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

Hi Marcus,

That's great. What could you hear/detect with the 90 kHz bandwidth?

Glen

> On May 15, 2019, at 5:28 PM, Marcus D. Leech <patchvonbraun@gmail.com> wrote:
>
> On 05/15/2019 03:23 PM, Brad Hein wrote:
>> Great suggestion thank you! This also gives me new topics to read up on as I am still a VLF amateur.
>>
>> [Sent from mobile device]
> I used a Berhringer "mini-MIC" microphone amplifier, which has a balanced, XLR, input, and has bandwidth out to
> about 90kHz. Worked a champ. Not as cheap as a DIY op-amp+transformer approach, but more convenient,
> to be sure.
>
>
>>
>> On Wed, May 15, 2019, 1:20 PM John Coppens <john@jcoppens.com wrote:
>> On Thu, 2 May 2019 16:22:24 -0400
>> Brad Hein <linuxbrad@gmail.com> 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
>>
>>
>>
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