Skip to main content

Weeknotes: Stabilizing the PicoW Autokeyer; Ionosonde Distance to a QSO Path; Starting Google Visualization Conversions

 The gang, (12 year-old Diaze aka KO6BTY, 11 year-old Mota, and 8 year-old Tawnse), and I did things with vector cross products, operated Raspberry Pis in the face of radio frequency interference (RFI) and started to update the ham radio exams Javascript charting package calls this week.

Ionosphere and Cross Products

KO6BTY and I put together kml files that show the approximated F2 skip of a QSO last year. The maps are very approximate because they only take the Pt Arguello ionosonde down the coast from us into consideration. To determine what other ionosondes to use data from, we needed to know how far each of the ionosondes was from the path between an arbitrary pair of QSO stations. In other words, we needed to work with spherical trigonometry. The first step was to figure out the algorithm. The solution was easy to find on StackOverflow, but it was hard to picture at first. I fixed that by getting back into using Sage for demos. The final step is shown below.


Raspberry PI RFI

KO6BTY and I built an auto-keyer for the her FT-840. It worked pretty well, but had RFI issues. Over the course of the week, we've isntalled a balun on her dipole, moved the keyer and the laptop that controls it, and shortened interconnect wires in the keyer. We're now able to key the transmitter on 10 meters at the rig's maximum power without the keyer rebooting.


Google Visualization Chart API Update

The chart API we've been using for the ham radio exams changed. More than a decade ago as it turns out. I'm working out how to assign the necessary updates as worksheet sort of assignments for the gang. This is a big experiment because I am mostly un-enamored of the whole worksheet model. The gang's schedule, and mine are getting too busy to easily support the talk-it-through while doing it model of unschooling learning that we've had really good success with until now though.


Coming up:

I'm starting to design a Datasette enabled version of the ham radio practice exams. It just makes sense. I used to widely distribute them as a Google App Engines deployment, but that's been a lot of work. Having something that's open-source and that just does the job for the gang and myself sounds pretty cush.


Labels:

Comments

Post a Comment

Please leave your comments on this topic:

Popular posts from this blog

More Cowbell! Record Production using Google Forms and Charts

First, the what : This article shows how to embed a new Google Form into any web page. To demonstrate ths, a chart and form that allow blog readers to control the recording levels of each instrument in Blue Oyster Cult's "(Don't Fear) The Reaper" is used. HTML code from the Google version of the form included on this page is shown and the parts that need to be modified are highlighted. Next, the why : Google recently released an e-mail form feature that allows users of Google Documents to create an e-mail a form that automatically places each user's input into an associated spreadsheet. As it turns out, with a little bit of work, the forms that are created by Google Docs can be embedded into any web page. Now, The Goods: Click on the instrument you want turned up, click the submit button and then refresh the page. Through the magic of Google Forms as soon as you click on submit and refresh this web page, the data chart will update immediately. Turn up the:
Post a Comment
Read more

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
10 comments
Read more

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 concept very sim
Post a Comment
Read more