Allsky camera, Electronics, Linux system development

Connecting HTU21D temperature/humidity sensor to the Raspberry PI using simple C i2c interface

Previously in my projects, I’m always used well-known DHT22 (AM2302) temperature/humidity sensors. But I found that these sensors are not very stable and subject to hung. In my case, this device is worked for about two weeks and then stops responding until the power is rebooted. This is absolutely unacceptable on some distant and autonomous devices. After some googling, I…

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Astro tools, Electronics

Isolated eqmod adapter for the telescope control

There are popular and quite cheap amateur telescope mounts from different vendors: Sky-Watcher, Celestron, etc. Most of those mounts contain motors and some controller schematic. Users can control these devices in different ways. One way is to use the mount’s hand controller. Another way is to connect to the computer and use some software to control and guide the telescope.…

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Linux kernel, Linux system development, Networking

Monitoring Linux networking state using netlink

Once in my work, I needed to monitor all changes in the Linux networking subsystem: adding or deleting IP addresses, routes, etc. Maybe the best way to do this is to use socket-based Netlink technology. Using Netlink, we can “subscribe” to some network-related notifications from the kernel. It’s also possible to send commands to the network stack and change the…

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Radio & antennas

144 MHz Yagi-Uda antenna

Yagi–Uda antenna is a directional and pretty effective antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of metal rods. The Best-known use of this type of antenna is as rooftop terrestrial television antennas, but it is also used for point-to-point fixed communication links and long-distance shortwave communication by shortwave broadcasting stations and radio amateurs. This…

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Astro tools, Software

Converting DSLR RAW images into scientific FITS format. Part 1: UI

FITS is an open standard defining a digital file format useful for storing, transmitting, and processing scientific and other images. FITS is the most commonly used digital file format in astronomy. Unlike many image formats, FITS is designed specifically for scientific data and hence includes many provisions for describing photometric and spatial calibration information, together with image origin metadata.  (Wikipedia…

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Allsky camera

Connecting MLX90614 infrared thermometer to the Raspberry PI

MLX90614 is a cheap and popular infrared thermometer from Melexis. This device is made in different versions for different purposes. You can get a general-purpose version with 0.5 accuracies or for medical purposes with accuracy up to 0.2. Also, you can choose the voltage you needed: 3.3v or 5v versions are available. With MLX90614, you can distantly measure the objects’…

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