<div dir="ltr">Thanks Zach, good stuff and I think we're on the same "wavelength". The ammo can prototypes got a lot of interest last year at Hamvention. Let's keep some fire on all of this and the potential help it can lend to your efforts. <br><br>If anyone's interested in seeing some more details about 'die Boxen' then here are some diagrams: <a href="https://github.com/phase4ground/documents/tree/master/Manufacturing/Virginia_Tech_prototypes">https://github.com/phase4ground/documents/tree/master/Manufacturing/Virginia_Tech_prototypes</a><br><br>Zach if you have anything else about them then feel free to stow it there in that folder. A brief discussion of the 10MHz signal (instead of the traditional 22kHz I'm guessing) Would be a great addition.<br><br>I'll try and add some photos. I know we took some!</div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div dir="ltr">-Michelle W5NYV<br><br><div dir="ltr">"Potestatem obscuri lateris nescis."<br></div><div><br></div></div></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On Mon, May 14, 2018 at 12:21 PM, Zach Leffke via Ground-Station <span dir="ltr"><<a href="mailto:ground-station@lists.openresearch.institute" target="_blank">ground-station@lists.openresearch.institute</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<p>Quick reply....haven't ingested everything yet.</p>
<p>For Transmit, 10 GHz: (not practical for balloon due to
weight/cooling, but maybe as a reference, or at least inspiration)<br>
</p>
<p>For the 10 GHz payload 'simulator' we built into an Ammo Can at
VT, we used the following Kuhne product:
<a class="m_6401723599266836186moz-txt-link-freetext" href="https://shop.kuhne-electronic.de/funk/en/shop/industrial/prof-converter/prof-up-converter/KU+UP+107+B++Up+Converter/?card=513" target="_blank">https://shop.kuhne-electronic.<wbr>de/funk/en/shop/industrial/<wbr>prof-converter/prof-up-<wbr>converter/KU+UP+107+B++Up+<wbr>Converter/?card=513</a>.
Nice part was the standard L-Band IF, so easy interface into a
B200 USRP. accepts 10 MHz ref, able to get up to +24dBm out
(datasheet spec, not measured). Part is likely to heavy for
balloon launch though, and requires cooling (heatsink definitely
too heavy for balloon launch). Used One of Kent's Vivaldi PCBs
for the TX antenna.</p>
<p><br>
</p>
<p>For 10 GHz receivers:<br>
We used the Ku band LNB 'trick.' PLL based LNB cost less than $10
bucks on Amazon and worked across the room (payload ammo can on
one side, gs ammo can on the other side). I forget the specific
model at the moment (X-squared maybe? But I might be mixing that
up with M2 antennas...), but it was one of the 'universal' LNBs
that extended the coverage to the lower end of the Ku-Band closer
to the satellite service freqs. Used pretty cheap minicircuits
components for the Bias-T, but I'm betting could drop that cost
significantly if you build your own (a little LC action) if your
trying to power up multiple LNBs for a phased array. In our
single channel demo, I used a little step up voltage regulator,
tied to the 13.9V input, plus a DPDT switch to select between
13.8V and ~18V for the DC on the coax, which switched between H/V
pol. All of that plugged into a B200 SDR, with the output IF a
bit lower than the standard L-Band IF for these things (upper UHF,
700MHz or so is bouncing around in my head). lots of super cheap
18 inch dish class parts on ebay for reflectors and such (at one
point, someone was selling a pallet of like 50 Dish network
dishes, with reflector, feed, and mount for about $200.00.....but
the XYL said 'no').<br>
</p>
<p><br>
</p>
<p><br>
</p>
<p>I'd be very interested in how the phasing of multiple LNBs plays
out. first question concerns the LO/ref freq. In our little Ammo
Can demo, the Bias-T I used also injected 10 MHz onto the coax for
'future use' at the LNB to discipline the LO. The intent was to
eventually figure out how to tie it into the LNB to help stabilize
the frequency, but never got around to finishing this. I'm
assuming something like this might be needed, with 10 MHz (or some
other reference freq) distributed to all the LNBs. Second
question is how does the phase shifting and combining step work
for this idea? I'm guessing all the combining is done at the IF
freq? Is this all being done in hardware with maybe tuneable
phase shifters to steer the beam? As to the LNBs themselves, any
thoughts on all the possible combinations of DC on coax for H/V
pol, hi-band/low-band diseq control, use of 'dual' or 'quattro'
LNBs with multiple outputs, how the designs of the dual/quattro
matter relative to the ref freq/LO distribution and the phasing,
etc. etc. I don't know any of those answers myself on that, but
am curious about how all that fits together and possibly could be
leveraged for this idea.<br>
</p>
<p>My interest in this is linked to something else I'm trying to get
into, which is building a monopulse tracking feed at 10 GHz, for
some large C/Ku band antennas we just came into 'possession' of at
the Hume Center. Sort of a '4 channel phased array' type
problem. Long term goal is to refurbish a 5m cassegrain design
antenna to work at 10 GHz, with monopulse feed assembly, but doing
the combining in software with a 4 channel SDR (X-310 USRP w/ dual
TwinRX, or maybe the N310 if the uhd random startup phase thing
doesn't kill the idea...). Idea is to precisely track
GEO/HEO/Lunar spacecraft w/ 10 GHz downlinks. The precise Az/El
derived from the error signals from the monoulse tracker unit
would then be used to 1) lock on and precisely track at 10 GHz for
the 5m antenna (sum beams used for data link). 2) deliver precise
enough information on the Az/El to due either orbit determination
or 'trajectory determination' if a Lunar mission and 3) feed the
computed Az/El to the 9m C-Band uplink antenna.</p>
<p><br>
</p>
<p>So I'd definitely be interested to know how the LNB phasing
goes. Perhaps the lessons learned from that effort could be
applied to a an 'easy' prototype of the above monopulse idea to
demo the concept with a 4 channel SDR in a effort to get more $$
for the real deal (like I said, long term goals......).</p>
<p><br>
</p>
<p>Good stuff!</p>
<p>-Zach<br>
</p>
<pre class="m_6401723599266836186moz-signature" cols="72">Research Associate
Aerospace Systems Lab
Ted & Karyn Hume Center for National Security & Technology
Virginia Polytechnic Institute & State University
Work Phone: 540-231-4174
Cell Phone: 540-808-6305</pre><div><div class="h5">
<div class="m_6401723599266836186moz-cite-prefix">On 5/14/2018 11:27 AM, Michelle
Thompson via Ground-Station wrote:<br>
</div>
</div></div><blockquote type="cite"><div><div class="h5">
<div dir="auto">For the balloon launch opportunity, and for
groundsat in general, we have been asked to consider a
lightweight inexpensive 10GHz transmitter for the balloon. And,
obviously, receivers on the ground.
<div dir="auto"><br>
</div>
<div dir="auto">Phil and the high school team doing the launches
are interested in live video from the balloon. Launch schedule
is flexible and it's an ongoing project.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Kit bash something from DirectTV? I think Kerry
and Drew got something working that way. </div>
<div dir="auto"><br>
</div>
<div dir="auto">Existing card or dongle?</div>
<div dir="auto"><br>
</div>
<div dir="auto">Design a board? We are capable. </div>
<div dir="auto"><br>
</div>
<div dir="auto">Effort invested improves groundsat side.</div>
<div dir="auto"><br>
</div>
<div dir="auto">We have a good handle on inexpensive 10GHz
receive hardware. Deploying enough of it? That's going to be
hard. How hard? We need to run the numbers for a variety of
powers to find out how bad. We aren't going to get continuous
coverage without seriously taking over the world. But, we can
figure out what coverage looks like with a variety of
configurations. </div>
<div dir="auto"><br>
</div>
<div dir="auto">(If we could just have a little telemetry app
running on everyone's satellite TV dish/receiver, then we'd
have a nice fat fence at least. DirecTV has not yet returned
my call about this...)</div>
<div dir="auto"><br>
</div>
<div dir="auto">People of Twittertopia say DirecTV LNBs as
phased arrays set up to wedge out likely high altitude paths.
So I looked at phasing up DirecTV LNBs, to shape the beam a
bit. You know it might actually work. Anyone done this already
or know of a paper? Beamwidth of the LNB by itself is about 40
degrees. </div>
<div dir="auto"><br>
</div>
<div dir="auto">Let's hear your video transmitter ideas and
leads for this use case. It will be fun for everyone and a big
learning opportunity and we might find (or forge) a really
good path forward. </div>
<div dir="auto"><br>
</div>
<div dir="auto">Since the "infiltrate all DirecTV receiver
installations across the US for amateur radio botnet" plan is
probably not going to work out any time soon, we need to come
up with buildable repeatable recipes and get them up and
running. </div>
<div dir="auto"><br>
</div>
<div dir="auto">After Hamvention I'll publish everything we have
about getting an LNB+PLL/bias-T/rtlsdr/odroid/<wbr>VPN station
deployed. Cost is not bad at all and it's very light weight
and portable. Maybe we can make a kit.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Another area for this receiver is to improve
performance by alignment to a fixed synthesized tone. Hardware
is figured out for that but the correction isn't tested yet. </div>
<div dir="auto"><br>
</div>
<div dir="auto">There's got to be other solutions or ideas out
there in various communities. If you are part of one of them
then please share this so we can learn.</div>
<div dir="auto"><br>
</div>
<div dir="auto">More soon!</div>
</div>
<br>
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