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Hillbilly Tracking of Low Earth Orbit

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    silent 30C3 preroll titles
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    applause
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    Travis Goodspeed: First I need
    to apologize for typesetting this
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    in OpenOffice. I know that the
    text looks like a ransome note.
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    But that's what happens
    when you don't use LaTex.
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    I'd also like to give a shoutout
    call, mallnarf (?) is here,
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    and our Dinosaur rock band.
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    laughs, applause
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    We're a Christian rock band - we're
    called 'Jesus lives in the ISS' and
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    we know that he is always watching us,
    but we think that it's easier for him
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    to hear our prayers when
    he's, you know, in an orbit
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    that passes over us. So we need to use
    orbital tracking to know when to pray!
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    laughter
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    As I'm sure you can guess I'm not
    recognized as a legal minority religion
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    in Germany. I'd also like to thank skytee
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    and Fabienne Serrière and Adam Laurie
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    and Jim Geovedi for some
    prior satellite tracking work,
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    and the scooby crew (?) at Dartmouth
    College for all sorts of fun
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    whenever I bounce out there.
    This is the mission patch
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    of the Southern Appalachian
    Space Agency (SASA).
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    applause and cheers
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    This was drawn by Scot Biben (?) and there are
    a few pieces of my people's native culture
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    that I need to point out here. On the
    right the little Dinosaur type thing
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    with his finger going out, you might
    call him E.T. but we call these things
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    'buggers'. They are like this tall, and
    they are green and that's why the man
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    on the left has a shotgun.
    laughter
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    Because he doesn't want to be abducted.
    You got a satellite dish in the middle
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    and it's sitting on sinter blocks because
    that's also a piece of my people's
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    native culture. There's a moonshine
    still in the background.
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    That's kind of like Waldcubbet (?), you
    make it at home and from corn.
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    And then there's the mountain... a piece,
    it looks like there are snowpeaks
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    on those mountain tops. But our mountains
    aren't tall enough to have snow.
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    These are actually that we've blown off
    the lids of the mountains for coal mining.
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    Which is another piece of
    my people's native culture.
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    And at the top, in space you can see
    the ISS, and you can see a banana,
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    and you can see what I think is a bulb.
    This is to signify space trash.
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    I mean there's a lot of stuff up there.
    And, you know it's symbolism that matters
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    in these things, you know?
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    At BerlinSides, in May of 2012
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    I did a lecture on reverse
    engineering the SPOT Connect.
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    The SPOT Connect is a litte
    hockey puck type thing
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    – this is what it looks like.
    And these things are great.
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    It weighs a bit more than your cell phone
    but it runs off of a couple of batteries,
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    it connects to your phone by Bluetooth.
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    Originally these were emergency locator
    beacons. So if you're going hiking...
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    have any of you seen the movie where
    the guy has to cut off his arm
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    with a dull knife? If you're hiking and
    you don't want that same experience
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    you buy one of these things. And
    then there's an emergency button
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    you can push that transmits your
    GPS coordinates by satellite
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    to rescue workers. But that was boring,
    so they had to add social media.
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    laughs, laughter
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    So in addition to keeping you
    from chewing off your own arm
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    this device will also allow you to
    tweet and make Facebook posts.
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    laughs, laughter
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    The idea is as you're running... here I'm
    crossing the Schuylkill River in Philadelphia
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    and the Android phone on the left is
    making a post. And I did an article
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    on reverse-engineering the Bluetooth
    side of these things. Because... I use
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    a weird brand of phone that Microsoft
    killed off, and I'm terribly bitter about it.
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    But I also figured out the physical layer.
    And that's what this diagram shows.
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    This transmits 1.6125 GHz. And it
    sends a pseudo-random stream, so
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    each one of these zeros is a long chunk
    where it's bouncing back and forth
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    between 2 different frequencies And
    the same for the ones. But the way
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    that the pattern works is that it switches
    the signal whenever it is going from
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    the 0 signal to the 1 signal. And
    internally, there are these little pops
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    that you can actually identify on
    a Software Defined Radio recording.
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    And this is how you can reverse-engineer
    the signal that the SPOT Connect is
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    sending up to its satellite network.
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    Everything is clear text on this.
    And it's completely unencrypted.
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    It just has your serial number, your GPS
    coordinates, and a bit of ASCII text.
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    If you listen on this frequency and you
    have the correct recording software
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    you can actually watch all of the SPOT
    Connect messages that are transmitting up
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    from your location. And this would be
    great except that this is designed for
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    hiking in areas where there's no cell
    phone service. So having an antenna
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    on the uplink frequency is kind of
    useless. You know you would actually
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    have to go out to a national park, find
    some guy who is about to chew his arm off,
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    and then you could listen to his uplink
    where he is like tweeting: "Hey I'm gonna
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    chew my arm off", you know?
    laughter
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    So that's great as a proof of concept,
    but it's not really anything practical.
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    The current state of that was that I knew
    the protocol and I could sniff the uplinks.
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    But I wanted to sniff the downlinks. So
    it's easy for me to get the thing that
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    goes up to the satellite. But what I wanted
    was what comes down from the satellite.
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    And that requires a satellite dish. But
    a geo-stationary dish isn't good enough
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    because the satellites that run this
    network – there are a lot of them,
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    it's called the Globalstar network.
    They fly really low across the earth,
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    and they fly across the earth in very
    tight, very fast orbits. So they move
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    from horizon to horizon in 15 to 20
    minutes. Which means that you either need
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    like a sweat shop army of kids trying to
    aim the satellite dish as it's going across.
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    Or you need to make
    it computer-controlled.
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    Stepping back from the SPOT Connect for
    a little bit, and discussing some prior research.
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    Adam Laurie did some work with
    geostationary satellites. These are
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    the satellites that stay in one position
    in the sky. He gave 2 sets of talks
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    – one in 2008 and the second in 2010.
    And he used a DVB-S card connected
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    to a satellite dish with a diseqc motor,
    so that it could move the satellite dish
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    left and right, in order to scan a region
    of the horizon. His tool is publicly
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    available, it's called satmap. You
    can grab it at this URL. And then
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    after he finds a signal, he has a feed
    scanner. Normally when you use
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    Satellite TV you provider gives you
    a listing of the frequencies, and
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    your provider gives you an exact orbital
    position to aim your satellite dish at.
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    But Adam's tool allows you to scan to see
    which frequencies are in use, and which
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    protocols are in use, once you've correctly
    aimed your dish. And he also describes
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    a technique for moving your dish left and
    right while doing this in order to identify
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    where the satellites are. This recording
    here is from a re-implementation
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    that I made of Adam's work, in order to
    catch up with it. In this diagram the x-axis
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    shows the azimuth, that shows how far left
    or right my satellite dish has moved.
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    And then the y-axis shows the frequency.
    And all of these dots are strong signals.
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    So every vertical bar in which you see
    chunks of frequencies, that's a satellite.
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    But these stay in the same position. So
    it's easy for me to repeat this experiment.
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    It's easy for me to re-run it, and to find
    the same satellites in the same position.
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    It's easy to debug this. But it can't move
    in elevation. This diagram is actually
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    a very small slice of the sky. We're
    looking at a single line, maybe
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    10 degrees across. Maybe only 5 degrees
    across. So hacking Ku-band
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    – the television satellites – has the
    advantage that you can use cheap
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    standardized hardware. I bought one of
    these DVB-S cards in Mauerpark, in Berlin
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    for 3 Euro. You can use standardized
    disecq motors, you can buy them at
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    a satellite TV shop. TV signals come with
    video feeds, so you can actually see
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    pictures. There was a scandal ca.
    4..5 years ago, where they were finding
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    drone [control] feeds that were being
    bounced across these satellites.
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    In the nineties it was very popular to
    listen to the sort of unedited sections
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    of interviews, when people would be
    interviewed over a satellite, before
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    Skype and such things became options.
    And there are also networking signals here
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    using TCP/IP packets. So you can actually
    turn your DVB-S card into promiscuous
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    ethernet adapter, and start sniffing
    all of the traffic that comes across.
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    This is also a great way to get free
    downlink bandwidth. Because you can just
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    flood packets at an address that, you know,
    will be routed to you, or several addresses,
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    and then you sniff it out as the legitimate
    receiver ignores them. But it also has
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    some disadvantages. It only works with
    geostationary satellites. If the satellite
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    is not staying in the same position
    relative to the ground then you can't
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    track it. Your dish also moves very
    slowly. And it only moves left and right.
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    It won't move up and down. And you're
    limited to standardized signals.
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    While it's great that you get video and
    TCP/IP you're never going to get anything
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    weird. You're not gonna get any mobile
    data, you're not going to get any
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    Brazilian truck-drivers – we will get to
    those in a bit. laughs
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    I misspoke, you actually will get Brazilian
    truck-drivers in this. So I bought
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    a satellite dish. One of the best things
    about living in America is that you can
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    buy industrial hardware cheap as dirt
    on ebay. I know things aren't likely
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    used to being a cat XXXX by human children
    anymore. But this satellite dish here
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    on the left – the one in the radome –
    that's my dish. And to the right,
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    that's the boat that it came from.
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    applause
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    This came from a military ship.
    But the dish itself is also available
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    for civilian use on very large yachts. The
    dish itself is a Felcom 81 and it was
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    intended for use with a network called
    Inmarsat. Imarsat allows for
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    telephone connections, and also data
    connections when you're on a boat.
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    So if the crew wants to call home
    or wants to go to AOL Keywords
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    or whatever was popular back when
    this was common they could do that.
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    And the dish was desgined to sit
    at the very top of a ships' mast.
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    The reason why is that at the top of
    the mast there aren't any obstructions
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    – it has a clear view of the sky in all
    directions. But there's a complication
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    with being on the top of the mast. Which
    is that the ship is rocking beneath you
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    and you're moving more than the rest the
    ship. So they have stepper motors for
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    azimuth, elevation and tilt. And then
    they have spinning gyroscopes.
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    Back before the iPhone there was this dark,
    dark time when gyroscopes actually spun.
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    And this is the sort of gyroscope that
    it has. It actually has 4 of them so
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    that it can measure its movement. And then
    it has a control computer. So the idea is
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    that the dish itself can be moved while
    remaining absolutely stable with regard to
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    the gyroscopes. So it compensates for
    the rocking of the ship beneath it as it's
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    targeting a stationary satellite.
    In America this costs 250 Dollars, but
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    it's electronics equipment. So while you
    think that would only be a 180 Euro
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    it's more like 2500. And that's before
    import duties and it being impounded.
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    We also have this lovely culture in which
    people love excuses to use their trucks.
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    So the guy that I bought this from offered
    to deliver it to my home from the 200 dollars.
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    It was an 11 hour drive. But if you wanted
    this you'd have to bring it back in your
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    carry-on luggage, and it could be awkward.
    I got this dish and I decided I had to do
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    something with it. So I created the
    Southern Appalachians Space Agency.
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    I'm from the state of Tennessee, formerly
    known as the State of Franklin until
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    North Carolina invaded us. It's ok,
    I know Europeans suck at history.
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    laughs
    laughter
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    Now I'm trying to think of how to show
    you on a map where Tennessee is
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    without having a map but, you know, it's
    okay I know you suck at geography and
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    we forget (?)
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    From audience: It's very
    near Texas, to the north.
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    Travis: Texas is our first colony. But
    it's actually a decent drive to the east.
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    Due east (?). You don't
    actually have to go anyways.
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    So what I did was I took these motors
    which were designed to be able to move
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    the satellite dish to compensate
    for the rocking the ship and
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    I re-purposed them to track through
    the sky while the ground is stable.
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    We don't have very many earthquakes in
    Tennessee. The last one that we had
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    made rivers run the wrong direction. But
    it's okay – it's a geography thing. So
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    this allows me to track things that
    are moving through the sky. But it
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    doesn't actually matter where they're
    moving in the sky because that's
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    just a software problem. So in addition to
    tracking objects that are in low-earth orbit
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    by a software patch I can also track things
    that are in deep space. It's not much harder
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    to track deep space probes or stars than
    it is to track items in low-earth orbit.
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    And then I added a software defined radio
    which allows me to record a signal now
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    and demodulate it later. Which is necessary
    if you intend to reverse-engineer a signal.
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    Because a lot of the downlinks from these
    satellites are completely non... completely
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    undocumented. And being able to tune in to
    the right frequency is only half of it.
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    You also need a recording of sufficient
    quality that you can reverse-engineer
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    after the fact. We are sort of spoiled by
    software defined radios. When doing
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    software defined radio work we usually
    have a very good signal to work from.
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    So having high quality signals for later
    reverse-engineering is necessary.
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    I really wanted to be able to identify
    undocumented downlinks for low-earth orbit
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    in the same way that we already do this
    for geo-stationary orbit, using tools
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    like the ones that Adam Loria and Jin XXX
    made. So I built a software framework
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    as a collection of Python daemons. And
    these run across a home area network
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    in my house. There's a Beaglebone inside
    of the Radome. And an x86 server
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    in the house. Or AMD64, whatever the kids
    call it these days. And then I used Postgres
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    for coordination. So that all of these
    daemons can talk to each other without...
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    without me really caring which machine
    they're on. So for maintenance I can have
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    my laptop pretending to be the dish,
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    and can have stepper motors on my desk,
    and I can watch them spin, and I can even
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    make a model of the dish and swap these
    components in and out without the rest of
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    the network being confused. This also
    allows for sequal (?) injec... attacks to
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    physically move my dish. Which is why the
    Sassin (?) network is not on one of those
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    fancy WEB 2.0 things. Because of you could
    inject, say, update targets at Namical's (?)
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    Voyager 1. Then my dish would physically
    move and start tracking Voyager 1
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    through the sky. Voyager 2 doesn't
    actually come into the sky because of
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    my position in the Northern hemisphere.
    So, it's okay, I know you suck at geography.
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    But Voyager 1 is going up, and Voyager 2
    is going down. There's a Realtek
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    Software Defined Radio for the radio
    reception. Although these things
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    are garbage. So I'm in the process of
    replacing this for the HackRF. There's
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    also an EiBot board for motor control.
    We'll get back to that in a minute.
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    And there's an Inertial Measurement Unit
    from Vectornerve (?) which actually measures
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    using the fancy MEMS gyroscopes and
    a MEMS compass how I'm moving.
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    This isn't accurate enough to target the
    dish, so instill (?) the counting steps
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    to move the dish. But it is accurate
    enough to tell me when my belts
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    have broken. Or when I'm up
    against the physical obstruction.
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    This is skytee helping me out with the
    dish. He's zip-tying it. Because, you know
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    we know everything about duct tape where
    I come from, but we know nothing
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    about zip ties. So I had to bring in
    a German engineer.
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    laughter
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    We call him a Gerry wigger (?) but, you know...
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    This is the satellite dish itself. And you
    can sort of see in this photograph
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    where we've strapped on the equipment.
    There's like an embillica (?) cord. Or more
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    like a spinal column that actually runs up
    the back of the dish. So we just added
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    new cables onto that line. And then
    zip-tied them in place. And skytee came up
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    with all these crazy ideas like that
    we should use chains and zip-ties
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    to make sure that the cables don't tear
    themselves out. And that worked
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    tremendoudly well in practice. So, as this
    thing spins around by the original design
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    there's a ring connector that all of the
    signals go through. That all of the
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    networking goes through. That all of the
    rest goes through. And that worked
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    in the nineties because it had no reason
    to send anything faster than 9600 baud.
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    But with the modern signals going across
    it - I need 100MBit/s or even GB ethernet.
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    That's not enough. I need more than
    2 wires. So there's a cable that comes
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    across it, and then I rely on the
    software to keep it from wrapping
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    that cable around itself. So it can only
    move, say, 400 degrees around.
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    But that's still more than a full circle.
    So by stopping halfway and moving back
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    I can prevent it from getting stacked (?).
    We've got the Beaglebone on the left,
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    in the middle there's a USB hub, and
    on the right is the motor controller.
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    The Beaglebone runs Debian Linux. And
    takes care of sending the software defined
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    radio recordings over the network. It also
    takes care of updating the motor positions
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    to be the ones that the database declares
    should be current. The stepper motors
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    themselves are the originals that the dish
    was designed with. And they're running
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    to an EiBot Board. The EiBot board was
    intended for plotting on Easter eggs
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    laughs
    I feel, you know... is that neat?
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    laughs
    applause
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    So you can actually aim a satellite dish
    that's as tall as you are, with of these
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    fancy motors using less sophisticated
    equipment than what's used
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    in a 3D printer. Don't panic, though.
    It's a hell of a lot more reliable
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    than a 3D printer. But we needed
    some sort of backup. In addition
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    to the inertial measurement unit telling
    us when the device had snagged itself.
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    It would also help to have a visual
    queue. Because the satellite dish
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    sits in Tennessee, and while I love my
    home town, and, you know I'm very
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    proud of being Tennesseean it's also
    a long way to travel when you need
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    to re-orient the dish. Using an
    accelerometer it's easy enough
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    to correct the elevation. Because you can
    use the accelerometer as a level, and
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    you can use that to tell how high up the
    dish is pointing, at an absolute scale.
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    But the compass isn't very accurate. So
    instead, as a backup we have a webcam
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    that's taped to the top. Taping
    is my people's native culture.
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    We have it taped to the top, and then
    it's pointing backwards. So this gives us
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    like a rear view camera, from the
    dish's position. So as the dish sits
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    inside of its radome... - junk cars in the XXX
    are also my people's native tradition!
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    So the dish sits there next to my
    brother's Toyota Supra. And that thing,
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    you know, that thing flies as soon as it
    gets an engine put back in it. So it is -
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    sits there and it's moving. But externally
    you can't see where it is. Which means
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    that I can't call my family in Tennessee
    and blackmail them into - yet again -
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    looking at my dish to tell where it's
    pointed. There are bolts that hold this
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    down. It takes half an hour to remove the
    lid, another half an hour to put it back on.
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    So instead we took the radome...
    that's Frank, he's my cat.
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    Give a "Cheers!" for Frank!
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    applause and cheers
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    Yeah, we had such a great time with Frank.
    And we never knew that she was pregnant.
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    If you happen to need kittens and wanna
    pay the custom's fees I'll hook you up!
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    So then we took tape and ran tape down the
    edges of the radome, and then marked it.
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    So from the markings you can tell
    which clock position the back
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    of the satellite dish is pointing at. So
    if you point the dish towards 12:00
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    you know that you're roughly at 6:00,
    so you know that it's pointing South.
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    And then you can sort of scan the sky
    for a stationary target, and navigate
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    off of that, to recover your position.
    Software-wise... Remember,
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    the whole thing runs through Postgres,
    so I just tunnel the Postgres over SSH,
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    and then I wrote a Python client that
    displays the satellite positions and
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    the satellite state in PiGame (?). This is
    intended for making those games (?)
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    really see the rabbit. And the rabbit
    jumps on the other rabbit. But it... works!
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    And it works perfectly well enough
    to target the dish. Because all that
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    this software has to do is plot the
    positions of the satellites, and
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    give orders back to the database when
    I click on a satellite, or click on a position.
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    It can also display stars. So the red
    items are satellites which are not selected.
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    The green item is Ghost3 (?) which is
    the satellite that I'm targeting. And then
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    the white items are stars in the sky. Now
    this is a plot in which the azimuth is
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    on the X axis, and the elevation is on the
    Y axis. But I can also arrange it into
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    a polar plot. Which sort of gives me an
    upside-down view of the satellite dish
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    looking at the sky. I doubt you can read
    it, but just above the green circle
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    in the center, that's Polaris which is the
    North star. It's also weird because,
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    you know, working on this, you know,
    I thought that I got really good at astronomy
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    until I realized that I only knew what the
    stars looked like during the day.
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    laughter
    laughs
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    And it being PiGame (?) you can actually
    run it on a mobile device. So the same client
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    that runs on my laptop can also run
    on my Nokia N900. laughs
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    applause
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    A significant portion of the GUI client for
    this was written while stuck on the U-Bahn,
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    connected over 3G, SSH through, and just
    using emacs on the phone. laughter
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    laughs
    applause
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    If you're one of those people who needs to
    complain about the N900 being too old,
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    it also runs on the N9. And then,
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    you can take the data out of this,
    and run it through scientific software.
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    In addition of the software defined radio
    recordings themselves being dumped out
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    to a text file or a binary file on disk
    you can also dump out things like
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    the received signal strength indicators
    (RSSI). So this is a screenshot in which
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    I'm identifying different satellites that
    I've seen in the sky. Based upon
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    their downlink signal peaks. You can see
    the noise floor there, at the bottom,
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    and then there's a rather strong signal on
    the left. And a weaker neverware (?) signal
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    on the right. Now, the daemons that build
    this up... you need an orbit prediction daemon.
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    Because you need to know where the
    satellites are, and where they're going,
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    and where they will be by
    the time you get to them.
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    You need to update the orbits themselves.
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    LEO satellites are described in TLE files.
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    These are called 'Two Line Entry'. And
    they're called Two Line Entry because
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    they're three lines long.
    laughter
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    These were originally used by Norad for
    inter-continental ballistic missile tracking.
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    And because a ballistic missile is
    basically in orbit, it's just that that
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    orbit happens to collide with the earth.
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    But this format isn't terribly accurate
    for satellites that adjust their own orbit.
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    So anything that has fuel, or has engines,
    or changes mass will vary it's position.
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    And this also doesn't account for drag.
    Because, you know, the missile itself,
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    you know it goes up it goes down, it's
    not orbiting enough for the light drag
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    in the upper atmosphere to matter. But for
    a satellite it does. So these Two Line Entries
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    will work for a matter of days or maybe
    a couple of weeks. But they don't last
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    longer than that. So you need a daemon
    that grounds (?) the new files from spacetrack.
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    And this is just a matter of like
    a recursive WGET, and then
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    parsing the files. And that still needs
    to be done. You also need motor control,
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    because you need to move the dish
    physically to track your target.
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    You need input for the Inertial
    Measurement Unit. This comes over
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    a low voltage serial port. And then
    you need radio daemons to handle
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    spectrum analysis or downlink recording.
    And, these, you'll have several of them,
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    you have to swap them out. So you'll begin
    by using the spectrum analyzer to identify
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    that your aim is accurate, that you're
    accurately tracking the targets
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    well enough to get a recording from
    them. And then after that you begin
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    to take software defined recordings off
    them. And, eventually, you might have
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    a standalone application that parses what
    you're receiving. Such as the Osmocom guys
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    did with OpenGMR. So for orbit prediction
    I began with a DOS program that had been
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    ported to Unix, called 'predict'.
    And this works, but it's garbage.
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    It only supports 20 satellites plus the
    sun, the moon, Venus and Mars.
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    But no other planets because it's designed
    for astronomy photographers who want
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    to get a picture of something as it comes
    over the horizon. You know, I need
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    to track hundreds of targets. And then
    write a script to opportunistically pick
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    the ones that I want to record.
    Because otherwise you have to like set
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    an alarm clock for the half-hour pass in
    which you can play with something.
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    That software does allow you to query the
    results by UDP, though. So you can just
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    send it a flood of request packets,
    then it will flood back with the data
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    you're looking for. So I switched to
    a library called PiFM which allows you
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    to track hundreds of birds. It has no UDP
    nonsense. It will also calculate satellites,
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    planets and stars. And the really nifty (?)
    thing about this is that you tell it...
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    you know, it being a library you tell it
    when to update the individual object
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    that you're interested in. So you can
    update objects that are out of view
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    or uninteresting more slowly than the
    ones that you care about.
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    So I managed to track every single
    item in geo-stationary orbit.
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    This thick ring here is the clarke-bell(?)
    of all satellites in geo-stationary orbit
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    as viewed from my Southern horizon.
    applause
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    The Two Line Entry files you can get
    freely from CELESTRAK.COM.
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    So this is just a simple script that grabs
    them and then inserts them.
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    And the prediction daemon will actually
    select them as it is loading up.
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    This all inter process communication is
    running through this Postgres database.
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    And this daemon can be moved to
    a different machine if I needed
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    more computing power, or anything like
    that. The motor control demon...
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    well, the Eibot board is designed to take
    stepper motor commands. It shows up
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    as USB Serial device on Linux. So as
    I plug it in to the Beaglebone it appears
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    as /dev/ttyACM0. And the baud rate doesn't
    matter. Because this is a USB device.
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    You could then send it simple commands.
    Like 'SM,3000,500,-400' means that I wanna
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    move a stepper motor for 3000 ms. I want
    the first motor to move 500 forwards,
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    that's UP, and the second one to move
    400 LEFT which is backwards 400 steps.
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    And then it will count that out, and
    then it sends me back an OK.
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    If I want to disable the motors, I send
    'EM,0,0'. This allows the motors to be
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    freely spun. Because normally a stepper
    motor will physically hold its position,
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    you need to turn them off in
    order to slide the dish around.
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    'EM,1,1' will enable both motors
    in 1/16-of-a-step mode.
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    Stepper motors can do fractional
    steps because they're
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    holding themselves in position.
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    You can see the motors themselves
    with the belts and the geartrain.
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    This thing on the right would probably
    be illegal for me to turn on.
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    The thing on the right is a 250 W amplifier.
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    The stepper motors themselves just have
    6 wires. In a lot of 3D printer type stuff
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    they ignore the middle two. So you just
    drop (?) off the middle two wires, you run
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    the other four to your stepper
    controller, and you're good to go.
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    The belts and stuff need to be measured
    in order to figure out exactly
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    what the georeduction (?) is. Because you
    need to know how many steps form a degree.
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    The IMU unit, this Vectornav VN100 (?),
    it's a MEMS gyroscope and accelerometer
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    and a compass in a single box.
    It costs $500 which was
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    more than all of the other
    equipment put together.
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    The compass is confused by the stepper
    motors because the compass is measuring
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    magnetic fields. So you need to
    mount this physically as far away
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    from the stepper motors as possible. And
    the gyroscope is confused by motor jerk (?)
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    which is a shame because stepper motors
    work as a series of jerks (?) rather than
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    as a single consistent motion. And the
    accelerometer is confused by gimble lock,
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    so you have to switch it to
    a quaternian (?) mode in order to get
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    consistent values out of it. And if I had
    to do this over again I'd really try
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    to drop this piece of garbage. But it's
    a lovely technology when it works.
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    some laughter
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    Now for position calculations, the
    elevation itself comes from the IMU.
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    The azimuth comes from the motor daemon.
    This is because the accelerometer
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    can very accurately tell which way
    the earth's gravity is pulling it
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    whereas the accelerometer has to integrate
    jerks (?) over time in order to figure out
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    its position. So the
    accelerometer will drift
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    and the compass will be confused by the
    magnetic fields while the elevation is
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    just a single accelerometer
    that doesn't drift.
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    And the IMU will become
    a backup for these things
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    in order to figure out how to make
    it reliable. But at the moment
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    the position measurement is infinitely
    more reliable. The tilt motor
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    I'm not using at present because on
    a ship that's rocking it's necessary
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    to tilt the dish. On a satellite dish
    that's staying still the only useful
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    tilting the dish is so that you can follow
    the arc of a satellite through the sky
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    by only moving a single motor.
    Photopgrapher do this when they're
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    trying to get long exposures of moving
    satellites. At the moment my software
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    doesn't support this feature. But
    if it turns out to be necessary
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    to get higher quality
    recordings I might add it.
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    The radio daemons. The
    first is a spectrum analyzer.
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    This just measures the signal strength
    on each frequency. And it does it by the
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    power spectral density function.
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    And the strength itself will
    vary with the position error.
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    So this allows you to figure out how
    far off you are by sort of testing,
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    by overshooting just a little bit,
    or undershooting just a little bit
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    to center on your target. The downlink
    recorder dumps the IQ values
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    in the software defined radio
    directly to an NFS share,
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    which can later be decoded and
    read and reverse-engineered.
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    We've got a whole table of spectrum
    data. And then I plot that in a tool
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    called Viewpoints which NASA releases
    for dealing with giant scatterplots
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    in multiple dimensions. Each view takes
    two dimensions, and it's tons of fun.
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    The client GUI is this PyGame. I have
    Postgres for communications, and
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    the server does all the heavy lifting,
    so the Beaglebone itself never has
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    to do anything complicated with
    regards to software defined radio.
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    This is also about these faint blue lines
    are positions at which I've seen
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    particularly strong signals in order to
    identify which satellites are active
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    and which ones are inactive.
    Because satellites die over time.
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    And particularly useful targets, we're
    reverse-engineering satellites that are
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    out-of-commission or outdated.
    I'm running out of time by these markers.
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    Does this mean that we're skipping
    questions, or does that mean that
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    I need to be off the stage?
    mumbling to stage
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    Not having Q&A, okay. So today I get
    accurate tracking of satellites.
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    And this thing can run unattended 24h
    a day for months without maintenance.
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    Like I said: it's nothing like a 3D printer.
    laughter
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    It takes software defined radio
    recordings, it can provide maps
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    of views of different satellites in the
    sky. The next step is I want to publish
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    a 'port scan' of the entire sky. So which
    frequencies are in use on which birds,
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    for every bird that ever comes above
    Tennessee, on every downlink that fits
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    my antenna. As well as a database
    of software defined radio recordings.
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    If anyone would care to donate a truckload
    of disks - that might be handy.
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    I'd also like to make other ground
    stations. The software that I've written
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    ought to be portable to new hardware.
    So there's nothing that should keep you
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    from being able to port this to run on
    your own dish. And I have a large yard,
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    so I could conceivably have
    a dozen of these things.
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    Another way that you can do it, and
    the way that it's traditionally done
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    for stationary (?)(?)(?) satellites is having
    Yagis or other loosely directional antennas
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    in order to receive the signals.
    I went with a dish because I wanted
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    more selectivity. I wanted to be able to
    get reverse-engineerable recordings
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    rather than intentional ones for which
    I already knew the downlink protocol.
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    So this is my van, my van is amazing.
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    applause
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    Thanks to Nick Farr. I had a bit too
    much to drink in Montreal and
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    I called Nick Farr and I said: "Nick,
    I want a dukw", like these amphibious
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    troop transport vehicles. And Nick
    said: "Sorry, I can't get you one but
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    you want a news-van. And I said:
    "Hell yeah, I want a news van!"
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    So - this pole in the background, that's
    not a lighting pole. That's actually
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    part of the van.
    laughter
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    This is the antenna retracted. This mast
    goes up 20m by pneumatic power.
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    There's an air compressor in the back.
    Here is the control panel, there's
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    an air-conditioned office in the middle.
    laughter
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    laughs
    This has four 19" server racks as well
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    as A/V equipment that was left over.
    I was particularly excited about
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    the video monitor which supports PAL
    which you folks are familiar with,
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    NTSC or "Never The Same Color"
    which is my people's native culture...
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    laughter
    But most importantly, it does SECAM,
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    the system essentially contrary
    to the American method.
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    laughter and applause
    laughs
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    So in addition to my radio equipment
    I'm adding my Soviet PDP-11 which was...
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    laughs
    ...and that's not a joke. I have a Soviet
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    PDP-11 thanks to the kind folks at the
    Positive Hacking Days conference.
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    This is the control panel,
    and that's my talk!
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    applause
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    Herald: Thank you so much. There
    actually is time for Q&A now.
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    Travis: Well, first I'd like to introduce
    you to my cat. If we could go back
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    to the prior image. This is Frank!
    We didn't know it at that time, but
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    Frank was not dead when this picture was
    taken. If you'd like kittens get in touch!
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    Okay. Are there any questions?
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    Question: Great talk. What's the most
    interesting signal you decoded so far?
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    Travis: At the moment I'm sort of stuck
    at the L band range. Because of filters
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    that I have yet to remove. So everything
    gets attenuated, and becomes annoyingly
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    quiet outside of the 1.5..1.6 -ish range.
    The Globalstar network is what I'm most
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    interested in targeting next. I cam't wait
    to see what people are tweeting
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    while they should be enjoying nature.
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    Herald: Is there a question
    from the internet?
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    Signal Angel: Yeah, the internet has
    many questions. So first one was:
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    Is there really no authentication or
    encryption on the Q band IP services?
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    So you can just spoof at will? And can the
    birds see the physical leakage and of
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    the source accurately enough to find who
    is spoofing?
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    Travis: I'm not an expert in Ku band. The...
    for the downlink the bird has no clue
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    as to the location of the dish. Because
    you're only listening. They can roughly
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    figure out your geographic area because...
    they need to figure out where
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    the spot beam is going. So they might know
    whether you're in, say, Germany or
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    in France. But they won't know whether
    you're in Heidelberg or Mannheim.
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    They do have forms of authentication for
    many satellite networks. Satellite TV
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    is one of the best-protected network
    services. Because of the satellite wars
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    in the 90's. In which TV pirates would
    fight back and forth with smart card
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    designers. But there are also many
    unencrypted links. And there are...
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    because of standard protocols those
    are particularly easy to find in Ku band.
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    Question: You've been talking about
    using RTLSDR from osmocom.
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    And you were talking about your spectrum
    analysis program. Is this one working
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    with RTLSDR?
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    Travis: So... RTLSDR... so I'm using
    the RTLSDR not the osmo-sdr.
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    Which are separate. The spectrum
    analyzer is working with the RTLSDR.
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    My complaint about the RTLSDR is that
    when you have a strong signal next to
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    a weak signal the weak signal is
    utterly useless for interpretation.
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    Question: Okay. Thank you.
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    Herald: Another question
    from the internet?
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    Signal Angel: Okay, next question from the
    internet is: how do you record the radio signal
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    from the dish, at what sampling rate?
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    Travis: The RTLSDR samples at 2 million
    samples per second. As soon as I switch it
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    over to the HackRF, well, we're having
    20 million samples per second.
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    The sampling rate can be reduced once
    the bandwidth of the signal is known.
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    For radio (?) storage. And the recordings
    can also be compressed.
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    But it's still a hell of a lot of storage.
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    Herald: Any other questions?
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    Signal Angel: The internet
    has more questions...
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    Herald: Okay...
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    Signal Angel: Did you look into obtaining
    a capacity of IBAN with copper (?), as used
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    for the rotary gentries in CT scanners?
    Those can apparently transmit contactless
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    several GBytes per
    second, bi-directionally.
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    Travis: I've not looked into those.
    It seemed better to have an Umbellaco (?)
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    cable and to be careful not to snap it.
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    The whole thing was done for a budget
    of less than 2000 Dollars, and can be
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    recreated for less than a budget of 1000
    [Dollars]. And they... so we tried to avoid
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    fancy parts. The local radio shack loved
    us because we'd swing in and buy all sorts
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    of crazy stuff. As soon as we told them
    that we wanted the satellite dish to
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    dance Gangnam style...
    laughs
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    laughter
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    Thank you Carnaugh(?)
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    applause
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    silent postroll titles
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    subtitles created by c3subtitles.de
    in the year 2017. Join, and help us!
Title:
Hillbilly Tracking of Low Earth Orbit
Video Language:
English
Duration:
47:03
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