|Topic Review (Newest First)|
|2013-05-23 08:20 AM|
Originally Posted by tmp31416 View Post
CTV2, CITY, CTS, OMNI.1, OMNI.2 and CHCH all broadcast from HC.
|2013-05-22 07:43 PM|
global is broadcasting from cf, not manotick?
whoa. good thing i did replace my ap8700 with a hdp269!
|2013-05-22 02:53 PM|
Originally Posted by tmp31416 View Post
|2013-05-21 09:24 PM|
Originally Posted by roger1818 View Post
i never had a problem with channel 6 (global) with my attic-mount db4.
the only time i could not get a specific station was when i tested a db8 in said attic and, for some reason, it was city-tv (rf channel 17) that i lost. putting back the db4 got me back all the local channels.
though the db8 was not in the exact same spot the db4 was, maybe it was in some sort of 'attic dead zone'?
(anyway, since i cannot realistically put two antennas on my roof, i'll have to sell my 'barely used' db8, so I won't be able to do further testing on antenna placement)
|2013-05-09 04:19 PM|
Originally Posted by envirogeek View Post
see what strength is coming in. My R&D was on the 2nd floor of my house by a window.
I was getting enough reception to know that the signal strength was sufficient for an attic install,
which is even stronger.
|2013-05-09 08:12 AM|
The other side of the coin is with an attic install, you are putting the antenna closer to sources of interference (noise) generated inside the home. This tends to not be a big issue with UHF and only a minor issue with VHF-HI, but it is a major issue with VHF-LO.
For this reason, here in Ottawa most people need an outdoor antenna to receive RF channel 6 reliably.
|2013-05-02 11:51 AM|
Another thing to consider with an attic install is how much signal you have to start with.
Losing 40% or more may not be a concern depending on where you begin.
In my Calgary attic install all of my channels are line of sight from three towers on a single broadcast location, with NB (dB) figures in TV Fool ranging from 51.2 to 66.8.
The signals pass through a 30 foot high spruce tree, a stuccoed exterior wall, a floor to ceiling row of bookcases, then an interior wall before getting to where my antenna is located.
|2013-05-02 10:48 AM|
As the other posters pointed out, 40% is a realistic starting value. The rest depends on your roof construction and house orientation wrt the transmitters. Don't forget there's tons of other factors, for example a lot of times older homes also have copper drains (stacks) that exit by the roof which can cause interference. Also remember than in the winter, if wet snow accumulates on your roof the signal strength inside the attic will decrease even further.
But every application is different. For example, I once installed an 91XG in an attic and was lucky as the location of the transmitters and orientation of the house allowed me to point the antenna through a large plastic gable vent, showing almost no loss.
|2013-05-02 10:28 AM|
Based on numerous actual tests, I presume the range of Attic Loss is about 13 dB +/- 7 dB.....or more in well shielded attics (e.g. metal roof):
Missing link to Bob Chase's In Attic vs Above Attic OTA Antenna Comparison Test (about 20 dB difference):
Some of the early OTA Test Results are embedded into this 65-VU graph presentation:
[I have several copies of early reports and presentations, but can no longer find them on the web.]
BTW, REAL Engineers use dB's vice percentages (and wear WHITE socks)...but if you insist, 13 dB is a power ratio of 20:1 or 5% remains (95% Loss), and a voltage ratio of 4.47:1 or 22.4% remains (77.6% Loss)...whichever way you prefer to be confuscated....
|2013-05-02 06:09 AM|
Or 99.9% (metal roof), or 50% or not too much. IOW, it varies hugely depending on construction materials.
You can guestimate that it will be anywhere from 3 to 20 dB. What cannot be guestimated is the indoor multi-path.
|2013-05-02 03:58 AM|
|north49||40%....really that much?|
|2013-05-01 10:22 PM|
I read you can lose up to 40% signal with an attic install. You will most
likely need a good preamp like the CM7777. Having said that, it could be
worth a shot. Many, including myself, have good results with an attic
|2013-05-01 09:38 PM|
OTA attic question
How much,if any, of the signal is lost from the roof with an attic antenna ? Has anyone ever done an experiment on this ?
|2012-03-26 04:29 PM|
I'm guessing it may have to do with efficiency- a fully ducted return would be easier to balance with the output side CFMs.
|2012-03-26 04:26 PM|
Originally Posted by lithOTA View Post
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