Re: VLF Sunrise Sunset effect at VLF using SDR and "LIL" Low Impedance Loop


the signal amplitude change over time is interesting .. but so, too, are the small changes in signal frequency caused by the acceleration and deceleration where the signal refraction takes place. 'good' measurements can be had starting with chip-sized TCXO references of the kind now cheap and prevalent. a GPSDO is quite sufficient for 'better' than 'good'.

On Wed, Jul 7, 2021 at 10:27 PM, Jean-Marie Polard wrote:
Here is such a plot of amplitude of DCF77 during half night and sunrise (a time signal vlf station in Germany) done with vlfrxtools of Paul Nicholson. But with Spectrum Lab one can do the same. Received with an UMC202HD usb soundcard and earth probes antenna

73's Jean Marie F5VLB

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