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Questions tagged [communication-satellite]

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

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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
254 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?
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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 ...
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1answer
373 views

How are multiple low orbit communication satellites per launch distributed along an orbital plane for global coverage?

SpaceX talks about launching 4,425 communication satellites into 83 different orbital planes at 1,100 km altitude. That's about 50 satellites per orbital plane. In terms of capacity to LEO, a Falcon 9 ...
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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 ...
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323 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?
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673 views

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?
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1answer
120 views

How can the data rate be increased in the space which is full of noise?

I am curious to know what can we do to improve the data rate in the space? I see that there are some noise sources in the Space that affect the signal quality between ground stations & deep space. ...
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Why are obsolete geostationary satellites re-orbited above the geostationary belt?

That seems a bit counter-intuitive, because in an orbit above the belt, the satellite would eventually lose gain velocity, so its orbit would intersect the orbital plane of the geostationary ...
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2answers
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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
256 views

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-...
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1answer
718 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 ...
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1answer
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How much will SpaceX's constellation of Internet satellites cost?

SpaceX has a plan to launch up to 4K satellites to provide global Internet access. Is there a reasonable estimate of how much this constellation would cost to launch? Also, as the minimum number of ...
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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 ...
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2answers
339 views

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 ...
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Could a smartphone really transmit to satellites in a space based internet system?

Space based internet systems, like the one recently proposed by SpaceX and Google, are said to use satellites to communicate directly with end users, without using cellular ground stations. But how ...
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2answers
326 views

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 ...
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Does a low-orbit communication network drive a sustainable launch market?

With SpaceX recent announcement of a huge satellite network in low earth orbit, I was wondering if such a network would motivate a sustainable large-scale launch capacity, i.e. a increase of scale of ...
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1answer
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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-...
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2answers
252 views

Earth-Mars Radio Blackout: Is it possible to define an extended solar radius to solve this as a geometric problem?

Solar atmosphere causes difficulties in communication during opposition (when Mars is almost behind the sun w.r.t. Earth). The question is: is it possible to define an extended radius for the sun, ...
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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....
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1answer
494 views

Inter-satellite linking for satellite constellations?

All the existent satellite constellations and the proposed ones talk about inter-plane communications as a very challenging issue due to issues as: High relative velocities between the satellites ...
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All Optical Global Network - how does the space-to-ground link avoid clouds?

I just saw the news item in Lightwave's online website: Laser Light to leverage free-space optics in space for Optical Satellite as a Service. All Optical Hybrid Global Network (or HALO, as laser ...
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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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1answer
340 views

Cost of different kind of band in satellite

I learnt that satellite can be equipped with transponder of different bands (L, C, Ku, Ka), and in term of bandwidth, L < C < Ku < Ka. My question is, am I correct to assume that, with a ...
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1answer
276 views

Satellite Remaining Life

How can I know the remaining life of a satellite? I have been using satbeam, and try to calculate it based on launch date + expected life, but it seems to have some problems. For example, for this ...
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Why do geosynchronous satellites appear to oscillate in North-Southward direction? How to I trace out their path on the surface of the earth?

During the course of a day, the geosynchronous satellite's position in the sky forms a 8-like figure. I'm having trouble visualizing the movement of geosynchronous satellite when viewed from the ...
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2answers
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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 ...
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331 views

How exactly does the live feed from ISS work?

Using my cell phone in a city to download lots of data very fast is common, thanks due to the dense net of base stations close to me (~1 km). But with the space station about 400 km above ground and ...
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1answer
484 views

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 ...
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1answer
1k views

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 ...
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1k views

Calculate communications window for LEO

I am designing a communication system for a small satellite. One of the major constraints is the duration of communication between the satellite and the ground station. I did link budget calculations ...
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Tools to evaluate telecommunications link budget [closed]

Can you name some of the commercially and non-commercially available tools to evaluate the link budget for a space mission? Aside Satellite Tool Kit, of course ;)
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736 views

How will SES-9 reach geostationary orbit from inclined transfer orbit (from F9 2nd stage)

This spaceflightnow article says near the end that the Falcon 9 2nd stage will leave SES-9 in an elliptical, inclined transfer orbit. This article says that this is a super-synchronous orbit, and that ...
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2answers
799 views

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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1answer
394 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 ...
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How do communication satellites remain positioned above a particular region?

From what I understand, an object has to keep moving in an orbit to not come crashing down to Earth. (The ISS is the first thing I think of for this.) How then, do satellites which are purpose built ...
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1answer
652 views

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)?
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Could a communication satellite that fails to reach GEO be repurposed?

When a launcher's upper stage fails to put a commercial communication satellite in geostationary orbit, it cannot be used as intended. But could it be used in satellite-to-satellite communication ...
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4answers
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Is it possible to replace Internet with LEO satellites?

Bulk information regarding anything in this world is available in a single touch through Internet. My question is whether it is possible to replace this Internet with a constellation of Cubesats in ...
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1answer
238 views

Are Sun-Earth Lagrange points SEL1 and SEL2 useful for communication and space surveillance?

SEL1 and SEL2 are about 0.01 AU away, 10 seconds light travel time back and forth, 4 times Lunar distance, 45 times the distance to GEO. From those two regions combined, all surface on Earth and the ...
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1answer
899 views

How can OneWeb constellation succeed where Teledesic failed?

Teledesic: 1994 backed by Microsoft Inclination: 98.2 degrees (sun-synchronous) Altitude: 700 km 840 satellites OneWeb: 2014 backed (?) by Google Altitudes: 800 or 950 km 650 satellites This is a ...
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Do space satellites have physical intrusion sensors? [duplicate]

Do satellites sent into space have a physical intrusion detection system on board to prevent tampering?
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715 views

How many dead sats near GEO?

It's my understanding a geosynchronous satellite will put itself in a graveyard orbit just before it dies. How many dead sats are in GEO or in neighboring graveyard orbits? What is their total mass?
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1answer
220 views

Cubesat communication services

Is there any known web-based API services that provide downlink/uplink testing facilities to some Cubesat? I don't want to have full hardware setup: antenna, sdr, auxiliary equipment. In same time, ...
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3answers
399 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-...
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2answers
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What is a feeder uplink/downlink?

I'm trying to understand the terminology used in the specifications of several satellite systems, such as those outlined on pages 9-11 here. I'm guessing a mobile uplink/downlink is RF uplink and ...
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1answer
539 views

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 ...
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1answer
298 views

How do polar satellites disrupt communications between GEO satellites and ground control?

I don't understand how we can get an uninterrupted line of sight with geostationary satellites with the presence of a high number of polar satellites in Earth's orbit. When microwave signals are used ...
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Can a satellite orbit Earth so that it always has the Moon in line of sight?

Could a satellite, without too much fuel consumption for station keeping, orbit the Earth so that it always has a line of sight to the Moon? It would need a near polar orbit which precesses in tandem ...