[mythtv-users] Understanding HD Antennas ( was HDHomeRun and jumpy video)

Jon Boehm boehm100 at comcast.net
Sun Sep 16 17:12:49 UTC 2007

Brian Wood wrote:
> Jon Boehm wrote:
>> I'm having HD antenna problems myself right now.  My signal strength is 
>> fine but I have unstable signal to noise ratio.  :-(  I have an 
>> HDHomerun, which I love, with a Antennas Direct DB4 in the attic.
>> http://www.antennasdirect.com/DB4_HDTV_antenna.html
>> The antenna is directly attached to tuner0 of the hdhomerun with no 
>> amplifier.
>> Antennaweb said that I needed a Small Multi-direction Antenna.  Since I 
>> was going to be mounting it in an attic I up sized to a Medium 
>> Multi-directional antenna.  I wonder if my noise problems are due to the 
>> Muli-directional antenna?  Any idea where I would go looking for the 
>> noise problem?  I have one of those DC offset amplifiers.  I'm going to 
>> give it a try this weekend.
> If you have sufficient signal strength but unusable signal the problem
> *might* be reflections, but it could be interfering signal(s), either
> on-frequency or even off-frequency if the signal is of sufficient
> strength to create mixer garbage in the HDHR.
> Sometimes *reducing* the input level to the tuner (with an attenuator)
> will actually make things better. You'd need a signal level meter or the
> like to really know what's going on.
> Does the signal look OK going directly into a TV set? (assuming you have
> one capable of ATSC)? Do you have any neighbors getting good or bad ATSC
> reception?
> beww

How does reducing the input level sometimes help things?  It seams to me 
that I'm STUCK with noise that is on the line.  Once noise gets into the 
signal its impossible to get out.  When you attenuate the signal the 
noise get promotionally attenuated giving the same signal-to-noise 
ratio.  And again, amplifying the signal proportionally amplifys the 
noise again giving the same signal-to-noise ratio. So how to attenuator 
and amps help in noise situations?


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