At the local hardware store ACE BEST or whatever
I found a signal cable suitable for underground buriel
which has some kind of grease impregnated beween the shield
and the cable jacket to keep moisure out.
I installed a 40 foot run of it several years ago
and it still seems good. The shield is heavy copper foil
which makes the cable not as flexable as it might be with
a braided shield. You just need to shield the jacket from sunlight
everywhere it might be above ground.

Also you should avoid what is called ground loops
which can indice unwanted noise inside the cable
this can be avoided by choosing your gound
and making sure the shield is broken at one side of the connection
or another to eliminate a DC path. I will typically
break the shield on the side opposite of the
side chosen as the primary ground.

DC/LOW FREQUENCIES will travel deep within a conductor.
But like over 1 MHZ the current exhibits a skin effect
and only travels like within the first 1/8 inch of the surface
with that skin getting smaller/thinner as the frequency increases.

I shoiuld imagine the impedance is also related to this skin effect.

It seems to play a role in antenna design visible as gamma matching.

Coaxial cable would be quite suitable for low frequencies
if 100% shielded and have a proper BALUNS to keep
RF out of the inside of the cable.
A BALUNS may be as simple as a series of
FERRITE beads at  the open ends of the shield.
The broader the frequency block the more
beads you need and they are not cheap.
They come in sizes for one wire or a whole 1/4 inch cable
as a split bead. I have seen them at Radsio Shack
in the past.
You want to make sure what flows on the outside of a coax
does not leak into the inside. And, Vice Versa.


----- Original Message ----- 
From: "GPayton" 
To: 
Sent: Wednesday, May 12, 2010 5:16 PM
Subject: Re: Electronic noise


> Jon, in the past I have observed that RCA type (audio) cable may not have
> complete shielding; some ever have had a small thread of wires and called it
> shielded.
>
> You might try coaxial cable.
>
> Regards,
> Jerry
>
>  ----- Original Message ----- 
>  From: Jón Frímann
>  To: PSN-Postlist
>  Sent: Wednesday, May 12, 2010 7:09 PM
>  Subject: Electronic noise
>
>
>  Hi all,
>
>  I did replace my cable the other day from Cat-5 shielded cable to a RCA
>  cable that is also shielded. But with the Cat-5 cable I did not get
>  electronic noise. But with the RCA cable I do. I rather do not want to
>  switch back to the Cat-5 cable, as it is harder to manage.
>
>  What might be the reason why I am seeing electronic noise on the RCA
>  cable ?
>
>  Regards,
>  -- 
>  Jón Frímann Jónsson
>
>  __________________________________________________________
>
>  Public Seismic Network Mailing List (PSN-L)
>
>  To leave this list email PSN-L-REQUEST@.............. with
>  the body of the message (first line only): unsubscribe
>  See http://www.seismicnet.com/maillist.html for more information.
> 

__________________________________________________________

Public Seismic Network Mailing List (PSN-L)