Re: SLF: Sidebands arround ZEVS in 1 mHz

[Markus Vester <markusvester@aol.com>]

Hi Stefan,

it seems these sidelines are about 10 dB down at +- 6 mHz. If they were real, we'd surely see them in 424 uHz at DL0AO, but there's nothing there.

What is strange ist that the main carrier is shown 2 mHz below the 82 Hz tick, wheras in reality ZEVS is only 10 uHz below nominal. So I suspect that the real input samplerate is around 24 ppm higher than what SpecLab thinks it is. This may cause periodic buffer overflows, where samples are lost and phasejumps occurs. The sideline spacing indicates that this is happening every 1000/6 seconds (~ 3 minutes). 

73, Markus

-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group@blacksheep.org <rsgb_lf_group@blacksheep.org>
Verschickt: Di, 18. Jun. 2019 17:53
Betreff: SLF: Sidebands arround ZEVS in 1 mHz

These days i'm calibrating the colours and angles in my ELF...VLF

spectrograms. The colour of ZEVS is now calibrated to deviate less than

3 deg. However producing a spectrogram in 1 mHZ FFT bin width, i can see

sidebands of ZEVS.

Did someone else observe a similar effect?

In a first thought i would assume it is my timing system that causes the

problem. But maybe it is ZEVS itselfe? Or even propagation?

73, Stefan

PS: Capture attached.