Signal strength questions

RodBarnes · 23-Apr-2011, 5:40 PM

Below is the link to my signal strength report. As you can see, all of my channels are almost the exact same direction. (Those few that are not aren't ones we get in this area anyway.)

Signal Strength map

My problem: I have periodic drop out of some channels. Specifically, the 8.x, 12.x, and 10.x channels. Looking at the map, I can see that all of these are in the "green".

Configuration: I have three televisions (Hauppage HVR-2250 dual-channel and two Vizio VW22LHDTV10T), connected through a four-way splitter (one input, four output), to an Antenna Direct ClearStream 2 mounted in the attic and aimed at the proper location indicated on the map.

Question #1:
Is my understanding correct that a splitter will reduce signal strength to each of the end points? That is, a four-way splitter will effectively reduce the signal strength to 1/4 to each end-point.

Testing seems to bear this out. I disconnected the two Vizio TVs and worked with adjusting the antenna while checking signal strength from the Hauppage tuners. I got it to where it was consistently strong for all channels -- even those where I had been experiencing drop-out. After I reconnected the Vizios, I again checked signal strength on the Hauppage tuners and found that the three channels I noted were now less than excellent -- sometimes good, sometimes not there at all.

Question #2:
Would purchasing an additional antenna -- or even one for each TV be a solution? Or would purchasing some type of amplifier be a solution?

GroundUrMast · 23-Apr-2011, 7:10 PM

For reception of real channels 14 through 69, the Clear Stream 2 is a good choice for your location.

Your problem channels are all high VHF (7 through 13). You can add a H-VHF antenna and solve the problem.

You will need a UVSJ. Antennas Direct offers a UVSJ with a weather-tight housing.

Antenna suggestions: CS-5 or Y5713. An alternative to a dual antenna system would be a small UHF/VHF combination antenna such as the RCA ANT-751 which would eliminate the need for the UVSJ.

You should not need any amplification, the signal power is more than adequate to drive up to an 8-way passive splitter. In fact, it would be likely that most amplifiers would overload, causing far more trouble. You have more than enough signal power, really.

John Candle · 23-Apr-2011, 7:44 PM

Read and understand this about , REAL Broadcast Digital Tv Channels , Virtual Broadcast Digital Tv Channels , Analog Tv Channels , http://forum.tvfool.com/showthread.php?t=695

RodBarnes · 23-Apr-2011, 8:03 PM

@GroundUrMast
I followed your link to the ClearStream 5 and saw it was a UHF/VHF (High). So I also checked out the ClearStream 2 and finally realized it is a UHF only antenna. Clearly I didn't look close enough when I purchased it.

Given my situation (attic mounted), I was thinking my best option would be to replace my CS2 with a CS5. Yet, even the CS5 isn't shown to cover VHF (low). On rare occasions I have problems with channels 2-6 -- so, would I need a different antenna to pick up that range?

GroundUrMast · 23-Apr-2011, 8:37 PM

As JC has pointed out, virtual channels are a source of confusion. The antenna has no 'awareness' of virtual channels. Only the real channel is relevant. Virtual Channel 2.1 is really on UHF channel 43 and VC 6.1 is broadcast on real UHF CH-40... both are UHF signals as far as antenna selection is concerned.

I hope ADTech will weigh in re. the CS-5. I am aware that it is sold as a combo VHF/UHF but UHF is not it's strong suit.

As you have already demonstrated, the 'UHF only' CS-2 does receive enough signal to often provide reception of real H-VHF channels, in part due to the high signal levels.

You may find that the construction of your roof and attic is too inhospitable for reliable reception. Because you are having trouble with UHF reception as well as H-VHF, I would strongly recommend trying the CS-2 outside, in the clear. You may find, as I have, that your roof is the biggest problem. When my roof is wet, there is too much attenuation and signal reflection for reliable reception.

John Candle · 23-Apr-2011, 9:00 PM

KOIN-DT is Real UHF channel 40 , KATU-DT is Real UHF channel 43 , and KRCW-TV VHF low band channel 5 is a fill in low power transmitter , KRCW's main transmitter is UHF channel 33 and UHF 33 is easly received at your location. The importance of knowing Real digital Tv Channels and Virtual digital Tv channels . . Next subject - Being that the antenna is in the attic , here is some important information. Attic locations reduce the amount of signal received , if the roof is any type of metal or foil backed insulation the signal will be reduced or blocked. If the roof is composition type singles - when the singles are wet the signals will be reduced. If the siding on the house is any type or kind of metal the signals will be reduced or blocked. If the house has brick from ground to roof the signals will be reduced. . For a attic installation I suggest a Winegard HD7696P antenna , for a roof top antenna I suggest a Winegard HD7694P antenna. . Here is how to point tv antennas , http://www.kyes.com/antenna/pointing/pointing.html

John Candle · 23-Apr-2011, 9:09 PM

If you decide to go with a roof top antenna here are Strong and Sturdy antenna mounts. tripod mount , chimney mount , peak of the roof eave mount. Here are places to buy antennas mounts and etc. , http://www.3starinc.com , http://www.solidsignal.com , http://www.starkelectronic.com , http://www.amazon.com

John Candle · 23-Apr-2011, 9:17 PM

Always check ALL coax and connections. Look inside the coax connectors on the ends of the coax - see if the outer foil shied / shield wires are pushed in toward center conductor , the center conductor carries the signal. Being that you are at a wet climate look for corrosion. .

John Candle · 23-Apr-2011, 9:54 PM

Here are free internet Tv guides , http://zap2it.com , http://tv.entertainment.excite.com , http://television.aol.com , http://www.titantv.com , http://www.tvzap.com

ADTech · 25-Apr-2011, 4:30 PM

Run down to radio Shack and pick up one of these: http://www.radioshack.com/search/ind...FM%20trap&sr=1

Keep your receipt just in case.

You'd be surprised how much FM and VHF signals the C2 actually can receive. The difficulty is in controlling it so it can be successfully exploited! I prefer to call it a "UHF-mostly" antenna.

Quote:

For a attic installation I suggest a Winegard HD7696P antenna , for a roof top antenna I suggest a Winegard HD7694P antenna.

He's only 6 miles away from his towers with LOS and there's no evidence of multi-path presented. Forecasted signal powers are in the teens and twenties A large directional antenna probably isn't needed. In fact, a 20 dB attenuator would probably do a world of good in conjunction with the FM trap. A 6-10' antenna is overkill for this situation.

If the FM Trap doesn't resolve the issues with 8, 10, 12, let me know and I'll see what stuff, experimental or otherwise, might be in my toy box.

PS We do have customer service/tech support folks here seven days a week. Customers are invited to call or email us directly for assistance.

Tower Guy · 25-Apr-2011, 6:26 PM

Quote:

Originally Posted by ADTech

You'd be surprised how much FM and VHF signals the C2 actually can receive.

I prefer to call it a "UHF-mostly" antenna.

A highly respected engineer rates this antenna as -40 dbd gain on channel 8, -44 dbd on channel 10 and -49 dbd on channel 12.

http://www.hdtvprimer.com/ANTENNAS/TemporaryPage.html

To call that "UHF mostly" is a "spin" that causes me to get dizzy.

ADTech · 25-Apr-2011, 8:17 PM

Quote:

Originally Posted by Tower Guy

To call that "UHF mostly" is a "spin" that causes me to get dizzy.

Please don't get so dizzy that you fall off the tower, the ladder, or the roof.

Yes, I know of Ken Nist's evaluations. However, those evaluations are of the loop geometry and do not include the (highly) variable reception afforded by the feedline/balun. As I noted, you have to know how to exploit the feature which isn't documented so it is understandable if it isn't known or understood by most.

Hey, I don't like using it for VHF/FM and I don't recommend using it for such, but, from numerous hands-on hours spent with both the antenna and a spectrum analyzer, I think it's safe to say that I know how the antenna works (and doesn't). Given that I have toys in my toy box than most people don't have, I do have a distinct advantage over the public. It isn't spin when you know what you're talking about.

Given that the reception on VHF is so iffy with the C2, the boss finally approved a design change that will add a simple VHF dipole with a diplexer to the C2 to allow a measurable and predictable level of high-VHF reception. We'll likely get the first shipment of this version in early this summer. I don't know where they'll end up, but I suspect they'll go to one of our large retail partners. The VHF add-on isn't pretty, but we were interested in getting something out there that works better and the current version. Our mechanical designer is working on something more aesthetically acceptable. I field-tested the C2 with dipole two weeks ago and found that it performs as well as can be expected - about unity gain on high-VHF channels 8 & 12. I expect it will be somewhat adequate for near-in (urban and suburban) high-VHF reception in uncomplicated situations. This will be a big improvement over the current "UHF mostly" model.

RodBarnes · 27-Apr-2011, 2:07 AM

@ADTech: Thanks, I'll try the FM trap and see if it makes a difference. But I find your recommendation for a 20db attenuator interesting. I would expect that to degrade the antenna's overall performance. However, having said that, I admit that when we had cable, we regularly had issues with ghosting on channel 8 -- which, I believe, indicates really strong ambient reception given it must've been leaking in through the cable connection.

GroudUrMast recommended moving the antenna outside -- which would be a fairly simple thing to do. It certainly seems that we experience increased degradation when the roof is wet -- which happens quite often around here.

Do you have any recommendations on how that might improve things?

Quote:

Originally Posted by ADTech

Run down to radio Shack and pick up one of these: http://www.radioshack.com/search/ind...FM%20trap&sr=1

Keep your receipt just in case.

GroundUrMast · 27-Apr-2011, 2:48 AM

I certainly agree with ADTech re. the FM trap. And as long as you are able to return it, you are only risking a bit of time and gas.

When the roof gets wet, it becomes a better conductor of electricity. That makes it more effective as a shield. The radio and TV signals are reflected and absorbed by the roofing materials. Put a load of wet snow on the roof and things get really tough for an attic mounted antenna. With out a signal level meter we are left to speculate how much attenuation is caused.

The signal level prediction indicates that the top six stations on your TVF report arrive at your location 1000 times (30 dB) stronger than the nominal level used in a MATV distribution system. You do not need an amplifier. I would hold off on the purchase of the 20 dB attenuator for the moment, but again, ADTech is certainly not off base for raising the point. I'm fairly confident your splitting losses are going to take care of potential overload issues.

Reliable reception depends on more than just raw signal level. The signal needs to be free from distortion and noise. Let's try the FM trap first, it's the easiest. Then if needed, let's try the existing antenna outside in the clear. We can regroup and consider the other options after that, if needed.

No static at all · 27-Apr-2011, 3:06 AM

I suspect attic enhanced multipath.(signal reflections) Getting the antenna out of the attic would be my first move. If the antenna must remain in the attic, I would first try relocating it & adding an FM trap. If this doesn't help, I would then replace the current antenna with a more directional antenna such as an HBU-33.

Signal overload is highly unlikely at 6 miles with any antenna unless it is amplified. OTOH multipath is many times more problematic as you get closer to the transmitter. A higher gain/directional antenna mounted outside is the best defense against multipath from my experience.

RodBarnes · 1-May-2011, 1:31 AM

I purchased the FM trap and installed it between the antenna and the splitter. Not sure but I think it has made some improvement. The 8/10/12 spread all comes in more reliably. I twiddled with the direction of the antenna itself for some additional improvements. However, my improvement could simply be because we have really good weather right now so there is likely less interference. Next plan is to move the antenna outside of the attic. Stay tuned...