[Linrad] Re: off subject Delta 44

[Stan W1LE <verizon.net; stanw1le@xxxxxxxxxxxxxxxx>]

Hello,

The Delta-44 PCI soundcard has a max sampling rate at 96,000 samples per 
sec at 24 bit quantization.
using a single channel, you can display/use up to 48 KHz wide spectrum.
Using I and Q channels, can display/use up to 96 KHz spectrum.

Lotsa broadcast band and other energy out there impinging on the 
soundcard input, when fed directly.
Add a band pass filter around you freq of interest and away you go.
Low pass filters or high pass may also be effective.
Lotsa more energy in a lightning storm at low freqs.
Do not forget the potent LORAN-C TX's at 100 KHz.

The 137 KHz and 160-190 KHz Lowfer bands would not be covered in a 1 or 
2 channel
setup unless you do a block down conversion after the antenna and before 
the soundcard.

Would work with the rare 17.2 KHz SAQ broadcasts from Sweden..

If you want to use the WSE stuff for lowfer work, , build a block up 
converter to feed the
 2.5 MHz IF box or the 10.7 MHz IF box or the 70 MHz IF box.

Others have put together a program with GUI for SAQ, 17.2 KHz RX 
directly from antenna into soundcard.

Now, If you had a 24 bit, 192 KHz sampled soundcard and  I + Q channels,
then you could make the 137 and 160-192 KHz RX work.

The commercial selective volt meters or receivers like the HP-3586A/B/C
or the RYCOM 6041 selective level meter would work, well with limitations.

For my VLF RX work I use a ICOM IC-703+, direct tunable down to 100 KHz
and with factory TXCO to stabilize the LO for QRSS/CW 120 copy and no 
freq drift.
I feed the fixed level audio output to the soundcard and use ARGO, WOLF, 
or WSPR
to decode.I also use a IC-706MK2G.

My plan is to add a G4HUP external reference to the 706 to
eliminate freq drift on RX (only) due to the fan thermal cycle.

IMHO the HP-3586 is a pig on AC power and operating position real estate.
But, you can use a GPSDO 10 MHz reference to stabilize most of the LO's
(but not the last LO).

The Rycom 6041 is a great portable RX but is not freq stable for QRSS/CW 
at 120 second dots.

Others use a ICOM R75 for lowfer RX

Stan, W1LE


Jeremy Alexander wrote:
> Aloha to all:
>
> I am curious about using the delta 44 and the Linrad for lowfer listening. What precautions should I follow before connecting antenna to input of the sound card. Also I am sure someone is doing this, what kind of success would one have with this setup over say a commercial selective voltmeter type receiver? The dual antenna thing is curious to me at LW and wonder who is doing it, please contact me: jeremy@xxxxxxxxx
>
> Mahalo! w7eme
>
> >
>
>   


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