From: stevem@gold.gvg.tek.com (Steve Miller)
Newsgroups: misc.consumers.house
Subject: Re: cablevision distortion on splitter
Date: 5 Oct 92 23:39:38 GMT
Followup-To: misc.consumers.house
Distribution: na
Organization: Grass Valley Group, Grass Valley, CA

In article <1992Sep25.160127.2006@yogi.hsc.ucalgary.ca> byron@yogi.hsc.ucalgary.ca writes:
>I've recently purchased a coax video splitter that accepts my one main
>video signal and outputs 4 signals of equal strength.  I've terminated
>all unused output ports.  Occationally, the television picture will 
>become very distorted, as if there was some sort of interferance.  So,
>after experimenting, I've found that:
>
>1. Turning on the microwave will distort the picture somewhat, but will
>   not cause as much distortion as I've seen at times.
>
>2. No other appliances seem to cause the distortion (eg. dishwasher,
>   refigerator, dryer, etc)
>
>Is the distortion I'm seeming likely caused by some type of radio wave
>or other air born wave etc?  If it is, what can be done?  Thanks for 
>any comments or suggestions.
>
>-- byron
>________________________________________________________________________
>Byron Draudson, Systems Manager               byron@yogi.hsc.ucalgary.ca
>Radiology, Foothills Hospital, Calgary, Alberta, Canada   (403) 670-2442

	It is electromagnetic interference.
	The most likely causes, in most probable order:

	1.  By connecting this splitter, you have effectively cut your
	signal level to less than 25% of what you started with.  The signal
	level supplied by your main cable/4 may not be enough to overide the
	various forms of interference in your area.  A 4 way splitter
	will divide the signal by four, plus, if I remember correctly, each
	tap has a loss of 2db across it.  (Is that right?)  In any case,
	it is alot lower than it was, and your TV may not like it.  It was
	OK when the signal was X4, but not now.  I think most sets like
	to have 0db or so, last time I checked (many years ago).  Can you
	find a way to measure it?  Can you beg, borrow or steal an RF meter?
	A 2 way splitter will only cut your signal by 1/2, try that.

	2.  It is a cheap splitter, and the shielding is not adequate to
	protect it from the interference in your area.  You could try
	grounding it to a real ground, but most likely, this will just
	change it, not remove it.  Can you try a more expensive one?

	3.  Maybe the new cables you have run are going through some
	very high interference areas.  Try unconnecting all of the cables
	except the one going to your original TV location, terminating
	all other taps, and see if that helps.  You may also have a
	partially (to radio waves, that is) shorted cable somewhwere and
	it is reducing the signal level.  Check all cables.

	4.  A combination of any of the above.
	
	You can call the cable company and they will come out and measure
	it and tell you what is wrong.  But they also may charge you a
	service call, charge you more per month, and accuse you of
	attempted robbery, depending upon the company.

	Good luck,

	Steve
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Steve Miller, Grass Valley Group, Grass Valley, CA. 95959, Mail stop N32B
916-478-3059, stevem@gold.gvg.tek.com.  The Six Phases of a Project:
  1. Enthusiasm  2. Disillusionment  3. Panic  4. Search for the guilty
  5. Punishment of the innocent  6. Praise and reward for the nonparticipants
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Newsgroups: misc.consumers.house