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Thread: Setup for weather satellite GK-2A

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    Default Setup for weather satellite GK-2A

    If you've been following the Himawari 8 thread, this is a similar venture but different satellite. In July of this year, Korea replaced it's ageing Coms-1 geostationary weather satellite with a brand new one called Geokompsat 2A or GK-2A for short. This satellite can be received directly on L band. The easiest transponder is the LRIT one on 1692.140 mHz. At first they carried a few different channels so colour images were possible, but unfortunately they now only have a single IR channel, though it is full disc at 2200x2200 resolution. If you want more channels there is always HRIT or Ultra HRIT but these need enormous dishes and more expensive receivers. The LRIT transponder only needs a small dish and an SDR to receive!

    So here's what I did. I already had a spare 2.5 metre solid dish just laying around so put it to use for GK-2A.

    Here it is here (left) next to the 2.3m dish for Himawaricast on Jcsat2B (right).



    GK-2A is located at 128.2E, a little above Asiasat 9.

    So I needed to make a feed. A can feed seemed logical so after some looking around I found people making them out of old Milo tins! I just happened to have some Sustagen tins that had nice yellow caps so I used that instead.



    Inside is a quarter wave feed pin. I used a can opener to cut off the end (not shown).



    I mounted this inside a can pan to make a kind of choke ring. Stuffed if I know what the illumination pattern is, but it looks good!





    Next to a C band feed.



    I bought a Nooelec SDR as this one has extended range to over 2 gHz, the cheap ebay ones are crap and don't make it to 1692 mHz.
    I also bought a Nooelec Sawbird filter that has a 2 stage LNA and 80 mHz band pass filter. This gives 30dB. However I have also used
    2 ebay $4 L band inline 20dB amps and they work fine too.



    My SDR waterfall display looks like this.



    I purchased Xrit decoder from USA-Satcom for a very good price, but if you're good with Linux, Sam makes great software for GK-2A for free!



    An image comes down every 10 minutes around the clock.



    The end result is this.



    I used an overlay map from the GK-2A internet server and overlayed it in Photoshop.



    That's it! Not colourful but fairly easy. Maybe they will add some more channels to the LRIT transponder in the future for colour.

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    Excellent work.
    Not responsible for any post written after the 28/10/2014. My pet hate, Corrupt Politicians, Corrupt Legal System + a legal system Australia wide that does not allow you to sue a Solicitor or Barrister for Professional Negligence (as Stated by the Law Society and prominent Lawyers) and Corrupt Cops. Not necessarily in this order. Please Note Lawyers are PROTECTED SPECIES IN THIS COUNTRY, PROTECTED FROM THEIR F..K UPS

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    Quote Originally Posted by Mr 672A View Post
    Excellent work.
    Thanks Mr 672A. It was fun setting up for this. It took a while to figure it out but I didn't rush it.

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    Very nice and note the Typhoon near Japan about to upset the rugby world cup.

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    Quote Originally Posted by apsattv View Post
    Very nice and note the Typhoon near Japan about to upset the rugby world cup.
    Yes that's typhoon Mitag, now weakened into a tropical depression.

    I've found some zoomed up higher res images in my folder today, along with a bunch of maps for sea level temps and wave height etc. Here's an image a few days old of Typhoon Mitag at it's peak.


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    Here's a comparison of GK-2A vs Himawari 8. Both received at 0210UT today, both with the same IR1 channel.


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    Some stunning images of super typhoon Hagibis this morning from GK-2A, even if it's only a single channel LRIT. This super typhoon is equivalent to a category 5 cyclone.

    Received at 2300UT today with a 2.5 metre dish, 2 x 20dB LNA's, Nooelec SDR and software by USA-Satcom.




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    Thought I'd try an old astronomy imaging trick, where chrominance is used as an overlay to a B+W image to produce a colour image. So I found a nice map of the Earth and overlayed the colour information only. The result is a nice psuedo colour image, much like colour maps are used in Wxtoimg for NOAA satellites. GK-2A image from today with Typhoon Hagibis in a slightly weakened state.


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    Default Looking to do this myself

    This looks amazing Learjet but I'm slightly confused as to what the function of the tin is, also where would I get such a 2.4 meter dish.

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    Quote Originally Posted by Maax View Post
    This looks amazing Learjet but I'm slightly confused as to what the function of the tin is, also where would I get such a 2.4 meter dish.
    Hi Maax, the tin acts as a sort of waveguide for the feed pin. It's called a cantenna feed. Any C band dish would work. They say even a 1m dish would work.

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    Default Thanks, and I'd like some info about your feed system

    Thanks so much for posting this.
    I bet you had heaps of fun trying to get it to work!
    As the polar weather satellites gradually die off, I'm thinking of moving to the Geostationary ones, if I can pull in enough signal with a small dish....
    I have a 1.2M offset dish which I may well use to try and receive gk-2a.
    I get the idea of the cantenna, but you have no LNB?! I wonder how you get around cable losses. What cable are you using, and how long is it?
    If I'm using my smaller dish, I'd want to keep losses to an absolute minimum, as I might lose my signal in the noise.
    I have the noolec smart sdr. Does that saw filter you're using need a bias-t, and how did you connect filter and SDR? Seeing them side by side was nice, but it'd have been helpful to see how you connect them together. Do you use a cable or some sort of solid, 2-way SDR adapter to connect them?

    Any ideas whether what I'm thinking of using will work?
    Chris
    Last edited by tasmedic; 25-01-20 at 09:24 PM.

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    Lightbulb Going to a pc less standalone setup.

    Learjet, This along with your Himawari setup are very interesting projects. Its had me thinking for a while now.


    Has any one thought along the lines of, maybe or seen anything using a dm500 or similar as data receiver for this L band and more so the Himawari C band data ?

    I would like to make a small box to just provide update pix of the immediate local area via the network port but avoid the need of a pc. Output as a webpage or FTP uploader.

    I guess just floating ideas but.

    I know a raspi and sdr is an option but both raspis and SDRs run hot, raspis eat SD cards, short on ram and a host of other issues, struggle with mathematical load and are a bit expensive for what they are.

    I have been searching around for someone converting an old stb like a DM500 to provide data like the Novra S300 as a starting point.
    The idea of tearing out the video code from one of the old Aurora linux boxes and dropping in some xrit code sounds appealing, possibly it might need something like an ESP32 module on the I2c bus as a co processor to give some more poke if needed.

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    Quote Originally Posted by tasmedic View Post
    I get the idea of the cantenna, but you have no LNB?! I wonder how you get around cable losses. What cable are you using, and how long is it?
    If I'm using my smaller dish, I'd want to keep losses to an absolute minimum, as I might lose my signal in the noise.
    I have the noolec smart sdr. Does that saw filter you're using need a bias-t, and how did you connect filter and SDR? Seeing them side by side was nice, but it'd have been helpful to see how you connect them together. Do you use a cable or some sort of solid, 2-way SDR adapter to connect them?

    Any ideas whether what I'm thinking of using will work?
    Chris
    Hi Chris, hope you're still reading! I forgot to subscribe to the thread and got no notifications. Silly me.

    No LNB. It's direct L band. Receiving antenna is just a 1/4 wave stub in the can.

    The Nooelec Sawbird is a dual stage LNA and bandpass filter, about 30dB gain I think it was. It makes up for the cable loss. Cable is 30 metres of crap dual shield Jacar stuff. I think my dish size makes up for a lot of losses.

    The Nooelec NESDR I'm using has inbuilt bias-T. The Sawbird filter is at the dish end, the NESDR is at the computer end some 30 metres away.

    1.2m offset should work, if losses are kept to minimum.

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    Quote Originally Posted by hca View Post
    Learjet, This along with your Himawari setup are very interesting projects. Its had me thinking for a while now.


    Has any one thought along the lines of, maybe or seen anything using a dm500 or similar as data receiver for this L band and more so the Himawari C band data ?

    I would like to make a small box to just provide update pix of the immediate local area via the network port but avoid the need of a pc. Output as a webpage or FTP uploader.

    I guess just floating ideas but.

    I know a raspi and sdr is an option but both raspis and SDRs run hot, raspis eat SD cards, short on ram and a host of other issues, struggle with mathematical load and are a bit expensive for what they are.

    I have been searching around for someone converting an old stb like a DM500 to provide data like the Novra S300 as a starting point.
    The idea of tearing out the video code from one of the old Aurora linux boxes and dropping in some xrit code sounds appealing, possibly it might need something like an ESP32 module on the I2c bus as a co processor to give some more poke if needed.
    I'm afraid what you speak of is way above my head. I don't have any experience with the DM500 or Linux gear. But if you can get pix, that would be good.

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    I had a couple of linux DM500s boxes left over from aurora and was looking at converting them to firstly into basic DVB ip receivers like the Novra you had on Himawari. Then if there was enough room, replace the satv apps in them with the linux xrit code, and have it ftp a 100km square hi res image every 10 minutes or again if there was enough ram have it just serve a web page with the last 6 local images.

    The idea being to generate a page showing the local cloud movement for the last hour at 10 minute intervals. A short term forecasting tool in one box not requiring a PC running..

    After spending days reading through old forums making notes, looking for lost downloads learning as much as I could about them from 10 years ago I found some software on Github for flashing into them which coverts them into Sat_IP servers which I figure I could modify. Effectively making them the same as the Novra. But since then I see the signal is DVB-S2 while the Github code is not. I have not yet worked out if the old DM500 hard ware can he modified for this, but I doubt it, it also means a small coding project possibly has become a big one.

    So that idea is pending.

    In the meantime I have got Sams GK-2A software running in Debian linux with the SDR. Now I am trying to get the open satellite project software going in Debian as well, Looks like it can do both HRIT and LRIT. The are quite a lot of linux apps to investigate now but most get the data online. Which would be ok if it was at 10 minute update real time.

    So on the GK_2A reception side I have some S band LNBs I brought for another project, I have modified one by bypassing in 2.5 gig band pass filter and the DRO/mixer to feed the SDR or a DVB-S2 receiver. It should make a fairly hot front end but I have not got it on the bird as yet.


    For Himawari, I moved a 1.8 solid C band dish on to the JC sat hoping to find the 3831H ABC signal to line up the dish shown in Lyngsat but I don't think my receivers can handle the multistream format used.

    Can you tell me if a normal DVB-S2 sat would will at least find the transponders and look for channels on it either JC sat or GK_2A in blind scan? Even with manually entered transponders they don't seem to but I don't think they normally react to data service transponders.

    Below are some pics of the S band LNB as converted for GK-2A. It seems good with a sig gen but as yet untested on air. The feed dipoles may need extending with some copper shim for the 1.7 gig signal.

    Modified





    Feed dipoles





    Original board

    Last edited by hca; 09-06-20 at 08:44 PM.

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    Hi hca, I did a blind scan of Jcsat2B with a DVB-S2 box but nothing locked. On C band the spectrum analyser is full of spikes, all data transponders presumably. I used the spectrum analyser function of my sat meter to peak the Himawaricast transponder on 4148H. I am using a 2.3m solid for that.

    For GK-2A, I don't comprehend Linux, but I follow Sam's work, sort of. He has successfully used a 40cm grid antenna for LRIT on GK-2A! On my 2.5m I get 100% signal with no or few vit errors using windows software from USA-Satcom. But it's very sensitive to computer use. I can't run any other programs at the same time as the sat software otherwise I get errors.

    GK-2A L band if full of signals. I get stuff everywhere, tuning with an IC-R2500 coms receiver.

    Here's a pic of C band on Jcsat2B from 2018 when I was setting Himawaricast up.

    Last edited by Learjet; 10-06-20 at 05:26 AM.

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    Thanks Learjet for spec an image from 2018 and running the scan for me, that confirms my observations here on JB sat with a couple of receivers. I can see similar carriers on it with the SDR as well.

    Sam's approach is quite good, it only took a few minutes to download and build it in Debian. Unfortunately the little windows app for the RF monitor required a 1.6gig download of MS dot net and a reboot to run. Such is life with windows. But being able to access the images from a web page means you can see the image with a phone even.
    Putting his code into one of the newer linux STBs might be worth investigating some of them have a lot of resources compared to the old DM500s. They are not cheap, but as I don't have one it could be an expensive option, Novra or DVB card in a PC could be more realistic.

    Re the USA-Satcom software, Its well spoken off but I have read differing comments while searching around, one one hand it costs 100 usd, on the other if you are a hobbyist and have the signal they will let you have it free?
    For now I will use the resources I have however it might be handy to use while figuring things out, but out of interest what generation PC setup do you have it running on?

    First off I need get the Lband signal on GK-2A.

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    Hi hca, I think the USA-Satcom software is normally $125 USD. I got it for a special price of $75 as GK-2A is only LRIT. In any case it's better than $500 USD for the Himawari Kencast software!

    My GK-2A PC is a 2011? Intel i5, Asus A55V laptop with 8gig of RAM and 1TB Seagate hybrid HDD.
    Last edited by Learjet; 10-06-20 at 10:01 PM.

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    Hi Learjet,

    That's quite some cash outlay, I guess the target market is met offices or other big dollar customers rather than hobbyists. Goes against the grain to pay for anything than runs on an MS OS. Somewhere I did see some other software for LRIT on windows that looked like it was free.

    There a lot of HRIT/LRIT linux image software on Github some SDR or RX driven but most looks like its downloading the data but could be adapted, being command line it should not be to hard to compile some of it into windows or run under cgywin.

    Thanks for the PC info your end, I think my pcs are i5 similar capability to yours so they should be good enough for the job. One is windows embedded7 and the other debian so I can go both ways with this project.

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    Hi hca, if you can make some software that would get pics from Himawaricast on Jcsat2B, you would be very popular, considering the cost and monopoly of the Kencast software. The PC is more demanding for that. While my i5 Windows 7 PC can handle it, it struggles with the 11,000 x 11,000 HRIT images. My i7 with 16GB is better for that job.

    I should grab a GK-2A image for today. I see something is brewing near the Philippines...

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