Where to begin

Hello all,

What would be the cheapest way to set up a rx for ULF, like Schumann –
5Hz to 50Hz (and above)? I searched through the archives and don’t see
any mention of vlf or ulf. (not entirely true as there is a discussion
participant named Ulf (^: )

I would like to do more later but for a start want to focus on ULF.

On Wed, Aug 6, 2008 at 8:54 PM, rhubbell [email protected] wrote:

Hello all,

What would be the cheapest way to set up a rx for ULF, like Schumann –
5Hz to 50Hz (and above)? I searched through the archives and don’t see
any mention of vlf or ulf. (not entirely true as there is a discussion
participant named Ulf (^: )

I would like to do more later but for a start want to focus on ULF.

I am not sure how low a sound card will actually go, but something
like that would probably be the best idea as long as the input can
handle the VLF/ULF.

Brian

On Wed, 2008-08-06 at 21:27 -0400, Brian P. wrote:

I am not sure how low a sound card will actually go, but something
like that would probably be the best idea as long as the input can
handle the VLF/ULF.

Brian

You’re saying use a soundcard since that would be the cheapest way? I
didn’t know that was a possibility. I’ll have to explore that and look
through the archive. Thanks for the tip.

rhubbell wrote:

You’re saying use a soundcard since that would be the cheapest way? I
didn’t know that was a possibility. I’ll have to explore that and look
through the archive. Thanks for the tip.

Just keep in mind that most audio cards have a “DC hole” due to the 20
Hz high pass filter on their input. If you’re looking for Schumann
resonances, these will be at 7-30 Hz, so it won’t work.

You can multiply your incoming signal (in the analog domain) by a sine
wave to move the frequencies off DC, then move it back down to baseband
digitally with GNU Radio. (You’ll need a PLL to synchronize the mixing
frequencies.)

I think someone has already done ELF with GNU Radio a few years ago, you
can try Google.

On Thu, 2008-08-07 at 17:24 -0700, Johnathan C. wrote:

You can multiply your incoming signal (in the analog domain) by a sine
wave to move the frequencies off DC, then move it back down to baseband
digitally with GNU Radio. (You’ll need a PLL to synchronize the mixing
frequencies.)

I think someone has already done ELF with GNU Radio a few years ago, you
can try Google.

I will look some more than, maybe not discussed here.

I notice the archive goes back only to Mon, 23 Jul 2001 16:40:38 -0700
but GNUradio has been around since 1998. So I’ll have to look for those
older discussions too. Thanks for the guidance.

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