: Global Ottawa DTV Transition - Aug. 16, 2011 - update in Post #331


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donj
2011-08-23, 08:10 PM
the effective erp in my location is 0.081 kw
81 w
and its working from my roof
its currently raining and im getting it at 60%
mind you it will not work inside
not even with antenna right against the window

as soon as a second tv is using the antenna global pixelates
if a recording starts global is done
so only one tv can view in order to get global here

i have a cm7777
How do you find out the erp at your location?

charettepa
2011-08-23, 08:38 PM
go to tvfool.com
enter your info
click on the channel in question
it will give you the info in relation to your location

charettepa
2011-08-23, 08:39 PM
I think a distribution amp might solve your issue.
when i use a distribution amp in addition to my cm7777
it overloads the tuners
if i add the distro amp without the cm7777
there is no signal at all from HC as its lost before it gets there

donj
2011-08-23, 10:41 PM
go to tvfool.com
enter your info
click on the channel in question
it will give you the info in relation to your location
Is tvfool up to date? All I see is one channel 6 entry and I thought that was the old analog signal since there isn't a -DT behind the name.

charettepa
2011-08-23, 10:51 PM
select
pending applications
only digital

you will not need to do that after sept1 once it is updated

donj
2011-08-23, 11:17 PM
Cool, thanks. This gives me an idea of what I can get come Sept 1.

FYI, the effective erp for my location is 0.613 kW and I can get Global pretty stable with a folded dipole in the attic with a preamp.

charettepa
2011-08-23, 11:33 PM
nice
thats about 7x the erp i get

stampeder
2011-08-23, 11:53 PM
How do you find out the erp at your location?The answer is that you cannot. The term "ERP" means Effective Radiated Power and is an engineering calculation that rates the power only at the transmitting antenna. So, I think we all know what you are trying to say but ERP is not a term you would use to describe the field strength at your own reception antenna.

For consumers looking at their TVFool reports one of the most important factors is the Noise Margin (NM), amongst other considerations. Post your TVFool Report link and our experienced members can give better advice.

If you really, really want to know in very detailed discussions of how the TVFool site reports work see the following thread:

TVFool Canadian Discussion (http://www.digitalhome.ca/forum/showthread.php?t=103476)

tvlurker
2011-08-24, 07:36 AM
Both stampeder and charrettepa are right. In effect, the ERP is at the transmitter site, but it does vary by direction.

Effective Radiated Power is a way of saying: for a receiver in a given direction, how much power would the antenna have to emit in every direction for the receiver to receive the field strength it is in fact receiving. In effect, you can think of it as "how much power is the antenna throwing in my direction".

So stampeder is right in the sense the receiver's distance from the transmitter is irrelevant. And charrettepa correctly noticed that TVFool reports a different effective power in every direction away from a directional transmitting antenna. However, all locations at the same azimuth report the same effective power .

charettepa
2011-08-24, 07:46 AM
thanks for clarifying
that makes sense to me

my real question now is to global
why do they throw over 400w in most directions and only 81 in my direction
its a dense population

unless they "TVFOOL" are taking terrain into consideration
then it would make sense as i am in a valley (bottom of hill in orleans, by the river)
global reffered to it as a "null"

charettepa
2011-08-24, 07:55 AM
ok just did a little test

TVFOOL is definatly taking terain into consideration when reporting the effective ERP (adjusted according to your location)

as i just checked using the in-laws postal code
from their house they use the same azimuth to aim (point in exact same direction on compas)
but are ~15km furter away but in same dirrection as myself in relation to the tower
yet have 4x the reported effective ERP
which of course gives them better reported dbm/nm values

tvlurker
2011-08-24, 08:22 AM
I can't reproduce your issue. When I look at the effective power in the power overlay feature of the online TV Map feature of TVFool, it does not vary for the same azimuth.

With respect to the low power level in the direction of Orleans, bear in mind that Global is using an antenna designed to protect channel 6 in Montreal. That's why it cannot send much power to the east.

Even post transition, channel 6 in Montreal remains an allotment that needs to be protected (but not as much, as up to 5% interference by population is permitted for vacant allotments.)

charettepa
2011-08-24, 08:55 AM
it reports 0.081 for me
and 0.12 for my mother in-law
keep in mind
only a small portion of orleans is in a valley
you are probably thinking of the "new" orleans which is top of the hill
i am "old" orleans bottom of the hill
in fact if you look at my tvfool report which is in my set homepage
you can see the map it draws when you select global
you can actually see the dip in the terrain
and the section that is in that valley
has much less power

roger1818
2011-08-24, 09:04 AM
I borrowed that Spartan 3 pre-amp and did some experimenting yesterday and I must say things are about as clear as mud right now.

I saw that Global was down late morning/early afternoon so I did the swap to see if it would help. It didn't. Frustrated I just left things alone and continued to try it throughout the day. It still wasn't coming in in the evening and I thought that maybe something changed and I need to do a re-scan, which I did and sure enough it started to come in again. So now I am not sure what problems are on the transmitter side and what are problems on my end. After the re-scan I did have it fail once but trying again immediately it was able to get a lock. I will probably keep the pre-amp installed for a while and see how well it performs, but at this point I am not holding my breath.

Just so everyone knows, I am using an HVR-950Q with MythTV for all my tests.

charettepa
2011-08-24, 09:20 AM
they did a change last week on wednesday i think
maybe thursday
it was a change to PSIP if i understood correctly
i too had to rescan for it to work
it has worked since
in fact signal has been better since then
very little pixelation in most cases none

OTAJuncqui
2011-08-24, 10:01 AM
If you're looking for a "clearer picture" of signal availabity download TVFool map overlays for google earth .
I doubt they have updated global info but you can use it as a benchmark

Fota
2011-08-24, 11:20 AM
If you're looking for a "clearer picture" of signal availabity download TVFool map overlays for google earth .
I doubt they have updated global info but you can use it as a benchmarkRabbitEars.info has current info... For fun, here's a comparison of current Global TV and CBC. What's not shown here is that on top of the weak broadcast signal, Global TV's VHF-low cannot traverse/penetrate anything.
So I'm in Ottawa per se and can't get Global TV because it just can't penetrate my apartment building at all (yet I get all UHF digital broadcasts from Camp Fortune perfectly fine).
Images from rabbitears.info (+ google) composited in GIMP.
http://i.imgur.com/kuRUq.gif

Trip
2011-08-24, 11:24 AM
To add to the ERP question, let me offer a link to a feature on RabbitEars that may help a little bit. (Does not work with IE versions older than 9, may have other incompatibilities I am unaware of but works in Firefox/Chrome/etc for me.)

http://www.rabbitears.info/oddsandends.php?request=ant_pat&ant_id=7927&rotation=0&erp=3.3

That is the CIII-TV-6 antenna pattern. If you hover your mouse over the little white dots, the ERP is displayed for that direction coming out of the antenna.

Not sure if it will help, but maybe.

- Trip

Trip
2011-08-24, 11:30 AM
RabbitEars.info has current info... For fun, here's a comparison of current Global TV and CBC. What's not shown here is that on top of the weak broadcast signal, Global TV's VHF-low cannot traverse/penetrate anything.

One comment I'd like to make about my coverage maps is that I actually adjust the maps for VHF downward in terms of coverage to attempt to account for the poor characteristics of VHF (It's adjusted 5 dB for high-VHF, and 13 dB for low-VHF) but since noise floors are not consistent everywhere, a station like CIII-TV-6 might be reduced significantly more than a station like KXLF/KTVM in Butte MT.

(If you're wondering where the numbers 5 and 13 came from, the "normal" numbers for the bands are UHF-41dBu, high-V-36dBu, low-V-28dBu. Do some subtraction and my laziness will come into focus. :D )

- Trip

old sparks
2011-08-24, 11:42 AM
Trip;

Thanks for the link! It really illustrates the directional nature of the CIII RF6antenna and why I can receive it with the equivalent of a 'wet noodle', whilst those who live in the east end are forced to take extreme measures!

CIII needs to migrate to a UHF channel if they really want to serve the City of Ottawa as well as Gatineau to their respective borders. This should be a minimum mandatory requirement...