Questions tagged [communication-satellite]

Questions about satellites designed to aid in communications, such as phone, TV and Internet satellites.

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SpaceX's 4,425 satellite constellation - what's the method to the madness?

The BBC article SpaceX aims to launch internet from space discusses the SpaceX proposal for a dense array of over 4,000 LEO satellites for global internet coverage, and links to SpaceX non-...
uhoh's user avatar
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Do antennae on the ISS have to constantly move to maintain data links?

In this question and answer pair I see that the ISS can maintain data links to earth through direct access to ground stations as well as through the TDRSS geostationary satellite network. What kind ...
uhoh's user avatar
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What are these very large, square panels on Inmarsat 5?

Question: What are these very large square panels on Inmarsat 5's? They seem to each have an extremely reflective mirror-like flat/smooth tiled-appearing side, and a nearly black side with a lot of ...
uhoh's user avatar
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Why do the geosynchronous TDRS satellites have this distribution of inclinations?

From the Tracking and Data Relay Satellite System (TDRSS) option on Celestrak's NORAD Two-Line Element Sets Current Data TLE page I've compiled current TLE ...
uhoh's user avatar
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Are commercial communications satellites in GEO being constantly monitored by telescopes?

I was trying to look up GOES-17 in Spaceflight101 but got sidetracked in the search result and ended up reading this thread about AMC-9, which links to the YouTube video Rough cut video of AMC-9 ...
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What (actually) makes Iridium "the world's only truly global mobile satellite communications company"?

In this article about how the SpaceX anomaly will affect Iridium it says: In its official website, Iridium describes itself as "the world's only truly global mobile satellite communications company....
uhoh's user avatar
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Why do these satellite antennas look so weird? (strangely shaped with little white dots...)

The NASA Spaceflight article Arianespace press onward with dual-passenger Ariane 5 launch shows a photo of Intelsat 39 during testing. The dish reflectors are strangely shaped: rather than being ...
uhoh's user avatar
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How do commercial broadcast satellites in GEO produce such carefully shaped signal footprints?

SES-10 will be launched in a few days on Space-X's first commercial launch using a recycled rocket. Screenshots from the three links (Brazil, Central America, South America) on Satbeams page for SES-...
uhoh's user avatar
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Are the SpaceBEEs still "illegal" or did they eventually receive approval to operate?

This answer to Might ISRO's 2018-004 launch be at least a technical violation of the Outer Space Treaty by India? clarifies some of the actions taken against Swarm Technologies for launching some ...
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What technology will SpaceX's StarLink satellites most likely use for sat-to-sat linking?

The question How does SpaceX plan to make money with StarLink Broadband? has got me thinking about how the satellites will link to each other. Wikipedia says it's something greater than 10,000 GHz and ...
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How does QUESS, China's quantum communications satellite experiment, relay entangled signals?

China launched the Quantum Experiments at Space Scale (QUESS) on the satellite called MOZI or Micius today, which will be used for quantum communications between China and Europe. Popular Science ...
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How much time does it take to circularize a GTO orbit using ion propulsion?

SpaceX launched two GEO comsats, and is about to launch two more, that use all-electric ion propulsion. Now, I'm wondering, how much time would it take to actually make a satellite like that ...
radex's user avatar
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How low is VLEO? (FCC's newest approval for SpaceX)

Engaget's SpaceX gets FCC approval to deploy thousands more internet satellites says SpaceX's plan to build a global, high-speed wireless internet network using satellites has taken another step ...
uhoh's user avatar
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When there is more power than needed, are satellite photovoltaics shunted or open circuit?

I saw the word "shunts" in this answer about DSCOVR's upgraded photovoltaic arrays when it was unmothballed and readied for space. Reading it, I get the idea that shunts are used to dissipate the ...
uhoh's user avatar
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Were solar concentrators on HS-702 just a stop-gap measure until triple-junction PV cells were available?

According to Gunter's Space Page discussion of early versions of the Hughes HS-702 Bus: The first version of the 702 used solar arrays with concentrators. These concentrators tended to early fogging, ...
uhoh's user avatar
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At what magnitude would adjacent large geostationary communications satellites see each other?

Imagine I'm sitting on a geostationary satellite. I can see the Earth in front of me. It's about the size of a soccer ball at arm's length. To the left and right, I can see similar satellites in the ...
Roger Wood's user avatar
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Is a space probe communication relay possible?

Is it possible to maintain a connection with space probes that are far away by sending other space probes behind it. For example - [earth] ------1---- 2-------3--------4------5....and so on if ...
user8278's user avatar
4 votes
1 answer
383 views

Is TDRS-M (TDRS-13) where it's supposed to be?

edit: Status 2018-Jan-01 inclination still about 7 degrees, location still not listed in Wikipedia. This question got me thinking about the location of active TDRS satellites, and the newest addition ...
uhoh's user avatar
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For constellations of circular LEO satellites, are there allocations of available "slots" in altitudes?

The BBC article SpaceX aims to launch internet from space discusses the SpaceX proposal for a dense array of 4,425 LEO satellites distributed among 83 orbital planes in five inclination groups as ...
uhoh's user avatar
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How to design a ground antenna for sending & receiving from a satellite?

Let's suppose there is a wifi router or a cell phone or similar transmitter in an orbit of 3000 km. How could one make a dish antenna to connect and receive the signal from that wifi router or cell ...
Hacker Gamer's user avatar
1 vote
1 answer
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How do Inmarsat 5 F4's beams correspond to all of these antennas and feeds?

note: This is an old-style @uhoh question meaning that it is a bit on the long side. In this case I think it really needs to be since the question is a bit complex; I'm trying to understand how all ...
uhoh's user avatar
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Receiver and transmitter in RF/optic satellite communication: distance vs data rate v2

The first version of this question is here. I have read the article "Optical communications work best over relatively short distances in space." by Toyoshima, M., Leeb, W., Kunimori, H. and ...
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Radiation pattern and signal strength of navigation satellite antennas

Where can I find the actual radiation pattern and signal strength of transmitting antennas used by GNSS navigation satellites/constellations (GPS, GLONASS, IRNSS, etc)?
akum's user avatar
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What will be "unique" about upcoming SES-9 GTO transfer profile by SpaceX?

In the SES-9 mission press kit, SpaceX mentions: "Given this mission’s unique GTO profile, a successful landing is not expected." What is considered "unique" about this transfer orbit's profile? ...
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How do we track the exact location of the spacecraft which is millions or billions of miles away from us?

How do we track the exact location of the spacecraft which is millions or billions of miles away from us? What things do we study for tracking purpose? How exactly do we predict?
Pras4's user avatar
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6 votes
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Can they watch TV at the South Pole? What satellites are used for data, comms, and entertainment?

edit: This answer adds one more piece to the puzzle, at least for data. For navigation, I believe GPS covers the poles. For data, there is at least Iridium (see answers to What (actually) makes ...
uhoh's user avatar
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3 votes
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712 views

Why do orbits in the Iridium constellation have an inclination of 86.4°?

Wikipedia's Iridium_satellite constellation; In-orbit spares says that Iridium satellites have an inclination of 86.4°: Significant orbital inclination changes are normally very fuel-intensive, but ...
uhoh's user avatar
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Point Ahead Angle and Doppler Shift Frequency Changes Calculation with the tangential/radial velocity component for Inter-Satellite Link

While calculating the Point Ahead Angle we work with Tangential Velocity vector component and to calculate the Doppler shift i.e changes in frequencies, we work with Radial Velocity Vector component. ...
JOY's user avatar
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"...extending the Starlink network using longer-range laser comms and relay satellites to reach Mars and Starships in-transit" (Musk & Shotwell)

I have it on good authority that SpaceX's Elon Musk and Gwynne Shotwell: ...have talked about extending the Starlink network using longer-range laser comms and relay satellites to reach Mars and ...
uhoh's user avatar
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1 answer
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How does a "hybrid orbital raising system" based on R-4D (N2O4/MMH) + SPT-100 (Hall effect) work exactly? (Intelsat 38 & 39)

Astronatix's Intelsat 39 lists the two engines SPT-100 Stechkin 1.35 kW Hall thruster. R-4D Marquardt N2O4/MMH rocket engine. 490 N. Question: Why is this combination on Intelsat 39 called "hybrid" ...
uhoh's user avatar
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0 votes
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How can the data rate be increased in noisy outer space?

What can we do to improve the data rate in outer space? I see that there are some noise sources that affect the signal quality between ground stations & deep space. As I've read so far in various ...
Pras4's user avatar
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17 votes
1 answer
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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",...
OZ1SEJ's user avatar
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13 votes
4 answers
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What is the most popular programming language in space?

For the purposes of clarification - will include machine code generated by a programming language on earth. - 'in space' includes anything in orbit and deep space transit. - special mentions of ...
CodingMatters's user avatar
12 votes
2 answers
699 views

How can just making the ground broadcast stronger neutralize a zombie(sat)?

In April of 2010 the Geo-not-so-stationary satellite Galaxy-15 stopped responding to ground commands. It operates as a "bent-pipe" or Transponder system, which means - roughly speaking - it will ...
uhoh's user avatar
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11 votes
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Will Curiosity and the Mars 2020 rover be able to communicate with each other via a Mars orbiter?

Curiosity's UHF antenna on sol 2439 Could Curiosity and the Mars 2020 rover communicate with each other via the MRO orbiter ? And would it have advantages ? (Like: " I just saw a meteorite, and it'...
Cornelis's user avatar
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9 votes
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Can I use Iridium as a receiver network for my satellite?

One of the operational costs for a satellite in orbit is maintaining a receiver ground station. Would it be feasible to send an Iridium transceiver along with my satellite, and then operate it from my ...
Jacob Krall's user avatar
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7 votes
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636 views

Is secure communication in space important?

How important is secure communication in space? Science-related research is often made public, but does that mean all communications must be unprotected?
Pras4's user avatar
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7 votes
1 answer
436 views

What is the expected lifetime of observable Iridium flares? [duplicate]

I enjoy spotting and occasionally attempting to photograph Iridium Flares: (Iridium flare with airplane trail) They're caused by sunlight reflecting off the antennaes of the satellites that make up ...
James Thorpe's user avatar
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6 votes
3 answers
861 views

How were Intelsat 1 “Early Bird” and Telstar 1's "hundreds" of simultaneous telephone conversations multiplexed/demultiplexed?

When did they stop routing long-distance analog phone calls through satellites? What was the maximum volume at its peak? contains images, sources and descriptions of both The Intelsat 1 “Early Bird” ...
uhoh's user avatar
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6 votes
3 answers
533 views

Could a (differently) inclined orbit remain above a Lunar pole half of every revolution?

Let's say that we want constant communication between the Lunar north pole and Earth. The 5.145° orbital inclination of the Moon means that the (mountain at) the Lunar north pole will have line-of-...
LocalFluff's user avatar
4 votes
1 answer
1k views

How were the 100+ antennas around Telstar 1 and 2 configured?

Telstar 1 and 2 demonstrated routing of telephone, television and other communications types between continents. The Smithsonian Air and Space Museum pages below contain images of the satellites. ...
uhoh's user avatar
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4 votes
1 answer
296 views

There are only a few suppliers of optical terminals: what is the reason?

I am conducting research into optical free space communication and small/nano satellites in LEO. I have found only a few companies which supply lasercom (laser communication) terminals (transmitter/...
Anna Koroleva's user avatar
4 votes
1 answer
435 views

How stable is an orbit of 335.9 km?

Spacex has recently begun deployment of its satellite constellation that will provide internet services. In their initial filings with the FCC they propose that they may have over 7,000 VLEO (very low ...
David says Reinstate Monica's user avatar
4 votes
0 answers
296 views

Did the Starlink precursor Tintin satellites ever talk to each other? If so, how? Did they demonstrate an optical communications link?

Tintin A and B are the first two exploratory and testing spacecraft for SpaceX's Starlink program. It looks like they are in very similar orbits in both space and time, and are probably that way so ...
uhoh's user avatar
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4 votes
2 answers
434 views

What are the reasons for the specific operating wavelengths chosen for laser communication?

I am reading the book: Kaushal, H., Jain, V.K. and Kar, S., 2017, Free space optical communication, New Delhi: Springer India. The operating wavelengths for beacon and data transmission were discussed....
Noel Miller's user avatar
4 votes
2 answers
527 views

How to compute each of these link budget terms?

The terms in Equation are all in decibels (dB), which is logarithmically scaled. In Equation, $P_{rx}$ is the received peak power, $P_{tx}$ is the transmitted peak power, $G_{tx}$ is the transmitter ...
Noel Miller's user avatar
4 votes
1 answer
2k views

How many communication antennas does a satellite need if it belongs to a constellation?

I assume (but I may be wrong) that in a communication satellite constellation such as the one spaceX plan to put into service: each full duplex link requires a dedicated antenna each satellite ...
Manu H's user avatar
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3 votes
2 answers
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How does a Hall effect ion thruster have a sea-level Isp of 800? Operates at 1 atmosphere?

Astronatix's SPT-100 lists the following: Stechkin electric rocket engine. Used on Meteor and Gals satellites. In Production. 1.35 kW Hall thruster. Thrust variable 2 to 20 kgf. Marketed in USA by ...
uhoh's user avatar
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3 votes
1 answer
1k views

What is OneWeb's constellation's "progressive pitch" and how does it avoid interference with Ku-band satellites in GEO everywhere on Earth?

The Wikipedia article section OneWeb satellite constellation; Design characteristics tells us: The satellites will operate in the Ku band, communicating in the microwave range of frequencies in the ...
uhoh's user avatar
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2 votes
1 answer
415 views

Inter-Satellite Link (ISL) for TV broadcast

Is ISL used for TV carriers? The information I found is that it is used for IP connectivity. I did not find any information on TV broadcast. If not, what are the applications of ISL?
david marchioni's user avatar