Transcription

• Speaker #0

  Hi everyone, welcome back to the GlobalSAR Hub podcast. I'm Nicolas and I'm glad you're joining us again for another update dive into the world of search and rescue. In our first episode, we explored the origins and mission of the Cospas Sarsat system. Today, we're going deeper. We're diving into the very core of the system, the three main segments that make Cospas Sarsat work. Let's break it all down and see how these parts interact to make real rescue happen. If you're part of the GlobalSAR community or just curious about how real rescues happen, make sure to follow and share this podcast with your team. You can find additional resources and tools on GlobalSARhub.com.

• Speaker #1

  Welcome to the Deep Dive. Last time, we were all kind of floored by that staggering number. Over 60,000 lives saved by the COSPAS-SARSAT system since 1982. It really makes you think about the sheer scale of impact.

• Speaker #2

  It really does.

• Speaker #1

  But it also sparks a fundamental question. How does the system actually pull that off, you know, in real time to achieve something so significant?

• Speaker #2

  Exactly. Today, we're going to get under the hood, exploring the architecture and the intricate flow of data. that allows a simple distress signal to travel from someone in immediate danger to the people who can bring them home okay think of this as understanding the engine that powers the life-saving magic we discussed previously right it's not just some satellites floating around up there hoping for the best it's a deeply interconnected and well intelligently designed network and at its heart the cospas sarsat system relies on three core components that make it all work together the spatial segment those very satellites

• Speaker #1

  then the terrestrial segment, the network of ground stations, and finally the user segment, which is you and me potentially carrying a distress beacon.

• Speaker #2

  And seeing how these three segments interact is crucial to truly grasp why this system is so effective. But before we dive into the specifics of each, let's quickly touch on the fundamental mission that drives it all.

• Speaker #1

  Absolutely. So at its core, the fundamental goal of COSPAS RSART is to provide accurate, reliable, and rapid distress alert and location data to international search and rescue authorities it's about shrinking that window of time between someone sending a signal and help arriving and pinpointing their location precisely and to make that happen as you said we have these three interconnected segments as the bedrock of the entire operation let's

• Speaker #2

  kick things off by looking at the first one the spatial segment The system's eyes in the sky.

• Speaker #1

  Okay, the spatial segment. This is where the detection process really kicks off. It's made up of constellations of satellites constantly listening for those critical 406 megahertz distress signals.

• Speaker #2

  Now, within the spatial segment, it's not just one type of satellite doing all the heavy lifting. There are actually three main kinds, each with its own unique orbit and strengths.

• Speaker #1

  All right, let's break down these different satellite types. First up, we have LEOSAR. That's Low Earth Orbit Search and Rescue. Tell us more about what makes them tick.

• Speaker #2

  Okay, Leosar satellites operate in a relatively low orbit around the Earth, about 850 kilometers up. They follow polar, sun-synchronous paths, which means they essentially circle the globe from north to south, ensuring that over time, the entire Earth is scanned. Now, their primary way of figuring out where a distress beacon is relies on something called the Doppler effect.

• Speaker #1

  The Doppler effect, we hear about that with sound waves, like how an ambulance siren changes pitch as it drives past. How does that apply to satellite signals?

• Speaker #2

  Exactly. It's the same principle. Just like the sound waves get compressed or stretched depending on the ambulance's movement, the radio waves from the beacon appear to change frequency as the Leosar satellite flies overhead. Oh,

• Speaker #1

  okay.

• Speaker #2

  By measuring this stretch or compression of the signal, this Doppler signature ground station, known as Leolats, can calculate not one, but usually two potential locations for the beacon.

• Speaker #1

  Two locations?

• Speaker #2

  Usually, yes. Yeah. But typically, as the Earth rotates and another satellite passes, this ambiguity can be resolved and the actual location pinpointed.

• Speaker #1

  So they can figure out roughly where someone is based on how the signal frequency shifts as the satellite zooms by. That's a clever bit of physics in action. But what about coverage? Is it continuous?

• Speaker #2

  Not continuously, no. Because these satellites are constantly moving, you have to wait for one to come within range of a beacon that's transmitting. This waiting period, or detection delay, varies depending on where you are on Earth. It tends to be shorter, closer to the poles, and can be longer, up to one to two hours, at mid-latitudes. This potential delay was a key reason why other satellite systems were developed.

• Speaker #1

  That makes sense. Waiting an hour or two in a critical situation could be a very long time. But I recall you mentioning a really important feature of LEOSAR that helps it achieve truly global coverage.

• Speaker #2

  Yes, the absolutely vital feature is its store and forward capability. Leosar satellites can actually record distress messages even when they are flying over a remote area and not in direct line of sight with a ground station. Oh, wow. They then store this data on board and transmit it later when they pass over a Leo load. This is absolutely crucial for ensuring that even in the most far-flung corners of the globe, like vast stretches of ocean, far from any ground infrastructure, a distress signal still has a chance of getting through. It creates a truly global safety net.

• Speaker #1

  So So even if there's no ground station nearby, when a beacon goes off in the middle of nowhere, the message isn't lost. The satellite holds onto it until it's in range. That's a fantastic level of resilience built into the system.

• Speaker #2

  Exactly. Historically, these Leosar instruments have been carried on meteorological satellites like those operated by an OAA in the U.S. and MEDOP in Europe. They offer good accuracy in pinpointing a location using Doppler, typically within a few kilometers. and that essential store and forward for global reach. However, the possibility of significant detection delays and that initial ambiguity in location were the main limitations that drove further innovation.

• Speaker #1

  Okay, so LIOSAR is like the reliable long-distance runner with global reach but a bit of a wait time. What's the next type of satellite in our spatial segment?

• Speaker #2

  Next we have GEOSAR, which stands for Geostationary Orbit Search and Rescue. These satellites operate in a much higher orbit, about 36,000 kilometers above the equator. Okay. The key here is that they appear to stay in the same spot in the sky as the Earth rotates. They're essentially parked over the same area.

• Speaker #1

  Geostationary like the TV and communication satellites. So how do they contribute to detecting distress signals?

• Speaker #2

  Well, unlike Leosar, Geosar satellites themselves don't inherently provide the location of a beacon. Because they're in a fixed position, there isn't that changing relative motion needed for the Doppler effect.

• Speaker #1

  Ah, right. No movement, no Doppler.

• Speaker #2

  Exactly. Instead, GeoSAR relies completely on the distress beacon to transmit its own location, which it usually gets from a built-in GNSS receiver, like GPS, and includes in the 406 MHz message. It receives the signal and instantly reflects it down. Now, in terms of coverage, each GeoSAR satellite can see a huge area, about one-third of the Earth's surface. However, because of their position over the equator, they don't cover the extreme polar regions, typically beyond about 70 to 75 degrees of latitude.

• Speaker #1

  Okay, so not global then.

• Speaker #2

  Not fully global, no. But their big advantage is speed. They offer near instantaneous detection, typically less than a minute for any activated beacon within their view.

• Speaker #1

  Less than a minute? That's a massive jump in speed compared to Leosar.

• Speaker #2

  It is. They act as immediate bent pipe relays. They receive the 406 megahertz signal from the beacon and... instantly retransmit it down to any ground stations within their footprint.

• Speaker #1

  So GeoSAR provides that crucial near instant detection, which is invaluable in emergencies, but it needs the beacon to provide its own location and doesn't cover the very top and bottom of the world.

• Speaker #2

  Got it. Now, what about the third type? You mentioned MEOSAR.

• Speaker #1

  Yes, MEOSAR, which stands for Medium Earth Orbit Search and Rescue. This is really the modern powerhouse of the Kaspasar-Sat system. These satellites operate in a medium Earth orbit at altitudes between about 19,000 and 23,000 kilometers.

• Speaker #2

  Higher than LEO, lower than GEO?

• Speaker #1

  Right. And what's really clever is that these are primarily the same constellations we use for navigation every single day. GPS, Galileo, GLONASS, and China's Beidou system. So the same satellites that guide our cars and phones are also helping with search and rescue. That's an ingenious way to leverage existing infrastructure. How do they work within the COSPAS-SARSAT framework?

• Speaker #2

  Exactly. These navigation satellites also carry specialized search and rescue payloads. Their method for locating a beacon is quite sophisticated. Triangulation. When a beacon transmits a burst, multiple Miosar satellites, because they're spread out in their orbits, receive that signal at slightly different times. Okay. Ground stations, called miokines, can then measure the incredibly precise time difference of arrival, or TDOA, and also the frequency difference of arrival, or FDOA, of the signal. as received by these different satellites.

• Speaker #1

  TDOA and FDOA. Got it.

• Speaker #2

  By analyzing these tiny discrepancies in timing and frequency, they can very accurately calculate the beacon's position. And this is a key benefit. They can do this even if the beacon doesn't have its own GNSS capability or if that has failed. This provides an independent verification and location.

• Speaker #1

  Wow, so they can pinpoint the location just by the signal arriving at different satellites fractions of a second apart. That sounds incredibly sophisticated, almost like a cosmic GPS triangulating. The distress.

• Speaker #2

  It is. And because of the sheer number of satellites in these medium-Earth orbits, MEOSAR provides continuous global coverage. At any moment, multiple MEOSAR satellites are visible from virtually any point on Earth.

• Speaker #1

  Continuous global coverage. Nice.

• Speaker #2

  This means it offers both near-instantaneous detection, similar to GEOSAR, and rapid independent localization, typically within about five minutes of a beacon activating. It's really the best of both worlds.

• Speaker #1

  So it combines the speed of GeoSAR with that crucial independent location capability that LeoSAR didn't have on its own. That sounds like a game changer.

• Speaker #2

  It really is. Furthermore, because these SAR payloads are hosted on multiple different global navigation satellite systems, it adds a lot of redundancy and robustness to the system.

• Speaker #1

  Makes sense.

• Speaker #2

  And the European Galileo constellation even offers a unique return link service, or RLS. This allows compatible beacons to actually receive a signal back, confirming that their distress alert has been detected, there must be a huge comfort for someone in a dangerous situation knowing their call for help has been heard.

• Speaker #1

  That return link must provide incredible peace of mind in a moment of crisis, a digital reassurance that help is on its way.

• Speaker #2

  Absolutely. The advantages of MIOSAR are significant, continuous global coverage, that near instant detection, rapid and accurate independent localization, the inherent robustness of utilizing multiple satellite systems. better resistance to signal blockage like in canyons or urban environments, and that reassuring return link service.

• Speaker #1

  So what's the catch?

• Speaker #2

  Well, the main challenge is that it requires a very complex ground segment, the meolites, which need extremely precise time synchronization at the nanosecond level to perform those accurate TDOA and FDOA calculations.

• Speaker #1

  Nanosecond level timing, that's some serious engineering. So how do these three different satellite types work together in practice today?

• Speaker #2

  Today, MISAR has really become the backbone of the system. providing that critical combination of speed and independent global localization. LEOSAR still plays a vital role, offering redundancy and its historical store and forward capability, which remains important for those truly remote regions. And GEOSAR continues to provide that immediate detection within its broad coverage area, which is particularly valuable for beacons that are equipped with and transmitting their own accurate GNSS position. This multi-layered approach. with each type of satellite contributing its unique strength, creates a very resilient and high-performing system.

• Speaker #1

  It sounds like a really intelligently designed and complementary system with these three different sets of eyes in the sky. Okay, so the satellites detect the signal and relay it. What happens next in this chain of rescue? That brings us to our second pillar, the terrestrial segment.

• Speaker #2

  Correct. Once the satellite relays a distress signal, it's the terrestrial segment that takes over. This is the global network of ground stations and mission control centers that process the raw data and ultimately get the alert to the search and rescue authorities who can take action. Right. It has two main components, local user terminals, or LUTs, and mission control centers, or MCCs.

• Speaker #1

  Okay, let's start with LUTs, local user terminals. What's their primary job?

• Speaker #2

  LUTs are essentially the satellite receiving stations located on the ground. They're equipped with large antennas that track the COSPAS-SARSAT satellites as they pass overhead. When a satellite relays a 406 MHz distress signal, the LUT receives it, performs some initial processing to clean up the signal, and calculates preliminary position estimates based on the data it receives.

• Speaker #1

  And you mentioned there are different kinds of LUTs depending on which satellites they're designed to work with.

• Speaker #2

  Exactly. There are Leo LUTs specifically designed to process the Doppler data from Leosar satellites to calculate those initial positions, and also to receive the stored distress messages. Okay. Then there are geolutes that receive the instantly relayed signals from GeoSAR satellites, primarily focused on decoding the message content, including any GNSS position the beacon transmitted. They don't independently calculate a location.

• Speaker #1

  Gotcha. Just relaying the info.

• Speaker #2

  Pretty much. And finally, we have meo-lutes, which are the most technically advanced. They need to simultaneously receive signals from multiple MeoSAR satellites that are all responding to the same beacon burst. They perform those complex TDOA and FDOA calculations that allow for the independent localization, and they also decode the beacon's message.

• Speaker #1

  Right, the super precise ones.

• Speaker #2

  Yes, and as we discussed, the precise timing synchronization between these MEO-LUTs is absolutely critical and often relies on high-speed fiber optic networks and dedicated, extremely accurate GNSS time receivers. A network of geographically spread MEO-LUTs is essential for good triangulation and truly global MEO-SAR coverage.

• Speaker #1

  So these LUTs are like the first responders on the ground, grabbing the signals from space and doing that initial number crunching to figure out where the distress might be. What happens to that information once they've processed it?

• Speaker #2

  The LUTs, which operate largely automatically 24 hours a day, seven days a week, then forward their calculated positions and the decoded beacon data to the Mission Control Centers, or MCGs. Think of the MCCs as the regional or national data hubs, the central coordination points for the terrestrial segment.

• Speaker #1

  Okay, so the MCCs are the brains of the operation on the ground. What do they do with all that data flooding in from the various LUTs? Well,

• Speaker #2

  the MCCs collect alert data from numerous LUTs, not just within their own country or region, but also internationally, as elutes can be detected by LUTs in other parts of the world. Their job is to first filter out any duplicate reports.

• Speaker #1

  Right, because multiple LUTs might see the same signal.

• Speaker #2

  Exactly. You might get the same alert information from multiple LUTs that have seen the same satellite pass, and to then validate the alerts as much as possible. They look for things like signal coherence and the timing of the transmission bursts to help determine if it's a genuine distress signal. Crucially, they also correlate information coming from different sources.

• Speaker #1

  Like comparing Doppler with MIOSAR or GPS data.

• Speaker #2

  Precisely. They might compare a position calculated using Leosar Doppler data with one derived from Leosar triangulation, or with a GPS location that was embedded in the beacon's message. But one of their most important functions is something called data enrichment.

• Speaker #1

  Data enrichment? What exactly does that involve?

• Speaker #2

  This is the point where the anonymous radio signal starts to gain critical real-world context. The MCC uses the unique beacon identifier, that hex ID we mentioned earlier, that's transmitted by every 406 MHz beacon. They use this ID to query the COSPAS-RSAD International Beacon Registration Database, or IBRD, and also any associated national beacon registration databases. This instantly pulls up vital information about the beacon itself, such as its type, is it an EPRB for maritime use, an ELT for aviation, or a PLB for personal use. Details about the vessel or aircraft it's registered to, who owns it, their contact information, emergency contacts, and even specific details like the hull color of a boat or the type of aircraft. This is a real aha moment, turning a simple anonymous radio signal into actionable intelligence about who is in trouble and potentially where they should be.

• Speaker #1

  That registration database sounds absolutely essential. Without it, the rescuers would just have a location but wouldn't know who they're looking for or who to contact. That's huge.

• Speaker #2

  Exactly. Once the MCC has validated the alert, determined it's likely a genuine distress, and enriched it with all that crucial registration data, its final key task is routing. Based on the most probable location of the distress, the MCC determines which specific rescue coordination center, or RCC, or SAR point of contact, or SPOC, is geographically responsible for that particular search and rescue region.

• Speaker #1

  Okay, sending it to the right people.

• Speaker #2

  Right. They then transmit a standardized alert message containing all the collected data, the location, the registration details, the type of beacon, etc., to that appropriate RCC or SPOC, usually via secure communication networks. They also play a vital role in managing the flow of alert data within the entire global COSPAS-SARSAT network, ensuring everyone who needs to know is informed.

• Speaker #1

  So the MCC acts like a high-tech international emergency dispatch center, taking these raw signals, verifying them, adding crucial identifying information, and then sending the complete picture to the right rescue authorities on the ground. It sounds like a very streamlined and remarkably efficient process.

• Speaker #2

  It is, and it's constantly being refined and improved. And speaking of efficiency for the SAR professionals working tirelessly at the RISG coordination centers, I wanted to briefly mention a really valuable tool developed by Global SAR Hub called Clear 406.

• Speaker #1

  Okay, Clear 406, what does that do?

• Speaker #2

  This is specifically designed to simplify how RCCs actually manage these very COSPAS SARSAT alerts that they receive from the MCCs. It has the ability to instantly decode those SIT-185 messages that's a specific standardized format used for these COSPAS SARSAT alerts and provide a clear... real-time visual representation of the distress information directly to the SAR personnel.

• Speaker #1

  That sounds incredibly useful for people working under immense pressure in an RCC environment. How does it make their jobs easier?

• Speaker #2

  Well, CLIR 406 displays the real-time geographical position of the distress beacons, whether they're EPRBs, ELTs, or PLBs, on a dynamic map interface. Crucially, it also shows essential details at a glance, such as the type of position data, whether it's from GPS within the beacon itself or an independently calculated location. And it even visually indicates the uncertainty areas associated with that location data, helping SAR planners understand the level of precision.

• Speaker #1

  Ah, so they see not just where, but how certain the location is.

• Speaker #2

  Exactly. Importantly, it's also designed to integrate with other mapping and information systems used by RCCs, which allows for quick identification of the agency responsible for a particular search area. And if the incoming beacon data includes an MMSI or HEX ID for a vessel, Clear 406 can often directly link to vessel databases.

• Speaker #1

  Wow, instant ship details!

• Speaker #2

  The core idea is to give RCC personnel immediate one-click access to all the vital data they need to make informed decisions quickly and speed up their response efforts. It bridges that gap between the raw technical alert data and actionable intelligence for the rescuers.

• Speaker #1

  So it sounds like Clear 406 is a vital tool that takes the complex CASPA-SARSA alert information and makes it immediately understandable and actionable for the people who are on the front lines of coordinating the rescue. That's a great illustration of how technology continues to evolve to directly support and enhance SAR efforts.

• Speaker #2

  Absolutely. It's all about getting the right information to the right people in the clearest and fastest way possible. when every second counts. Now, let's move on to the third critical pillar of the COSPASARSAT system, the user segment.

• Speaker #1

  The user segment, these are the beacons themselves, the devices that send out that initial crucial call for help.

• Speaker #2

  Exactly. These are the distress beacons carried by individuals on aircraft, vessels, and as personal safety devices. Their fundamental purpose is to, when activated, transmit a signal indicating that someone is in distress and needs immediate assistance. Right. Activation can occur automatically in certain situations. For example, an EPRB is designed to activate upon immersion in water, or an ELT upon the violent forces of an aircraft crash. Or, activation can be manual, as is the case with a personal locator beacon, or PLB, when the user presses a button.

• Speaker #1

  And what kind of signal do these beacons actually send out?

• Speaker #2

  They transmit short digital bursts on that key 406 megahertz frequency at regular intervals, typically about every 50 seconds, and each transmission lasts for about half a second.

• Speaker #1

  Short bursts.

• Speaker #2

  Got it. Many modern beacons also have the capability to transmit a lower power continuous homing signal on 121.5 MHz. This lower frequency signal has a shorter range and is primarily used by rescue teams in the final stages of a search to pinpoint the beacon's exact location using handheld direction finding equipment. Ah, okay. Think of the 406 MHz as a long-range distress call and the 121.5 MHz as the local, here I am, deacon for a rest of yours closing in.

• Speaker #1

  So the 406 mHz is for that initial alert to the satellites reaching across vast distances, and the 121.5 mHz is like a localized beacon to guide rescuers right to the person or vessel. What specific information is actually encoded in that short 406 mHz burst?

• Speaker #2

  Each burst contains several vital pieces of information. First and foremost is that unique beacon identifier, the HEXID, which, as we've discussed, is the key that unlocks all the crucial registration data.

• Speaker #1

  The magic key.

• Speaker #2

  Right. If the beacon is equipped with a GNSS receiver like GPS or Galileo, and it has a valid position fixed precise moment of transmission, that highly accurate latitude and longitude is also encoded within the message.

• Speaker #1

  So it can send its own coordinates.

• Speaker #2

  If equipped, yes. Additionally, the signal can contain other important data, such as the specific type of beacon is in an EPIRB, ELT, or PLB. The nature of the distress if the user or the beacon itself can indicate it.

• Speaker #1

  like a medical emergency or a sinking vessel and sometimes even the time of the last known valid position fix so a modern beacon can essentially say this is who i am this is exactly where i am right now and this is the type of trouble i'm in that's an incredible amount of potentially life-saving information packed into a very brief signal it is and there are several main categories of these beacons each designed for specific environments and users as

• Speaker #2

  we mentioned epirbs are specifically for maritime use and are often designed to activate automatically when they come into contact with water.

• Speaker #1

  EPIRB for maritime.

• Speaker #2

  ELTs are for aviation and are engineered to activate upon detecting the impact forces of a crash.

• Speaker #1

  ELT for aviation.

• Speaker #2

  PLBs are personal devices intended for use on land, at sea, or in the air, depending on the specific model and any relevant regulations, and they are typically activated manually by the user.

• Speaker #1

  PLB for personal use.

• Speaker #2

  And then there are also SS or Ship Security Elude systems, which While their primary purpose is to alert authorities to security threats on a vessel, can in some cases also utilize the COSPAS-SARSAT network to send a discrete alert.

• Speaker #1

  Okay, so we have the three core pillars. The satellites constantly listening, the ground network diligently processing and routing, and the beacons ready to send out the call for help. The COSPAS-SARSAT system is a truly remarkable achievement of human ingenuity and cooperation. Every single component, every segment we've discussed plays an absolutely vital role in this silent, ever-present, life-saving network. It really gives you a new appreciation for all the unseen infrastructure that constantly works to keep us safe. Join us next time on the deep dive for episode three, where we're planning to delve into the often underappreciated but absolutely crucial topic of beacon registration. Exploring exactly why it is so vitally important to register your beacon properly. And we'll also be sharing some compelling real-world examples of Casper Sarsat in action, highlighting the very human impact of this extraordinary technology and the lives it touches.

• Speaker #2

  Looking forward to it.

• Speaker #1

  Until then, keep exploring, stay curious, and perhaps take a moment to consider the technology quietly working behind the scenes to ensure our safety.

• Speaker #2

  Indeed. Stay safe out there, everyone.

• Speaker #0

  That's it for today's episode. In our next episode we'll zoom in on the mission control centers, the brains of the operation and we'll also take a closer look at different types of beacons, eburbs, ELTs, PLBs and even some you may have never heard of. So don't miss it! Until next time, stay safe and stay curious. If you found this episode helpful, Don't hesitate to subscribe, leave a review or share it with your colleagues. And of course, for more updates and exclusive SAR content, visit our internet site globalsarhub.com.