• C-Band ADSB

    When you write it down, in one sentence, its really very simple;
    6′ dish -> PLL LNA -> 18v DC pass-through PSU -> RTL-SDR -> SDR# -> Jaero -> VRS.
    And with that signal path, you will have planes on a map. 100+ planes from half the planet. Easy right. Ah. It could be, but if you are reading this, you probably have hit some snags.
    Also, if you are reading this, you probably have an idea of what you are trying to do, so I will skip the intro and go straight to how I did it.
    And just to be clear, we are talking about ADS-C, not ADSB, but it looks so similar that many (me included) often get it mixed up.

    You can (apparently) get by with a 4 foot dish, but I did not want to be scrapping around in the noise, so opted for a 6 foot dish, the wife was not so excited, so we both compromised and went for a 5 foot dish. If I was going to do it again, I would go a 6 to 9 foot dish, anything bigger and the pointing accuracy is going to be a ‘problem’ and not worth the extra signal strength.

    The LNB (feed-horn) matters. You want something with low frequency drift, something that is temperature stabilized would help as well. If you find something that fits the bill, let me know.
    I was recommended this one; https://www.amazon.com/gp/product/B00HVM08JI
    Having nothing to compare it with makes it a bit hard, but the short of it is that its not really stable enough. The drift will put the signal out of range of the bandwidth every hour or so. You will be chasing the signal over a few hours. Okay for testing, but no fun for something that you just want to leave running unattended (which is my plan).
    The LNB has two voltages, 13 for one polarization, 18 for the other (horizontal and vertical for example). I did not have 13 on hand, so went with 21. A little on the high side, but it runs fine through 50 feet of coax. This is the one I used; https://www.amazon.com/gp/product/B005AME7Y8
    You need to make sure that your power injector can pass through a 1.5gHz signal, that is the down converted signal from the LNB.

    From the LNB power supply, you then have your RTL-SDR. Anything that will work at 1.5gigs should be fine for a test, but you really need something that is stable and sensitive. If you find something that works, stick with it.
    This is the one I am using; https://www.amazon.com/gp/product/B0129EBDS2
    Again, I have nothing to compare it with. (I just wonder if this is not the source of the drift I am fighting with).

    I chose to use SDR#, its free, simple to install and basic enough to do the job. Sure, you can get fancy and run some other software, but its mostly a headless setup, so simple is better.

    Once you have the signal, you need to decode it. I only know of one application that can do it, Jaero. Jonti’s work is amazing, be sure and give him a few bucks if you go this way.
    What you do with the information I will leave it to you. There seems to be two main paths, Plane Plotter or VRS (Virtual Radar Server). I went with the second option since that’s what I already run (I also run PP, but not to the same extent as VRS).

    Ok, so that’s the easy part, now getting it to all play nice together and get planes on a map……

    We bought the dish new off eBay. it arrived, free shipping, in two weeks from Canada.
    Took me about 2 hours to put it together, seems pretty straight forward. If I had to do it again, I would get at least 6 foot and something that mounts on a pole, not a base.

    The LNB was brand new from Amazon. Long story short, it was faulty. I spent a week working with it for hours and saw nothing but static.
    One evening I just gave up and voided the warranty and opened it up. Sure enough, it had a dry joint and was open circuit on the input. A quick touch with a hot soldering iron and put it back together (interesting note aside, the heat sink is there for looks only, it has zero contact with any parts – made me smile a little).

    After spending a week looking at nothing but noise, once I powered it back up I was met with wall to wall signals, it was very exciting and a big ups that I was not losing my mind.

    SDR#. Install it and run it.

    Now the really hard part. What frequency should you tune for? In the end, I could not really find a solid answer since it depends on the down converted frequency of the LNB and the specific satellite you are tuned to. I am looking at Inmarsat 4-F3.

    There are a few lists floating around, but they did not agree and in the end it was a single screen shot on Jonti’s website that got me close.
    it helps to look and see what sort of waterfall pattern the adsb messages makes as well. I mostly went by visual on the waterfall more so than the frequency.
    I wish I had something more solid to give you than ‘look for this pattern’, but that’s really what it came down to. I just could not find anyone that had documented the frequencies for the different sats with the LNB I was using.
    Here are some examples from my setup.

    This next one is a bit more zoomed in on the frequency scale and shows you both the frequency I was tuned to and what the waterfall looks like.

    Now for the next hard part. Aiming the dish.
    A few things to try.
    You can get a compass and inclination meter and point it using those. Not a bad way to do it, and I got in the ball park with this method, but it was not really accurate enough. BTW, the metal in the base will throw things off, so use a plank of wood to extend the dish and put the compass at the end of the wood to get more accurate.
    You can also use one of the satellite aligning apps on your phone. I also did this and found it really good.
    Here is a screen shot looking next to the satellite. (I found the arc of geostationary satellites really fascinating).

    The third way takes a little more gear, but is rather interesting (thanks again go to Jonti for his description of this method), disconnect the LNB and put a modified GPS patch antenna at the center of the feed horn and tune your SDR to the L-Band signals coming from the sat. Now you can pretty easily move your dish around for peak signal from the sat.
    Here is some of the gear I used to test this.
    GPS patch antenna, LNA and bias T injector.

    Here it is on the feed-horn.

    I also did this to see what it was like and it works pretty well.
    So in the end, I used all three options to get the dish pointing in the right rough direction.

    By now, you should have a pretty solid waterfall of signals, find the short staccato signals and start to tweak things for maximum signal.
    One important thing to note, Jonti mentions that I would need the bit of dielectric stuffed in the feed-horn to turn from direct (horz or vert) polarization to circular. He is right. Listen to him. The key is to get it inserted the correct way, there are two ways to put it in, they are 90 deg to each other (up and down or left right if you have the ‘heat sink’ uppermost).
    Make sure you test both ways. One way will make the signal weaker, the other way will make the signal stronger. No dielectric will be somewhere in the middle. You clearly want the strongest of the options.

    Hone in on a likely looking signal and fire up Jaero and see what gets decoded.
    As far as setting it up for the basics, you need to select 10500 bps burst and I found the best decoding to happen when the locking is set to 1800 or 900 hz and AFC is on. (Note, this may or may not make much of a difference. But please experiment with it. I am finding some differences but need more time with it testing).
    Set SDR# to 10500 bandwidth (or wider, but not narrower) and USB.
    You should start to see ACARS data. If in the SU’s tab you see a LOT of ‘Bad R/T Packet’ messages, you are close, but don’t have things setup quite right. Go back over my notes and take a look at my settings and yours.


    IMPORTANT NOTE. In this screen shot I have ‘Locking’ set wrong. It should be 1800 or even 900.

    Once you are getting good clean ACARS data you should straight away notice that you are getting a lot of reports with Lat/Long in them.
    We can push these messages to another bit of software and get the final goal of all this, planes on a map.

    If you are using Plane Plotter, Google will guide you. I cant help.
    If you are using VRS, here is how you set things up…..

    Jaero is a little ‘odd’ in that you set the Basestation address to be 0.0.0.0:30003. You can change the port number, but you MUST leave the IP address to be all zeros.
    This is the odd bit and cost me a ton of time, but in the end, Jonti himself set me straight in a very kind email.


    (Note. In this screen shot I have the ACARS option ticked and its going to the same PC as VRS on a different port number. You wont need to do this for just ADSB.
    I am also interested in looking at the ACARS data in Node-RED. Read about it on my aircraft page.)

    In your VRS then, you need to put the IP address of the PC running Jaero (assuming its on a different PC, if its the same, then its just 127.0.0.1 and the port number) and the port number you picked.
    Of course the type has to be Basestation. Tick the box, ‘Is Sat-com’ to give yourself the longer time out.

    Ok, Phew. By now you can take a breath and check out some amazing data flowing in. You should, within just a few minutes (yes, it really does happen that fast) see planes from all over the world (just about). The foot print of the satellite is amazing.

    Want to double the amount of data/planes you are getting?
    Notice that there is another ADSB signal next to the one you are on….. If you tune over it you will see much the same ACARS/ADSB data but from different aircraft.
    Install the VFO plugin for SDR# and also install VAC (Virtual Audio Cable).
    Now you can set 1 cable for the main frequency and 1 for the VFO.
    Now copy paste a second instance of Jaero on the desktop, right click and set its properties to be -s line2 and now you can start another instance of it and have double the messages.

    Here is the key, you cant run them both on the same port number. The second instance still must be 0.0.0.0 but the port number MUST be different for each instance.
    So set up a second receiver in VRS and make sure you are getting another set of data / aircraft.
    Then set up a merged feed with the two feeds into one to see the total of the two frequencies.

    To-do.
    1. The output of the LNB drifts. I don’t know if its due to temperature, PLL instability or Doppler from the sat moving or drift in the RTLSDR. At the moment I have to tweak the VFO in SDR# a few times a day. This will not do. I need to solve this asap.
    2. The satellite drifts in a slow figure 8 pattern. The dish needs re pointing a few times over 24 hours. At the moment, it looks like just in elevation. I have a linear actuator on order and will see about automating it as a matter of some urgency.

    Hope that helps. I have written what I found scatted all over the place, a lot of what was not written anywhere and the rest is what I wish was written down somewhere.



  • Satellite Dish

    After much back and forth between Freddy and myself, we settled on a dish.
    I needed a 6 foot, she said 4 foot, so we bought a 5 foot, that way neither of us got what we wanted.

    Unfortunately, the guys website with the most information is currently down, so I cant link you to it… But the short of it is aircraft tracking.
    There is a geostationary satellite that re-transmits aircraft positions for aircraft over the oceans. The sat I am going to tune into is over Hawaii and so will get aircraft over the Pacific. It should pick up data from planes that are entering my current system so is perfect.

    We will be moving from the middle of the lawn where I put it together into the garden where it should hopefully be less obvious over the weekend.
    Once there we will need to align it and then tune into the data stream.
    All of which sounds a lot easier than I expect it to be.
    The data comes in bursts, so its going to be hard to find and tune into.
    More details to come…. But enough to say, I have been looking forward to this project for about 3 years.



  • Little Hike

    A mate and I are going to (hopefully) be hiking the north rim of the Grand Canyon in about 2 months, so figured it would be a good idea to start putting on some hiking miles.
    We did 4 miles as a warm up at our local trails at Dripping Springs.
    There are no springs, but there are some nice trails and views.

    You can get a sense of what its like from the photo.
    Lots of wild flowers this time of year, some great views and a nice single track trail.

    Anyway, a nice few hours out in the fresh air with a mate was welcome.



  • Chrome be gone

    Dont get me wrong. I love the new car, I really do.
    Driving it is great… Its just the look of it I cant stand.
    For the most part, its all the chrome.

    Duno exactly what about the chrome, it just triggers a shudder in me when I see it.

    So, paint or wrap?
    I wanted to be able to undo it for any reason (not that I would not like it, but just wanted it reversible).
    So wrap it was.
    Got a quote of 800 bucks. Yes, eight hundred dollars to do it.
    Yeah. Nah.
    Ordered some vinyl off Amazon for 8 bucks. Just a small sheet to start.
    Spent about an hour doing one side.

    Better, Much better.
    Ok, so ordered about 30 bucks of vinyl this time and spent another hour or so doing the other side.
    Then did the front and back chrome bits, bumper and emblems and number plate surrounds.
    That leaves the wheels. What to do about the wheels…. I was not confident about wrapping them and not scratching them up, so plastidip to the rescue.

    Better. Much better.

    Should I also the roof racks?



  • Catalina Island

    Freddy and I decided to get away for a few days together. (Its been a while – yeah yeah).
    Our destination for no reason other than we both wanted to see it… Catalina Island.
    Its due west of Dana Point, not far off the coast, but far enough to make it a little interesting.

    Of course, to get there, you have to take a boat. We chose the smaller of the two that fairy back and forth. Turns out we won’t be doing that again. The bigger boat is much faster and smoother. It means another 1/2 hour to our drive to get to the point where it docks, but eh, it will be worth the drive to save the sea time.

    Once on the boat we just sit and chat. It took a solid hour and a half. Neither of us felt great going over, it was pretty rough and the staff warned us as much. (It was a pretty windy day).

    When you get there, you have two methods of getting around, walk or golf cart.
    Cars are not banded on island, but its just so small that the number of cars is severely limited (I’m told the wait list is about 10 years long). Where as every resident automatically gets a golf cart permit. So yeah, noisy, smelly golf karts are everywhere.
    Here is the local supermarket parking lot to give an example.

    Some people try and hot them up, or deck them out, make them a bit interesting, but for the most part, they just look like golf karts. There is also more than the fair share of them broken down in the streets. I guess it costs too much to get them repaired and its very expensive to ship them back to the mainland to dispose of them.
    And yes, 99.9% of them are two stoke…. Electric ones were very rare. Reason being most people don’t have a garage and so have no way of recharging them. You are not allowed to drape a power lead across the sidewalk (footpath), so it limits your recharge options a lot.
    We looked at hiring one, but at 50 bucks an hour, it was a bit rich for us.

    So, we walked. It was beautiful weather and just a delight to walk about taking in the sites.
    First place we walked was up a hill!

    Well worth it.
    Short version short, we walked 7 miles the first day. Had a nice fish and chips lunch…

    Just hung out and had a nice day.

    Next day the goal was to check out the botanical gardens and the Wriggly memorial. Yup. More walking.

    It was the weekend of the annual marathon, so there were some runners out and about. Nice uphill slog for them from the starting line, but they turned around at the memorial.

    The memorial is just amazing. High up on the hill (but not at the very top) and pretty massive given its location. 100 steps exactly from the base to the top.
    It would have been amazing in its day, as it stands now its still very impressive and beautiful with brass doors, blue tiles and amazing marble inlay.
    Photos do not do it justice, but here is a panorama of the inside along one wall.

    Remember, you can click on pictures to make them bigger….

    We hung out there for a good while just soaking up the place.
    It was also very quiet when we were there, we had got up and got going pretty early and so not one was around, the runners were well below us and focused on running, not sightseeing, so yeah, it was bliss.

    I wanted to hike to the top of the island and see the Ocean on the other side, Freddy said that as long as I took my time she was in for the hike up the hill, so we set off to the summit of this smaller ridge.

    Lets try this little movie… Not sure it will work for everyone, but eh, try something new…

    If you cant play it, its a short movie of me puffing trying to hold the camera still and pan from one ocean to one sea.

    All in all that day we ended up doing around 14 miles on foot. Nice effort.

    Next morning, it was just a matter of taking the boat home. We goofed and did not get in line quick enough and so the only seats left were outside…. It was rather cold (we were NOT dressed like the people in this photo), but on the upside we did see a few whales and Freddy was thrilled about that.

    All in all a very nice weekend. We have decided that island life is not for us. I love my high speed Internet and 2 day Amazon deliveries and Freddy likes long drives.