Receiving Starlink satellite beacons

  • Hi,


    the famous SpaceX/Starlink satellites have downlinks in the Ku-Band as shown in this band allocation below.




    This is indeed the same band used for Direct-TV geostationary satellites and also QO-100 (there are also downlinks in the Ka-Band for the Gateway-Links, but this is not the scope here).


    OH MY GOD - ITS FULL OF STARS


    here you can find some Starlink Coverage Tracker:

    https://satellitemap.space/

    https://starlink.sx/


    Same minds, same thoughts...

    So, why not using a simple LNB as we use for QO-100 and try to receive Starlink satellites instead. Just point the LNB in the Sky and use an SDR to check if you can see something in the waterfall spectrum with your favorite SDR software. Indeed you may see only part of the signal as it is high bandwidth, but there are also some telemetry beacons like on 11.325 GHz.


    Starlink Downlinks are usually circular polarized (RHCP/LHCP), so your LNB's linear polarization (H/V) does not matter!


    Some people (including I0LYL) have just used their QO-100 installation and waited until a Starlink satellite just (quickly) passed through the antenna beam...


    Here is a pretty nice article from Derek OK9SGC with full explanation and further links:

    https://sgcderek.github.io/posts/starlink-beacons/






    Have fun!

    73s Peter DB2OS

  • You only need to wait a few minutes and you will see something like this, as seen on my QO-100 dish (SDR console tuned to 11.325 GHz):



    Also keep in mind that we are only seeing a side lobe as usually the main lobe is more or less directed perpendicular to the user station on the ground. So if you just mount your LNB without reflector looking vertically up, you might even see more...


    73s Peter

  • Hallo Peter...


    i made a test with my QO-100 station about 2weeks ago (20nov2021) after reading the info in rtl-sdr.com


    https://www.rtl-sdr.com/receiv…th-a-hackrf-supercluster/


    looks working (maybe also without a dish)...timeline of waterfall in screenshot about 20min


    73 de dg0opk

  • Actually it's a surprise that we even do see something from Starlink with the QO-100 dish pointing to 25.5°E.

    To avoid interference between geostationary (GSO) and non-geostationary (NGSO) satellite systems, FCC and national regulations require that the user beams are switched away to an alternative satellite when the user terminal is pointing to the geostationary belt and GSO downlinks...

    Maybe we are seeing are actually the side lobes or something else. On the other hand, these signals are probably some telemetry beacon downlinks used for initial tracking when searching and aligning the Dishy terminal for the first. They might carry some sort of satellite elements. Remember that Dishy does not have any internet connection and does not know where it is located and where to point in the sky to establish first contact and align itself..



    Anyway.. fascinating technology behind this and fun to play with..

    Next thing would be to use a bare LNB pointing straight up..


    73s Peter

  • The Beacons are actually the Satellite-to-User Downlink traffic in 250 MHz channels (see chart in my first post) at 11.075, 11.325 and 11.575 GHz. Other channels might not be in use yet.


    Christian Hahn in California made some cool observations and analysis:



    The central 1 MHz of each 250 MHz channel is occupied by ~9 tones spaced at 43.9495 kHz. 1 tone on the channel center, 4 tones on each sideband.



    Christian found out that the central 9 tones sometimes are missing.

    There is still some guess that the tones in the middle are low speed data carrying the satellite id number and orbital elements of nearby or all active satellites for tracking...


    73s Peter

  • Hi Peter

    many thanks ...this looks very interesting....


    So i hope that SPACEX will accept the RULES of the other KU band USERS .... TV SATs and so on....


    The REGTP (corr. Bundesnetzagentur) has only given a time limitied LICENCE for SPACEX in DL until now...

    WE WILL SEE ....


    73 de DG0OPK