It can often take a long time - several hours, for a message to come through a Yahoo group. Useless for activity alerts. Sometimes messages are lost completely, or appear in the group archives but ar
Yes, the signal was too wide, except during the initial tuneup when the pure carrier sat nicely inside one frequency bin. I should think so. And still easy to read from the spectrogram. And gain mayb
It is encouraging to see interest in amateur tx experiments in the VLF band. Calculations suggest that ranges of 100km or more would be possible with QRSS given about 1mW ERP which is not an unreason
Oh, rather a cone shaped coil. That will alter my overtone calculations. They are important if you are driving the coil with a switching waveform, as the system will happily ring on each edge and ra
Stefan schrieb: I have already used every trick possible - the rx sensitivity at 9kHz is as good as it can be. I can think of no electronics or signal processing that will make further significant im
I just looked up QRB. Michael Oexner: 72km Wolf DL4YHF: 264km Renato IK1QFK: 544km Markus DF6NM: 179km Uwe DJ8WX: 461km Henny PA3CPM: 367km Jim M0BMU: 665km -- Paul Nicholson --
Yes you did! I am following your lead with this 1/sqrt(r) thing and the exponential factor. And it is working - it is giving the right answer for Stefan's signal! 3dB per 1000km (daytime) is mentione
Stefan schrieb: Well, to extrapolate so far from a single data point would be very silly. But silly can be fun, so .... Given B = sqrt( 9.5e-21 * ERP/r) * exp( -r/a) where a = 2.9e6 for daytime path,
Got the 2nd K here on the oriented loops. For the first K the noise bearing was too close to the signal bearing. Now the noise is changing bearing again. I will make a spectrogram from the omni loop
Could be a good day today for 9kHz tests, the background noise is very low. http://abelian.org/vlf/nb.shtml Now shows the amplitude spectrum when the loop pattern is rotated to null the average beari
Yes, I get the same answer for that loop and current. I am finding it is well worth orienting the loop to null the average direction of the prevailing VLF background. There is nearly always around 6d
Stefan schrieb: Thanks, that was a good field trip in the best amateur radio tradition. Ironic how we are at the same time using the most hi-tech, but also the simple batteries, kites, wires, big coi
Many good whistlers rxed nr Bielefeld last night by Wolf, http://abelian.org/vlf/events.php?stream=vlf6&page=0 and so on for four more pages. Short interruption to the downlink here Wolf? http://abel
I agree with Alexander, 10kV is not so high. If you were looking at > 30kV or 40kV or so, then it might become an issue. But even then it can be controlled at the ends. I think it just has to be trie
I've been reading up about the Austin-Cohen formula, originally an empirical determination, valid only for long waves (> 200m): signal strength proportional to exp( -alpha * r/sqrt(lamda)) where alph
Stefan Schäfer schrieb: I ran this info through a modelling program, with a guess that the wire is 26awg:- Ldc: 482mH Rdc: 258.3 ohms Resonances, unloaded, base grounded, stood vertically 10cm above
That's a step forward. Up to now we've tried B = sqrt( 9.5e-21 * ERP/r) * exp( -r/a) where a = 2.9e6 for daytime path, or 4.3e6 for nighttime path. This assumes radiated power is spread uniformly ove
No wonder it is called 'natural' radio. But not half as strange as Saturn's aurora recorded by Cassini, http://www.nasa.gov/wav/123163main_cas-skr1-112203.wav This emission was 50-60kHz, 27 minutes
Nice work Piotr. I'd like to see a plot of signal strength against distance for 70km ionosphere and see how it compares with the simple model in http://abelian.org/vlf/9k Too bad we are stuck with th
Bearing was 78/258 deg +/- 4, NWC is on 82.4 deg and the GC paths are 13650km and 26380km, difference is 12730 km along the ground, or 12810 at mid height of Earth-Ionosphere waveguide. Resulting int
