[mythtv-users] HDHomerun signal strength required

[backuppc at sundquist.imapmail.org]

On Thur, Feb 21, 2008, 2:07 PM, beww said:

> The pcHDTV card is a digital and an analog tuner, but the analog tuner
> is a simple frame grabber, thus you will have to encode using your
> CPU. Myth will record your VHS tape, though it's a bit of overkill.
> Myth only supports RTJpeg or MPEG4 with a frame grabber card, the
> former is suggested unless you have a fast CPU.

I have a 2.2 GHz Core 2 Duo so that should handle it.  But this should
be rare anyway; it's just something that came up recently now that it's
school vacation and my daughter was looking for something to do.

> I would not do that. Although a hybrid splitter will act as a combiner
> (backwards) you might (actually almost certainly will) wind up
> transmitting the channel 3 signal out your antenna, causing outfits
> like the FCC to take an interest in your activity.

Yeah, I didn't think it would be a good idea, but not for that
reason though!

> Combining two or more antennas can work, and is often done, but you
> have to be sure you have the phasing correct, and this will be
> affected by things like cable length (inches make a difference).

...and later beww said...

> True rain fades are rarely very long though, 20 minutes is a
> long fade.
>
> If your signal gets poor in bad weather for much longer periods, your
> problem might be poorly weatherproofed connectors in your antenna
> feed, Trees in the path becoming laden with water, snow building up on
> your antenna and other factors only indirectly related to the bad
> weather.

This image can address both of these comments:

http://www.remotecentral.com/hdtv/toronto-buffalo.png

I am located right about at the southeast corner of the box that says
"WIVB 4/39".  So the two directions from which I need to receive signals
from are almost 180 degrees apart, with the old big 3 networks to the
south-southeast, and the rest on on Grand Island to the north-northwest.
My understanding is that so long as they are in opposite direction
things are OK.  But I should probably check the aim.  The antennas, 300-
75 ohm connectors, and 3-foot leads to the splitter/merger are
identical, so phasing should be OK.

Another goal is to try to get some of the stations on the CN tower in
Toronto (same direction as Grand Island).  It's far away, but it's the
tallest freestanding structure in the world so a lot of people in the
area can pick up (at least NTSC) stations from there.

Also, as you can tell from the map, the "bad weather" I refer to is
snow, not rain.  I also have some evergreens near the house that can
collect snow.  Right now the antenna is the attic, so weatherproofing
isn't an issue, but I may consider moving it outdoors next summer.

And that bad weather is actually good weather -- I'll be out skiing this
weekend even though my HDHR will be beckoning me for to set it up!

rogerheflin at gmail at Feb 21, 2008, 2:49 PM wrote:

> I have 2 directional antenna's combined with a splitter and it works
> decent, I probably have decent luck simply because the 2 signal
> sources are almost exactly 180 degrees apart, so the interference from
> the one antenna picking up the other antenna's channels is minimal, I
> have a mast type amp after that and then a attenuator to cut the
> signal down before the distribution amplifier, too much signal causes
> poor analog and digital signals. Whether you need an amplifier or not
> depends on how far you are from the signals, and you may need to lower
> the signal strength to get things to work after the amp (if you do get
> adjustable attenuators, it is pretty easy to adjust things to maximize
> the signal quality), also the mast type amplifiers are supposed to
> have a lot better 1st stage (less noise, cleaner) than most tuners
> since tuners don't need to be any good any more since few are using
> them for OTA.

Sounds like my situation, although my antennas are now in the attic.  My
RG-6 run from the merger to my FE/BE box is 50 feet, so I may consider
an amplifier if the HDHR and tweaking the antenna aiming doesn't improve
my signals.  Any suggestions for decent quality amplifiers (keeping
price in mind)?

Thanks for everybody's input.

J.S.