TVFool Canadian Discussion

[quatro]

Thanks very much mr weather. That is a very useful tip for me to start with. Can you elaborate on how to compensate for low NM values? Is there a ratio to adjust or inprove NM values with gain of antennas in general?
Thanks.

[BLT]

Heres a little example for you. We will use an antenna gain of 10dbd to make it simpler.
If you hd a NM of 20 for a particular station, you would add your antenna gain+your NM of 20 to get you a NM of 30.

If you add in a preamp(we will use a channelmaster 7777 for example) it has a NM of 2.0 so you would subtract that from your NM of 30 which would be 28.

If you dont use a preamp you have to subtract your cable losses,splitters,combiners,etc. and add all those losses up and subtract from your NM.

If you have enough gain on a preamp it will make up for cable losses,etc. downstream.
Its nice to have a "padding" of 10 db on your preamp to make up for these losses.

Another thing on NM's is its nice to have a 5 to 10 db "padding" if you want "truly reliable reception" without dropouts due to atmospheric condition changes,multipath,etc.

Just remember when selecting an antenna, to look at the gain across the whole spectrum as it will vary. HDTV primer is a good site to compare commercially available antennas, and others have built their own antennas with good results as found on this site.

Hope this helps:

Bob

[quatro]

BLT,

I will need to read this over and over, before understanding. Most of the terms are quite new to me. Nonethless this is an excellent start. Thank you very much.

[RamKat]

BLT, Somewhere in your calcs there should be some credit for the improvement of the pre-amp's Noise figure (NF) over the TV tuners' NF. I believe that the TVfool folks use some standard value for the NF of a Tuner to get to their Noise Margin figures. If the preamp does better than that, then I would expect that to be in the napkin calc as well ? no?

[BLT]

RamKat:

Yea your right, I forgot about that. I'm not really sure what they use, but I know a good figure of 5-10 is probably about right for a lot of tuners. I'm not really sure what they would use as a standard value.

Bob

[tvlurker]

The Noise Margin calculation does NOT include any presumed Noise Figure values. I think it's the difference from -90.8 dBm, which comes from the theoretical thermal noise floor at -106.2 dBm, minus the average SNR required to decode an ATSC signal, which is 15.4 dB.

Note that:
- your receiver may require slightly more or less than this value
- the actual thermal noise floor in your environment may be different from -106.2 dBm

and of course the Longley-Rice calculation does not take into effect local non-terrain obstructions or incursions into the Fresnel zone, like trees and nearby buildings.

For a full explanation from Andy Lee, the owner of the TVFool.com website, see the post in another forum at http://www.avsforum.com/avs-vb/showp...&postcount=397

[otaota]

Just today, TV Fool posted an update (link) saying that they now use Industry Canada data for the Canadian transmitters. Can anyone tell if this is any more accurate than before?

[stampeder]

Andy Lee hasn't recently mentioned pumping the IC database, just putting back the Canadian and Mexican analogue stations from before. This must be new.

EDIT: well, I just tried my own coordinates near Vancouver and only Global and CBC are showing up on the digital channels report, with no CTV. It lists a station called "HDTV" on channel 18 from Mt. Seymour, which does not exist. The SeaTac and Bellingham digitals remain the same as before since they're from the FCC database.

My take is that Andy has not integrated the Industry Canada database, or else maybe he has but not completely.

[balm]

wow, my TvFools look completely (almost) different now,

its showing some canadian digital channels I was having difficulty getting with NMs in the -20 dBs, thats really strange because although i was having difficulties, they are coming in, but at -20 dB, I dont think so

[zapperman]

Originally Posted by stampeder

... I just tried my own coordinates near Vancouver and only Global and CBC are showing up on the digital channels report, with no CTV. It lists a station called "HDTV" on channel 18 from Mt. Seymour, which does not exist. The SeaTac and Bellingham digitals remain the same as before since they're from the FCC database.....

I actually just ran mine again as well but I find that the results are more indicative of what I'm actually experiencing real world (except for that phantom "HDTV"). I now have NM's of -12 and -13 for Global and CBC, which explains why I have them, but just barely! I notice that they've corrected the ERP's for those transmitters as well, which probably explains the adjustment (I used to have NM's of around +8 for both of these stations on the old TV fool report).

I suspect CTV isn't there yet because they are still only showing as "authorized" in the database until they bump their power? Stampeder, you likely know the status of CTV better than the rest of us!

[tvlurker]

I've had just a brief look at Andy's new Canadian data-driven TVFool. It's much improved, but there are still some issues. Aside from the HDTV and SUNTV stations that are left over from their CRTC applications, there seems to be some problems with the base data for VHF analog stations. For example, thePower and ERP values for many VHF analog stations are overstated -- CBOT at 115 kW, for example.

Also, he doesn't seem to include the "TO" (Temporary Operating") stations, which are equivalent to the FCC's STA, so CBFT-DT and CBMT-DT don't show. Neither does CIVM-DT for that matter, although CFJP-DT does.

When I get a chance to do some more checking, I'll be sending Andy an email with the discrepancies.

Overall, it's a big improvement. we just need to get a bit of the data cleaned up. It's possible his data pump is misreading some of the IC data fields.

[stampeder]

Does TVFool have an option to display reports in metric? If not, can you ask Andy to add that?

[roger1818]

Originally Posted by tvlurker

Aside from the HDTV and SUNTV stations that are left over from their CRTC applications,

I susspect he is filtering out Canadian stations from the FCC data by looking for call signs that begin with C and so HDTV and SUNTV aren't being filtered out. A better approach would be to filter based on state/province.

Also, he doesn't seem to include the "TO" (Temporary Operating") stations, which are equivalent to the FCC's STA, so CBFT-DT and CBMT-DT don't show. Neither does CIVM-DT for that matter, although CFJP-DT does.

Also, when including "Pending applications" he doesnt' include the "UC" (Uncer Consideration) stations such as CITY-DT-3. Strangely when I did my address, "Pending applications" digital only, it added the 3 French stations from Hull, but they are still listed as "AL" but none of the Ottawa stations with this category were listed.

Overall, it's a big improvement. we just need to get a bit of the data cleaned up. It's possible his data pump is misreading some of the IC data fields.

Do you know if he is getting information about the direction of the broadcast, or is he assuming they are all omni-directional? Regardless, it is a huge improvement!

[RamKat]

Originally Posted by tvlurker

When I get a chance to do some more checking, I'll be sending Andy an email with the discrepancies.

Overall, it's a big improvement. we just need to get a bit of the data cleaned up. It's possible his data pump is misreading some of the IC data fields.

When you contact Andy just relay our appreciation for this great tool. Even though there are some discrepancies it is still VERY useful.

[tvlurker]

I've had a conversation with Andy over at the "other" forum site, and we've settled the discrepancies.

Andy explained that the analog power levels were summed to include both the Audio and Video peak power to make them comparable to the FCC data.

The "UC" stations may be added at a later date.

The HDTV, SUNTV, and other spurious entries will be removed.

What I though were attenna pattern discrepancies turened out to be non-problems.

Do you know if he is getting information about the direction of the broadcast, or is he assuming they are all omni-directional? Regardless, it is a huge improvement!

The antenna pattern data comes from the IC database.

I wholeheartedly recommend the Canadian data on his site now.

When you contact Andy just relay our appreciation for this great tool.

Done