8 ms·
Receiving unintentional voice transmissions from GPS satellites
- 1letterunixname 3y agoAnd possibly intentional misuse for criminal and perhaps non-criminal activity too. 121.5 and 243 MHz are no longer officially monitored for voice distress signals, but I wonder if they're still being gathered on the fleet. Perhaps the best mitigation, I suppose a reduced set of these signals are monitored for voice distress calls. The satellites should support geofenced/location-selective rejection of signals on 406 MHz and 1544.2 MHz identified as non-emergency traffic to prevent misuse by pirates, drugs dealers, and warlords coordinating attacks.
- dweekly 3y agoWhat is your basis for a claim that 121.5 (guard) is unmonitored? As a pilot I can say that claim is false - guard is very actively monitored everywhere in the United States. Were you referring to some other locations?
- jcrawfordor 3y agoCOSPAS-SARSAT no longer monitors 121.5, for various reasons, so no satellite systems regularly monitor 121.5. This means that 121.5-only ELTs are obsolete, and prohibited for installation by the FAA since 2018. Modern ELTs are COSPAS-SARSAT transponders like EPIRBs and PLBs with only minor aviation-specific features. ATC does still monitor 121.5, but that's with an eye towards voice transmissions, not radio beacon activations. COSPAS-SARSAT has never carried voice traffic on 121.5, the satellites attempted onboard Doppler direction finding of the beacon tone (not very accurate at all, one of the reasons it is obsolete). At the same time, ATC no longer has RDF capability from most (all?) GATRs, so receiving the ELT beacon tone is mostly useless to ATC, and ATC is unlikely to receive it anyway since GATRs have very poor coverage down to ground. ELTs do still transmit on 121.5 for convenience of search aircraft, but it's becoming increasingly irrelevant with high COSPAS-SARSAT coverage (if the ELT activated at all, rescue coordinators already know the location by GPS coordinates) and increasing rarity of direction finding equipment (and pilot experience with RDF) on aircraft. One way to sum it up is this: 121.5 is monitored for distress calls from aircraft in the air, but it is not monitored for distress calls from aircraft on the ground. The latter is the goal of search and rescue systems, and the use of 121.5 has been replaced by the much more modern COSPAS-SARSAT system originally developed for maritime rescue.
- doctor_eval 3y agoI had to look this up. Wow! https://en.m.wikipedia.org/wiki/International_Cospas-Sarsat_Programme https://en.m.wikipedia.org/wiki/International_Cospas-Sarsat_... > The International Cospas-Sarsat Programme is a satellite-aided search and rescue (SAR) initiative. It is organized as a treaty-based, nonprofit, intergovernmental, humanitarian cooperative of 45 nations and agencies (see infobox). It is dedicated to detecting and locating emergency locator radio beacons activated by persons, aircraft or vessels in distress, and forwarding this alert information to authorities that can take action for rescue. Member countries operate a constellation of around 66 satellites orbiting the Earth which carry radio receivers capable of locating an emergency beacon anywhere on Earth transmitting on the Cospas-Sarsat frequency of 406 MHz.
- tialaramex 3y agoIt turns out that humans are all mutually interested in the general idea that we should rescue lost people. The reason for the name (half Russian, half English) is that this is an early peaceful purpose programme negotiated between the US and Russia. For a long time the only obvious reason to put things in space was so that you could kill the enemy, but COSPAS SARSAT is a system which needs space and doesn't kill anybody.
- dweekly 3y agoHelpful additional data on COSPAS-SARSAT, thank you! I didn't realize ELTs that only output on 121.5 were no longer a thing. That said, the claim I was responding to was "121.5 and 243 MHz are no longer officially monitored for voice distress signals", which is pretty obviously false.
- jcrawfordor 3y agoWhat you're proposing is an enormous increase in complexity of equipment, which would have an impact not only on price but also reliability of the space segment. A "bent-pipe" space segment with minimal control logic is a well-established norm in communications satellites for a few reasons, ranging from reliability to making it possible to use existing transponders with future modes. Even still, more and more communications satellites use digital transponders that can authenticate source messages, and so this issue mostly exists with legacy satellites that can't be retrofitted. Besides, there's not really much motivation to mitigate this problem. First, pirate satellite communications by SARSAT transponders are rare compared to other satellite systems very popular with pirates like legacy US Navy communications satellites. Second, satellite piracy isn't that popular overall. Mitigating the ability of criminal organizations to communicate this way would require taking down a lot of different satellite systems, and then they would just fall back to HF radio, which is already the more popular approach. It's doubtful there would be any major reductions in crime and the type of crime that seems to motivate the most use of satellite piracy---unlicensed fishing near the Phillipines---isn't super high on the list of international priorities.
- patrakov 3y agoQuick summary: > Many navigational and meteorological satellites carry a search and rescue (SAR) repeater which is intended to receive UHF emergency locator beacons and rebroadcast them in the L-band or higher. However the repeaters appear to be picking up all sorts of other signals from the ground, including voice transmissions.
- actionfromafar 3y agoMakes me wonder if these ever were used out-of-spec for transmission deliberately by parties. (Thinking spy stuff but it could also be just hijinx.)
- zoklet-enjoyer 3y agoI think you will find these stories interesting https://www.wired.com/2009/04/fleetcom/ https://www.wired.com/2009/04/fleetcom/ https://archive.ph/1WyGR https://archive.ph/1WyGR https://www.wired.com/2009/12/insurgents-intercept-drone-video-in-king-sized-security-breach/ https://www.wired.com/2009/12/insurgents-intercept-drone-vid... https://archive.ph/xyW4E https://archive.ph/xyW4E
- deleted 3y ago[deleted]
- IshKebab 3y agoThe article suggests pirates which makes some sense.
- wildzzz 3y agoUnless someone has proof otherwise, I'd bet that they've never been used for that purpose. Every major government is listening to this SARSAT downlink so it's probably better to use something less visible.
- actionfromafar 3y agoNumber stations are also a thing.
- somethingsaid 3y agoShouldn’t we link to the original YouTube video? This website just reposts it with no analysis, a bunch of ads, and some janky scroll hijacking.
- superkuh 3y agoIt's text and not video. Just speaking personally I wouldn't have clicked on or commented on a youtube video link. rtl-sdr.com is pretty decent aggregator as far as hobby SDR goes despite their bias in promoting their custom rtl-sdr dongle.
- somethingsaid 3y agoYeah, I understand the preference for text, and I’m not against the site itself for posting it (I don’t have enough knowledge to comment on its quality), but I think we should give credit where credit (and ad revenue) is due, and link to the original creator’s work where possible.
- Retric 3y agoIn the vast majority of cases I prefer text, but in this specific case the video is actually useful for all the little details about what he’s doing that aren’t in this article or the words he’s using. https://www.youtube.com/watch?v=U_pCHTeamn8 https://www.youtube.com/watch?v=U_pCHTeamn8
- fortran77 3y agoSubmit the link and see if it gets voted to the front page.
- acaloiar 3y agoFew things evoke feelings of the early internet like intercepting unencrypted communications in the wild with off the shelf hardware and software. It's some how comforting to realize this is still possible today.
- charcircuit 3y agoConsidering how much progress that has been made in encrypting internet traffic radio seems painfully slow in evolving to be more secure. Edit: specifically radio protocols not carrying internet traffic
- TechBro8615 3y agoAren't there FCC regulations that forbid encryption over non-military radio?
- mirashii 3y agoFor amateur radio, but no in general.
- tarxvf 3y agoAnd it's not even actually illegal for amateur radio though there continues to be debate on the topic due to the phrasing. I do think that encryption is firmly outside of the amateur culture in most cases, but legality is well covered here: https://www.n5dux.com/ham/files/pdf/Data%20Encryption%20is%20Legal.pdf https://www.n5dux.com/ham/files/pdf/Data%20Encryption%20is%2...
- Gordonjcp 3y agoIn the UK, it's illegal to encrypt for the purposes of obscuring communication. There was a lot of noise about G3RUH modems in the olden days when 9600bps packet was starting out, because they used a "scrambler" to whiten the spectrum of the data being sent, and people assumed that meant it was using a secret key to encrypt traffic. I mean, in a sense it was - you're trying to make thing with long runs of patterns look as much like noise as possible, which is the goal of encryption - but in order for it to work as a modem both ends have to have the same "key" which was a very short LFSR that would pull into sync during the training burst. In practice, at least in the UK, you can more-or-less do what you like as long as you're not making a nuisance of yourself. You literally cannot pay Ofcom to investigate anything on the amateur bands, although you might get a lot of grumbling from daft old bastards.
- runjake 3y agoDirect link to video: https://www.youtube.com/watch?v=U_pCHTeamn8 https://www.youtube.com/watch?v=U_pCHTeamn8
- scrum-treats 3y agoAlternative link to video: https://invidious.tiekoetter.com/watch?v=U_pCHTeamn8 https://invidious.tiekoetter.com/watch?v=U_pCHTeamn8.
- libpcap 3y agoWhat did the conversation overheatd in that video say?
- OnlyMortal 3y ago"People of Earth, your attention, please. This is Prostetnic Vogon Jeltz of the Galactic Hyperspace Planning Council. As you will no doubt be aware, the plans for development of the outlying regions of the Galaxy require the building of a hyperspatial express route through your star system. And regrettably, your planet is one of those scheduled for demolition. The process will take slightly less than two of your Earth minutes. Thank you."
- _notreallyme_ 3y agoApparently it is related to some "taxes services" in China. At least that's what the author of the video says.
- Gordonjcp 3y ago"Taxi service" would be more likely.
- deleted 3y ago[deleted]
- bryancoxwell 3y agoA fun video and well explained.
- userbinator 3y agoSome of those voices sound like Chinese... and I wouldn't be surprised if cheap walkie-talkies and the like are used over there, which are either actually using a frequency that gets picked up by these satelllites, or have poor/nonexistent filtering that their signal harmonics are.
- _whiteCaps_ 3y agoIf anyone is interested in satellites, check out your options for amateur radio licensing in your country. The ISS has a repeater that even the most basic license holder is able to use. It's using VHF/UHF frequencies, and a low power 5W radio is enough to work it. Occasionally the astronauts will get on the radio as well and chat with you! I haven't been lucky enough to do that yet. But I have heard them talking when passing overhead. https://amsat.org https://amsat.org has more information.
- wkat4242 3y agoYes the repeater has several modes by the way. Amsat shows which is active. There's also APRS and sometimes SSTV. When the astronauts are on air there's a strict protocol, they will generally call for people in a certain area. Of course the ISS has a pretty huge footprint so radio discipline is very important.
- _whiteCaps_ 3y agoWhen it's a scheduled contact, yes, strict protocols are used, but I've heard them on their downtime making contacts, it basically goes: ISS: NA1SS is listening HAM: NA1SS this is whiskey one alpha whiskey in Hartford, Connecticut ISS: W1AW, welcome board the ISS! HAM: 73 repeat for everyone trying to make a contact :-)
- great_psy 3y agoAre the any options that are small enough to make a remote contact radio ? Basically something I can take with me while hiking, and have somebody else in civilization listen and have some conversations with ?
- _whiteCaps_ 3y agoYes, lots! Depends on what you want to do. For satellites, any dual band VHF/UHF radio will work. A cheap Baofeng from aliexpress can get you started: https://www.aliexpress.com/item/1005004895672032.html https://www.aliexpress.com/item/1005004895672032.html. You'd likely want to get a programming cable for it as well. They also can use Resource Road frequencies if you're going anywhere with radio controlled roads. Ideally a radio for satellites is full duplex (you can hear simultaneously while transmitting). Those radios cost much more though. Many people just use two radios. For shortwave radio, you could use something like the trusdx: https://dl2man.de/ https://dl2man.de/ Note that in both of these cases, to transmit, you'll need a license... and if you want to talk to someone specific it may be hard to do. Talking to random amateur radio operators is much easier. The options I posted are cheap - you can easily spend tens of thousands of dollars on radios, antennas, amplifiers, towers, etc.
- NoZebra120vClip 3y agoMy father is a radio lover, a DXer, and sometimes nearly contemplated a ham license. So I grew up with him listening to shortwave and other bands, he explained all the concepts, WWV would be on for two hours at a time (you could literally count every minute). Another fixture was the police/fire scanner that would be on most evenings, especially when we heard sirens. Dad put up a nice rotary Yagi VHF/UHF tower for the television set, so we would play with the rotary control to dial in better reception, whatever channel we watched. So then I found channel 70-83 on the TV, and discovered that AMPS cell phone conversations would drift in and out on those channels if I just let them sit for long enough. So Dad strictly enjoined me not to reveal what I learned from those conversations. And I lost interest, because not much interesting was being said, and the broadcasts were partial, probably because the typical use of AMPS was for car phones, not people walking by on the sidewalk.
- actionfromafar 3y agoI love how wholesome it is to not discourage you from listening.
- wkat4242 3y agoI guess you're in the UK? The UK has this really weird law where it's legal to listen to anything but you may not repeat what you heard. I don't know of any other country that has that stipulation. In most of Europe you can listen all you want and talk about it. I think in the US some frequencies were forbidden to listen to and to this day these are blocked on scanners. Not sure why as analog cellphones are long obsolete.
- thejsa 3y agoEven listening is in a grey area in the UK; it’s a separate offence to “use wireless telegraphy apparatus with intent to obtain information as to the contents, sender or addressee of any message” where you aren’t an intended recipient. But the intent bit is probably hard to prove in practice.
- gnfargbl 3y agoI'm not sure we do have that law in the UK? The relevant legislation seems like it would be https://www.legislation.gov.uk/ukpga/2006/36/section/48 https://www.legislation.gov.uk/ukpga/2006/36/section/48; but that makes it illegal to either intercept or disclose.