Help with Reception in Tonawanda, NY

[nkreed]

Hello all,

I am posting on behalf of my friend who wants to add an antenna to their house. (They signed up but have been awaiting posting privileges for a few days).

Here is the TV Fool Report.

I have been advised that he is looking to receive as many Canadian channels on the list as possible along with the major American stations.

American (Real Channel): 32, 14, 33, 39, 33, 38, 49, 7
Canadian (Real Channel): 20, 19, 41, 44

Any other channels after this will just be extra.

He has 3 TVs he would like to attach to (possibly 4, but it's rarely used). One TV will have a DVR (either a Dual tuner or Quad tuner).

So I guess what I am looking for is what is the antenna he should purchase and where he should point it? (I'm thinking directly at 330 deg, but am fearful of the strong signal that may be picked up from 32).

Also, what other add-ons should he figure on purchasing. For instance a powered 4 way splitter to distribute the signal, a preamp (probably not but worth asking), or anything of the like.

I will advise him to place the antenna on a tripod on his roof. I have grounded my antenna in the past, so I will make sure that the tripod/mast and the coax run will be grounded before entering the house.

If there is anything else I have missed please advise.

As an aside, I must say that this forum helped me immensely in attaching my antenna to my home. It has been awesome not having to deal with cable or satellite company BS anymore. It has been a worth while investment to say the least.

Thanks.

[Tower Guy]

I'd try a DB-4, but remove the reflector before you install it. It will give you a bidirectional pattern. Aim the antenna for Toronto and Colden. The Grand Island stations will just come it slightly misaimed. If you don't have enough signal after a 4 way splitter get a Channel Master 3414 distribution amplifier. If you want WBBZ on channel 7 you'll need a VHF antenna plus a UVSJ.

[nkreed]

Thanks for your quick response! I have a few questions...

Originally Posted by Tower Guy

I'd try a DB-4, but remove the reflector before you install it. It will give you a bidirectional pattern. Aim the antenna for Toronto and Colden. The Grand Island stations will just come it slightly misaimed.

First, the DB-4 is discontinued, but the DB-4e is available, is that the antenna you suggest? Also, would the bottom set of bow-ties point at Colden (channels 39, 33, 38) and the top Toronto (20, 19, 41)?

Wouldn't you expect the GI farm (the strong signals 32, 14, 43) to overload this antenna? The polar gain plot for the DB-4e looks to have a significant amount of gain in the direction of GI if I pointed the antenna at Toronto.

If so, could that be tampered down a little with an attenuator to possibly help receive the Toronto stations NE of the farm?

Not all installations are the same, I know that, but I used a CM2016 antenna to reach Toronto and receive the Buffalo stations through the back it. The only difference between the installations (other than my antenna is 10 miles closer to Toronto) is that the GI farm was 2 miles ESE of my antenna. Do you think an antenna like this will receive the Toronto signals?

Originally Posted by Tower Guy

If you don't have enough signal after a 4 way splitter get a Channel Master 3414 distribution amplifier. If you want WBBZ on channel 7 you'll need a VHF antenna plus a UVSJ.

I will ask my friend if he feels that WBBZ is necessary. Thanks again for your insight.

[rabbit73]

Hi, nkreed:

I started to answer your question earlier today thinking that your friend's situation is like yours, after reading your previous thread:

Help with Reception in Buffalo 17-Jul-2013
http://forum.tvfool.com/showthread.php?t=13457

One thing I know will be a problem is the broadcast tower 2.5 miles away. My little research has found that I cannot use any power within my system. I am looking to receive the Buffalo and Toronto broadcast signals. These stations are nearly 180 degrees apart.

I was going to tell you to use the same solution for him that you used, but I suddenly realized there was a big difference between the two locations. Your TVFOOL report was no longer available, but it seemed that your strong local signals were south of your location and his are north of his location. This is a big difference, because when the antenna is aimed north the local strong signals are in the same direction. So, I backed off and let Tower Guy make a suggestion. He is a TV station engineer with a lot of experience, and his solution is a simple and elegant one. It is the best simple solution for your friend's location.

First, the DB-4 is discontinued, but the DB-4e is available, is that the antenna you suggest?

They are pretty much the same. The DB4E has been redesigned for the new 14-51 UHF band, has wires that are less hazardous, and has more eye appeal for the ladies.

Also, would the bottom set of bow-ties point at Colden (channels 39, 33, 38) and the top Toronto (20, 19, 41)?

No, I don't think he meant that. He told you to remove the reflector to get North and South with equal gain.

Wouldn't you expect the GI farm (the strong signals 32, 14, 43) to overload this antenna?

They wouldn't overload the antenna, but they might overload the tuner.

The polar gain plot for the DB-4e looks to have a significant amount of gain in the direction of GI if I pointed the antenna at Toronto.

Indeed, that's what makes the situation so difficult. You could use an antenna with a little less gain, but the local signals would still be vastly stronger, and the ratio between the two would be the same.

If so, could that be tampered down a little with an attenuator to possibly help receive the Toronto stations NE of the farm?

An attenuator will make all signals weaker by the same amount, so from the standpoint of signal strength, it wouldn't matter, because the difference in dB between the weak and strong signals would stay the same. This is called the Dynamic Range. A TV tuner is only capable of handling a certain Dynamic Range because the strong signals create spurious signals from distortion in the tuner that wipeout the weak signals.

The advantage of inserting an attenuator is that you can optimize the antenna system for the particular signals at that location to preserve as many weak signals as possible. This works, because for every one dB of attenuation, the spurious signals are reduced 3 dB. I have proved this to my satisfaction by making numerous overload tests. It works for tuners as well as for preamps:
http://www.digitalhome.ca/forum/1597002-post3490.html

Not all installations are the same, I know that, but I used a CM2016 antenna to reach Toronto and receive the Buffalo stations through the back it. The only difference between the installations (other than my antenna is 10 miles closer to Toronto) is that the GI farm was 2 miles ESE of my antenna. Do you think an antenna like this will receive the Toronto signals?

I think you need to try some tests with a temporary setup before any permanent mounting.

[rabbit73]

American (Real Channel): 32, 14, 33, 39, 33, 38, 49, 7

Two 33s?

Canadian (Real Channel): 20, 19, 41, 44

I didn't see 20 until I clicked on Pending in the report.

There are ways to solve the problem, but they are complicated and expensive. Your friend might have to settle for what he can get. A CATV system uses single channel antennas, and a lot of filters like this:



It is possible to combine two antennas to put a null in the pattern in the direction of the strong signals. This is what hdtvprimer calls the two antenna trick:

The towers for Sacramento and San Jose are only 15 degrees apart, but the San Jose towers are visible on the horizon. Pointing an amplified high-gain antenna in this direction will cause both preamp overload and adjacent channel interference. Putting San Jose in a null will permit the reception of Sacramento. Set the masts 40 inches apart. Reversing the polarity of one antenna will cause the null direction to not change with frequency, and all the San Jose stations can sit in the null.

The difference between GI and Toronto is 304 - 329 = 25 degrees.

And finally, there are custom bandstop filters made by Tin Lee that will tame the strong GI signals:
http://www.tinlee.com/MATV-Bandstops.php?active=3#CR7

Your friend has some very strong local FM signals that will interfere with TV reception. Insert an FM filter/trap or a HLSJ (high and common ports) in the coax line. I did an FMFOOL report based on his estimated location, which puts him about 5 blocks SW of Northtown Plaza Shopping Center. See attachment 3.

[rabbit73]

The strongest TV signal is WNLO with a Noise Margin of 73.2 dB, which puts it in the overload category. To that you can add ~10 dB of antenna gain which brings you up to a NM of 83.2 dB.



Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html

Going on the basis of Signal Power dBm in the report, WNLO is -17.6 dBm, and adding 10 dB antenna gain gives -7.6 dBm.

ATSC Recommended Practice:
Receiver Performance Guidelines
Document A/74:2010, 7 April 2010

RECEIVER PERFORMANCE GUIDELINES

5.1 Sensitivity

A DTV receiver should achieve a bit error rate in the transport stream of no worse than 3x10E-6 (i.e., the FCC Advisory Committee on Advanced Television Service, ACATS, Threshold of Visibility, TOV) for input RF signal levels directly to the tuner from –83 dBm to –5 dBm for both the VHF and UHF bands.

5.2 Multi-Signal Overload

The DTV receiver should accommodate more than one undesired, high-level, NSTC or DTV signal at its input, received from transmission facilities that are in close proximity to one another. For purposes of this guideline, it should be assumed that multiple signals, each approaching –8 dBm, will exist at the input of the receiver.

You can see why an attenuator might be necessary.

I will advise him to place the antenna on a tripod on his roof. I have grounded my antenna in the past, so I will make sure that the tripod/mast and the coax run will be grounded before entering the house.

Good, that will reduce the chance of strong TV and FM signals from causing interference. They can get directly into the TV set if the coax isn't grounded with a grounding block.

The coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety and to reject interference. For further compliance with the electrical code (NEC), the mast should also be grounded in a similar manner to drain any buildup of static charge, but the system will not survive a direct strike.

[nkreed]

Thanks both of you for your quick and awesome responses!

Tower Guy I'd try a DB-4, but remove the reflector before you install it. It will give you a bidirectional pattern.
NkreedAlso, would the bottom set of bow-ties point at Colden (channels 39, 33, 38) and the top Toronto (20, 19, 41)?
Rabbit No, I don't think he meant that. He told you to remove the reflector to get North and South with equal gain.

I like the DB4 antenna idea. Now that I understand that by removing the reflector panel, the antenna will act bidirectionally NW and SE and decrease the overall gain NW. This will help decrease the amount of signal received from the strong WNW braodcast towers and allow the antenna to receive the SE stations better.

Two 33s?

Sorry. Poor proof reading by myself, the first 33 should have been 43

5.2 Multi-Signal Overload

Quote:
The DTV receiver should accommodate more than one undesired, high-level, NSTC or DTV signal at its input, received from transmission facilities that are in close proximity to one another. For purposes of this guideline, it should be assumed that multiple signals, each approaching –8 dBm, will exist at the input of the receiver.
You can see why an attenuator might be necessary.

I like this extra detail re: Multi-Signal overload. This will help in both my friends antenna situation and mine!

Your friend has some very strong local FM signals that will interfere with TV reception. Insert an FM filter/trap or a HLSJ (high and common ports) in the coax line. I did an FMFOOL report based on his estimated location, which puts him about 5 blocks SW of Northtown Plaza Shopping Center. See attachment 3.

I have never thought about FM interference, this is a simple addition into the line with very minimal (if any?) signal loss and helps decrease the noise. Your responses help both my friend and me at the same time! It was definately worth looking into this for my friend, as I am learning more and more. (You can call me a geek if you want, but I find this all very interesting)

Again TowerGuy and Rabbit73 I thank you for your quick and well organized posts. There is a ton of information to help make a suitable decision for my friend, while upgrading the signals I receive at my home at the same time.

I like the attenuator idea to attempt to decrease the strong signals from wiping out the weak ones. I had just understood that an attenuator will take db's out of yor signal, so you will just lose the weak stations. The idea that those weak stations may work better because of less overload from strong stations makes me want to attempt this at my house.

A question regarding this is should i purchase a variable attenuator to see if this works, find a good attenuation level (if possible) and then opt for a specific filter at that attenuation level? (I dont even know if i would be able to measure the attenuation) Or do you think i should purchase a few 3 db attenuation pads and maybe a 6 db one and attach them in combination until I receive the best results? (Did i really just turn this into my antenna setup?!?)

Thank for all of your help and quick responses! I appreciate all of your insight and expertise! I will definetly let you know how things work when we order the parts and install the antenna. If I have any more questions, I will definetly ask.

[rabbit73]

Ah, good. My suspicions were correct. I made my posts long because I thought you wanted to know the "why" behind an idea.

I suggest you purchase a variable attenuator and a few fixed attenuators. Experiment with them and then replace the variable and fixed with equivalent fixed if they help. They are not very expensive and you might learn something useful.

The link in my signature is about using an attenuator to test TV signals in the UK. They use the term DTT for what we call OTA.

I use a variable attenuator to test the sensitivity of tuners. I connect the antenna to the attenuator and then to a splitter to feed two TVs. I increase the attenuation to see which TV drops out at the "Digital Cliff" last; it's the winner. OTA signals are constantly changing in strength, so it doesn't work to remove the coax from one TV and connect it to the other. See attachment 1 for my test setup.



variable attenuator:
https://www.antennasdirect.com/store...ttenuator.html

fixed attenuators:
http://www.3starinc.com/drop_in-line_attenuator.html
http://home-automation.smarthome.com...=&w=attenuator
http://mjsales.net/collections/atten...ant=1083705673
Attenuation values 1, 3, 6, 8, 10, 12, 16, 20dB (FAM)
click on 1 dB for other values; the up and down arrows are faint

The idea that those weak stations may work better because of less overload from strong stations makes me want to attempt this at my house.

If the technique doesn't give improvement when increasing attenuation because you run out of weak signal, it means that the Dynamic Range is too great for the attenuator technique.

FM filters:
http://www.mcmelectronics.com/produc...804247%2Cd.cGU
https://www.antennasdirect.com/store...on_filter.html
or
http://www.solidsignal.com/pview.asp?p=zhlsj
http://www.atvresearch.com/hlsjvhfba...-combiner.aspx
http://www.nsccom.com/hlsj.aspx

Attachment 2: MCM FM filter curve
Attachment 3: Antennas Direct FM filter curve vs Radio Shack
Attachment 4: HLSJ used as an FM filter