Topband: Deliberate interference

[Larry via Topband]

Tom said-

"Message: 10
Date: Sat, 7 Feb 2015 23:58:32 -0500
From: "Tom W8JI"<w8ji at w8ji.com>
To:<topband at contesting.com>
Subject: Re: Topband: K1N DQRM Tracking Project
Message-ID: <94B927F7C90146B19C8C27DE0BC0388D at MAIN>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
	reply-type=original

It would be nice to set something like this up that works, but it would take
more than just how loud someone is.

Strength alone is pretty much useless. "


Well, strength by itself isn't conclusive, but it can be useful.
It depends on the MUF, the band, and the time of day.
It also requires someone to assemble and analyze the information.

If the jammer is are very strong, (+40 db or more) they're probably close.

If they are strong on a low NVIS horizontal
antenna but much less so on a vertical, (during the day on 160, 80 and 40)
they are outside groundwave or LOS and inside 300-500 miles.
If they are as strong or stronger on the vertical as they
are on the horizontal, they're probably inside LOS/GW range and can be DFd.

Three strength reports from the same general area can narrow things down a lot,
especially if there is local terrain.  That can really help.
Once the general area is known, LOS DF works pretty much as well on HF as it
does on VHF. A loop or a phased array of small verticals will give you a line,
and three lines gets you close.

I know where my neighborhood's active stations are, and not because of QRZ.com.
It does take time away from operating, but the principles of DF are not that hard to learn
and some practice can be eye-opening.

Best regards,
Larry KD8WSP