[SBE] OTA digital TV interference

[jon]

My office is about 100 feet from railroad tracks. Our transmitter (RF 
Channel 7) is about 5 miles away as the crow flies.

When I'm using marginal antennas (like low-quality rabbit ears) I will get 
breakup as a train passes. When I use a high quality antenna, or a 
directional antenna, the problem goes away. So, improving the antenna 
would be my suggestion.

And, I agree with the previous posters that it's reflection/multipath from 
the train. One of these days, I'll have to setup my spectrum analyzer to 
see what the electrical noise is like from a train.

Jon

On Mon, 16 Mar 2015, David Baker wrote:

> The location is within 10 miles of the station transmitters on Chicago's
> west side, and signal strength is strong on most channels while the trains
> are not on the tracks.
> Partial or total breakup/loss occurs while trains are moving on the tracks
> or standing still.  Some types of trains have a stronger effect than others,
> for example if a freight train is moving through or stopped, vs a commuter
> train.  Also, some channels are strong during train presence, with minimal
> breakup,
> while others have total loss at the antenna.  This led me to think EMI over
> reflections.  I have to admit I have not yet put a spectrum analyzer in
> place
> to see what is happening there.
> 
> On Mon, Mar 16, 2015 at 9:50 AM, George J Molnar <George at molnar.com> wrote:
>       When I was Chief at a station in Chicago, we saw both train
>       (“L") reflection and pulse noise from the electrical system as
>       interfering possibilities. Especially where the tracks were
>       reasonably close (say in direct sight, and between the RX and
>       TX).
> Filter unlikely to help, sadly. Only better antennas & feedlines,
> 
> 
> 
> George J Molnar
> KF2T | AFA9GM
> Nevada, USA
> Twitter: @GJMolnar
> 
> 
>
>       On Mar 16, 2015, at 7:46 AM, John Peterson
>       <jpeterson at prairiepublic.org> wrote:
> 
> How far from the tracks/trains is the recieve site?I would think
> you are dealing with reflections off the trains, rather then
> EMI.
> 
> John Peterson
> CSTE
> Fargo, ND
> 
> On Mon, Mar 16, 2015 at 9:30 AM, David Baker
> <dbaker at addison-il.org> wrote:
>       Good morning!
> I'm wondering if any TV station engineers are addressing
> the problem of OTA digital TV interference and loss near
> trains, or if a solution can be recommended for this
> problem.  For apartment buildings especially where antenna
> height is not an option, if that would fix the problem at
> all.  Can a filter be installed between antenna and TV
> that would help to remove what I think is EMI coming from
> the trains?
> 
> Thanks for any suggestions!
> 
> --
> Thank you,
> 
> David Baker, CBTE, CBNT
> Media Production Coordinator
> Community Relations Dept.
> Village of Addison
> office: 630-693-7554
> cell: 708-935-7829
> www.addisonadvantage.org
> 
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> 
> --
> Thank you,
> 
> David Baker, CBTE, CBNT
> Media Production Coordinator
> Community Relations Dept.
> Village of Addison
> office: 630-693-7554
> cell: 708-935-7829
> www.addisonadvantage.org
> 
>