Receiving Starlink Beacons with a HackRF Supercluster
Over on Reddit member u/OlegKutkov has recently posted about his success at receiving Starlink beacons at 11.325 GHz with his HackRF "supercluster". Starlink is an Elon Musk / SpaceX venture that aims to provide fast global satellite internet access for low cost. The venture is advanced enough that in most locations the service is now operational, and there will be Starlink satellites in the local sky at any given time.
Oleg's setup to receive the satellite beacons consists of a small hand tracked satellite dish with LNB feed connected to his HackRF "supercluster". The supercluster is 8 HackRFs connected to the same antenna via a splitter, resulting in 160 MHz of bandwidth. Oleg's blog post from last year appears to contain a bit more information about the start of the supercluster. The 11.325 GHz beacon frequency is out of range for the HackRF which covers up to 6 GHz, so a standard satellite TV LNB is used to downconvert the frequency. The LNB had to first be converted to circular polarization, and is fed via an 'invacom' feedhorn.
Update Notes: Thank you to @dereksgc for pointing out that the HackRF supercluster and modified LNBs aren't actually required to receive Starlink beacons. Derek notes that the Starlink beacons are actually very easy to receive. All you need is an RTL-SDR V3 and a stock "astra" LNB (or the Bullseye LNB) which will convert the 11325 MHz beacon frequency to 1575 MHz which is in the range of the RTL-SDR. The bandwidth of the beacons including doppler shift is also small enough for the RTL-SDR. The beacons are circularly polarized, but strong enough to be received with an unmodified linear LNB and small offset TV dish. So receiving the beacons is possible with modest hardware, provided you have a way to power the LNB. Oleg's setup appears to be gearing up to receive the actual wideband data from Starlink, or some other wideband satellite signals.
In the spectrum waterfall image, the doppler shift of the beacons is clearly visible due to the speed at which the satellites orbit.
More information about his setup is available from his followup Reddit comment and the Twitter links he provides there. You can also visit his Twitter directly at @olegkutkov where he shows more images of his HackRF supercluster and the hardware he' using.
In the past we've posted about how IU2EFA and Jan de Jong were able to track the Starlink satellites via an alternative means involving reception of the European GRAVES space radar being reflected off the satellite body.
STARLINK have plans to use signal freq up to 30 Ghz. Satellites are at 550 km altitude.
Compared to lower bands, radio waves in this band have high atmospheric attenuation: they are absorbed by the gases in the atmosphere. Therefore, they have a short range and can only be used for terrestrial communication for distances UP TO ABOUT 1 kilometer. Absorption increases with frequency until at the top end of the band the waves are attenuated to zero within a few meters. Absorption by humidity in the atmosphere is significant except in desert environments, and attenuation by rain (rain fade) is a serious problem even over short distances.
So, ummm, can someone explain that, please?
I do not think so, the H2O absorption line at about 22.235 GHz would be somewhere between 10 to 20dB of additional attenuation over 550km.
(ref: )
I can also see Starlink beacons on my OScar-100 dish in Openwebrx https://ibb.co/SsZXq06