Signal analysis vs. reality

[edstevens]

signal analysis is at http://www.tvfool.com/?option=com_wr...d243c8201b0521

Given the limitations on my antenna placement, my reception may just be "it is what it is", but I'd still like to get some understanding of what I'm seeing vs. what I expected.

Installed Mohu Skye in the attic. 100 ft. of 18g RG-6 quad shield to the tv. Based on the signal analysis I expected at least the ABC/NBC/FOX/NPT affiliates. But when the tv scanned for channels, the television identified the 'found' channels as

- 4.1 - WSMV
- 4.2 - CMT
- 39.1
- 39.2
- 44.1 - WJFB
- 44.2 -

Of those, WSMV is the only really strong signal.

I can't even correlate what the TV tells me it found vs the signal analysis map. I'm getting channels that I can't identify at all on the analysis, and stations that should be as strong as WSMV (according to the analysis) are not found at all by the TV.

Any "education" would be appreciated.

[GroundUrMast]

'Bashing' the Mohu product serves little if any positive purpose... so I hope the following comes across as 'constructive criticism'.

I have not been able to find any useful technical spec's on the Mohu web site. So I'm left to speculate as to the real performance of the antenna. The Mohu web site does claim 15 dB of gain... The only credible explanation for that gain is that it is produced by the amplifier that's built into the assembly. No amplifier adds to the true gain of the antenna, and no amplifier 'pulls' signal from the air, antenna or coax.The antenna performance should be considered independent of any amplifier, but the published gain claim is clearly a combination of the antenna and amplifier performance. Mohu is not the only vendor to use such misleading statistics manipulation, but they are being just as misleading as some scam antenna peddlers when they mash antenna and amplifier gain figures together as if they are the same.

The exterior shape of the Sky leads me to believe that it simply a 2-bay UHF bow-tie design with no reflector. If this is true, one would reasonably guess that the actual antenna can not produce more than 1 or 2 dB of gain. One would also have to assume that the antenna would be bi-directional which would make it a poor choice if multi-path interference is present.

Attics are widely variable in their ability to block, reflect and absorb radio waves. They are also prone to having significant amounts of interference due to the wiring in them and proximity to the electrical and electronic equipment in the building below.

You own the Sky... So, have you tested reception with the antenna outside, clear of obstructions such as trees and structures?

If I was starting from scratch, with a report like yours, I'd not presume that attic mounting was impossible, but I would not be surprised if the results were unreliable. I'd be prepared to mount outside in the clear. Antennas such as the Winegard HD7694P and Antennacraft HBU-33 would be the smallest I'd consider using. A premium solution such as a two antenna array, consisting of an Antennas Direct DB8E + Antennacraft Y10713 would not be overkill in my opinion.

+=>

For Maximum Reception of as many Broadcast Tv Stations/Channels that Can Be Received.

Above the Peak of the Roof in such a manner that reception is not , obstructed , impeded , blocked , by the , attic , roof , building , in the directions of , North West , North , North East , East.

Install a , Antennas Direct , DB8e , Current UHF channels 14 thru 51 antenna.
Buy at , http://www.amazon.com.

Aim the DB8e antenna at about 340 degree magnetic compass direction.

Also install a , http://www.antennacraft.net. CS600 VHF channels 2 thru 13 antenna.
Also aim at about 340 degree magnetic compass direction.

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Here is how to aim antennas , http://www.kyes.com/antenna/pointing/pointing.html.

Use a Real and Actual magnetic compass to aim antennas , do not trust a , cell phone , tablet and etc. compass.

As a assist of the best reception most Digital Tv's have a Signal Strength Meter and some Digital Tuners also have a Signal Quality Meter.

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Install a , http://www.antennacraft.net.

10G221 preamp.

Connect the DB8e antenna the the UHF connection of the 10G221 preamp.

Connect the CS600 antenna to the VHF connection of the preamp.

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Here are some above the roof antenna mounts.

http://www.ronard.com/909911.html. Install the 3 foot or 5 foot tripod antenna mount.

http://www.ronard.com/34424560.html. Install the , ronard(4560) , eave antenna mount.

http://www.ronard.com/ychim.html. Measure around the chimney and use a , ronard(2212) , ronard(2218) , ronard(2224) .

http://www.ronard.com.

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Home Depot has , 10 foot 6 inch length - 1 and 3/8 inch diameter , TOP RAIL , chain link fence , PIPE , that makes excellent antenna mast/pipe. The price is low at about 12 dollars.

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For 1 Tv connected use No splitter.

For 2 Tv's connected use a , Holland Electronics , HFS-2D , 2 way splitter.

For 3 Tv's connected use a , Holland electronics , HFS-3D , 3 way splitter.

Buy the , HFS-2D , HFS-3D , splitters at , http://www.hollandelectronics.com , or , http://www.amazon.com.

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Also Know this.

As always , trees and tree leaves , plants and plant leaves , have a Negative Effect on Broadcast Tv Reception and so do buildings and other obstructions including your own , attic , roof , building.

The Best Practice for Reliable Reception is to install antennas at a location that has the least amount to no amount of obstructions of any type or kind in the directions of reception including your own , attic , roof , building , in the directions of reception , North West , North , North East , East.

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Tvfool is showing the reception location as having , Analog Broadcast Tv Channels and Digital Broadcast Tv Channels.

Here is the Analog Broadcast Tv Channel , http://en.wikipedia.org/wiki/WETV-LP. Channel 11.

In the Tv Setup Menu select and channel scan for Digital Broadcast Tv Channels and Analog Broadcast Tv Channels.

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When Doing a Channel Scan Do Not Channel Scan for Cable Tv Channels Only.

The reason is the Tv is not connected to Cable Tv.

It is connected to a Tv antenna.

[edstevens]

I understand that my antenna may not live up to expectations. I understand that I've mounted it in a less-than-optimal-location. I understand that roofs, trees, and the fact I live at the base of a ridge between me and all of the stations I'm interested in can contribute to sub-optimal reception. That wasn't my question.

My questions are:
1) Given that I can clearly receive channel 10 - WSMV (see strength report linked in my OP) I would have expected that despite any and all sub-optimal conditions, I should be able also receive channel 27 (WKRN), channel 8 (WNPT) and most likely channel 15 (WZTV) and channel 25 (WTVF).

2) I do not understand the lack of correlation between the channel as reported by my television and what is shown on the signal-strength report.

3) Possibly related to (2), I have channels that I can't correlate at all on the report.

[ADTech]

If you're back in "tight" to the back side of a sharply changing bit of terrain, the signal calculations become grossly overestimated, especially on UHF channels. If there are trees in the signal path, the problems gets even worse.

I put your location as a bit north and west of the intersection of Almaville and Spantown Roads, perhaps at or next to the Methodist church. You're right, quite a hill behind you in the direction of the main towers which are mostly located on top the hill on I-24 heading west. Two of the three stations you're receiving (WHTN & WJFB, virtual channels 39.x and 44.x (incorrectly identified as 66.x) transmit from Lebanon and are not terrain-blocked. WSMV transmits from a tower out on I-40 two miles west of the I-440 split and it's less blocked close-in by hills. That explain the three stations you're getting.

There is no direct correlation between actual signal power and the readings provided by most TV sets. Most internal meters display some product of the bit error rate and AGC applied to the tuner.

Simply getting the antenna out of the attic and up in the air would very likely improve your situation. Leaving any antenna in the attic will be a failure.

[GroundUrMast]

1) Given that I can clearly receive channel 10 - WSMV (see strength report linked in my OP) I would have expected that despite any and all sub-optimal conditions, I should be able also receive channel 27 (WKRN), channel 8 (WNPT) and most likely channel 15 (WZTV) and channel 25 (WTVF).

An antenna will only be able to receive signals that are present at it's location. All of the variables we've acknowledged can easily combine to make some signals strong and others weak at a given point in space. Transmission impairments are rarely if ever the same at different frequencies. It's entirely possible that moving the antenna a few inches or feet will put it in a location that is favorable to different frequencies. If the antenna was located outside, clear of obstructions, several impediments to reliable reception may be eliminated... in which case, your expectations and assumptions would stand a better chance of being fulfilled. But as you add more impediments to reception, the net result becomes less and less predictable.

2) I do not understand the lack of correlation between the channel as reported by my television and what is shown on the signal-strength report.

3) Possibly related to (2), I have channels that I can't correlate at all on the report.

Your OP lists the following:
- 4.1 - WSMV
- 4.2 - CMT
- 39.1
- 39.2
- 44.1 - WJFB
- 44.2 -

TV Fool focuses on reception of the real channel, regardless of how many virtual channels are carried on the channel. Regardless of how many virtual channels are actually carried, TV Fool only lists the first one as an aid to correlating call sign, real channel number and virtual channel(s). Resources such as rabbitears.info provide more help with identifying the virtual channels.

Per rabbitears.info, WSMV carries two traditional TV channels and a mobile DTV channel. Your TV sees the MPEG-2 mux overhead in the data stream and recognizes the to virtual channels, 4.1 and 4.2 as video/audio streams that it can display. The MDTV channel is not shown to you by the TV because it doesn't have the capability to decode and display that format.

Virtual channels 39.1 and 39.2 are no doubt from WHTN. Many of the smaller stations lack the hardware and or staff that's needed to edit and maintain the guide data stream that would provide the call sign, and program guide, as a result, your TV may have no information to label the virtual channel with.

The information at rabbitears strongly suggests that the TV Fool database entry for WJFB is in error. TV Fool depends primarily on the FCC database (which has a few errors) for our information about each station. Because we are not primarily focused on tracking virtual channels, but rather on helping people get information about the physical 'real' channels, (so the can receive what ever may be carried), I would deffer to sources such as rabittears for information on virtual channels. The two virtual channels you listed, 44.1 & 44.2 agree with the data provided by rabbitears.info.

This link may prove helpful to you,
http://www.rabbitears.info/market.ph...n=WSMV#station

Your opening statement,

Given the limitations on my antenna placement, my reception may just be "it is what it is"

is quite true, particularly if you can not or will not consider any changes to the location or type of antenna.

[edstevens]

Originally Posted by ADTech

If you're back in "tight" to the back side of a sharply changing bit of terrain, the signal calculations become grossly overestimated, especially on UHF channels. If there are trees in the signal path, the problems gets even worse.

I put your location as a bit north and west of the intersection of Almaville and Spantown Roads, perhaps at or next to the Methodist church.

Correct. We are on Spanntown, right behind the church. Turn west out of my drive and within 0.25 mile you are headed up hill.

You're right, quite a hill behind you in the direction of the main towers which are mostly located on top the hill on I-24 heading west. Two of the three stations you're receiving (WHTN & WJFB, virtual channels 39.x and 44.x (incorrectly identified as 66.x) transmit from Lebanon and are not terrain-blocked. WSMV transmits from a tower out on I-40 two miles west of the I-440 split and it's less blocked close-in by hills. That explain the three stations you're getting.

Exactly the kind of info I was seeking. Thank you for looking into it.

Simply getting the antenna out of the attic and up in the air would very likely improve your situation. Leaving any antenna in the attic will be a failure.

I really didn't want to go to an outdoor setup, but I guess I need to look into it. My highest gable is actually pretty accessible from a lower portion of the roof, (allowing self-install) and that location would allow me to use the current pull of coax. Next question there is -- what do I need to do about lighting arrest?

[edstevens]

Originally Posted by GroundUrMast

. . . But as you add more impediments to reception, the net result becomes less and less predictable.

In principle, I knew that but did not fully appreciate the degree to which that factored in.

TV Fool focuses on reception of the real channel, regardless of how many virtual channels are carried on the channel. Regardless of how many virtual channels are actually carried, TV Fool only lists the first one as an aid to correlating call sign, real channel number and virtual channel(s). Resources such as rabbitears.info provide more help with identifying the virtual channels.

Good info. I figured those types of questions were a bit off-topic for this forum but didn't know where else to turn. Thank you for the lead. (I am active on several forums within my profession, and on some, people seem to take the attitude of "your question indicates you need a hardware store and this isn't a hardware store. End of discussion. Now go away." instead of "your question indicates you need a hardware store - here's the address of one." )

Your opening statement, is quite true, particularly if you can not or will not consider any changes to the location or type of antenna.

Had not wanted to go to the additional complexities of an outdoor mounting, especially since all indications were that the few channels I was interested in should have been available. Will reconsider. See my previous reply in this thread.

[GroundUrMast]

Will reconsider. See my previous reply in this thread.

Please forgive me if I came across as being short or terse. I certainly want you to get reliable reception.

[edstevens]

Originally Posted by GroundUrMast

Please forgive me if I came across as being short or terse. I certainly want you to get reliable reception.

Not short or terse at all. I appreciate the help.

[GroundUrMast]

...what do I need to do about lighting arrest?

Please look at this summary on grounding, http://forum.tvfool.com/showthread.php?t=901, post #20 in particular. If this raises questions, please feel free to ask.