QUISK and linrad

[Leif Asbrink]

Hi Keith,

You might try Linrad today, using your soundcard as your 
only hardware. Just connect an antenna to it:-) 

It will probably be necessary to add a high pass filter to avoid 
saturating the soundcard with mains hum if you do something really
simple. You would receive a lot of interference from power 
supplies, low energy lamps and stuff if you just connect a wire 
to the signal side of the audio connector. At very low frequencies 
you normally need to isolate the antenna from local fields.

There are many vlf antennas on the Internet, such as
http://www.vlf.it/easyloop/_easyloop.htm
http://www.vlf.it/torsten/_B3CKS-ANTENNA.htm

The antennas are extremely small with respect to the wavelength
so they can not be impedance matched without loosing bandwidth.
They are sensors for the quasi-stationary E-field or H-field.

Easiest is to use a high impedance FET for E-sensors or low
impedance current amplifiers for H-sensors. The trick is to
isolate the sensor (antenna) from current/voltage reaching it
on the screen of the coaxial cable used to connect to it.

I made 4 videos to try to explain the essentials. You will
need some patience, they are long, but I hope they would
make it possible for you to go on listening on VLF pretty soon.
http://www.youtube.com/embed/ItLkn8r4s3E
http://www.youtube.com/embed/zsZTX7MQSGQ
http://www.youtube.com/embed/kgMbaJDFu9M
http://www.youtube.com/embed/C65u7Pmz7a0

There is low cost hardware such as rtlsdr
https://www.amazon.com/RTL-SDR-DVB-T-Stick-RTL2832U-R820T/dp/B00C37AZXK

The rtlsdr with R820T would give something like 24 to 1766 MHz coverage.
You can get it with an up-converter: DX-patrol or Soft66rtl. Alternatively
you could use it with a ham-it-up converter.

Other alternatives that you can use with Linrad under Linux are:
Airspy, SdrPlay, BladeRF, Afedri, ELAD FDM-S1, Perseus, 
CloudIQ, Excalibur and more.



73

Leif








> I am new to the list. Ham, inactive for many years while playing in the
> software domain. Now I have put up an antenna and fired up my old rig. Very
> interested in SDR. Tried to run QUISK in f23 and it fails. Google search
> suggests others have tried and given up. Does anyone know how to run QUISK?
> 
> Or should I just try linrad? Or gnuradio?
> 
> Notably I do not have any SDR hardware yet, so thoughts on interesting (for
> a ham) SDR would also be useful.
> 
> TNX
> 
> Keith
> AA0FD