Steffan Watkins  Profile picture
Feb 15, 2023 9 tweets 4 min read Read on X
🇺🇸 People stop me on the street all the time and ask me, Stef, how can you tell where in the United States there are too few #ADSBexchange receivers to geolocate aircraft that aren't broadcasting their precise location data using multilateration (#MLAT)?
Great question!
Here's what you do:
filter by altitude, between 10,000-40,000 ft, that restricts the results to aircraft which are flying high enough that we should home four or more receivers are in line of sight, a requirement for #MLAT.
Then filter so you only see the Mode-S-transponder-transmitting aircraft
Let's take USAF KC-135 61-0311 as an example

We can tell more or less where they are, somewhere around the loop they're doing over Washington and Montana, but over on the left under Signal you see they have 1 receiver that's got them in line-of-sight (LOS), and #MLAT requires 4.
If you wanted to pick up the rough location of that aircraft you'd need to deploy another 3 receivers to locations beneath/nearby their flight path so you *might* get 4+ receivers to collect their Mode-S transmissions simultaneously and estimate their location in the sky.
Wherever you see a Mode-S plane icon, there's a need for another ground based receiver, to try and use multilateration to derive their real location, Mode-S locations on the map are only accurate to *hundreds* of km.

(NB: multilaterate = 4 data points, triangulate = 3 points)
There are 140+ other aircraft worldwide in the same boat right now. If you live near any of these plane icons, consider deploying an #ADSBexchange receiver to collect the transmissions from the planes above your house.
inaccurate.adsbexchange.com/?filterAltMin=…
How to set up an SDR receiver to collect ADS-B / Mode-S transponder data and feed the data to #ADSBexchange.

adsbexchange.com/how-to-feed/

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More from @steffanwatkins

Jun 17
🇨🇦⚓️ Since the Royal Canadian Navy refuse to take pictures or publicise the RCN's operation tailing the Russian Navy since June 1, once again the Americans will do the work for us. Thanks DVIDS! You keep Canadians better informed than our PAOs. 🧵
📸 Taken June 9, Published June 14

ATLANTIC OCEAN (June 09, 2024) Canadian Navy Cmdr. Peter McNeil, commanding officer of the Canadian Halifax-class frigate #HMCSVilledeQuébec (FFH 332), and U.S. Coast Guard Capt. Johnathan Carter, commanding officer of the Legend-class cutter U.S. Coast Guard Cutter Stone (WMSL 758), identify a Russian naval vessel from Stone’s bridgewing in the Western Atlantic June 9, 2024. U.S. maritime forces, in conjunction with allies and partners, consistently monitor the activity of foreign vessels operating within the U.S. Second Fleet area of operations in support of homeland defense. The U.S. Navy protects international law and safeguards freedom of navigation for all nations. (U.S. Coast Guard photo by Ens. Alana Kickhoefer/Released)Image
📸 Taken June 6, Published June 14

ATLANTIC OCEAN (June 06, 2024) The Arleigh Burke-class guided missile destroyer USS Donald Cook (DDG 75) identifies a Russian naval vessel in the U.S. Second Fleet area of operations June 6, 2024. U.S. maritime forces, in conjunction with allies and partners, consistently monitor the activity of foreign vessels operating within the U.S. Second Fleet area of operations in support of homeland defense. The U.S. Navy protects international law and safeguards freedom of navigation for all nations. (U.S. Coast Guard photo by Ens. Alana Kickhoefer/Released)Image
Read 12 tweets
Jun 10
🇷🇺 On May 17 the Russian MoD announced a flotilla of Russian Navy Northern Fleet ships departed Severomorsk for a long out of area deployment. Within a week, they had published a high quality video of Frigate Admiral Gorshkov performing exercises in the Atlantic. #ВМФ #СФ
The four vessels in the flotilla are:

Project 22350 Frigate Admiral Gorshkov, commissioned July 26, 2018

russianships.info/eng/warships/p…
Project 885M Yasen-M class SSGN Kazan (K-561), commissioned May 7, 2021

russianships.info/eng/submarines…
Read 22 tweets
Mar 13
🇨🇦🇮🇱 About an hour ago #RCAF CC-130J Hercules 130603 #C2B53F fell victim to Israeli GNSS/GPS spoofing & jamming. 130603's transponder ceased transmitting accurate position data, then stopped transmitting position data at all.
globe.adsbexchange.com/?icao=c2b53f&l…
Image
It is unclear if flight #CFC2503 is air-dropping relief to Gaza, or transiting near #Israel.

It is clear that Israel is not pausing their months long electronic warfare attack on all civilian and military aviation in line of sight, and the media doesn't want to mention it.
(link showing documented GPS jamming will only work after March 13, ie, March 14+) h/t @lemonodor

gpsjam.org/?lat=32.82722&…
Read 4 tweets
Jan 26
🇨🇦⚓ Royal Canadian Navy Harry DeWolf-class arctic and offshore patrol vessel HMCS Margaret Brooke departed Halifax on January 12 for a six week #OpCARIBBE deployment. 🧵

#AOPV431 IMO:4702515 MMSI:316014540
call sign:CGMB #HMCSMargaretBrooke
marinetraffic.com/en/ais/details…
Read 11 tweets
Aug 11, 2023
🇨🇦⚓️ Where #HMCSMontréal has been since March 26, when they departed Halifax on #OpPROJECTION, using @MarineTraffic AIS-T and AIS-S data. 🧵

This thread serves as a guide, to you the reader, of what to look for in Royal Canadian Navy communications; it's your crackerjack box secret decoder ring when they're vague.

All of this information has been broadcast by the ship's AIS transponder over the airwaves, picked up with every SIGINT satellite in orbit, military and commercial, every plane in line-of-sight(LOS), collected by every significant adversary, and included in a dossier with other intelligence, that was reported up their chain of command, before I woke up this morning.

Our military and government public affairs officials can, without compromising national security, speak plainly and include everything up to (at least) this level of information, because every adversary already knows; they told them. They got the memo.

This is also the minimum amount of detail that the public should expect in any media story about HMCS Montréal's deployment; all this information is at journalists' fingertips too. Public affairs should be more forthright to make journalists' lives easier. This information isn't a secret to the outside world.

All times in UTC, unless otherwise mentioned.
🇨🇦⚓️ Royal Canadian Navy Halifax-class multi-role patrol frigate #HMCSMontréal's first port of call was Lisbon for 4 days from April 4 to April 8.

Fighting erupted in Sudan on April 15. #OpPROJECTION

🇨🇦⚓️ #HMCSMontréal arrived at the Port Said anchorage on April 17, traversed the Suez Canal into the Red Sea on April 18, then stopped transmitting AIS from April 19 until they arrived in Salalah, Oman on May 8. #OpPROJECTION

Read 54 tweets
May 24, 2023
🇬🇧 41% (9) of the RAF A400M Atlas fleet of 22 do not fly. Of the remaining 59% (13) that do fly, some of them are deployable, and some are homebodies doing training and certification. #ZM406 returned from the Airbus depot in Getafe, Spain 🇪🇸. Image
🇬🇧 RAF C-130J Hercules #ZH869 #43C198 was sent to Cambridge 🇬🇧 to be decommissioned, bringing the number of Hercs remaining to 5, all of which are flying regularly, except #ZH870 #43C04C hasn't flown in a week.. maybe they're next? 🪦
+ No coverage of the Herc flight to Benghazi. Image
🇬🇧 Only RAF C-17 Globemaster (#ZZ172 #43C172) hasn't flown for over a month; it's probably undergoing indepth maintenance. 88% of the fleet is regularly in the air. Image
Read 4 tweets

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