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Transponders

Discussion in 'General Discussion' started by PhantomFanatic, Nov 28, 2014.

  1. PhantomFanatic

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    While reading in the news sections about FAA's list of 'encounters,' there was mention of one UAV having a transponder. First, let me say that the list read as sightings to me, not encounters. But, the UAVs were in flight airspace.

    This makes me wonder if the FAA might insist on transponders on commercial UAVs. My question: Does anyone know how small transponders can be made and what the cost might be?

    Besides regulation, maximum altitude, etc., this would make sense. Therefore, the FAA won't ever think of it, right?!

    Your thoughts?
     
  2. MadMitch88

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    They still haven't located Malaysian Flight 370 after 8 months of searching by 10 countries --- and it appears they never will.

    I dunno about you --- but I hope the world's aviation authorities spend a LOT more time worrying about how to install reliable, fail-safe transponders that can communicate GPS coordinates to orbiting satellites than figuring out how to put them on little plastic toys that people fly in their backyard.

    There's about 300 families of the dead corpses rotting away at the bottom of the Indian Ocean who would agree with me on this topic. :oops:
     
  3. PhantomFanatic

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    I was speaking of commercial drone use, not backyard fliers.

    I agree with you regarding finding downed planes. I still can't figure out how they messed that one up. They had the signal from the plane and they had it for days, if not longer. Why they couldn't get on top of it (literally) and send a submersible down is beyond me, unless they refused help from those who had such equipment.

    There are other 'crashes' that the cause of was covered up. That is criminal. Hundreds of eye witnesses seeing a missle heading to the plane, followed by an explosion. At least one pilot reported that too. There was a USA submarine launching missles nearby. Any idiot can surmise what happened.

    Sorry, you got me going...
     
  4. MadMitch88

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    I sort of forgot all the details of that story --- but they had only recorded one "ping" from the ACARS system that was picked up by one orbiting satellite --- which is why they could only extrapolate a northern arc and southern arc search path based on that one ACARS ping.

    A more reliable system that needs to be developed for tracking aircraft is simply a transponder that can transmit GPS coordinates every 30 seconds to orbiting satellites. That provides worldwide coverage and doesnt rely on ground stations like it does now to receive that GPS data --- because how many ground stations are located in the vast stretches of the southern Indian Ocean? NADA. :oops:
     
  5. Meta4

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    Your information just isn't correct. Unfortunately the real situation isn't that simple.
    They had something they thought may have been a signal but it wasn't.
    In any case hearing the "signal" doesn't give a location, it's just the start of a process to find a location.
    In this case it indicated that the source could have been anywhere in an area of over 850 square kilometres of the ocean floor.
    That's why they "couldn't get on top of it (literally) and send a submersible down"

    Lots of search effort later they still had no other signals to help pinpoint a location so they did a multimillion dollar sonar search of that over 850 square kilometres of the ocean floor but failed to find anything. Further analysis of satellite data has given some new search areas to investigate and that is still going on.
     
  6. PhantomFanatic

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    Actually, to my knowledge, a transponder doesn't continue to broadcast while underwater. It is for air traffic control to see the altitude, speed, direction, etc. of a plane. What you are referring to is the black box as it broadcasts a signal for up to a week, depending on conditions.

    The black box did its job, the people did not. I'm not privy to whether a black box transmitts GPS coordinates, but I think not. One is supposed to hone in on the signal using direction finding antennas.

    Hams have 'games' where a low signal transmitter broadcasts a signal. Hams use directional antennas, along with experience, to locate the transmitter. If only any of the searchers had experience, the equipment and common sense, they could have put a ship right over the black box. I am angered by this and I can only imagine how the families feel.

    I'm off subject here, but I wanted to share that.
     
  7. PhantomFanatic

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    I wasn't there, I am stating what I recall. However, as I just posted, using directional antennas from altitude, it should be a simple task to locate a reasonably small search area. While radio propagation isn't the same in water, as in air, the theory has merit. Many planes, that crashed in the ocean, have been found using the black box signal.

    As I recall, the USA offered help, but it was refused for days, maybe longer. Whatever the case, we are off topic here.
     
  8. Meta4

    Meta4 Moderator
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    Your recollection is quite wrong and your details are too - like thinking you can detect radio under 10000 feet of seawater.
    The reason you can't figure out how they messed up the search for MH370 is that you have no idea what they were searching for or how.
    The black box ELT never made any radio transmission on impact.
    The search was for the underwater locator beacon which emits an ultrasonic 10ms pulse once per second at 37.5 kHz ± 1kHz for approx 30 days after contact with water.
    Search all you like with using directional antennas from altitude and you'll never hear it because it isn't radio.
    It isn't radio because radio waves just don't work under the sea.
    You need to use sonar equipment under the water to find the black box.
    The ability of the sonar equipment to hear the black box pings at distance is very limited and if you have half an ocean as your search area the chances of finding it are slim.
     
  9. MadMitch88

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    I never implied the transponder was pinging while underwater. The last known ping from the ACARS system that was picked up by an orbiting satellite was received while the plane was still in the air. Also, transponders don't transmit any data about altitude, speed, etc --- they are simply an ID device to let air traffic control know what plane is assigned to a particular transponder.

    I'm not sure where you're getting your information but it's incorrect. Commerical airliner black boxes don't transmit GPS coordinates. They only emit uniform 32 KHz pings every second, or somewhere around there, so that radio receivers will have a good idea it's a black box and not some other anomaly like a whale that is transmitting a sonar signal in a non-uniform pattern. Absolutely no other data is included in those pings.
     
  10. Timtro

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    Sound travels better through water than radio signals, particularly very low frequencies. An underwater locator beacon (ULB) or underwater acoustic beacon, is a device fitted to aviation flight recorders such as the cockpit voice recorder (CVR) and flight data recorder (FDR). ULBs are also sometimes required to be attached directly to an aircraft fuselage. ULBs are triggered by water immersion; most emit an ultrasonic 10ms pulse once per second at 37.5 kHz ± 1kHz. http://en.wikipedia.org/wiki/Underwater_locator_beacon. The audio signal is referred to as a "ping", not to be confused with the same term as it applies to Sonar detection. However, the effective range of the ULB is limited to less than 14 miles under the best conditions.

    The older ELT transmitters operated on 121.5 mHz while new models use 406 mHz. Many if not all of the newer models do include GPS information data in their transmissions - http://www.acrartex.com/products/catalog/elts-general-aviation/elt1000/#sthash.Zj08XPv8.dpbs - but a large number of aircraft still have the older model ELTs.

    The satellite monitoring of the 406 mHz frequency is currently being used to affect rescues, on land and sea - http://www.sarsat.noaa.gov/ While many aircraft still carry the old 121.5 mHz ELT transponders, SARSAT stopped monitoring that frequency in 2009 - http://www.sarsat.noaa.gov/background.html. ELTs transmit signals when activated by a crash. The radio signals do travel through water, but are obstructed by the same kinds of things that obstruct signals on land, namely terrain.

    While any aircraft radio can receive 121.5 mHZ signals, ELTs do not rely on Air Traffic Control facilities because crashes do not always occur within range of an ATC tower.

    I hope this information is helpful to the discussion.
     
  11. PhantomFanatic

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    My latest post vanished!

    I posted about transponders. I was not the one who took it off topic, to an airplane crash. I reported what I heard. That is apparently different from what the two of you heard. Yes, a sonar ping works better than radio propagation in water.

    We have submarines that can determine the shapes of objects, the speed, depth and more that is classified.

    Anyway, I didn't ask for or desire an argument about an off topic subject. My entire life has been in the electronics field, both as a hobby, degree and a career. Until a drunk driver ruined my life, requiring me to go out on disability and suffering from unimaginable excruitiating pain, that is a daily affair.

    I know about what I speak. However, I wish I had just googled the information rather than making a post. Thanks for the warm welcome to the forum, by the way. There are nicer ways to state that you are correct. (Or you think you are correct.). The proof that backs up what I say, isn't something I'm capable of validating.

    I am very sorry for my part in this. I only wish to make friends, learn more about our drones and to help others. Somehow, in this simple post, it all went awry. My apologies. I will not comment further.
     
  12. SteveMann

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    The MA370 ACARS system was turned off by someone in the cockpit, which is why there was no accurate data for the search.
    ELT's don't do much if they are underwater, but they need to be transmitting when a satellite is overhead. That takes a few minutes.
    What really surprises me is, why isn't the transponder designed to be jettisoned when the aircraft is a few hundred feet underwater and float to the surface?

    To answer the OP's question - here is the smallest transponder I have found: http://www.aircraftspruce.com/catalog/avpages/trigtt21.php.
    It weighs one pound, before you add the antenna and encoding altimeter, though it may have a built-in pressure altimeter. But you do need a data feed from the GPS for ADSB-Out.
    And it costs $2500.00

    If the NPRM says that commercial sUAV's under 55 pounds need a transponder, then the volume of outraged comments will be huge.
     
  13. Narrator

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    Regarding the OP question,

    I looked into these a couple of weeks back. They already have tiny transponders available for UAV's. They're about the size of a 9v battery. I don't recall the cost.
     
  14. Fyod

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    I don't see a reason why UAVs under 20kg should have one, commercial or not, unless flying dangerously close to airports and being in communication with the tower and them knowing about your intent. Maybe knowingly filming airplane takeoffs/touchdowns.

    Everyone should consider lightweight UAVs like a bicycle on roads. The cyclist should know the rules, but doesn't require a license, license plate, DMV registration, road taxes etc.
    And I consider cycling in cities much more dangerous for all parties. Just look how many fatalities happen each year.