Re: [Discuss-gnuradio] Tuning in VLF with a sound card

[John Coppens]

On Thu, 2 May 2019 16:22:24 -0400
Brad Hein <address@hidden> wrote:

> I took a Raspberry Pi and attached a 48KHz USB sound card, with a big
> magnetic loop antenna fed into the mic.

Just a suggestion: If you have a loop antenna, which is a symmetrical antenna,
and couple it to an asymmetrical input (MIC), you will make the antenna
more sensitive to static noise. I'd suggest you use either a transformer or 
an 'instrumentation amplifier' with an operational amplifier to convert
the signal from the antenna to asymmetrical signal.

A transformer would be easiest to install at the base of the antenna (no
need for a supply). The op-amp amplifier would cover a larger bandwidth.
(it would also offer some protection for your computer).

John