New Year 2020: Excellent inversion over Poland

Ten wpis jest dostępny także w języku polskim: Nowy Rok 2020: Rekordowa inwersja nad Polską

This year’s winter in Poland is very mild and it does not resemble such a season in our country at all. In fact, it looks like late autumn with possible light frosts. The forecasts for the most part of January are still in line with current weather, so this month should be definitely warm. Starting from the end of December 2019, subsequent high pressure systems began to move to Poland from west. Such a weather favors good propagation, which can significantly increase the range of radio emissions. An inversion in the troposphere can enhance the reception in a wide frequency range, starting from the lower VHF (typically 50-70 MHz), through broadcast radio, television, microwaves and even… optical waves.

My DX equipment consists of RocketDish 5G31-AC antenna with DBII F52N-PRO radio on the top of a 18 m mast with a rotor near Płock, Poland (114 m ASL).

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Laptop upgrade: Dell Latitude E7440 → E7270

I have been using my Dell Latitude E7440 laptop (i7-4600U / 16 GB RAM / 480 GB SSD) literally every single day for almost 6 years. I still say this is the best laptop ever built. I’ve been looking for a upgrade for quite a long time though. However, I could not wait any longer, because my current laptop would require some expensive investments, including new:

  • High-capacity battery – that would be the third one (original $100).
  • Keyboard – that would be also the third one (original $50).
  • LTE Cat 6 miniPCIe module – to replace the Cat 4 modem ($100).
  • Some case elements – e.g. bottom cover with rubber feet, but also palmrest w/ touchpad in the near future…

In fact, no wonder that I could not find anything suitable for a very long time, because my requirements for a new laptop were very detailed and specific. 

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MikroTik RouterBOARD hardware disappointment

I’ve been lately looking for a small 10/100M Ethernet switch with a USB and both PoE input and output port (Power over Ethernet). The MikroTik RouterBOARD hAP (RB951Ui-2nD) looked pretty good, so I ordered one. The 2.4 GHz Wi-Fi interface was unnecessary, but the price was acceptable anyway, as I found a used device in excellent condition at just $25 including shipping.

As usually, the first thing I did after receiving the package was the teardown. The PoE ports are usually dedicated for some remote devices connected with long Ethernet cables and located outdoors. Therefore, a special protection should be included in the front of the controller (QCA9531 SoC in hAP). Unfortunately, this is not the case of RB951Ui-2nD. Although the engineers designed the PCB of this device with TVS diodes on both PoE input and output ports, the final product does not contain them. Protection for other ports was not planned at all.

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Arduino Uno R3 failure

Recently I’ve got a genuine Arduino Uno R3 from my friend to repair. The problem with his board was actually very generic – it has just stopped working. Personally, I don’t buy such boards, because  they are extremely overpriced. I have been using several Chinese clones around for years and I have not encountered any problems so far.

At first sight, the USB interface was working fine and the board was detected by the system without any problems.

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Warflying (Wi-Fi scanning) in an airplane up to 450 km

Recently I was traveling by plane over Europe. Of course, I could not resist to check what could be received on 5 GHz there, at an altitude of over ten kilometers…

I took the following equipment for Wi-Fi scanning onboard:

  • Mikrotik Routerboard SXT 5HPnD (AR9280),
  • Raspberry PI 3B with GNSS receiver, RTC and 10 V PoE output – see more: Wardriving @ 5 GHz,
  • USB power bank (5V/2.1A),
  • Nexus 7 tablet.

I was scanning using MikroTik SXT antenna with a built-in radio module. This device is as small as 14×14 cm. The dual-polarization antenna rated at 16 dBi is even smaller, at just 11×11 cm. It was connected to Raspberry PI single board computer.

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June 2019: London, Manchester and Cardiff via tropo in Poland

Ten wpis jest dostępny także w języku polskim: Tropo: Londyn, Manchester i Cardiff w Polsce

The early morning of June, 27th 2019 brought one of the biggest tropospheric propagation from Western Europe we have ever observed from Poland. Looking at the results, it can be stated that it was the strongest tropo on the VHF FM band 87.5-108 MHz from the territories of England, the Netherlands and Belgium for at least 15 years (probably since ever), with many transmitters and areas received for the first time. The received signals reached the stereo and even RDS quality on many frequencies, and the maximum distances exceeded 1500 km.

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