The commercial devices use a projector and a fancy lens/mirror to make a full
sphere image
That way you can project a basemap (i.e a picture of the Earth) with overlays -
the one here is fairly fancy in that they have a day and a night image of the
Earth, and they blend between them along the terminator.
On Thu, 15 Jan 2026 13:09:10 -0700, David Gilbert <ab7echo@gmail.com> wrote:
Hhmmm ... that is a truly interesting idea and I think it could be
accomplished without a ton of cost, although not with particularly great
resolution. Here's a few thoughts.
1. PSK Reporter can provide an almost real time data stack of reports
that includes SNR and 4 digit grid.
2. Several microprocessor units like a Pi or even ESP32 can access the
internet via WiFi.
3. The processor unit could control a couple of servos that spin a
laser inside a translucent globe. The servos could probably access all
points on the surface of the globe except for Antarctica, and there's
only one semi-active station (the German one) down there now anyway.
4. The laser could illuminate the surface of the globe to show the
locations of PSK Reporter results, and the output of the laser could
maybe even be modulated to sort of represent SNR.
Depending upon the speed of the servos the resulting spots wouldn't
appear simultaneously, but it wouldn't be difficult to get the picture.
It might be possible to do it inside a globe less than a foot in diameter.
It would be even easier if you didn't require absolutely real time
results ... and the free version of PSK Reporter has a timed usage limit
anyway.. You could use WiFi to get a periodic data dump from PSK
Reporter that then gets plotted until the next data dump.
All of that stuff is pretty inexpensive. You could even program it so
that the data accessed from PSK Reporter cycled though various grids for
reception location. That grid could be identified on the glob by having
the servos draw a star there or something.
Just musing. ;)
Dave AB7E
On 1/15/2026 12:10 PM, Jim Lux wrote:
>
> I would love to have a globe that displayed propagation on the surface.
> (Yes, I know you can do it on a flat panel with any number of tools)
>
> At JPL we have a big (>1 m diameter) spherical glowing ball, with a
> projector, that can display all sorts of "earth centric" data - either in
> real time, or time lapse. It's quite fascinating to watch. I think they
> built it originally when there was a "Heartbeat of the Earth" thing - looking
> at how the Earth changes on various time scales - days, months, years. I've
> seen similar ones hanging from the ceiling in museums with 3 projectors
> illuminating it.
>
> That one is, I'm sure, seriously pricey. I want a small one as a "desk toy"
>
>
>
> On Thu, 15 Jan 2026 12:02:50 -0700, David Gilbert wrote:
>
> What is say is absolutely true, but in today's world it would be
> possible to actually quantify some of those things.
>
> For real time propagation it is hard to beat PSK Reporter's map of FT8
> activity, assuming you have a receiver posting reports to it ... or
> somebody living near you that is doing so.
>
> As for as monitoring real time arrival angles of incoming signals, I
> keep telling myself I'm going to write a browser-based application that
> takes the 2-channel audio feed from a rig with two phase locked
> receivers (a K3 with new synths in my case, but there are other rigs
> that can do it) connected to two antennas and computes/displays the
> phase difference. It's the kind of thing that is often used for
> diversity reception in the horizontal plane, but it could be done with
> over/under dipoles as well. It works in a browser because the relative
> phase of two RF signals is preserved in the conversion to audio.
>
> The app could also incorporate phase shifting of one signal and then
> adding or subtracting it from the other to achieve directional beaming.
> The volumes could be equalized just using the knobs on the rig.
>
> I haven't done it yet, though. And it might be simpler just to buy an
> SDRduo and run it using SDRuno in diversity mode. No reason that it
> couldn't be done with over/under dipoles.
>
> In all cases, a small oscillator (crystal controlled or something like
> the popular Silicon Labs programmable ICs) positioned between the two
> antennas could provide a reference to compensate for the phase
> difference in the two feedlines.
>
> Dave AB7E
>
>
>
>
>
> On 1/15/2026 11:25 AM,kq2m@kq2m.com wrote:
>>> It's sort of like ionospheric propagation - you can use VOACAP and
>>> it's ilk, which make some simplifying assumptions (Chapman layers,
>>> etc.) or you can just use PHARLAP (which is a full on 3D raytracing).
>> Or you can operate a lot and learn how propagation actually works in
>> real-time by observing the constant changes in path, wave-angle,
>> signal strength, etc. and have fun working people too!
>>
>> And then, when you become a propagation master, you can start to
>> predict what will happen next just by listening to subtle changes in
>> the band noise. That's way beyond VOACAP or any propagation program
>> that exists.
>>
>> 73
>>
>> Bob, KQ2M
>>
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