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From Scratch: building a Time Domain Reflectometer

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TDR or Time Domain Reflectometry is a method for measuring transmission lines - cables and alike - used for the transmission of high-speed signals. TDR can be used to check the length of the cable, can detect the presence and the place of a short, break, and other errors. First, let's take a look at what we're going to build and what we can do with it.

Installing Kubernetes on my Ubuntu laptop

Why? Since the company I'm working with uses Kubernetes in production, I like to have a sandbox handy to try upgrades and just for general experimentation. Prerequisites I'm using Ubuntu 19.04 "Disco Dingo". I'm going to install Kubernetes v1.15.4. The current newest version works a bit differently that makes the latest stable flannel release not to work properly. The procedure below can probably be repeated with now-current (in reader-time :) ) versions as long as they're compatible. Docker The docker I choose is version 18.09 . Check the supported docker version with your  Kubernetes version. Do not skip this step. I found this information in the release notes for v1.15:  https://v1-15.docs.kubernetes.io/docs/setup/release/notes/ Flannel I'm using flannel with the local installation. The latest stable at this time is v0.11.0. I found no information on the compatiblity of different flannel and Kubernetes versions, so I just tried the late

Building a radiation detector from scratch 4 - Detector MK II

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Since I'd like to keep up with the head-spinning pace of interesting articles, let me present you this year, :) the In the last episode I described an ion chamber radiation detector. It works very well: stable and sensitive enough for doing simple experiments. It can be improved though in several ways. Here follows a series of ideas and a circuit diagram. :) I did not build this yet, but I'll build it "soon". In this decade, or the next. :P

Contacting the International Space Station

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The International Space Station (ISS) is a huge (>400 tonnes mass, >900m3 pressurized volume) habitable satellite on low earth orbit. It orbits the Earth at about 400km high with a speed of 7.67km/s (27,600 km/h), and goes around it in about every 93 minutes. It's permanently crewed, can support up to 6 astronauts, and provides a platform for many scientific experiments. Besides astrobiology, astronomy, materials science, and many other fields, it hosts experiments for the ARISS - "Amateur Radio on the International Space Station" project. ARISS experiments give opportunities to observe or even contact the station with simple amateur radio equipment.

Building WSJT-X 1.7.0-rc1 from sources on Ubuntu 16.04.1 Xenial

WSJT-X is a great desktop application for communicating via radio using various weak signal modes. I use it on the HF bands to contact amateur radio operators literally all over the world. The new 1.7.0-rc1 alpha release features a new algorithm for decoding, and it is quite a bit more effective than the previous 1.6.x versions. One of the most important parts is decoding Reed-Solomon codes. The previous versions used a proprietary decoder, this one uses a new, open-source method. Since I work a lot in JT65 and JT9 on short wave, building the new version definitely worth the struggle.

Building a radiation detector from scratch 3 - a stabilized detector

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In this chapter I'm going to show you how to build an atmospheric ion chamber for detecting radiation. The detector will have little drift, can be set to zero, and can be used to compare the radioactivity of samples, measure weak sources, or follow the decay of short half-life sources for hours or days even. These features all require that the detector to be stable, and the readings don't drift around with temperature. Temperature drift is very likely the worst offender to our previous ion chamber design, so we're going to deal with that one this time.

CUDA accelerated linear algebra with Python and Theano

Theano is a Python module that enables one to construct mathematical expressions with matrices and/or tensors (basically more than 2 dimensional "matrices"). These expressions are than can be evaluated using Python, but Theano can translate the expression into a C program and compile it to binary. This way it can achieve respectable performance. But wait, there's more! Theano can build the program so certain - or all - parts of it run on a GPU. Yes, on your video card. Modern cards can do calculations in a way that makes them especially fit for doing linear algebra and similar operations. In "similar" I mean the execution of simple operation on lots of data in parallel. A GPU-s can be several (tens or hundreds of) times better, than your CPU. I'm going to show you how to exploit an NVIDIA GPU, using Python.