Copasetic Flow

  I follow both SolderSmoke and Ham Radio Work Bench, so I've been avidly watching the SolderSmoke driect conversion reeiver challenge thrown down by Bill Meara. Bill's said something for year's that's intrigued me: you gotta be able to understand how an RF mixer works. That was paraphrased, of course. I haven't had much success along those lines until today.  Looking at the Wikipedia entry for Frequency Mixers, I bludgeoned my way through the diode section, and I finally get it. (OK, I'm a little miffed that I have to take on faith the expression for the current through an ideal diode, but I can let that slide for the moment.) Lo and behold, after a series expansion and a binomial multiplicaiotn, there was the promised expression for the sine of one frequency times the sine of another. Using a high school trig identity, that can be rewritten as a sum of waves one of which is the sum of the two frequencies and one of which is the difference. That's not al...

 I made the first release of the package yesterday. The case for finding the shortest distance from the point to the path when the distance is not along a perpendicular to the path has been implemented . The package has been released with the tag 0.1 .

 I got to play around with spherical trig last week under the guise of improving the accuracy of the model that KO6BTY's and my F2 skip maps utilize.  Today, I took the first steps towards formalizing the algorithm I modeled into a datasette plugin so we can use our kml plugin to create skip maps (I'll probably also add a configuration flag to turn skip mapping on and off.) Using datasette-haversine as a model, I created datasette-haversine-point-path . The new plugin allows users to specify three lat/lng pairs that define the enpoints of a QSO and the location of an ionosonde. Given this information, the newly defined sqlite method will return the shortest distance between the ionosonde and the QSO's propagation path along the Earth. (I still need to add the special case where the shortest distance to the path is in fact between the ionosonde and one of the endpoints. I'll talk about this in my next post.) I re-puprosed the test case from datasette-haversine as wel...