The Othernet Bullseye BE01 Ku-band Low-Noise Block-downconverter features a tunable 2 ppm TCXO, a 25 MHz reference output, and extended coverage for QO-100 reception. In this article I discuss its specifications, internal construction and performance.
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Since 2019-02-14, licensed amateur radio operators can videoconference via QO-100, the first amateur transponder in geostationary orbit. In this article I explain how to receive some downlink signals with affordable off-the-shelf equipment and open-source software. I also discuss the current limitations of this approach relative to existing solutions. *** Work in progress ***
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In this article I document the internal construction of several off-the-shelf Ku-band low noise block downconverters (LNB/LNBF) from the perspective of amateur radio applications.
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LeanTRX adds a web interface to the LeanSDR toolkit. Its main purpose is to turn embedded SDR platforms into user-friendly, multi-mode RF modems which can be controlled with any web browser. Potential applications range from handheld transceivers to Internet-connected networks of ground stations.
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In this article I explain how to demodulate Outernet L-band satellite broadcasts with leandvb . Note The Outernet L-band service was terminated in early 2018. The techniques developed for this project may still be relevant to other low-cost narrowband applications such as amateur satellite telemetry.
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In this project I try to make dry ice by cooling carbon dioxide to -80°C with Peltier modules.
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A shoulder-mounted dish, tracking system and SDR receiver for amateur radio communications, originally designed for receiving HamTV digital video transmissions from the International Space Station.
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leandvb is a lightweight implementation of portions of the DVB-S and DVB-S2 standards in plain C++. It is developed primarily for receiving Digital Amateur TV from the ISS and from the QO-100 geostationary transponder. **Work in progress** As of 2019-02-12 the software and documentation are being actively updated. Expected discrepancies.
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How to receive DVB-S digital video transmissions from the International Space Station with a bit of hardware and a lot of software.
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This web page documents my attempts to assemble Linux smartphones and tablets with as few non-mainstream components, binary blobs and potential backdoors as possible. Currently the best candidate is a Lenovo Yoga Tablet 2 851 running Fedora 22.
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Many Google Nexus smartphones and tablets have a serial console which can be accessed through the headset socket. This is an invaluable tool for software development. Unfortunately there are no suitable off-the-shelf adapters on the market; therefore some tinkering is required.
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We add FPV and RC functionality to a LEGO Mindstorms EV3 vehicle with a PlayStation gamepad, USB webcams, a smartphone-based stereoscopic head-mounted display, and the alternative operating system ev3dev.
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In this project we attach a depth-sensing camera to a head-mounted stereoscopic display (think: Kinect + Google Cardboard). The resulting portable device allows users to see their surroundings in unusual ways.
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We show how to interface LEGO Mindstorms EV3 directly with off-the-shelf Bluetooth gamepads and joysticks such as the PS3 SIXAXIS and DualShock 3 controllers.
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We review 20 common misconceptions about the Bitcoin crypto-currency system and show how the reality helps predict its endgame: centralized mining, then centralized governance. We suggest that enforcing national mining quotas might be the lesser of many evils if centralization is to be avoided. More generally, we introduce the idea of maximally-distrustful oligopolies as a practical solution to distributed consensus.
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How an engineer looks at kiddie pools: tensile strength of curved walls, thermal conductivity, evaporative cooling, blackbody radiation, Sun ephemerides, and water sanitation techniques.
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One week after the disclosure of the Heartbleed vulnerability, security experts are still discovering new ways it could affect online security. This document attempts to classify attack patterns and their countermeasures as they emerge. It will help you understand whether you really need to change your passwords, why it was unwise to do it too early, and why you should know whether your browser detects revoked certificates.
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A collection of little-known, counter-intuitive or otherwise enlightening facts in various fields of science and technology.
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Digital circuit theory meets gasoline engines as we design a monotonically-adjustable, low-component-count dummy load suitable for testing electric generators in the kilowatt range.
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Got a PlayStation Move and an old vinyl turntable ? You can try to detect Earth's rotation, find geographic north, and determine your latitude.
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linmctool provides minimal support for popular Bluetooth motion-sensing game controllers on Linux: PlayStation Motion Controller (PS Move), Sixaxis, DualShock3, Wii Remote (Wiimote).
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WXHMD is a Gumstix Overo Fire computer-on-module driving a Vuzix VR920 head-mounted display: Stereoscopic 640x480, audio in/out, 3D tilt sensor, 3D magnetic compass, TI OMAP3530 @ 600 MHz, Linux, WiFi, Bluetooth, 1 amp @ 3.7 volts, 180 grams. Potential applications include secure telepresence over WiFi, and "head-mounted computing" with Bluetooth peripherals.
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For the last few years hobbyists worldwide have been experimenting with inkjet PCB printing, i.e. manufacturing electronic circuit boards with inkjet printers. This is a report on my experience with this technique.
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I argue that manufacturers of home servers and NAS appliances should standardize on the half-depth ETSI subrack form-factor and cabling conventions: 19" mounting plate, 240 mm deep, all connectors on the front panel.
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pxaRC is a collection of drivers and utilities for remote-control and robotics applications on Linux/PXA255/PXA270-based platforms such as the Gumstix basix, connex and verdex motherboards.
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This document explains how to connect a digital CMOS image sensor directly to the CompactFlash port of a Gumstix Connex computer (or similar PXA255-based platform).
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RC model helicopter prices have reached a point where all sorts of challenging (i.e. crash-prone) robotics projects become affordable. This document explains how to build a 300 g helicopter with embedded Linux and Bluetooth datalink from off-the shelf components for less than 500 EUR.
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