VLF Preamplifier

Hi Clive.

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<p style="margin: 0cm 0cm 10pt;"><span lang="EN-US" style="color: #333333; font-family: 'Georgia','serif'; mso-ansi-language: EN-US;">The pre amp that you have suggested has a wide frequency response and therefore will amplify all the stations, it is not selective, and if I am correct you cannot feed this into a A to D converter for transferring over the internet via software. Am I correct in this assumption Or am I up the creek as usual.</span></p>
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<p style="margin: 0cm 0cm 10pt;"><span lang="EN-US" style="color: #333333; font-family: 'Georgia','serif'; mso-ansi-language: EN-US;">Malcolm T</span></p>
 

Hi Malcolm,

Yes, you are correct that the preamp  design I posted is relatively wideband, (at least as far as the VLF transmitter frequencies are concerned) and not selective. I've used this feature as in my RPi based VLF receiver I'm interested in receiving across the VLF spectrum. As I demonstrated at the last radio group meeting, the "receiver" is a USB sound card and then I use some python code on the RPi to extract more than one VLF signal after averaging a number of ffts.

You should still be able to use this preamp to increase your signal level, the "selectivity" being achieved by tuning the resonant frequency of the antenna to your desired transmitter.

Regarding posting charts over the internet, I believe you could do something  similar using Spectrum Lab which has a set of instructions that might allow you to post charts from the Watch Window . You will have to research this one, as I haven't tried it from the Watch Window although I've had success posting waterfall plots.

Best of luck.