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

Wed May 30 09:37:02 PDT 2018

Douglas recommended WebSDR. That is still in process because it hit a snag
on Odroid.

Tony Stone recommended
https://www.wimo.com/kiwisdr_receiver_webradio_e.html and
outlined a path to include remote receiver data there. He related some
experience with LNB temperature stability and ideas for compensation.

OpenWebRX worked on the first try and we have an LNB on a Stick on the web
at their site.

See https://sdr.hu/?q=w5nyv

For OpenWebRX, things to do include:

Get the receive frequency displayed instead of the IF frequency displayed.
Have it come up in a more useful USB or CW mode instead of FM mode. Brennan
Ashton pointed out that this could be changed in spectrum_thread_function()

For OpenWebRX, the architecture got some criticism, as it streams the data
from the machine attached to the SDR out to every single user. Please give
it a shot and see if you can copy the local beacon. I'll leave it pointed
that way for now.

The advantages here are a quick way to stand up an LNB on a Stick on the
web for terrestrial operation and experiments. There's a map view and a way
to incorporate GPS. There's a way to incorporate the view from a webcam
into the background as well, so you can see what the site looks like.

Total cost so far is $60 Odroid + $25 Noelec Smart RTLSDR + $0 SDMG loan
Bias-T + $35 sprinkler box with outlet + $25 linearly polarized PLL style
LNB + $0 scrounged wifi dongle + $20 10ft mast + $40 outdoor umbrella stand
+ $15 USB 3.0 hub + $0 hand-made F and SMA cables from in stock tools and
connectors

For a total of $220 or so. Not bad!

This is AC powered. Going off grid would require battery/solar and if you
wanted GPS to automagically update then you need a GPS update of some sort.
The outdoor umbrella stand is the most egregious expense so far, because
you can get by with other less expensive bases/stakes/rebar/guying.
Decorative umbrella stands work well for my backyard and make it look like
it belongs and blends in - use whatever works for you. Adding a way to
rotate the LNB and a digital compass would be groovy and had been suggested
a couple of times.

Tracking something like a balloon via APRS is possible. We wrote an article
for TAPR a while back about using APRS to help with pointing. Read "The
Problem is Pointing" here: http://www.tapr.org/psr/psr107.pdf

So, for satellite operations, we want to be in SatNogs. We talked with
Pierros and other Libre Space people at Hamvention, and getting microwave
band ground stations (like Phase 4 Ground) working in SatNogs is welcome
and strongly encouraged. They have VHF/UHF covered pretty well, but do not
feel like they have enough coverage of microwave broadband digital.

People that are doing things like weather satellite reception really want
it to be in SatNogs as well. There's a lot of potential collaboration and
support and targets here. There is tons of things to learn and build that
are shared components.

https://satnogs.org/

We have most of a SatNogs station built up here. I know some of you have
either started a station or have been really seriously thinking about. Make
now the time to dig in and get it finished.

To be most useful, an SDR capable of 10MHz bandwidth is required to handle
the full air interface.

Don't let that stop you from using something like an RTL-SDR in the
meantime!

Our version for CubeQuestChallenge was something that an RTL-SDR could do,
and we're going to finish that version, so if that's what you have, plunk
it down and get the station up and running.

More soon,

-Michelle W5NYV

On Tue, May 29, 2018 at 4:40 PM, Michelle Thompson <
mountain.michelle at gmail.com> wrote:

> 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
>>
>> <Screenshot 2018-05-29 10.21.19.png>
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>>
>>
>
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