11.0°E to 12.0°E Ka Band Craft

  • /edit by s-band: Split from RE: 11.0°E Inmarsat-5 F5




    Assuming that the information is correct from the NIT, here is a signal from 11° East that could help experimentors modding surplus commercial Ka equipment to get there LO's in the right place and also getting polarity set-ups right. I quickly fabricated a band B Hughes lnb/poloriser lump together the other day and this signal info is making me re-check my installation :77:

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


    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)




    It does get a bit confusing - - i think i need a lie down

    Using the NIT from this locked freq 20.535 which was seen on the edge of our previous scans it stated 11° E.

    I then tweaked the dish position using specificaly the freq 20.535 for maximum

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  • ... The mind boggling continues but possibly might help with identifying some sats & positions - Iv'e removed the circ poloriser from the Hughes Band B set-up and done another scan of the ~11° E in Linear only

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  • The Inmarsat 5 F5 thread is getting a bit confusing. From the UK I think we see:

    11.0°E Inmarsat-5 F5

    11.8°E Sicral 1B

    12.0°E Blagovest 4?

    Sicral 1B beacon


    Pointing at each in turn I did LHCP and RHCP scans. There are a few things to note:

    • The cross polar rejection of the feed is only around 20dB
    • The cross polar rejection gets worse if the dish is off axis from the target
    • Due to the scan rate, the TDM signals from Sicral 1B show randomly
    • The sensitivity may not be exactly the same for RH & LHCP
    • The sensitivity tails off by a few dB above 20.5GHz
    • 9E signals are just visible in some plots
    • Sircal 1B's beacon on 20.25GHz is below threshold for the bandwidth used
    • The RF bandwidth was 300kHz and video BW 300Hz
    • Sicral 1B appears to have linear polarisation
    • Equipment used: 1.2m Prodelin Ka Offset dish with Gilat AN8024 ODU



    Here are my plots with the dish pointing at 3 craft in the 11-12E region.


    1.2m Prodelin 1224 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): Octagon OSLO mod for C120 & ext ref 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

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