Over the air digital television

[PZ]

Can anyone recommend a signal booster for a rooftop digital television antenna?

I've seen a few online, but many appear to have bad reviews.

[Art Blade]

No idea, PZ.. I don't even watch TV

[Dweller_Benthos]

Thing is, most amps or boosters do not increase the signal gain you get, only a better antenna will do that. Amplifiers will take the signal you have and increase it so you don't lose signal over a long run of cable to the TV, so if you have the antenna on one side of the house on the roof, and the TV on the other side and need to run 150 feet of wire to get to it, a booster will preserve what you have over that long cable run.

To get better reception, you need an antenna that will retrieve the signal you can get in a high enough gain to allow the TV to tune to it. Go to http://tvfool.com/ and enter your location and it will tell you what stations you will be in range of and what signal power you're likely to get. A good thing to read about what they will tell you is this FAQ http://tvfool.com/?option=com_content&task=view&id=57 Once you get the plot of stations, you can see what stations are in range for your antenna. The most important value is the noise margin listed as NM(dB) in the chart. So for instance, on the chart I looked at for my aunt & uncle's place in the mountains, all the stations are at least -5 dB signal:

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So, what they need is an antenna that will have enough gain in signal to boost that over at least 1 dB, the more the better. The antenna must also be able to receive the frequencies those channels broadcast on, listed as the real channel in the chart. So, basically channel 13 up to 31, we're only looking at the top six stations on that chart as the rest are too far away with too weak a signal to even think about getting them without extreme measures.

Looking at https://www.channelmaster.com/ we find the Extreme 80:

https://www.channelmaster.com/Digital_HDTV_Outdoor_TV_Antenna_p/cm-4228hd.htm

and looking at the tech specs we see it's VHF (channels 14-80 or however high they go) gain is +12dB which will boost those low signals, well above zero, which should improve the chances of getting those stations. The VHF gain (channels 2-13) is only +5dB which is just barely enough to get channel 13 in the chart above zero, so that will be borderline whether reception will be good or not. Probably will depend on the weather and time of year. Winter with cold dry air and no leaves on the trees is generally better for reception where summer with humid air and leaves will scatter the signals more and cause unreliable reception.

So getting a booster won't do much good, unless you have a decent signal and long cable run, but getting a better antenna that is suited for your location and signal strengths from the stations you can receive is better. For instance, if you have mixed VHF and UHF stations, you may need something like this:

https://www.channelmaster.com/Digital_HDTV_Outdoor_TV_Antenna_p/cm-3018.htm

Where the gain isn't as high as the extreme 80 but is good for both UHF and VHF signals.

Get a chart from TV Fool and post it and we can see what you have to w0#k with.

[PZ]

Wow, that's a detailed report D_B - many thanks and definitely a +1!

Here's my signal strength map:
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And oddly enough, a couple of years ago I managed to stumble onto this purchase:

https://www.channelmaster.com/Digital_HDTV_Outdoor_TV_Antenna_p/cm-4228hd.htm

...which is currently mounted on my roof. However, I do not know if it is aimed properly, and because transmitters are located at odd angles, I'm wondering if I can get some kind of motorized position device.

[Dweller_Benthos]

OK with that antenna you should easily get everything in the green and yellow bands at the top of the list, no problem. Signal strength is plenty high, the only one that won't is that PBS station on real channel 7, that antenna will have trouble getting that low a frequency, it's not made for it and doesn't have the elements of the right length to receive the transmission. The channels listed in the pink and grey sections are more borderline, that antenna might pull them in, but it's uncertain, will depend on conditions in the atmosphere and how your house is situated in the surrounding topography. So, if you're having issues getting decent reception on some or all stations, then the antenna is not aimed correctly. That antenna is directional, it only receives on the side with the elements (the wire bow tie shapes), the other side will receive nothing, the grilled wire mesh actually blocks any signal from that side, to make the front side be more receptive. So, you need to be able to point the antenna at the transmitter, and if your stations are from different directions, you need a rotator. This one is pretty fancy, normally I'd recommend the rotator from Radio Shack, but they don't exist anymore, so the options are more limited, and this one does pretty much everything:

https://www.channelmaster.com/TV_Antenna_Rotator_p/cm-9521hd.htm

Because it has a remote, you can tell it to rotate the antenna until it's positioned correctly for the channel you want to watch. That's where the other part of the TV Fool chart comes in handy, the circle part. It will tell you what stations are coming from what direction relative to your house. You can then decide what ones are important to you and what ones you can ignore.

You can use this website to find what each station is:

https://www.rabbitears.info/

Type in the call sign in the top text box and it should find most of them and tell you what they are. It looks like they are repeaters for other transmitters, which is why they don't all have normal call signs like KREM-DT, which should be on the repeater K26LJ-D so you shouldn't have to worry about getting the actual KREM, as it's repeated on K26LJ, at least that's what it looks like on rabbit ears if I'm reading it right.

In many TV markets in the US, they've tried to go over to as much UHF as possible, and to have a single, powerful transmitter to cover the whole market area. That way one antenna can get all the stations available in a certain market. At least that was the plan, but it doesn't always follow through. So look at the circle graph, or post that part (or the whole thing) and we can see where your stations are and what direction you need to aim the antenna, maybe you don't need the rotator.

[PZ]

This is my signal map. If I am reading it correctly, I should aim my antenna at "13" because it is in the middle of the roughly 180 degree range receivable by my antenna. Is that a correct interpretation? Thanks for the information on the rotator.

This is what I was thinking:

• Aim at 13 and see if I get all the channels (except of course the two in the extreme southwest)
• If that does not w0#k, aim at the northeast cluster to see how many I get
• Aim at the western cluster to see how many I get

That might determine if I need a rotaor

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[Dweller_Benthos]

Yeah that thick line for "13" is just channel 13, KXLY, and only that station. You want to aim at the long line of numbers just east of north, 45, 18, 46, 41, 26, & 40, that is your main set of repeaters. You may have decent enough signal to aim in between those two lines in the NNE, as the antenna might just have enough of a wide receiver area to get both sets. Heck, channel 13 is so strong, I'm surprised you're not hearing that off the fillings in your teeth! So you may pick that one up even not aiming directly at it. So I would aim just a few degrees east of true north, not magnetic north, I'm pretty sure these plots are true north (duh it says true north right there), and let the TV do a scan, and see what you get. This is where the trial and error comes in, as TVs sometimes don't scan a channel if it's not a real strong signal, but really, those are so strong, I think you'll have no problem, once you turn the antenna in the right direction. If it still has problems, check your cable, maybe replace it, especially if you have splices or splitters on it. Do a single run of cable from the antenna to the TV, then scan, see what happens.

[Art Blade]

I've been following this topic because I find it strangely interesting although it is of absolutely no practical use to me

[PZ]

Many thanks D_B 

As soon as the snow clears off my roof I'm going to head up there and do some aiming 

[Art Blade]

I hope it doesn't end in something like, *crieeeeek...CROCK!* "what was that, did something brea..UUAAAAAaaaargh!!"

[PZ]

 

[Dweller_Benthos]

Yeah, be sure of your footing! Or, make sure the wife is filming so you can get on one of those reality TV shows, it might help pay the hospital bills!

[PZ]

 

[Art Blade]

 

[nex]

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