[Ground-station] 10GHz Remote Receiver - update, and how best to do the web interface?

Tue May 29 16:40:26 PDT 2018

Quite possibly!

I'll try websdr asap and see if that does the trick.

We're currently trying to blow up LNB on a Stick by aiming a DB6NT at it
from next door.

-Michelle W5NYV

"Potestatem obscuri lateris nescis."

On Tue, May 29, 2018 at 4:22 PM, Douglas Quagliana <dquagliana at gmail.com>
wrote:

> Hi Michelle,
>
> Can you run a websdr station to talk to the RTLSDR dongle?  That would
> make the RTLSDR's receiver bandpass accessible/visible to everyone in
> realtime.
>
> www.websdr.org if you havent seen this in action. There are other
> receiver on the web packages too.
>
> Or am I missing something here?
>
> Regards,
> Douglas KA2UPW/5
>
> On May 29, 2018, at 5:22 PM, Michelle Thompson via Ground-Station <
> ground-station at lists.openresearch.institute> wrote:
>
> Attached is a screenshot from rtlsdr_scanner (https://github.com/
> EarToEarOak/RTLSDR-Scanner) and some other photos of LNB on a Stick. This
> is a DirecTV LNB mounted on a mast and received on an RTLSDR. The RTLSDR is
> run by an Odroid which is reachable by WiFi link.
>
> LNB on a Stick is intended to be a remote receiver looking for things like
> balloons and payloads (and people!). Right now, the receiver is pointed at
> the local 10GHz beacon here in San Diego and is successfully receiving it.
> The beacon is the spike towards the middle of the screenshot. This is a
> half-watt 12dB gain beacon 23 miles away over terrain.
>
> Yes, you get even more gain with a dish, but then we lose that cool 40
> degree beamwidth. Think of this as more like a spotting scope. Additional
> gain can come on board when remoting, reporting, and processing functions
> are nailed down.
>
> If you're looking at the screenshot and wondering why it's at 618MHz, it's
> because that's the IF frequency received by the RTLSDR from the DirecTV
> LNB. The beacon is on 10,368.36 MHz. The IF is 9,750 MHz. The signal sent
> to the RTLSDR is at 618.36 or so. The beacon does drift. The RTLSDR is not
> calibrated (yet). The LNB is a PLL version and that does help. Further
> stability can be obtained by aligning the received bandwidth with a locally
> generated stable tone. We have several synthesizer boards that can be
> pressed into that service and are working on that angle as well.
>
> We want to be able to turn this receiving station around and point it
> north (or wherever) and ask the SBMS etc. to yell down at it just as soon
> as a not-completely-janky way of recording/sharing/showing the receiver (on
> the web) emerges. I want them (and anyone else) to be able to transmit and
> see whether or not they are heard at the receiver. To hear LA I might have
> to move the receiver higher than where it is in Carmel Valley, but I think
> we should try it a couple of times as-is and see. A simplistic link budget
> and what I know about the stations that have participated in the tune-up
> parties in SoCal makes it look like the link can close.
>
> So - easily seeing the receiver on the web is the pressing question.
> Currently, in order to see anything at all on this receiver, you log in
> from the local LAN using VNC (and ssh port forwarding) and start gqrx or
> rtlsdr-scanner or whatever. This works. However, that’s like a sysop
> approach. What I’m after is a receiver interface on the web that anyone can
> reach.
>
> rtlsdr_scanner (running on the Odroid) can produce .csv files for scanning
> runs. With rtlsdr_scanner running, I can stash the scan results in a .csv
> file and then post that to a website ever so often. But - there’s got to be
> a more elegant way that gives immediate results along with storing/posting
> the historical archive of the scanner runs (the .csv files).
>
> Is there some magical HTML5 approach? Packages we should be looking at?
> Let me know? This is a solved problem? Adding immediate visual feedback of
> successful receive is the goal. I wanted to ask around before picking
> something not-quite-right.
>
> This prototype is the foundation of remoting the full-blown Phase 4 radio,
> so getting the right ideas worked out for simpler or narrower bandwidth
> applications (like the 10GHz balloon and some satellite payloads) I think
> will pay off in the long run.
>
> So far, the odroid+rtlsdr+LNB+biasT+wifiDongle in a sprinkler box on a
> mast is hanging in there and working well. Odroids do seem to run hot and
> being in a box has resulted in temperatures from 65C up to 75C - so far.
> This Odroid does has a fan and it does run. This box does have
> downward-facing holes for ventilation.
>
> The VNC isn't exactly robust (Using Chicken of the VNC here). It drops
> with "protocol errors" and "rectangular problems" and sometimes it just
> drops. Also, the entire thing is AC powered and not, say, powered from a
> solar panel. In other words, it's not off-grid or Burning Man Ready - yet.
>
> But if it was battery/solar powered, and if the backhaul wasn't wifi, but
> perhaps cellular or something else, then LNB on a Stick would be very
> grab-and-go.
>
> Future stuff? Tracking an APRS-revealed signal (like a balloon or person
> or vehicle). Trying phased arrays of LNBs. Receiving live video.
> Experimenting with adaptive coding and modulation in DVB-S2/X.
>
> More soon!
> -Michelle W5NYV
>
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