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

[Glen I Langston]

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 <address@hidden> 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 <address@hidden wrote:
>> 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
>> 
>> 
>> 
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