[HN Gopher] Receiving Starlink Beacons with a HackRF Supercluster
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Receiving Starlink Beacons with a HackRF Supercluster
Author : lightlyused
Score : 58 points
Date : 2021-11-21 13:36 UTC (9 hours ago)
(HTM) web link (www.rtl-sdr.com)
(TXT) w3m dump (www.rtl-sdr.com)
| nippoo wrote:
| This is really cool! For anyone looking to do a similar project,
| it's worth noting that HackRFs are pretty low-spec SDRs by
| current standards: a number of more recent models, such as the
| XRTX-CS, based on the Lime LMS7002M front-end, achieve far
| greater tuning bandwidth - you wouldn't have to build a cluster
| of them, and could get the same throughout for a lower price and
| complexity!
| kregasaurusrex wrote:
| Very cool, I didn't know there were better models available
| than the HackRF & LimeSDR!
| dariusj18 wrote:
| Things like this remind me how little I understand of
| electromagnetism and radio signals.
| syedkarim wrote:
| I don't believe that the HackRF cluster is required for receiving
| the beacons. After the 11 GHz signal is down converted by the
| LNB, an RTLSDR should be fine for reception. happysat77 on Reddit
| used a PlutoSDR, but an RTLSDR should be ok, since the down
| converted signal is around 1600 MHz. The bandwidth of the beacon
| is only 1 kHz or so.
|
| https://www.reddit.com/r/RTLSDR/comments/qtofau/comment/hkq2...
| petschge wrote:
| You don't need a cluster of HackRFs to see a single beacon. But
| the combination of several HackRFs does give you larger
| instantaneous bandwidth and the ability to track an individual
| beacon over a wider range of Doppler shifts and hence for a
| longer time / part part of it's orbit. And the ability to see a
| whole bunch of beacons at once.
| system2 wrote:
| It is humbling to look at the pictures and read it carefully then
| don't even understand what the heck he accomplished by doing the
| bizarre contraption.
| R0b0t1 wrote:
| He's just receiving the signal.
|
| EDIT: My selective reading kicked in, if you check his twitter
| he's also doing something more modern.
| tgsovlerkhgsel wrote:
| The text says the 8 cards are connected to one antenna. To me
| it sounds like he's doing it because each card only gives him
| a fraction of the bandwidth he needs to cover.
|
| Edit: I don't understand why he needs that much bandwidth
| though - maybe he just happens to have the cluster, but I
| suspect he could get basically a 1/8 slice (full height, but
| only covering 1/8th of the width of the picture) with only
| one receiver.
| jsjohnst wrote:
| You definitely don't need 160Mhz bandwidth. Based on other
| articles on the source blog, it's something he had and the
| additional bandwidth let's you track more spectrum at once.
| exikyut wrote:
| The linked article is fairly light on details and doesn't quite
| emphasize the interestingness of some of the inline links.
|
| https://old.reddit.com/r/RTLSDR/comments/qtofau/starlink_sat...
| is particularly interesting and also contains a couple more links
| (scroll down)
|
| Also https://twitter.com/olegkutkov/status/1411124689414541313
|
| The author's blog https://olegkutkov.me/ definitely looks
| interesting as well (I don't see an article specifically about
| the OP topic yet, but there's a lot of other stuff)
| ncmncm wrote:
| Outrageously off-topic... but I bet if SpaceX put a camera under
| the satellite, customers would love getting real-time imagery of
| their house from the exact satellite listening to their Dishy
| McD.
|
| I gather you need a license to collect satellite imagery, which
| is weird. Or to broadcast it, or something. (But what if it is
| narrowcast, instead?) SpaceX could totally afford such a license.
|
| Speaking of broadcast, the Starlink terminals could be equipped
| to pick up and cache packets broadcast from a satellite, with a
| proxy server inside that can deliver cached content. That way,
| the satellite only needs to send one copy of its Earth View, or
| the running World Cup, or the new Marvel release, and everybody
| in the reception cone gets it from the one broadcast, saving
| bandwidth and system load all around.
|
| (Of course, something in the customer's player would need to know
| to use the proxy server to get video frames. But that is just
| software, therefore easy. Ish.)
| teruakohatu wrote:
| Can the doppler shift be used to build a pseudo GPS? If so, with
| the number of Starlink satellites, how accurate could this
| theoretically be?
| JaimeThompson wrote:
| Check out this link [1] "SpaceX satellite signals used like GPS
| to pinpoint location on Earth"
|
| [1] https://news.osu.edu/spacex-satellite-signals-used-like-
| gps-...
| jack_riminton wrote:
| Great! now can anyone explain what that means?
| jsjohnst wrote:
| This guy chained 8 HackRF SDRs together with a bunch of other
| radio gear to see the beacons (radio impulses) from Starlink
| satellites.
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(page generated 2021-11-21 23:01 UTC)