Rooftop antenna selection in Montreal NDG - Canadian TV, Computing and Home Theatre Forums

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post #1 of 21 (permalink) Old 2017-09-17, 12:18 PM Thread Starter
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Rooftop antenna selection in Montreal NDG

Hi everyone,
I just moved into a new home, and I have easy access to the roof. My current setup consists of two TV sets which share the signal from an RCA ANT1251Z rabbit ears type amplified antenna oriented NE in front of a 2nd floor window. I am piggybacking the previous owners' cable wiring, and made sure only one splitter is present on the signal path. I currently receive between ten and 17 channels, but my main issue is that I am not receiving TQ on channel 26 which is currently blocked by the Mont-Royal. The TV Fool report seems to indicate that I should be able to receive this channel with a rooftop antenna. Of course, I would also like to continue receiving the US Networks from across the border. What are my cheapest options for a roof antenna? Will I need a pre-amp?

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post #2 of 21 (permalink) Old 2017-09-17, 02:42 PM
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Welcome to the forum, jimi00

Your tvfool link doesn't work. There are some numbers missing from the end.

The last part of your link is this:
?option=com_wrapper&Itemid=29&q=id%3de6a4dfb

but a report for the intersection of Boul Cavendish / Av de Monkland in NDG looks like this:
?option=com_wrapper&Itemid=29&q=id%3de6a489bb4a378f

This is the active link for that location:
TV Fool

Please redo your report with an accurate address or coordinates.

CIVM TQ on real channel 26 is much weaker than your strong local channels. Depending upon your location, the amp in your antenna might be overloaded, making it difficult to receive the weaker TQ. You also have TQ on CIVS 24.
https://en.wikipedia.org/wiki/T%C3%A...A9-Qu%C3%A9bec

If your post is missing, the moderator might have moved it to a local reception thread.

If you can not measure it, you can not improve it.
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post #3 of 21 (permalink) Old 2017-09-17, 03:23 PM Thread Starter
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Sorry about that. TV Fool
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post #4 of 21 (permalink) Old 2017-09-17, 05:48 PM
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Thank you. That link works.

Your local signals are very strong; a preamp and your tuner would probably be overloaded. Your strongest channel listed (current) is CFTM with a signal power of -23.7 dBm, but if you click on pending you will see CBFT with a Noise Margin of 76.8 dB and a signal power of -14.0 dBm.



Interpreting Noise Margin in the TV Fool Report
Chuck's Digital TV Page

If you can not measure it, you can not improve it.
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Last edited by rabbit73; 2017-09-17 at 09:10 PM.
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post #5 of 21 (permalink) Old 2017-09-17, 06:59 PM
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It appears that you MAY NOT "NEED" to receive any Stations towards the East (i.e. 99-deg re True North)...TVA on Ch7 is duplicate to Ch10 (29-deg) and note that weak TQ on Ch24 (99-deg) is duplicate to weak Ch26 (28-deg). Also very weak Ch11 and Ch30. If this is NOT the case, then you will "NEED" a Rotator [or Multiple UHF Antennas] to cover all three directions [99-deg is at about Right Angles to the other directions and hence in the NULL of most Antenna Patterns].

IF you point a Hi-VHF Antenna towards (weak) ABC on Ch11 (149-deg), then Very Strong Ch10 and Ch11 (towards 29-deg) can't help but come in on the BACK LOBE of the Antenna. [And as discussed above, you likely don't "Need" Duplicate Ch7, Analog Ch8 and very weak Ch11.]

IF you point a UHF Antenna towards (weak) FOX on Ch43 (149-deg), then Very Strong Ch35 and Ch15 (towards 29-deg) can't help but come in on the BACK LOBE of the Antenna. Pointed towards 149-deg, you should also get CBS on Ch22, NBC on Ch14, PBS on Ch32, and likely the other PBS on Ch38 (194-deg).

HOWEVER, the UHF Antenna would probably NOT receive TQ on either weak Ch24 (99-deg in SIDE LOBE) or weak Ch26 (26-deg on the REAR LOBE).

To receive TQ, you would need to either use a ROTATOR.....or add a SECOND UHF Antenna pointed toward Ch24 (99-deg, the stronger of the two TQ stations). To prevent Multipath and other Noise from one Antenna degrading the Other Antenna, you should use a Single Channel 24 Insertion Filter when combining the two UHF Antennas, such as:
http://www.tinlee.com/PDF/AC7-custom...kup%20Info.pdf [AC-7.ch24]
Jan Jenca antenna components

And the combined UHF Antenna Coax is then combined with the output of the Hi-VHF Antenna using a UHF/VHF Antenna Combiner/Splitter, such as:
https://www.antennasdirect.com/store..._combiner.html

There are a variety of Hi-VHF/UHF Combo and individual Hi-VHF and UHF Antennas to chose from....but for best results I'm going to recommend using any of the 4-Bay Bowties [typ. 12-15 dBi UHF Gain, e.g. HDB-4X] with the fol. Stellar Labs 9-El Hi-VHF Yagi, both pointed towards 194-deg and ANOTHER 4-Bay Bowtie pointed towards 99-deg:
Stellar Labs Fringe Directional Antenna VHF-Hi HDTV 174 - 230MHz | 30-2475 (302475) | Stellar Labs
Xtreme Signal HDTV 4 Bay Bowtie Outdoor TV Antenna 45 Mile VHF/UHF (HDB4X) from Solid Signal

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands
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post #6 of 21 (permalink) Old 2017-09-17, 10:08 PM
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As holl_ands has indicated, you have a difficult location with your desired channels in different directions.

There is no easy fix; you must be prepared to experiment.

You also have some strong FM signals that might interfere with TV reception, if your FM report is correct.
http://www.fmfool.com/modeling/tmp/f...4/Radar-FM.png

Your coax should be grounded with a coax grounding block connected to the house electrical system ground, to reduce interference.

You can do your own FM signal report here, but it doesn't link the same way as the TV signal report.
http://www.fmfool.com/index.php?opti...pper&Itemid=29

If you can not measure it, you can not improve it.
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post #7 of 21 (permalink) Old 2017-09-17, 10:43 PM Thread Starter
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Thank you for your help. I am new to this, so I have some questions.
Given that the only weak VHF channel I would be aiming for is ABC on channel 13, wouldn't this be sufficiently high in the VHF spectrum to be received with a good UHF antenna or even a combo? Also, getting a separate antenna just for TQ on channel 24 or 26 seems overkill to me, my favorite being channel 26 because they broadcast in higher definition. I'm ready to take the risk of maybe failing to receive TQ if that would mean buying only one good all-around antenna. Which antenna and what orientation would allow me to reach such a compromise?
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post #8 of 21 (permalink) Old 2017-09-17, 10:45 PM Thread Starter
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I should add that, since I am using the old cable box wiring, my coax is already properly grounded.
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post #9 of 21 (permalink) Old 2017-09-18, 12:32 PM
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Quote:
Given that the only weak VHF channel I would be aiming for is ABC on channel 13, wouldn't this be sufficiently high in the VHF spectrum to be received with a good UHF antenna or even a combo?
Maybe with a UHF/VHF combo, but I wouldn't call it sufficiently high for a UHF antenna. WVNY is the weakest of your 149 degree channels. You will have to try it to find out.
Quote:
Also, getting a separate antenna just for TQ on channel 24 or 26 seems overkill to me, my favorite being channel 26 because they broadcast in higher definition.
I think a separate antenna is the only way you have a chance for reliable reception of CIVM, but you are welcome to try anything you want to try.
Quote:
I'm ready to take the risk of maybe failing to receive TQ if that would mean buying only one good all-around antenna. Which antenna and what orientation would allow me to reach such a compromise?
I don't know of any antenna that will satisfy that requirement.

You will need a separate antenna and a custom filter from Tin Lee Electronics for CIVM TQ 26.

There are several strong UHF channels in the same direction that are 60 dB stronger than CIVM:



You also have some very strong FM transmitters in the same direction:



You are behind a mountain:



in a weak signal area:


If you can not measure it, you can not improve it.
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post #10 of 21 (permalink) Old 2017-09-18, 02:06 PM Thread Starter
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Thank you rabbit for your detailed report on channel 26. Would I still have a chance of receiving TQ on channel 24 by the side if I used a good quality combo like the WG HD-7694P, even if it were oriented 149-Deg?


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post #11 of 21 (permalink) Old 2017-09-18, 02:31 PM
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Je ne sais pas

Maybe. CIVS is also in a weak signal zone for you.

Try aiming it at 99/113 degrees for CIVS TQ 24. If it comes in, then aim the antenna at 149/163. If that doesn't work, try aiming between 99 and 149.




If you can not measure it, you can not improve it.
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Last edited by rabbit73; 2017-09-18 at 03:36 PM.
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post #12 of 21 (permalink) Old 2017-09-18, 02:42 PM Thread Starter
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Thank you rabbit. I'll keep you posted.
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post #13 of 21 (permalink) Old 2017-09-18, 03:16 PM
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Due to the EXTREMELY High FM Signals, you should insert the fol. inexpensive FULL BAND FM FILTER on the Output of the above recommended VHF/UHF Combiner, so it is effective against FM signals picked up by ANY of the three Antennas:
https://www.antennasdirect.com/store...on_filter.html

===========================================
I've never seen an Antenna Model study of the HD-7694P, other than the incomplete charts in W-G's Spec Sheet, which claim a UHF Front/Back Ratio on the order of 20+ dB [i.e. towards 28-deg, for TQ on Ch 26]. HENCE, when pointed towards 194-deg it will be acting as an ATTENUATOR with LOTS OF LOSS [although NOT shown in the spec sheet, this loss could be MUCH, MUCH HIGHER, see discussion below].

Also note that the -3 dB BEAMWIDTH on Ch24/26 is about (or less than) 60-deg. IF UHF Antenna is pointed HALF-WAY between TQ on Ch24 (towards 99-deg) and FOX on Ch43 (towards 149-deg), then EACH would lose 3 dB by being a bit off from the Max Gain point. Since HD-7694P only has about 11.0 to 10.5 dBi Gain (Max) on these channels, you would end up with ONLY about 8.0 to 7.5 dBi Gain respectively on TQ Ch24 and FOX Ch43. Compare that to the 11.0 dBi on Ch24 and 12.2 dBi on Ch43 provided by each of two HDB-4X's when pointed directly towards the desired station:
http://www.winegard.com/kbase/uploads/HD7694P.pdf
http://manuals.solidsignal.com/hdb4x-gainchart.pdf
[This also illustrates the superiority of separate Hi-VHF and UHF-ONLY Antennas vs Hi-VHF/UHF COMBO's.]

Although we don't have an Antenna Model for the HD-7694P [a 5-Element LPDA with 3 Yagi-type Directors and a Reflector SYSTEM], we DO have some Antenna Models that illustrate the EXTREMELY High F/B and F/R Ratios typical for LPDA's, such as fol. 14-Element LPDA that provides roughly same Gain as HD-7694P:
UHF 14-El VEE LPDA + Shorting Stub - OPT
Note that F/B and F/R Ratio MINIMUM is about 20 dB....but on some Frequencies it reaches EXTREMELY High values. So it is extremely unlikely to receive any weak to moderate UHF stations on the BACK of the HD-7694P Antenna.

Although Gain was quite a bit less than the 5-El LPDA+3 Directors+Reflector in HD-7694P, the fol. "comparable size" 8-El LPDA also illustrates the Extremely High F/B and F/R Ratios typical of LPDA Designs:
http://imageevent.com/holl_ands/zigz...veelpdastubopt

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-09-18 at 03:37 PM.
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post #14 of 21 (permalink) Old 2017-09-18, 07:20 PM Thread Starter
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Thank you Holl. I'll take your advice regarding FM interference. Being in an urban environment, should I also be concerned with LTE interference?
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post #15 of 21 (permalink) Old 2017-09-21, 05:24 PM
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Given the wide range of ERP's that MIGHT be used in 700 MHz Band LTE Cell Towers [and the narrower TX Beamwidths used in Advanced-LTE], the fact that the Cell Tower Transmissions [728+ MHz, USUALLY AT&T and NOT Verizon] are significantly HIGHER than Ch51 [602-608 MHz] and the fact that they are spaced fairly wide apart [whereas higher freq Cell Towers are MUCH closer together], the likelihood of Interference from Cell Tower Transmissions is fairly LOW....and it would need to be within a few miles of your TV Antenna. [BTW: Multiplicity of Cell PHONES begins just above Ch51...and YOURS would be the primary Interference Source.]

Bear in mind that some LTE Filters can have significant LOSS on Ch51....so I wouldn't be too concerned about it unless you experience reception problems on one of the HIGHER Channel Numbers, e.g. Ch40 and above....and you KNOW that there is a nearby 700 MHz Band 4G/LTE Cell Tower.

See my fol. post for information re finding Cell Towers near YOU [you ONLY need to worry about the 700 MHz 4G/LTE Band...there are OTHER LTE Bands on higher Freqs]:
The Official AVS Antenna and Related Hardware Topic! - Page 547 - AVS Forum | Home Theater Discussions And Reviews

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands
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