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Old 3-Apr-2010, 12:30 PM   #1
Skibble5150
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Join Date: Apr 2010
Posts: 4
Digital Channels (Montreal, Quebec, Canada) EDITS

Great site guys! Thanks for including Canada! Well done.

Some edits for the Montreal/Plattsburgh/Burlington area...

There are sub channels for both PBS VT & NY.

VPT (PBS Vermont Public Television)
33.1 is digital (the only one you have listed)
33.2 is only 480i digital
33.3 is only 480i digital
33.4 is only 480i digital

WCFE (PBS New York)
57.1 is digital (the only one you have listed)
57.2 is only 480i digital
57.3 is only 480i digital


WPTZ 5.1 has a secondary channel.
It is the THIS network on 5.2 only 480i digital.
The THIS network is all over the USA in multiple markets.


WCAX 3.1 has a secondary channel too.
It is basically weather and runs the news if a sports event interferes.
The channel is 3.2 and is only 480i digital.




I am currently pointed to Mount Mansfield in the US at 167 degrees and can pull in 15 digital and 9 analog channels.
2.1, 3.1, 3.2, 5.1, 5.2, 6.1, 17.1, 33.1, 33.2, 33.3, 33.4, 35.1, 57.1, 57.2, 57.3


I am in the middle of the island with the antenna on a mast at about 35 feet above ground. Mount Royal does not interfere with my trajectory to the US from my location.

As Canada comes closer to the August 2011 CRTC digital mandate, I will provide you with more informaiton when newer digital channels go live.

Once again, I really appreicate your site and I am looking forward to its future!


P.S. Not sure if it is possible, but some tweaking of the STARTMAPS section may be needed for areas in higer altitude, yet actually much further from the transmitters.
My bother lives in Rawdon, Quebec which is postal code J0K 1S0.
Putting in his data shows very little sucess, but because of the altitude, he can actually receive many more channels than I can from the Island of Montreal.

Is there a site that provides info on true "feet above MEAN SEA LEVEL"?
Does the STARTMAPS database take this into account?


Greg
Montreal, Canada
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Old 3-Apr-2010, 5:17 PM   #2
mtownsend
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Join Date: Dec 2009
Posts: 632
Thanks for the updates!

Just FYI, the main goal of our tools are to help with identification of transmitters and choosing the right antenna for the job. Since digital sub-channels don't really matter for selecting an antenna (whether an RF channel has 1 sub-channel or 99 doesn't really make any difference), we don't bother listing sub-channel information. The #.1 virtual channel numbers shown in the listings are just there as a reminder to let users know that the major virtual channel shown on their screen might be different than the true RF channel number. Since all of the sub-channels are carried on the same RF signal, if you can get one of the sub-channels, you should be able to get them all (assuming the broadcaster has put actual content there).



Quote:
Not sure if it is possible, but some tweaking of the STARTMAPS section may be needed for areas in higer altitude, yet actually much further from the transmitters.
My bother lives in Rawdon, Quebec which is postal code J0K 1S0.
Putting in his data shows very little sucess, but because of the altitude, he can actually receive many more channels than I can from the Island of Montreal.
The mapping tools should take into account any terrain and elevation of your brother's location. If you're using the Interactive Mapping feature, you may need to adjust the pointer's location (drag and drop the orange marker) to get an accurate location for your brother's house. You can also edit the antenna height field to experiment with higher antenna installations.

If you enter just a postal code, the marker might be placed at an arbitrary location in the middle of nowhere. In hilly terrain, it's important to place the marker accurately to get a more realistic analysis. A slight mis-placement of the marker might put you in a valley or behind some terrain blockage that makes signal reception impossible. By adjusting the location and setting the antenna height appropriately, you should be able to get a better analysis result.



Quote:
Is there a site that provides info on true "feet above MEAN SEA LEVEL"?
Does the STARTMAPS database take this into account?
Since it's your relative height above the terrain that determines terrain blockage of signals, your absolute height above mean sea level doesn't really help much.

If you want to convert a AMSL height (like from a GPS) to a height above terrain, that depends a lot on how the terrain data is referenced. Each terrain database is referenced to a specific vertical datum. Some are referenced to mean sea level (EGM96), some are tied to the WGS84 reference ellipsoid (no adjustment for MSL variations), while others may use a completely different vertical datum (like NGVD29 or NAVD88).

In other words, converting from an AMSL value to an AGL value is not straightforward, and is completely dependent on how the terrain height data was derived.

For propagation modeling purposes, the best way to get accurate results is to use the antenna height above ground. That way, no matter what terrain reference is used, you're more likely to get an accurate terrain blockage estimate because everything is relative to the terrain levels.

Sorry for the long explanation, but I hope this helps you understand why we can't reliably use mean sea level elevation data.
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