I run a Raspberry pi Zero W device which feeds data to the FlightRadar24 web site.
The receiver comprises a dedicated antenna covering the SSR frequency range (1,030 to 1,090 MHz), a high quality multipole cavity RF filter, a direct conversion digital radio receiver front-end (which you may recognise as a modified USB Digital TV receiver stick) and a Raspberry pi Zero W computer (RPi).
The processing of the signals is dealt with entirely within the RPi which runs a cut-down version of Linux and a special processing package provided by the FR24 service. In addition, the RPi runs BOINC grid computing software to ensure maximum use of resources.
The antenna is currently located indoors in the roof space above our garage. This will be upgraded to an outdoor mast on the side of the garage once planned refurbishments works on the garage have been completed during early 2023.
The most important part of the received, perhaps surprisingly, is the multipole cavity filter. With relatively low insertion loss and very high out of band rejection the filter renders the receiving chain more or less immune to interference from other sources. This improves the signal-to-noise of the wanted in-band signals received by the DVB-T stick. The DVB-T stick receiver has zero front-end filtering and although the device that I use has been upgraded with a higher quality local oscillator and better front-end components, the device will still have a relatively poor intermodulation characteristic. As a conseqnence, additoin of any front-end filtering is bound to reduce the level of intermodulation products caused by more or less any received signals in the DVB-T stick's reception range, notionally 50MHz to 2.2GHz!
Addition of the front-end filter more than quadrupled the average range of the receiver system overnight!
For maximum availability the ADSB receiver system is powered from a UPS. The limiting factor on the availability is the long-term stability of the FR24 software. At the moment, anecdotally, the device needs to be re-booted about once every 2-4 weeks. The underlying Raspbian linux OS will stay up for much longer. I have had one of these devices running for nearly one year without a reboot. It wasn't doing any work, though.
For a number of years I have supported grid computing initiatives such as BOINC and WorldCommunityGrid (WCG). In so doing I have amassed a number of merit points from WCG in particular.
What is Grid Computing?
Grid computing is a general term used to describe the distribution of a large number of computation tasks amongst (typically) a large number of client machines. Each machine typically carries out only a small part of the very large calculation. However, in so doing, the user gains access to a vastly more powerful computational engine than he or she might otherwise have been able to afford.
Grid computing has been used for analysis of computational chemistry tasks such as looking at how certain drugs might interact with certain known molecular receptors on cancer cells.
Using the BOINC engine, grid computing systems such as WCG make use of 'spare' CPU, memory and GPU capacity in a user's (say) desktop machine to work on the grid tasks. The user is unaware of the work taking place. This is usually because the modern operating systems are very wasteful of computing power - the grid tasks fit in the spaces otherwise wasted in the CPU's agenda.
Machines dedicated.
I run the BOINC client on my laptop and desktop machines (Mac-OS and Window$) and also on a number of ARM based Raspberry pi computers. There are fewer client tasks, currently, for the ARM CPUs than for INTEL based systems.
For the INTEL based systems I exclusively run WCG clients but since late 2022, when WCG has become erratic in its supply of work units for ARM based machines, I have added the LHC (Large Hadron Collider) and Universe clients to the ARM based machines. The ARM machines are, as it happens, more available than the INTEL based machines because they run other 24/7 projects and are supported by a UPS.
It's easy to get started creating your website. Knowing some of the basics will help.
What is a Content Management System?
A content management system is software that allows you to create and manage webpages easily by separating the creation of your content from the mechanics required to present it on the web.
In this site, the content is stored in a database. The look and feel are created by a template. Joomla! brings together the template and your content to create web pages.
Logging in
To login to your site use the user name and password that were created as part of the installation process. Once logged-in you will be able to create and edit articles and modify some settings.
Creating an article
Once you are logged-in, a new menu will be visible. To create a new article, click on the "Submit Article" link on that menu.
The new article interface gives you a lot of options, but all you need to do is add a title and put something in the content area. To make it easy to find, set the state to published.
Template, site settings, and modules
The look and feel of your site is controlled by a template. You can change the site name, background colour, highlights colour and more by editing the template settings. Click the "Template Settings" in the user menu.
The boxes around the main content of the site are called modules. You can modify modules on the current page by moving your cursor to the module and clicking the edit link. Always be sure to save and close any module you edit.
You can change some site settings such as the site name and description by clicking on the "Site Settings" link.
More advanced options for templates, site settings, modules, and more are available in the site administrator.
Site and Administrator
Your site actually has two separate sites. The site (also called the front end) is what visitors to your site will see. The administrator (also called the back end) is only used by people managing your site. You can access the administrator by clicking the "Site Administrator" link on the "User Menu" menu (visible once you login) or by adding /administrator to the end of your domain name. The same user name and password are used for both sites.
Learn more
There is much more to learn about how to use Joomla! to create the website you envision. You can learn much more at the Joomla! documentation site and on the Joomla! forums.
This is a test article.
It has been written to test and understand the editor functions and content management functions of Joomla!
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