11.0°E Inmarsat GX5

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    Linear, vertical, feed on 1.2m dish
    Some transponder noise visible around the stronger signals

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    I hope I've got this right, The previous plots were taken when this satellite was at 28W. I think today's plots are also from Inmarsat 5 F5 which is now at 11E. They are LHCP (as opposed to linear vertical) and show something strange around 19.8GHz. It looks like a signal sitting on a very high transponder noise floor but that seems unlikely, any ideas? There is also a CW signal at approximately 20680.7MHz which I had not seen before on this satellite. (This is above normal top end of the LNB)



    1.2m Prodelin 3122 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): SMW Q-PLL type C, Prodelin feed. Ku (Extended): 11.3GHz LO SMW & Prodelin Feed Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Looking at 11° E & pushing my Norsat pll Band A up to the top of it's limits i can see 19.257 but have'nt got any band B lnb on the changer at the mo

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    Here's a normalised spectrum which shows the transponder noise that seems to cover the whole of band B with a higher level below 20.2GHz. The latter may match the plot from when the satellite was at 28W. There may be 2 other 45Ms signals at around 19.475 and 19.95GHz. The small hump at 20.53GHz is from a satellite slightly to the east of this one, to be investigated. The LNB used was a Gilat AN8024.


    Checking RHCP, there is little to be seen apart from side lobes from 9E.


    1.2m Prodelin 3122 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): SMW Q-PLL type C, Prodelin feed. Ku (Extended): 11.3GHz LO SMW & Prodelin Feed Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Here's a normalised spectrum which shows the transponder noise that seems to cover the whole of band B with a higher level below 20.2GHz. The latter may match the plot from when the satellite was at 28W. There may be 2 other 45Ms signals at around 19.475 and 19.95GHz. The small hump at 21.53GHz is from a satellite slightly to the east of this one, to be investigated. The LNB used was a Gilat AN8024.


    Checking RHCP, there is little to be seen apart from side lobes from 9E.



    ... just wondering s-band, are you going to be keeping an eye on this position for a while ? ... i can fabricate these Band B bits into a working piece if so and have a look around. The Hughes lnb has been modded to go down to 19.25 up to 20.65 G on it's extreem edges.


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    ... just wondering s-band, are you going to be keeping an eye on this position for a while ? ... i can fabricate these Band B bits into a working piece if so and have a look around. The Hughes lnb has been modded to go down to 19.25 up to 20.65 G on it's extreem edges.

    Until i swap the electronics again. It would be good to keep an eye on this one. I can't work out what the 19.7-19.95GHz thing is all about. I'll put an SDR on it some time to se if there is any structure in the thing. BTW, the G2 polariser is for band D and will attenuate B. An unmodified AN8002 will give something over the range 18.7-20.7 with some droop at the ends.

    1.2m Prodelin 3122 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): SMW Q-PLL type C, Prodelin feed. Ku (Extended): 11.3GHz LO SMW & Prodelin Feed Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Until i swap the electronics again. It would be good to keep an eye on this one. I can't work out what the 19.7-19.95GHz thing is all about. I'll put an SDR on it some time to se if there is any structure in the thing. BTW, the G2 polariser is for band D and will attenuate B. An unmodified AN8002 will give something over the range 18.7-20.7 with some droop at the ends.



    Ok re: the Gilat polorisers - iv'e got three of those all with different part number label idents but they all seem to have identical dimensions. I'll most likely use the Hughes one. I have'nt got an 8002 at hand - i wonder if Nelson had the one for sale ?.

  • Unfortunately ...no signal here :37:

    they said here : https://www.satbeams.com/satellites?norad=44801

    72 Ka-band spot beams to provide Very High Throughput Satellite (VHTS) services across the Middle East, Europe and the Indian subcontinent
    this time no thing for Africa !

    Unlike Inmarsat-satellites before ; they coverer half of the glob !

    https://www.inmarsat.com/about…echnology/our-satellites/

  • I hope I've got this right, The previous plots were taken when this satellite was at 28W. I think today's plots are also from Inmarsat 5 F5 which is now at 11E. They are LHCP (as opposed to linear vertical) and show something strange around 19.8GHz. It looks like a signal sitting on a very high transponder noise floor but that seems unlikely, any ideas? There is also a CW signal at approximately 20680.7MHz which I had not seen before on this satellite. (This is above normal top end of the LNB)






    I quickly made up a Ka Band B L/R circ lnb lump today to have a look at the signals you saw - we correspond with each other.

    The lump is not at correct FP on the dish and the poloriser needs slight adjustment to null out opposite pol so the sig level is a bit down in strength.

    ..............................................................................................................................................................................................................................................................................


  • There is also a CW signal at approximately 20680.7MHz which I had not seen before on this satellite. (This is above normal top end of the LNB)

    some thing @ 20680,L :40:

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    some thing @ 20680,L :40:

    That's probably the beacon. If so it looks like they haven't switched your beam(s) on yet.


    /edit This replies to jaes 11.0°E to 12.0°E Ka Band Craft


    Hmm, I think that's from Sicral 1B which is inclined so wanders a bit. If you've got inclined tracking you may be able to confirm that. I can't demod it as it's above 2350MHz IF but the spectrum plot is from slightly to the east of Inmarsat at 14:20UTC.


    I looked on RHCP and there is another 45Ms/s TP on 20325MHz a bit weaker than the LHCP ones. I don't think it was there yesterday as I can see it X polar today and it doesn't show on previous plots. (AN8002 feed on AN8024 today)

  • qwer

    Hat den Titel des Themas von „11.0°E Inmarsat-5 F5“ zu „11.0°E Inmarsat GX5“ geändert.
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    My circular left scan - some changes:

    19586 L 45000

    19810 L 45000

    19913 L 35400

    19991 L 45000, unlocked

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    19810 L 45000

    Circular right scan. So (it seems that) 19810 is from (strong signal in) circular right polarity:

    19810 R 45000

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    At first I thought hat the wide band (200MHz) thing was TP noise but I now think that they are WB, GS. I wonder if I was seeing 2 signals, from different beams, superimposed. Today's plot is different. I get 2 x 45Ms/s GS and 2 x ~220MHz GS (probably) on LHCP.


    There is also an unusual narrow signal at 19701 L. It is about 1.4MHz wide with some amplitude components including one at about 500Hz. The spectrum plot has normal and max held displays.


    19810R is much weaker with me.


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    ...just for fun in cirlcular left low band B (including band A)... :168:

    Bilder


  • ... nothing here too! :77:

    Bilder

  • New scan.

    Helyszín: Nádudvar, magyar.

    ECHOSTAR X-12 3,8 m hálós antenna.
    2.4.x2.7.m Laminas.
    2,2 méteres fókusz.
    1.8.x2.0.m Északi műhold NSC 18-1
    1,8 m elsődleges fókuszban Dyras.
    C, Ku sáv 95.0Kelet-55.5West.

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    feci01,

    thanks for your scan! I can see, you can lock 19993 L 45000. This one was not possible for me in december scan. Opposite polarity in your scan. :3:


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    Just my first scan in circular left here in 2021... :72:

    Not in BS from my place today: 19586 L 45000 (no signal) and 19991 L 4500 (-0.5dB).

    Bilder


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