[hpsdr] Ozy with Gb Ethernet

[jeff millar]

Donald Kay wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> Hi Fred,
> It was very bad here. The original setup had a couple of
> 65 ft runs of cat 5e, one to the front of my house and
> one to the rear where the shack is. The network equipment
> was all linksys so maybe that had something to do with it.
> Also, although I have some 100BT here it was mostly older
> 10BT stuff. I have seen speculation on the web that these
> are harmonics of the frame rate but I don't know that for
> sure.
> 
> The interfering signal shows up every 30 khz but every other
> one is quite strong. I saw it from about 80 meters through
> all the HF bands.
> 
> Moving to a wireless network solved the problem.

I think the problem came from the Ethernet cable carrying some switching power supply noise on the 
_outside_ of the cable.  If the interference came from frame rate, it should have created moving 
spurs because frame rate comes from a variety of random processes.

A 30 kHz switching supply would produce even and odd harmonics with different amplitudes.

Look for an old piece of equipment, because 30 KHz is a low frequency for modern switchers.

jeff, wa1hco

 1173958375.0