David,

You should have a look at the code from Joe Taylor for JT9, JT65 or FT8, as=
 that code will dig signals buried deep into the noise.

I think that the code is public domain, but I might be wrong.

Just a thought,
Jean-Paul
N1JPL

> On Jan 10, 2019, at 11:21 AM, David Van Horn <david.vanhorn@backcountryac=
cess.com> wrote:
>=20
> I have no control over the source.  The signals are all through the band.
>=20
>=20
> -----Original Message-----
> From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> On Behalf Of Russ=
ellMc
> Sent: Thursday, January 10, 2019 4:29 AM
> To: Microcontroller discussion list - Public. <piclist@mit.edu>
> Subject: Re: [EE] DSP algorithms for very narrow band applications
>=20
> On Thu, 10 Jan 2019 at 09:10, David Van Horn < david.vanhorn@backcountrya=
ccess.com> wrote:
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>> I'm looking for info on DFT or similar approaches to detect very weak=20
>> CW signals buried in noise.
>> I'm only interested in a 200Hz window, and I can control where it=20
>> falls frequency wise, between 150Hz (center) and several kHz.
>> I need as much frequency detail as possible, sub 1Hz definitely, but=20
>> the "dot" is pretty short. At 20WPM that works out to well below.
>> https://www.w8ji.com/cw_bandwidth_described.htm
>>=20
>> Is the CW signal
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>=20
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>> originated from a remote source over which you have no control wrt=20
>> time of origin, pattern etc
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>=20
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>> or
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> do you have control of tx and rx ends and want to establish how/if it tra=
nsits some medium.
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> I assume the former but, in the event of the rather niche latter case, a =
lock-in-amplifier may well be what you want
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> https://wiki2.org/en/Lock-in_amplifier
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> and *a zillion more
> <https://www.google.com/search?ei=3DtSs3XOrLJsyBvgTP8YqwBg&q=3D%2B%22lock=
-in+amplifier%22&oq=3D%2B%22lock-in+amplifier%22&gs_l=3Dpsy-ab.3...125380.1=
35482..135883...0.0..0.260.2171.0j10j2......0....1..gws-wiz.......0i71.7PLp=
_sOahnA>*
>  (Garglabet search)
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>=20
>             Russell
>=20
>=20
>>=20
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/cha=
nge your membership options at http://mailman.mit.edu/mailman/listinfo/picl=
ist
>=20
> --=20
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist

Just my $0.02,

Jean-Paul
N1JPL




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