SDR transceiver PCB assembly |
The German magazine Funk Amateur has a new all-band 1W SDR transceiver kit in the October edition. This will sell for around $170 US and looks a very interesting project. More details from the link above.
Simple QRP projects, 10m, 8m, 6m, 4m, FT8, 160m, WSPR, LF/MF, sub-9kHz, nanowaves and other random stuff, some not related to amateur radio.
SDR transceiver PCB assembly |
137.5kHz WSPR reports so far today - with <20uW ERP! |
G3XIZ's 137.5kHz WSPR reports today |
137.5kHz WSPR TX transverter |
A research-technician-grade position is available at the Armagh Observatory funded by the EuroPlanet Research Infrastructure (RI) under the Seventh Framework Programme of the European Union (EU). Salary will be in the range £18,486 - £29,719 per annum, the exact figure depending on individual experience.
The primary aim of the project is the construction of a working instrument prototype able to (a) record and store, in digital form, electromagnetic (EM) radiation signals in the ULF/ELF/VLF frequency range (3Hz-30kHz) (b) pick up naturally-occurring radiation while screening/filtering out manmade interference in this frequency range (c) be optimised for the high-quality reception of radiation thought to originate from meteors in the Earth's upper atmosphere. In addition, the equipment should be capable of operating in the field and at remote sites with a high degree of autonomy.
G'day Roger,
I read with interest your observation of the behaviour of the "in the air" loop via WSPR.
"On 136kHz the best report was about -20dB S/N whereas on 500kHz it was +10dB. This is a difference of
30dB
!!"
I am not surprised at the 30dB difference as the radiation resistance varies with the 4th power of frequency for the same dimensions giving 23dB difference (i.e. 10 log ((136/500)^4)). In addition WSPR reports a S/N against in-band noise. Atmospheric noise is inversely proportional to frequency and there is about 36dB difference (500kHz being quieter) between 2200M and 600M. This difference is effectively reduced by man-made noise which is higher wrt to atmospheric noise at 500kHz compared to 136kHz. This reduces the difference in noise levels from 36dB to about 10dB to 15dB (depending on location). Therefore I would expect about (23 + 10) = 33dB to about (23 + 15) = 38db difference between WSPR reporting for 2200M and 600M.
Your measurements are reasonably close to this - given there would be other differential effects such as ground loss.
Keep the interesting stuff coming !!!
73 Steve Olney - VK2XV
It was written in 1981 by David Harkins. See http://www.poeticexpressions.co.uk/You can shed tears that he is goneOr you can smile because he has lived
You can close your eyes and pray that he will come backOr you can open your eyes and see all that he has left
Your heart can be empty because you can't see himOr you can be full of the love that you shared
You can turn your back on tomorrow and live yesterdayOr you can be happy for tomorrow because of yesterday
You can remember him and only that he is goneOr you can cherish his memory and let it live on
You can cry and close your mind, be empty and turn your backOr you can do what he would want: smile, open your eyes, love and go on.
See http://solarscience.msfc.nasa.gov/images/ssn_predict_l.gif |
136kHz TX transverter |
My 20uW ERP QRSS3 signal as received by G3XIZ |
WSPR Reports today |
Russia invading Ukraine was clearly wrong. What I am unsure about is Russia's intentions afterwards . In the end I suspect some of Ukra...