43

Yes. The space shuttle could. I recall in shuttle ascent abort training, when the crew was executing an East Coast Abort Landing to an airbase / airport on the East Coast, the commander would communicate with the tower on "guard" as they were approaching the site. These airports included civilian airports such as St. Johns, Wilmington, Stephenville, etc. ...


37

He replied that we actually received the signals in just 1-2 seconds with the help of MarCO CubeSats. Later on followed up with confusion from other users with his statement and asked for clarification, he then mentioned that it is relating to quantum entanglement for communications. This is nonsense; the MarCOs received the signals in 1-2 seconds, but ...


28

It depends on what you mean by "broadcast to the whole world". According to the annotated transcript (h/t to Organic Marble for finding it) John Young said it into a "hot mike", i.e. with the air-to-ground communications loop open: [In the following, John doesn't realize he still has a hot mike. Charlie is only faintly audible through John's mike and ...


27

Yes. The Soyuz Escape Capsule Responding Instructions explicitly document 121.5 MHz capability, including voice: c. Morse code: “AN” (dot, dash, dash, dot) broadcast on VHF 121.5 during descent. d. Emergency Locator Transmitter warble on VHF 121.5 interrupted only by crew broadcasts. e. Crew has a survival radio with beacon and voice capability on VHF 121....


25

First you lock on to energy at (or near) the expected frequency. That’s carrier lock. Then you start to look for patterns in how the phase changes. The transmitter is coding groups of bits as phase-change “symbols”, and you want to find the time-pattern of those: symbol lock. But those are not yet bits because the coding works in blocks of bits. Once you ...


23

Apparently not: I like this Quora answer. Here's part of it, the rest is worth reading as well: No experiment conducted using entangled photons has ever demonstrated faster than light communication! There have been many such experiments. They were not looking for faster than light communication. They were testing quantum mechanics against Einstein's ...


21

It's a great question! Trajectory To get a few decades more out of them, you can launch Voyagers 3 and 4 sometime around now and get by with a maximally-boosting flyby of Jupiter since you wouldn't target Saturn as well. If you had to wait for Jupiter and Saturn to line up with the original pair's trajectories again, it would be too long of a wait. ...


18

As someone deeply involved in quantum information/entanglement research: You cannot, under any circumstance, use entanglement to communicate faster than lightspeed. Ever. The "no-signalling principle" says that no information can be transferred faster than lightspeed, even using all the tricks in the quantum book. If it were to be violated, a bunch of ...


15

You have a few problems with doing that which @uhoh unit has already elaborated. Even if you could surmount those you have a bigger problem, which is the Voyager probes will have to shut down their science instruments due to power constraints before a probe launched now would be able to get in a position to do any good. There are 4 instruments running on the ...


11

If the question is that if spacecraft independently initiate communications with random civilian ATC unit, the answer seems to be no. Civilian ATC units operate on VHF frequencies (118-136MHz) with AM modulation. Besides that, spacecraft should be able to tune in any frequency within the range that an ATC unit is using. Or they could use universal emergency ...


9

Two items of note: Luna 9's initially released pictures came from scientists at Jodrell Bank Observatory in England, which could be received because they were in a standard format. This came ahead of the official release of the first photographs from the surface of the Moon. Apollo 11 signals were received and decoded by Amateur Radio operators. Many ...


9

The Americans did worry about the possibility of Soviet interference. The navigation computer was could be updated from the ground, but this was only done after confirmation via a voice channel: Apollo’s design did reflect some early concern about possible Russian sabotage. For example, in the air-ground conversations you’d often hear the ground ask the ...


8

The wavelength dependence of the definition of free space path loss (FSPL) is an artifact of the way the receiver's antenna gain is defined in the same link budget calculation. It's referenced to an ideal isotropic antenna with a receive area of roughly 1 square wavelength, which for high frequency gets very small. If you do them together (transmit gain, ...


7

note: Here are two examples of "hijacked signals" that include "public release of the images or data that included the admission that it is 'stolen' or 'hijacked'." I am sure there are a few more. One is backyard audio and the other is intercepted video! From Lunar Eavesdropping in Louisville, Kentucky by C. Graney, Jefferson Community & Technical ...


7

MRO uses the Electra software-defined radio: Electra is a telecommunications package that acts as a communications relay and navigation aid for Mars spacecraft. Toward the end of the primary science phase, other Mars missions launched in 2007 and beyond will begin to arrive. Mars Reconnaissance Orbiter will use its Electra UHF radio to support any ...


6

The space segment of the Cospas-Sarsat system has two components, SAR signal repeaters (SARR) and SAR signal processors (SARP). The Sarsat instruments [...], receive these messages. They are downlinked to the distress terminals — known as Local User Terminals (LUT) — distributed around the globe. The message are then processed and distress alerts ...


6

The answer is given within the question, the emergency signals are received by the the International Cospas-Sarsat Programme satellites. From wikipedia: Space segment The Cospas-Sarsat system space segment consists of SARR and/or SARP instruments aboard: Five satellites in polar low-altitude Earth orbit called LEOSARs Seven satellites in ...


6

Signals are not repeated, but instead coded in a special way that allows to reconstruct the original data on the receiver side in presence of noise/errors. It is called forward error correction. FEC schemes are more efficient than just blindly transmitting the same data twice (though they of course increase the total amount of data that has to be ...


5

There's no minimum power for any receiver if you don't specify the type of transmission and the amount of knowledge about that existing at the receiver! For example, a GPS receiver has way worse characteristics (for example, a 4-bit ADC) than a digital TV receiver. So, who needs higher power to work? GPS works well below the noise floor because the data ...


5

I tried to understand this topic for years but never really got it. But the first answer provides a great article which made it finally click for me. The part that is missing in a lot of explanations and the most important part is: It’s a brilliant plan, but there’s a problem: entanglement only works if you ask a particle, “what state are you in?” If ...


4

LHC is Left-Handed Circularly polarized, and RHC is Right-Handed Circularly polarized. See here. As explained in this answer, spacecraft radio signals are often circularly polarized, because -- unlike linearly polarized radio waves -- they don't care about the attitudes of the transmitter or receiver. There are three different "gains" on the antenna. The ...


4

There's no such thing as a globally applicable "good" SNR. To make a earthbound comparison: While your good old analog TV needs maybe an SNR of 40 dB to be somewhat enjoyable, GPS reception on very similar frequencies can work with signal well below the noise floor, so let's say -5 dB. What SNR you'll need depends on how fast you want to transport data. ...


4

Once the communications get to earth the latency increase is minimal in comparison. In telecommunications and networking we generally use milliseconds (ms or thousanths of a second) to measure communications delay. 1.25 seconds is 1250ms. There's 2 major components to latency: Digital Signal Processing of the satellite feed, both sending and receiving: this ...


4

Different airports were prepped by NASA to be backup landing places all around the world. Seeing NASA would know about the emergency landing prior to them needing these alternate airports, NASA would contact the local Air Navigation Service Provider (ANSP) letting them know the shuttle was making an emergency landing. The shuttle would be treated as an ...


3

note: based on discussion in comments the question has been revised and more details added, so I will be updating this answer with the day. I'll address the current title: What power and signal-to-noise-ratio is required to send a signal from an asteroid to the DSN? The short answer is that it depends on the required data rate. A 12 bit 1024 x 1024 ...


3

Just a single repetition would not help. If there is a single error within those two data blocks, you do not know where the error is and have no chance to correct the error. If the data is transmitted three times and you get two identical copies, you may assume those identical copies are correct and one or more errors are in the third block. A better ...


3

You can still have arbitrarily high bandwidth even with high latency (e.g., a FedEx transporter full of hard disks driving around the country has awful latency, but incredible bandwidth). If you use TCP/IP as communications protocol, you are limited by the fact that you cannot transfer more than one tcp receive windows per round trip time. Using the TCP ...


3

Spectrum management is both science and art. One way of avoiding interference is using separate frequencies for different systems. If the spectrum can be confined to national boundaries, then usually it is licensed by the country administration (FCC, Ofcom etc.) however, if you want to operate a global system, the allocation must be done on an international ...


2

The XML shows downlink frequencies as a high-precision number in Hz and uplink as a round number in MHz. It's not stated explicitly in the XML, but that's the pattern. There's some logic to that choice: uplinks can be done at a fixed frequency (except when your receiver has a fault that requires exact transmissions, see Huygens). for downlinks you get a ...


2

What are the prospects for (and roadblocks to) comms with cubesats using "normal" internet connections where your cubesat has something like an IP address or similar, easily-obtained token or ID Short and sweet answer. Several groups have used or plan to use Globalstar to communicate with their CubeSat. Check Out: Presentation by Taylor University ...


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