Posts by KC9SGV

    Image: NASA

    Here is a "back of the envelope" link budget calculation by Ron, W6RZ.

    For the downlink only.

    Here's a rough link budget. The Earth subtends an arc of about 2 degrees from the Moon, so a 1 foot dish on the gateway is about as large as it can get and still cover the entire Earth. So about 29 dBi of gain.

    100 watts = 50 dBm

    1 foot dish EIRP = 79 dBm

    Worst case path loss at 10.45 GHz = 225 dB

    power density on Earth = -146 dBm

    Noise floor at 29K and 10 MHz bandwidth = -114 dBm

    1 meter dish gain = 39 dBi

    Signal at DVB-S2 receiver = -107 dBm or 7 dB above noise.

    7 dB S/N could support 8PSK at 2/3 rate, which would provide 16.5 Mbps. Enough for several HDTV channels.

    Or a 0.5 meter dish could work at QPSK 1/2 rate, which would provide 8.2 Mbps.

    Image: NASA

    Hi All,

    The ham radio payload on the future Lunar Gateway will be interesting.

    At the recent AMSAT-NA symposium we heard:

    10 GHz downlink.

    100 Watts

    DVB-S2 DATV, etc.

    Existing QO-100 receivers should be able to receive the signals from the Lunar Gateway.

    Tests could be done now already with the DL0SHF moon beacon.

    Please ensure this important moon beacon is operational for 10 GHz receiver testing world wide.

    Join the email list at



    Wow !

    I must have hit a nerve here with my honest request....😀

    Some of us fellow radio amateur hobbyists here in North America (and South America, Australia, etc.) have started building receiving hardware following some of the excellent ideas on this forum.

    But now we can only listen to the beacons of commercial GEO sats above us !


    No way of operating your excellent new satellite.

    I guess an OSCAR 100 DXpedition is my future 👍

    This is an example what could be done with the RCForb server freeware from

    It could be set up as a club station only, giving more oversight and only allowing trusted members to operate in turn.

    It could also be set up on one fixed frequency only, allowing only one transmission (and reception) mode.

    The greater effect of this will be to attract more radio amateurs to the satellite operations facet of this hobby. Entice them to acquire their own hardware...

    Also, see this excellent short article on IRB operations by K5PA.

    Note, this was written before the advent of an available GEO sat for ham radio operations.…logy/pdf/QSTWhyRemote.pdf


    Hi All,

    I respectfully propose a request for the setting up of an Internet Remote Base (IRB) somewhere in the footprint of QO-100, in one of the almost 140 countries illuminated by the satellite.

    IRB's have been part of ham radio for decades, and are legal in many countries, with certain conditions attached.

    Many amateur radio operators, outside of the footprint, or those who do not have access to the necessary hardware to operate this exciting new satellite, might benefit from such a venture.

    If this is done correctly, it could be a force multiplier for this fantastic effort.

    I have previously mentioned the idea of doing this through Echolink, or the RCForb freeware from on the Shoutbox.

    See the freeware at:


    We realize that some excellent WebSDR's are available for this satellite, but these have no transmit capability.

    We also realize that AMSAT-DL and QARS have the final say.

    Please give this proposal serious consideration.





    From another board...

    No dish antenna...

    Graham Mar 7 #50885

    New test with Bi-quad loop and 150 mW carrier power ..

    Rx still via web sdr

    14:27 1296963 EA5DOM de F1ABL Op05 478 mi -22 dB F:1% in JN24OF SWL SDRWEB QO100 1339,8 Hz with 0.15w + NO DISH - Biquad HPol

    interestingly , op05 is decoding down to -23 dB s/n ,

    2019-03-07 13:44:35 EA5DOM IM98WN F1ABL JN24OF 771 1.296.964 -23 Op05__~23dB





    Graham Mar 7 #50887

    Group of stations monitoring the down link , for opera op05 ,

    to use the sat link , with web-sdr-rx only requirement is the ability to

    on/off key a carrier on 2.4 GHz , power and Ae requirements appear to be minimal


    PA1SDB: reports using up link qrg, 2.400,1012960 GHz

    downlink at 10.489,603500 GHz

    24 hours snap shot , sat users

    2019-03-07 17:56:36 PA3ARK JO33LF PA0KNW JO33MD 11 1.296.600 -8 Op05_||||||||||||||||||||||||_~8dB

    2019-03-07 13:02:35 PA3ARK JO33LF PA3ARK JO33LF 0 1.296.600 0 Op05_||||||||||||||||||||||||||||||||||||||_~1dB

    2019-03-07 09:31:58 EA5DOM IM98WN F1ABL JN24OF 771 1.296.964 -18 Op05_||_~19dB

    2019-03-07 09:31:57 EA5DOM IM98WN PA0KNW JO33MD 1.712 1.296.600 -21 Op05__~21dB

    2019-03-06 11:16:14 PA1SDB JO33KH PA0KNW JO33MD 22 1.296.600 -8 Op05_||||||||||||||||||||||||_~8dB

    2019-03-06 09:24:46 PA1SDB JO33KH F1ABL JN24OF 1.017 1.296.964 -3 Op05_||||||||||||||||||||||||||||||||_~4dB