[RFI] Cisco IPTV Receiver RFI emissions

Jim Miller JimMiller at STL-OnLine.Net
Sun Dec 7 11:13:28 EST 2014

I got called out to a subdivision problem with garage doors that would not
function all of a sudden on Sunday morning.  It has been 2 or 3 years ago
now and there were 3 or 4 that had the problem and by the time I was able to
get there, 9 was the total they knew about.  I had been successful a couple
of times before on this RFI locating and wound up with this call.  I told
the contact fellow several times I didn't know if I could help or not.  

Going to the bottom line - It was a box that had coax cable connected to it
and only said ARRISS on it.  We googled it and found it to be TV stuff.  The
fellow wasn't home.  I went back to the house where my contact was and one
of his neighbors was talking to him and I told them I would show them what I
had found and the neighbor walked with me back to the box and he was totally
convinced.  It was VERY obvious.  When we got back to the guy who had called
me (he could barely walk at all) the neighbor said "you won't believe who it
is". The caller said " Oh NO".  Turns it was their subdivision problem guy.
Anyway I left.  I called back a week later and got the rest of the story.
It did get taken care of after they got the police (for their own safety)
and the subdivision trustee to go with them to talk.   One of the neighbors
said he had seen a guy in a cable truck working on something on Saturday but
the owner denied everything.  I had told them it could be just a bad
connection on one of the cables causing the problem.  

Nothing fancy, 2m tape measure beam and HT.  I had him keep pressing his
garage door remote until I found the frequency and used that to hunt the
problem.  (It was very dominant in the horizontal plane.  Somewhere just
above 300mhz if I remember right and only the new openers that had replaced
the originals that had crapped out after about 10 years so it was spotty but
within less than a couple of blocks.  (Reflections drove me crazy until I
realized what was happening, it was coming from everywhere, even cars).
Anyway, interesting experience.

73, Jim KG0KP

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Ed-K0iL
Sent: Sunday, December 07, 2014 12:26 AM
To: Rfi at contesting.com
Subject: [RFI] Cisco IPTV Receiver RFI emissions

Those who have run into this with AT&T's U-Verse wireless receivers won't be
surprised by this.

I've migrated to CenturyLink's Prism TV from their Telechoice cable TV
system.  Love the Prism TV picture, but found a slight problem that was
causing RFI to one, possibly both, of my garage door openers and wiping out
weak AM broadcast radio signals in all bedrooms.

While trying to determine where my S9+20dB 80-meter RFI was coming from (or
verify it is from powerline noise, and it is), I discovered my new Prism
IPTV wireless receivers are putting out a lot of RFI noise starting at
around 1.6 Mhz and up.  Not sure how high it goes as powerline noise blanks
it out above 3.5Mhz in the ham shack.

The IPTV wireless receivers (I have 2 of these) emit noise very short range
for about 25-30 ft dropping below noise floor after that.  One is located at
about 20 ft from my ham ground mount antenna so the noise is too weak at
3.5Mhz to hear under stronger powerline noise.  

I also have a hard-wired Prism box connected via Cat 5/6 cable to the
incoming Prism router, and it does not seem to emit any RFI noise at all.

All of this system is manufactured by Cisco.  
Here's the info on the wireless IPTV receivers that emit noise: 
Cisco model ISB7005
P/N 4040838

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