Generate radio coverage maps with SPLAT!

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SPLAT! is a cross-platform, open-source software that can be used to analyze a radio link between two locations and to generate coverage maps of RF transmitters. Coverage maps are calculated using Longley-Rice Irregular Terrain Model (ITM) algorithm. SPLAT! can predict RF coverage for any frequencies between 20 MHz and 20 GHz. It is thus useful for ham radio, broadcast radio, terrestrial television and wireless networks.

To use SPLAT!, you need to know some parameters of the transmitter. These are the exact location (coordinates), antenna height, transmission frequency, polarization and effective radiated power (ERP). SPLAT! can then compute coverage maps. The procedure of installing SPLAT! is described in a previous article. You can generate two kind of maps. There is the regional coverage analysis mode that will output line-of-sight coverage map assuming all waves propagate in a straight line. There is also the path loss analysis mode that uses the ITM algorithm to compute either a field strength map or a received signal strength map.

Install Sky Digital Key (AverMedia A867) on PC

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Sky Digital Key is an USB DVB-T tuner designed to be used with this provider's satellite receivers. There are two variants, one with green LED and the other with blue LED, the last being an AverMedia device with Maxlinear MxL5007T tuner and Afatech AF9035 USB demodulator.

The DVB-T key can be installed on PC too. However the driver installation is not quite straightforward. The device is a copy of AverMedia AverTV Volar HD Nano with two small differences: there is no remote control sensor on Sky key although the PCB has the pads for it and USB IDs are different for the two devices. This aspect makes drivers installation difficult.

This article will describe the installation procedure on Linux and Windows. The USB tuner can be used to receive DVB-T signals with BDA compatible software on Windows (such as ProgDVB) and Kaffeine on Linux.

Install Sky Digital Key (AverMedia A867) on PC
AverMedia A867 - Sky Digital Key

Show last updated date in Blogger posts

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Although this is not the kind of post for this blog, I decided to write about this because there are opinions saying it is impossible to show updated date in Blogger posts. Blogger offers support only for the date when a post is published. You can, of course, edit the post and change published date, but that is not what most people want.

The method that follows is completely automatic and it will print the last date when you used the post editor on the specific post. It makes use of data stored in blog feed, because, although there is no tag for updated date in Blogger (something similar to published date tag data:post.timestamp), the updated date is stored in your blog feed. I first noticed this when I registered my blog on Tapatalk and noticed that updated posts appeared on top of the list.

Show last updated date in Blogger posts

Remove non-latin fonts from Ubuntu

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The default Ubuntu installation comes with a lot of fonts. This is a good thing. Many of the latin have good support for Extended character sets. But no matter what locale and/or installation language you choose, Ubuntu will install by default some non-latin fonts for Japanese, Thai, Ethiopian, Myanmar, Lao, Tibetan, Korean, Punjabi, Sinhala, Arabic and Khmer languages.

I don't know whether these fonts are ever needed by the operating system (i.e. for the language choosing settings or for displaying some web pages) but as a latin alphabet user I don't need them and I didn't like the fact that they were cluttering my font selection dialog without being of any use to me. So I decided to uninstall them.

The list below is tested on Ubuntu 16.04. I managed to free about 100 MB by removing these fonts. And now, my font selection box (in LibreOffice, GIMP, Inkscape, etc.) is filled with latin only fonts that I can use. You can see in the screenshot below how it looks before and after removing the unneeded fonts.

Remove non-latin fonts from Ubuntu

Radio link analysis using SPLAT!

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SPLAT! is a cross-platform, open-source software that can be used to analyze a radio link between two locations and to generate coverage maps of RF transmitters. Coverage maps are calculated using Longley-Rice Irregular Terrain Model (ITM) algorithm. SPLAT! can predict RF coverage for any frequencies between 20 MHz and 20 GHz. It is thus useful for ham radio, broadcast radio, terrestrial television and wireless networks.

To use SPLAT!, you need to know some parameters of the transmitter. These are the exact location (coordinates), antenna height, transmission frequency, polarization and effective radiated power (ERP). SPLAT! can then calculate both path loss and received signal strength.

The procedure of installing SPLAT! is described in a previous article. The point-to-point analysis calculates some useful parameters like: azimuth and elevation of receiving antenna, distance to transmitter, mode of propagation, received signal strength and density. You must also supply a receiver parameters file to SPLAT!. This will contain the location, antenna height and some other terrain parameters. SPLAT! will generate a report and a graph if you have Gnuplot installed.

SPLAT! height profile graph
SPLAT! height profile graph