Anything easy I can do to help improve reception?

Ken:

What happens if your eliminate the splitter just for a test, and connect the antenna only to one set?

You have plenty of signal so you should not see break-up. My only concern is that you have the 4-way splitter located in your wiring panel. I would relocate the splitter somewhere else that is far away from any power cable. It's probably very noisy electrically inside the panel and the cable is probably picking up the noise. Are you using RG-6 coaxial cables?

Excellent question. A baseline needs to be established to recommend the best solution(s).

Make sure your antenna is pointed in the right direction, which in your case is SW.

If you do the test bypassing the splitter just using one TV, and all channels come in fine, then you probably need an amp. Or you can put the antenna outside and gain more signal strength thus not needing an amp.

To temporarily bypass the splitter, remove it and reconnect a single coax, using a barrel splice. Radio Shack or home centers usually have them.


What is your roof made of?

Is your antenna pointed correctly? In this image, the stations are to the right of the antenna.

--------------------------------------> TV towers

At 30+ miles from the towers, I don't think you'll have very reliable signals with an attic antenna. It probably should be outside, and ten feet above the roof (unless you are on a hill already). Still, getting a few feet away from the roofing and the indoor stuff will help.

The structured wiring system should be fine, as long as the connections are done properly and the connectors are tightly screwed on (just a bit more than 'finger tight").

KVIE is on channel 9, a high-band VHF channel. Many things in the home (even the TV set itself) can cause interference to the VHF frequencies. So, getting the antenna outdoors, and up away from the ceiling/attic wiring and air-conditioning ducts should help a lot. You might also look at the remaining analog stations, and see if they have interference at times. Something could be causing a momentary "pop", which would equate to a second or two dropout in Digital.

After Kenglish's suggestion - the next thing I'd try would be either a preamp from the structured wiring box to the antenna, or a distribution amp in the SW panel. But even doing this - you don't want to overdrive your amp, so you want just enough to fix the problem, no more.

Mostly - you want just enough to cover your splitter losses (and other cable losses).

I'm in the Sacramento market also and I know that if TVFool is saying you have LOS to Walnut Grove and is showing Noise Margins >50 dB then you have tremendously strong signals. It's next to impossible that you're not getting enough signal. The much more likely problem is multipath.

You can probably solve the problem entirely by putting the antenna on the roof. What else is the antenna looking into close by? Are trees or buildings blocking the view to Walnut Grove?

You should easily be able to get 100% reception if you can position the antenna so that it clears most of the local ground clutter.

Just to compare, my TVFool report shows the Walnut Grove stations ranging from -9 to +4 dB Noise Margin and I'm 54 miles from the transmitters over 2 ridges and I get 99% reception, but I have a fancy antenna setup.

Chuck

Since the signal is split 4 times, you only get 1/4 of the signal going to the TV, splitting 2 times means the TV get 1/2 of the signal.

Degradation of your signal with the 4 way splitter is a classic sign that you are not getting sufficient signal to the TV. That is why a pre-amp is recommended. A properly chosen pre-amp would allow you split the signal without seeing any degradation.

If all desired stations are reliable with one set connected, but deteriorates with multiple splits, a distribution amp is usually best. (Especially with a lot of strong signals around)

A preamp will not solve multipath. With such strong signals it's likely to overload and make the problem worse.

I'm using a preamp because I have no other choice with a 525' run of coax. My one strong station here is KUVS and TVFool shows it to have a Noise Margin of 55 dB, similar to most of your stations. I had to install a channel 18 notch filter ahead of the preamp because that one station overloaded my preamp. You have a dozen stations in that signal strength range.

There are really only two issues affecting reception of any DTV station. Is it strong enough and is the signal quality being degraded by multipath? A third issue is interference from something in your house but that's a distant third with the signal levels you have.

I had to go look up what a Panamax was. It's spec'd at <0.5 dB insertion loss. A typical 3-way splitter is 3.5 dB loss and a 4-way is 7 dB loss. So what you're planning to do will get you 4 dB. Eliminating a jumper cable might get you another 1 dB. You'll never notice an increase of 4 or 5 dB when you have 50 dB.

I think I can safely say that the signals are not too weak so that leaves multipath. There's no point in worrying about preamps, cable loss and splitters when you have 50 dB to play around with. These are things to consider when you have weak signals. You need to look at solutions that address multipath. Getting it out of the attic is the #1 solution. The #2 solution is moving the antenna in the attic and hoping you can find a more optimum location for all the stations. A larger and more directive antenna might help.

I've seen the difference between an attic mounted antenna under a wood shingle roof and an outdoor antenna on the same house and it is stunning.

Chuck

Attic (ideal) will probably kill 50-75% of signal - not to mention it can greatly contribute to a multipath problem (or even be creating the problem in the first place). As always - the best solution is to put the antenna where it was designed to work - outside in free space. You DON'T have to put the antenna in the middle of your tile roof (I'd recommend against that for other reasons), but putting it on the end of a gable 3-10 feet above the tile could only help your situation.

For anyone not familiar with dB, it's hard to get across how big of a number 50 dB is. For power, it's a factor of 100,000.

A reduction in power of 75% is still only 6 dB. Even a reduction in dB of 75% out of a 50 dB Noise Margin would leave you 12.5 dB, which should still give you a signal quality number in the low 90's without multipath.

Let's say KOVR at 1 MW provided a 53 dB Noise Margin. They could reduce their power to 10 watts and you'd still be able to receive them.

At my location 14 miles from KMMW (channel 28) from Angels Camp, the FCC antenna pattern shows they should have 370 watts in my direction. I receive KMMW with a 40 dB noise margin. They could reduce power to 100 milliwatts and I'd still receive them.

KUVS has >60 dB noise margin with my antennas on the hilltop. I can receive KUVS with a little whip antenna inside my house while being blocked by the 100' manzanita covered hill that my antennas sit on.

This is why I say with a predicted Noise Margin of >50 dB you can rule out signal strength as the problem with certainty.

Chuck

Putting your antenna in the attic should not cause any problems. Any multipath present in the attic can easily be handled by the equalizer in the TV.

I have my antennas (separate VHF and UHF antennas) in the attic and use a pre-amp and receive all local stations with no problem. I ran a TVFool analysis and I can receive KCET which has a signal power of -84 dBm which is lower than your values. Note that all my reception involve one edge paths which includes multipath.

My TVFool results are:

http://www.tvfool.com/?option=com_wr...4bbabadb1bba15