In 2019 i’ve written that the SQ5BPF grabbers will be temporarily offline and should return in winter 2019. Unfortunately this “moment” got extended to august 2021.
Now, finally, I’m trying to reactivate them, The VLF antenna has been installed again. For now I’ve activated the ZEVS 82Hz and VLF 8270Hz grabbers. Because of changes in vlfrx-tools noiseblanker from versions 0.6 to 0.9, i will be trying to find the parameters for best reception, so please stay tuned, the grabbers might not be operating at their best right now.
Due to the ongoing (on 20 august 2019) rescue operation in the Wielka Śnieżna Cave in the Tatra mountains we decided to write about cave communications.
Rocks and soil attenuate radio signals well. Despite of this some means of communications in caves and mines are needed.
The attenuation rises with frequency. Normal VHF communications gear can’t be used, sometimes the distance can deteriorate to meters, depending on the geology and shape of tunnels. Of course cell phones are totally out of the question too. Shortwave radio behaves only a bit better.
Much larger distances can be achieved using low frequencies.
This is probably the first VLF signal which has been transmitted from Poland after World War II. We are not aware of any military or other transmissions. Before the war we had the Babice Transatlantic Radiostation (callsigns AXO/AXL/SPO/SPL), which was similar to Grimeton/SAQ.
The RSGB LF Reflector is the most important group for low-frequency enthusiasts. For many years list members have been witnesses to milestones in the 136kHz, 73kHz, 500kHz, 472kHz, VLF and lower bands. Many posts have great historical significance.
In the beginning this archive spanned from 2014 up to now. Recently we imported archives kindly donated by Dave G3YXM and Markus DF6NM. Thanks to them the archive now spans from February 1999. 20 years of radioamateur longwave (and medium-wave) radio history!
Sadly the NDB BIA on 474kHz in service at Rzeszów Airport has been turned off.
For many years the carrier at 474kHz and the sidebands at 473kHz and 475kHz were used by polish radioamateurs to check their 630m equipment. Foreign radioamateurs used this NDB to judge the propagation to Poland.
This will change the way we work in the CW segment in the 630m band in Europe. Up to now we had to use 472-472.7kHz or around 473.5kHz, and a narrow filter was necessary. After BIA is switched off we can use the whole 472-475kHz segment, also with wider filters.