Dish antenna for the amateur radioastronomy

In the previous article I discribe low noise amplifier for the 21cm band. Today I wanna show you construction of the dish antenna where this amplifier can be used.

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Low noise and low cost amplifier for radio astronomy, 21 cm band.

21 cm band also known as Hydrogen line is one of the important bands in radio astronomy.

Please read this wikipedia article if you not familiar with Hydrogen line.

Nowadays even radio amateurs can observe this signal from the outer space, thanks to modern hardware.

One of the most important part of the any receiver is antenna and input stage. Typically input stage is some kind of the amplifier with extremely low noise and high gain due to weakness of the space signals.
In this article I want to describe simple and cheap amplifier for the first stage of the receiver.

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Powerful DC motor driver using IR2110

To control speed and rotation direction of the DC motor we need some type of the motor driver, one of the most popular schematic is H-Bridge. For the low current and voltages we can use some integral solution like L293D and so on. But if we need more power and reliability we have to build some custom H-bridge using mosfet transistors. This type of the transistors requires careful and proper driving itself. One of the most popular integral solution for driving mosfets is IR2110 from Infineon.
In this article we will discuss how to use this IC to build powerful DC motor driver.

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Autonomous Allsky camera with Raspberry PI. Part 3: shooting night sky in FITS using QHY5-IIM camera

This is a third part of the Allsky cycle.

Please read previous articles to get complete information about this project:

Part 1. Autonomous Allsky camera with Raspberry PI: overview.
Part 2. Autonomous Allsky camera with Raspberry PI: powering and lightning protection

This time I will show my utility and script for shooting night sky and processing of the images.

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Converting DSLR RAW images into scientific FITS format. Part 2: working with LIBRAW

In the previous article I’m started to describe my Raw2Fits converter. It was a brief note about GTK user interface development.
Now I wanna talk about LibRaw library. This is a great library for reading RAW files obtained from digital photo cameras (CRW/CR2, NEF, RAF, DNG, and others).

Take a look at the LibRaw project web page and official documentation.

I highly recommend to always use latest stable release from this site instead of precompiled version from Linux distros.

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Isolated USB to RS485 adapter

RS485 is a standard for use in serial communications systems. Electrical signaling is balanced, and multipoint systems are supported. This communication standard is used in a wide range of computer and automation systems. RS-485 is used as the physical layer underlying many standard and proprietary automation protocols used to implement Industrial Control Systems, including the most common versions of Modbus and Profibus, also used in building automation as the simple bus wiring and long cable length is ideal for joining remote devices. It may be used to control video surveillance systems or to interconnect security control panels and devices such as access control card readers.

In this article I will show how to build simple and reliable USB to RS485 adapter with galvanic isolation and ESD protection.

Take a look at the second version of this adapter.

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Autonomous Allsky camera with Raspberry PI. Part 2: powering and lightning protection

This is a second part of the Allsky cycle and I want to describe powering and protection of this device.

Please read first part to get basic information about this project.

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Autonomous Allsky camera with Raspberry PI. Part 1: overview.

Allsky (or weather) camera is one of the most important part of the modern observatory.
It’s very important to monitor sky condition during night observations, especially when observatory is remote controlled or should be fully automatic. Different vendors provides different solution. But all they are share the same problems: very high prices, lack of autonomy (PC is required) and lack of useful sensors like a temperature, sky temperature and so on. So, to build complete system you need: camera itself, PC, weather station, cloud sensor. Full price and complexity of this system is very high.
But this not a Jedi path, right?
With this article I’m starting the cycle of the materials dedicated to fully autonomous device, based on Raspberry PI. This device contains two cameras and a lot of sensors.

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Simple Linux character device driver.

Character device is a one of the simplest way to communicate with module in the Linux kernel.
This devices are presented as special files in a /dev directory and supports direct reading and writing of any data, byte by byte, like a stream. Actually most of the pseudo-devices in /dev is a character devices: serial ports, modems, sound and video adapters, keyboards, some custom I/O interfaces. User space programs can easily open, read, write and do custom control requests with such device files.
Here I describing how to write a simple Linux kernel module which can create one or multiple character device.

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