Seems noise level depend strong on the location. Anyway it is obvious for industrial noise. Theory confirm this empirical rule. Few years ago i do some a theoretical study of optimal signal reciepti
Dear Jim, with such a noise Stefan's signal should be detectable in QRSS100 at 100 km. Seems to be worth if such noise level takes place every day and every night. It is naturally to assume noise le
Dear LF, sometime back in 2000 I attempted to measure the daytime noise background at 9 kHz (see http://www.qru.de/vlf-theorie.html). I was using my regular LF antenna at my suburban QTH. The effecti
Andy, certanly AFTER filtering noise became gaussian. But matter of fact is that if noise is nongaussian then to get optimal reception one should make some nonlinear processing (limiting in simplest
Dear Markus, LF Group, I checked the noise level again during the daytime, and the noise level was about 6dB lower than last night, i.e. about 13uV/m per sqrtHz One possibility for the discrepancy be
Dear Alexander, LF, the frequency rulers of the modified Argo are actually correct, and you can see how I reduced the bandwidth when going further away. The minimum setting was 90 second dots, giving
Dear Markus, In what qrss mode (FFT-bandwith) you resived such a signal? P=1uW D=6km yelds E=1.3uV/m It seems to be usefull to estimate noise level. But we should normalyze this to bandwith. Regards,
Dear LF Group, As a quick experiment to estimate noise level at 9kHz, I coupled a sig gen into my broadband RX loop antenna using a "current transformer in reverse" arrangement to induce a known EMF
WSPR looks at the energy in 1.5Hz bins, or chunks, and effectively filters the signal to this bandwidth. If the noise impulses ar eof significantly shorter duration, they will be smeared outas well
MNI TNX Markus. Thus noise level on 9 kHz can be expected abt 1.3*SQRT(1/0.063) = 5.2 uV/m in 1 Hz by this data. Essentually less then Jim mesured. Thus Stefans sigs with 20 kV on kite ANT should be
Yet another comment. Today a have find some web page (www-star.stanford.edu/~vlf/south_pole/south%20pole.htm) where presented waterpole picture with some signal E ~ 4uV/m near 10kHz. It is dificult t
Jay, Marcus, LF, When sferics are weak or absent, I often see a "dark band" in that region, even with a nonresonant antenna (for example an E-field probe which is "flat"). Yes, and that is probably w
Dear Jim, LF, yes I'm aware of the fact that the shielding from trees etc is more significant at lower frequency. Their ohmic conductance becomes a better shunt in comparison with decreasing capaciti
Seems noise level depend strong on the location. Anyway it is obvious for industrial noise. Theory confirm this empirical rule. Few years ago i do some a theoretical study of optimal signal reciepti
Here is the full VLF spectrum rxed at Todmorden on orthogonal loops, http://abelian.org/vlf/spectrum.shtml Hello Paul, very nice. Are the 3 red peaks between 10 and 15 kHz from the Russian Alpha nava
No, there is a pre-amplifier using LT1028 op-amps. Input transformers match the 20 square metre loops to the op-amps for optimum noise performance. The 'receiver' is calibrated using the thermal nois
Am 03.03.2010 12:50, schrieb Paul Nicholson: Yes, given a low Z source - no good for E-field rx. On the input of the E-field antenna i use a JFET (BF862), then a narrow band pass filter and after tha
It looks like Horst Stöcker is using 8.79kHz and Stefan Schäfer is on 8.97kHz. Anyone else? The crucial factor is the level of natural VLF background noise after sferics have been removed. A couple o
Yes, they're from the RSDN-20 'Alpha' system. 11.904761 kHz, 12.648809 kHz, and 14.880952 kHz. These signals are quite strong and the first two are useful for frequency calibration. More info availab
Hi Roelof, and at 8.970 kHz it is 7.7 dB. That's pretty close to IK1ODO's meaurements some time ago, he measured -7,9dB at 10kHz. 73 Clemens DL4RAJ Hello Paul, Thank you very much indeed for the desc
