Receiving unintentional voice transmissions from GPS satellites

https://www.rtl-sdr.com/receiving-unintentional-voice-transmissions-from-gps-satellites/

by thcipriani • 3 years ago

190 86 3 years ago

And 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.

dweekly2• 3 years ago

What 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?

jcrawfordor2• 3 years ago

COSPAS-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attempted onboard Doppler direction finding of the beacon tone (not very accurate at all, one of the reasons it is obsolete).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 The latter is the goal of search and rescue systems, and the use of 121.5 has been replaced by the much more modern COSPAS-SARSAT system originally developed for maritime rescue.

jcrawfordor2• 3 years ago

What 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• 3 years ago

Quick 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.

actionfromafar3• 3 years ago

Makes 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• 3 years ago

I think you will find these stories interesting

https://www.wired.com/2009/04/fleetcom/ https://archive.ph/1WyGR

https://www.wired.com/2009/12/insurgents-intercept-drone-vid... https://archive.ph/xyW4E

IshKebab• 3 years ago

The article suggests pirates which makes some sense.

wildzzz• 3 years ago

Unless 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.

joshspankit• 3 years ago

As mentioned in the video; that would be inadvisable. Not only is it illegal and constantly monitored, but it’s almost trivial to triangulate the source of the transmissions.

You could probably get away with sending a couple messages while pretending to be someone doing it accidentally, but you’d be holding up a “pick me” sign visible to any type of scrutiny.

somethingsaid2• 3 years ago

Shouldn’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• 3 years ago

It'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.

somethingsaid2• 3 years ago

Yeah, 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• 3 years ago

In 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

fortran772• 3 years ago

Submit the link and see if it gets voted to the front page.

runjake• 3 years ago

Direct link to video: https://www.youtube.com/watch?v=U_pCHTeamn8

scrum-treats• 3 years ago

Alternative link to video: https://invidious.tiekoetter.com/watch?v=U_pCHTeamn8.

acaloiar• 3 years ago

Few 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.

charcircuit3• 3 years ago

Considering 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• 3 years ago

Aren't there FCC regulations that forbid encryption over non-military radio?

withinboredom10• 3 years ago

That’s because there isn’t a point. In order for encryption to work, you need to exchange keys at some point. Doing that half a world away is rather pointless. Doing it over the air, how do I know Alice won’t intercept and broadcast her keys louder than me? Or just interfere and prevent me from sending keys?

As we all learned in WWII, a code is better than encryption when you need complex PKI to achieve encryption. It’s more flexible, and can even convey nuances not intended. Ah, sorry I mean a language, not a code. But still, code words and phrases are still a thing.

ajsnigrutin• 3 years ago

Most of them are pretty secure, a few really old or intentionally open (ham radio) are not, but the rest, are (wifi, 5g, ...)

aleph_minus_one• 3 years ago

Considering how much progress that has been made in encrypting internet traffic radio seems painfully slow in evolving to be more secure.

An important reason that I see is because (at least in Germany, I guess worldwide) ham radio operators are not allowed to encrypt their traffic. Commercial companies are a lot more conservative concerning encryption than "hacker people".

ianpenney• 3 years ago

The amateur radio service is not permitted to encrypt our traffic. That doesn’t mean we can’t. Theoretically (not legally tested) you could post the AES256 keys for your DMR radio to the public over the internet and then do it since you disclosed the necessary tools to decode your traffic.

Modern radios sync their keys when they are within range of wifi at HQ.

Also, see: https://www.cbc.ca/news/canada/toronto/toronto-police-tow-tr...

ezoe• 3 years ago

If you keep emitting radio wave of these frequency for general communication purpose, the local authority will eventually catch you.

If the local authority or civilization corrupted, good luck rebuilding it.

libpcap• 3 years ago

What did the conversation overheatd in that video say?

OnlyMortal• 3 years 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_• 3 years ago

Apparently it is related to some "taxes services" in China. At least that's what the author of the video says.

Gordonjcp4• 3 years ago

"Taxi service" would be more likely.

bryancoxwell• 3 years ago

A fun video and well explained.

userbinator• 3 years ago

Some 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_3• 3 years ago

If 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 has more information.

wkat42426• 3 years ago

Yes 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_3• 3 years ago

When 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• 3 years ago

Are 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_3• 3 years ago

Yes, 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. 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/

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• 3 years ago

My 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.

actionfromafar3• 3 years ago

I love how wholesome it is to not discourage you from listening.

wkat42426• 3 years ago

I 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• 3 years ago

Even 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• 3 years ago

I'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; but that makes it illegal to either intercept or disclose.

Receiving unintentional voice transmissions from GPS satellites

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