Yes, mille, we are still at 443kw

Thanks FraserR ,
very interesting explanation about propagation ....

Also, I only understand this stuff in the simplest of terms, so if I've made a mistake or an oversight, chime in you guys.

Very good explanation, Fraser. Don't worry about the length, it was fine.

The only point I would add is that the FCC specifies ERPs for directional stations as the maximum E(I)RP, so to clarify the case for WPTZ and WCAX:
- WCAX sends out 443 kW in all directions in the horizontal plane. (I'm ignoring the beam tilt here for simplicity).
- WPTZ sends out 650 kW in its best horizontal direction. It has, as you say, a deep null towards Sherbrooke.

By contrast, Industry Canada tracks stations maximum and average ERP in its database.
(But then they make it harder to find the antenna pattern, since its stored in a separate database file.)

By the way, I always wondered how you get an omni directional pattern for ch 22 and a directional pattern for ch 14 off the same physical antenna. Is this a multi-panel antenna with one or more panels that transmit only channel 22 and not ch 14 in order to achieve the nulls? Is there a splitter at the end of the common transmission line that does this?

An interesting note: the newest UHF antennas do not need to reach up above the new highest channel in the UHF band (51???) Since the new ones cover from ch 14 to 51 (I think) they are more uniform across the band. The older ones had to cover from ch 14 all the way up to the old highest UHF, you guys can tell me, is it like around ch 70. Since it covers a much wider set of frequencies, gain was not as uniform for all the channels.Exactly the case - some of the UHF antennas on the market today were designed in the 1960s and 1970s for channels 14 through 83, and then adapted later for 14 through 69. Any new models coming to market will ideally be tuned for 14 through 51.

FraserR, the Grey Hoverman antenna designed here at our site is specifically tuned for 14 through 51 with an almost flat gain curve across that whole band, with very high gain that easily beats commercial antennas. The latest GH versions have tuned resonators that allow VHF-Hi 7 through 13 together with UHF 14 through 51 and they are not hard to build. :)

What is a Gray Hoverman TV Antenna:

http://www.digitalhome.ca/forum/showthread.php?t=81982

I hope you'll pass on that great info to your viewers. In these tough economic times it is great to know that the best antenna out there can be made at home with a list of parts and materials from a hardware store. :)

TVlurker, (post 1286),,,Our signal is split 75/25%, in the building. The 75% feeds a combiner that combines it with WPTZ's full power. Then it goes to the antenna combined, thru 6 inch line, feeding the W, S, E panels. The 25%
is fed to a separate combiner, where it is combined with a very small amount of power tapped off from the WPTZ side, (like, maybe 1%???), which then travels to the north panel in a 3 inch line.

The 75% feeds a combiner that combines it with WPTZ's full power. Then it goes to the antenna combined, thru 6 inch line, feeding the W, S, E panels. The 25%
is fed to a separate combiner, where it is combined with a very small amount of power tapped off from the WPTZ side, (like, maybe 1%???), which then travels to the north panel in a 3 inch line.

Thanks for the explanation. I think I was confused by some of the FCC filings which didn't mention that there were TWO transmission lines. It all makes sense now.

Fraser: Thank you for your explanations.

One more question: the fact that WCAX use omni directional signal propagation was a technical decision? Or a constraint due to the fact that WPTZ is using the same transmission tower?

Smog,


What is you elevation above sea level in Prevost and what is the height of your tower?

I'm interested because I will be trying to pull in DTV from Mt Mansfield about 123 mi away, from a location west of Morin Heights between Laurel and Lost River. The elevation there is 815 ft with the UHF antenna on a tower at a height of 35'.

sparky mtl
the antenna is at 300 M (990 ft)

the antenna is at 300 M (990 ft)
wow, thats high, my antenna is only about 6 feet off the ground...

One more question: the fact that WCAX use omni directional signal propagation was a technical decision? Or a constraint due to the fact that WPTZ is using the same transmission tower?

I don't understand your question.

WPTZ needs to use a directional pattern to protect a channel 14 allotment on Sherbrooke.

WCAX does not need to protect any other stations, as according to FraserR they have negotiated with the CBC to allow for an interference zone with channel 22 in Ottawa in some backwoods part of upstate New York. Since they don't need a directional antenna pattern, they don't use one.

Note that the fact that WCAX uses an omnidirectional antenna pattern does not mean that their actual pattern is omnidirectional, as the actual peak of Mt Mansfield shades their signal from propagating much at all to the direct north. Luckily, this does not affect Montreal Island.

wow, thats high, my antenna is only about 6 feet off the ground...
over sea level and 280 meters over the St lawrence level (being the lowest point between my house and MtMansfield

the antenna tower is the regular cheapo triangular stuff and is about 30 feet high

the antenna is at 300 M (990 ft)

Smog,
Thanks for the info. Couple of more questions came to mind.
1) Is your antenna clearing all the nearby trees, at the 30' tower level, in the direction of the transmitters on Mt Mansfield and Lyon Mountain?
2) Are you at the highest elevation point or are there higher mountains in the distance?

sparky mtl

TV Lurker, I do not believe I said we worked anything out with ch 22 from Ottawa. I said that areas where both signals are present could be a problem for either signal to work properly.

We use an omni signal so we can reach to the north, as we always have. There is a shadow from the highest point of Mt. Mansfield. There are viewers just north of the border, in the shadow, who get us with a good antenna. People who live closer to here are not able to get us, if they are in the shadow.

Has anybody noticed any changes to their reception of WVNY-DT and WFFF-DT. Since Tuesday, I'm getting WVNY-DT.

My usual signal meter strength for WVNY-DT was around 30%. Since Tuesday, it's been coming in at between 40-45%. The signal is also more stable at night. But, at the same time this was improving, WFFF-DT was getting worse. It use to be around 52% for me, but now it's around 35-43%. My picture lock on my Sharp TV is at 34%.

Does anybody now if there are changes occuring at the transmitter site. I have changed nothing on my end of the antenna set-up.

TV Lurker, I do not believe I said we worked anything out with ch 22 from Ottawa.

Sorry, I must have misunderstood.

wfff for me also seems to be lower than normal, i figured it was weather related..

I noticed that up until Apr 6 WVNY came in pretty well, with SNR 17 (out of 30) on my Hauppauge Digital Signal Monitor, enough to watch without interruptions. Since that day it has been down to SNR 11.5. All other US stations (WCAX, WPTZ, WFFF, WCFE and WETK) come in unchanged, at SNR 27.

Is WVNY experimenting with power levels?

WVNY is coming in much stronger in St-Hubert right now (about 65% and stable instead of 49 or 50% with constant break-ups).

WFFF is a little weaker (76%) but is always stable so it doesn't bother me.

WVNY is coming in stronger since ~2 week's, it's now at 92-95% and before it was 80-85%. On the other hand WFFF is coming at 75-80% and before it was 95-97%.

Some break-ups on WVNY this morning... so I guess the problem isn't completely solved. :(

Any idea what happened though? Did the wind slightly turn their directional antenna clockwise?