for space exploration robot telecommand when outside of microwave/mm wave range?
Is it practical for HF skywave propagation to be utilized for space exploration robot telecommand when outside of microwave/mm wave range? Currently it appears that only the C band and UHF is used in ...
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1answer
204 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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3answers
14k views
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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2answers
157 views
Feasibility of Interstellar Probe Communication
So, I understand that to transmit information across interstellar distances, you need to use a lot of power (or less bandwidth?), something for example a small space probe wouldn't exactly have.
If we ...
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1answer
155 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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1answer
76 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 ...
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3answers
2k views
Do satellite uplink/downlink signals spread or leak into space?
Satellite communication generally involves three types of nodes: the ground station (also known as teleport), the satellite in geosynchronous orbit, and the satellite receiver/transceiver. I am ...
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1answer
377 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
485 views
Is there really a radio on Elon Musk's solar-orbiting Tesla Roadster? Can we communicate with it? [closed]
Various media have reported that there is a radio on Elon Musk's Tesla Roadster, now in orbit around the Sun, and that this radio is playing music (for example: BBC reporting that David Bowie's ...
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1answer
195 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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2answers
1k 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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1answer
483 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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102 views
Satellite Intra link [closed]
I read there are sometimes intra-satellite links.
Is it already used or just a project in the future ? How is is used and why ? and for what services ?
thanks
david
thanks for interesting answers. ...
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2answers
343 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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2answers
997 views
Would adding satellites between Earth and Mars improve communications latency?
Would adding satellites along the path from Earth to Mars decrease the amount of time it takes to send and receive messages between them?
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2answers
303 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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1answer
245 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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4answers
818 views
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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3answers
9k views
Why would GPS availability be reduced by high demand (or solar eclipse)?
This Newsweek article states that "GPS...will likely be nonexistent near the eclipse zone" because of all the people going to that area. While it makes sense that cell towers might be overloaded and ...
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2answers
166 views
Is the utility PREDICT good enough for operational orbital prediction?
I'm looking for a cheap and cheerful, but ultimately working utility or library for tracking a cubesat and predicting link windows. I've been looking at using Orekit. I'm a student, so a lot of its ...
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0answers
243 views
How do satellites communicate with a relay satellite?
Although the exact usage of the system is classified, NASA has a system called TDRS which is used by other government agencies for relaying data to ground stations.
To maintain communications with a ...
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1answer
219 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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1answer
899 views
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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2answers
191 views
Are sun outages having more limited impact in some cases?
Sun outages occur when a satellite, usually one in a geostationary orbit, passes between a ground station and the sun. Seen from the point of view of the ground station, the sun looks like it passes ...
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1answer
203 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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1answer
564 views
Real time communications in space
Today we use audio and video communications (using UDP protocol) over IP networks (VoIP) for communicating (Skype, Whatsapp, FB messenger). This works fine on planet Earth (although there are various ...
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5answers
401 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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1answer
297 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 as yet unanswered question How well can Voyager 1 separate Earth ...
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1answer
374 views
Faster than light communications in space [closed]
Today communication with different spacecraft is limited to speed-of-light. Around the Earth it is not such a problem, but when you have to work with a spacecraft on the surface of Mars, it becomes an ...
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2answers
821 views
Is it possible for small satellites to orbit in MEO or GEO?
I am researching satellite technology, and in particular I am looking at the rise and implications of smallsat technology. As far as I know, there are currently no satellites beyond LEO that would be ...
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1answer
227 views
Characteristics of the modern satelite radio transmitters
I'm trying to find some data concerning current Earth-satellite radio communication systems, namely general characteristics of the equipment currently used on satellites. Specifically, I'm interested ...
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1answer
632 views
Why were the two Quindar tones so close in frequency and not apodized?
This and this answer explain the function of the Quindar_tones within Apollo mission comms.
At 2525 and 2475 HZ they are only 50Hz or 2% apart in frequency, and the duration is 250 ms or 0.25 seconds....
