Ham Radio KML QSO Animated Map Time Stamps Restored... Almost Completely

This setting goals thing just might work.

The day after I set the goal to find a new time icon solution for the animated kml QSO maps a solution appeared. I was studying (again) the new Google Charts API, hoping it might be similar enough to the old visualization API to provide a solution—it was not—when I looked at the new map chart, more for the fun of it than for any other reason, and there it was: the answer I'd been looking for. Mind you, the answer was not in fact the chart API itself. The answer came in the form of map marker icons.

Allow me to give you a little background and/or catch you up. Google Earth Pro map animations are very cool. We use them to watch QSO frequency during POTA and SOTA activations, and have more than once used them to observe that our overseas QSO were in fact gray line QSOs. But, it's very difficult to see the tiny time indicator on the animation play controls.

That's OK though because there's a way to fix the issue. The kml screen overlay tag displays images on a map. Clearly, I just need an image that contains text designating each time of interest. With the deprecated chart API, this was a simple matter. The API returned PNG images intended to be displayed on web pages. I used the text bubble visualization specifically. It accepted an argument for the text it displayed. Simple. Then, it went away. (To be fair, the API has been 'deprecated' for a little over a decade.

So, I was back out on the streets looking for a way to get pictures of arbitrary timestamps from somewhere... anywhere really... on the web. Which leads us back to the new Google Charts API. For supported charts there's a getImageURI method that outputs raw PNG data representing the chart. (I'm going to use this method to display elevation charts, and therein lies the solution for displaying callsigns with the timestamps ala elevation chart titles... Anyway.)

That solution wouldn't work for timestamps thought, and as of today, there are no charts whatsoever that just dump out text. So, seemingly no solutions there, but wait! As I was browsing through the map chart docs, I noticed an offhanded reference to an online icon warehouse that could be used for map pins. It was exactly what I needed! I only had to browse the icon catalog for a few minute to find what I was looking for: a collection of 48 pixel wide icons each displaying a single decimal digit. To display a single one of these digits, I can use a URL like this:

https://icons.iconarchive.com/icons/twitter/twemoji-alphabet/48/Number-0-icon.png

To display the time down to the minute in the kml jinja template I used four blocks like this one:

<ScreenOverlay>
<name>Map Time{{loop.index}}</name>
<Icon>
<href><![CDATA[https://icons.iconarchive.com/icons/twitter/twemoji-alphabet/48/Number-{{ map_minute.11 }}-icon.png]]></href>
</Icon>
<drawOrder>{{loop.index}}</drawOrder>
<overlayXY x="0" y="1" xunits="fraction" yunits="fraction"/>
<screenXY x="0.10" y="0.1" xunits="fraction" yunits="fraction"/>
<rotationXY x="0" y="0" xunits="fraction" yunits="fraction"/>
<size x="0" y="0" xunits="fraction" yunits="fraction"/>
<TimeStamp>{{ map_minute }}</TimeStamp>
</ScreenOverlay>

And voila! The time labels are back!

Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

Now available as a Kindle ebook for 99 cents ! Get a spiffy ebook, and fund more physics The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems , there seem to be fewer explanations of the procedure for deriving the conversion, so here goes! What do we actually want? To convert the Cartesian nabla to the nabla for another coordinate system, say… cylindrical coordinates. What we’ll need: 1. The Cartesian Nabla: 2. A set of equations relating the Cartesian coordinates to cylindrical coordinates: 3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system: How to do it: Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables. The chain ...

The Alcubierre Warp Drive Tophat Function and Open Science with Sage

I transferred yesterday's Mathematica file with the Alcubierre warp drive[2] line element and space curvature calculations to the +Sage Mathematical Software System today, (the files been added to the public repository [3]). If you haven't used Sage before, it's a Python based software package that's similar in functionality to Mathematica. Oh, and it' free. I also worked a little more on understanding the theory, but frankly, I made far more progress with the software than the theory. What follows will be a little more of the Alcubierre theory, plus, a cool Sage interactive demo of one of the Alcubierre functions[1], as well as a bit about my first experience with using Sage. Theory The theory is fun, but it's moving slowly. Here's the chalk board from this morning's discussion Alcubierre setup the derivation using something called the 3+1 formalism which means we consider space to be flat, (in this case), slices that are labelled ...

The Valentine's Day Magnetic Monopole

There's an assymetry to the form of the two Maxwell's equations shown in picture 1. While the divergence of the electric field is proportional to the electric charge density at a given point, the divergence of the magnetic field is equal to zero. This is typically explained in the following way. While we know that electrons, the fundamental electric charge carriers exist, evidence seems to indicate that magnetic monopoles, the particles that would carry magnetic 'charge', either don't exist, or, the energies required to create them are so high that they are exceedingly rare. That doesn't stop us from looking for them though! Keeping with the theme of Fairbank[1] and his academic progeny over the semester break, today's post is about the discovery of a magnetic monopole candidate event by one of the Fairbank's graduate students, Blas Cabrera[2]. Cabrera was utilizing a loop type of magnetic monopole detector. Its operation is in...

Copasetic Flow

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