Parma, OH: Trying to pull 1 out of the weeds... - AVS Forum
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post #1 of 13 Old 02-05-2013, 06:54 AM - Thread Starter
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http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d1dda9554652940

Generally speaking, I guess I am pretty lucky with where all the stations are located when it comes to pointing an antenna. Can anyone offer their opinion about the Winegard HD-4400??

http://shop.winegard.com/Merchant5/merchant.mvc?Screen=PROD&Store_Code=winegard&Product_Code=HD-4400

Do you think this would pull in WVPX? Given the close proximity to WJW & WOIO (3 miles, but VHF) will it pull those in?

I plan to locate the antenna in the attic as we are renting the house ( as soon as we purchase it, I will toss the antenna up on the roof).


**Edit - I will be using 2 TV's so I assume I will need a splitter...

Thanks in advance for the advice!
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post #2 of 13 Old 02-05-2013, 08:53 AM
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WOW....those are some of the strongest signals I've ever seen.....6 UHF and 2 Hi-VHF. WJW and WOIO are very strong....they'll come in, even when attenuated by a 4-Bay UHF Antenna.

First of all, insert a Variable RF Attenuator between Antenna and RF Splitter to see if simply reducing the signal levels by about 6-10+ dB makes any difference:
http://www.solidsignal.com/pview.asp?p=1296f&d=antennas-direct-20db-variable-attenuator-for-vhf-uhf-hd-off-air-reception-1296f&sku=853748001293
The 3rd Order Intermod Noise generated in each TV Tuner's front end is reduced 3 dB for each 1 dB of attenuation, so 10 dB reduces Noise Level by about 30 dB. The goal is to insert just enough attenuation to push the Intermod Noise down to the level of the Thermal Noise...so try small increments at a time and rescan each time, keeping a log of results. Unfortunately, the inexpensive attenuators don't have any calibration markings, so it's very trial and error.....

If that isn't enough to receive the ION Network on Ch23, a Tin-Lee "Single Channel Signal Injector" (or hard-to-get C-M JoinTenna) tuned to Ch23 can be used with a second antenna, with NO attenuation on the Ch23 (Single Channel) Antenna and the Variable RF Attenuator on the Broadband side:
http://www.tinlee.com/PDF/AC7-customer%20general%20hookup%20Info.pdf
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post #3 of 13 Old 02-05-2013, 09:08 AM
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I have used the high gain antennas in my photo with similar strengths with NO attenuators (other than an FM trap) & NO problems. In more than 1 location to boot. You will very likely NOT need attenaution.

Install the Antennacraft HBU-22 in your attic & you should do just fine with both sets connected. The 4400 is not VHF antenna, so I don't recommend it.
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post #4 of 13 Old 02-05-2013, 10:03 AM
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It all depends on how much INDOOR LOSS you experience in a particular location in your Attic and the Overload characteristics of your Tuner(s)....YMMV.....A LOT.....
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post #5 of 13 Old 02-05-2013, 10:15 AM
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At 3 miles away, I would bet even an indoor antenna in the attic would work like this one from Radio Shack:
http://www.radioshack.com/product/index.jsp?productId=2103077&znt_campaign=Category_CMS&znt_source=CAT&znt_medium=RSCOM&znt_content=CT2032189

Point it towards the SE. Even if it does not work, you can return it.
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post #6 of 13 Old 02-05-2013, 10:32 AM
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Quote:
Originally Posted by holl_ands View Post

It all depends on how much INDOOR LOSS you experience in a particular location in your Attic and the Overload characteristics of your Tuner(s)....YMMV.....A LOT.....
Mounted 10 feet above the roofline, in the clear & NO overload with numerous tuners (Samsung, LG, Insignia, Zenith, Channel Master, Toshiba, Zinwell, Hauppage, Magnavox, Panasonic) Even used a Channel Master 3414 distribution amp with no problem. Same set-up at 3 locations inside the beltway with NO overload. Amplifiers overload, not antennas. It is VERY rare that an antenna by itself will overload a tuner in the REAL WORLD with a modern tuner.

Here's the strongest TV Fool report in case you want to crunch the numbers, I'm sure the calculations will add up to WARNING WARNING, YOU MUST ATTENUATE.
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post #7 of 13 Old 02-05-2013, 11:21 AM - Thread Starter
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I should clarify (this is what I get for posting before my morning caffeine intake)... I currently have the amplified Leaf antenna. I get most of everything we want with the exception of ION (WVPX) and one other channel that I forget at the emoment. My dear wife says "No cord cutting until I can get my ION!". Thus the reason to pull in that one additional station in the midst of all the others in the southeast.
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post #8 of 13 Old 02-05-2013, 11:26 AM
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OMG, an amplified antenna with those red hot signals. Better get out the fire extinguisher!! You'll need at least 10 attenuators.
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post #9 of 13 Old 02-05-2013, 11:43 AM - Thread Starter
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And that's the problem. WVPX is located behind and beyond all the hot signals. No amplifier = no WVPX and lots of local stations. Amplified Leaf = no WVPX but some local stations.

I'm afraid if I go to a bigger antenna to get ION, it will be worse than using the amp'ed Leaf?

I guess I need to sit down tonight and do a "site survey"...
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post #10 of 13 Old 02-05-2013, 12:10 PM
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If you want ION, I would suggest a step up from my previous suggestion of the HBU-22 to the HBU-33. I seriously doubt you will have any overload issues.
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post #11 of 13 Old 02-05-2013, 02:17 PM
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Yeah if you want Ion, then the Radio Shack indoor antenna I suggested might not get it, but you never know until you try,
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post #12 of 13 Old 02-05-2013, 02:28 PM
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I prepared a Preamp "Overload" Spread Sheet Calculator, based on limited info from those few manufacturers who provide specs. But "Overload" can also be a problem when the Tuner is subjected to very strong signals on the OUTPUT of a Preamp....and when close to broadcast towers, when NOT using a Preamp. When the Input of a Tuner is "Overloaded", it actually means that the non-linearities in the device result in Intermodulation Distortion (IMD) products being generated, which can reduce the sensitivity on particular channels when the IMD Noise levels rise up above the Thermal Noise Floor, which normally determines the Sensitivity level of about -85 dBm (+/- 5 dB).
http://www.odyseus.nildram.co.uk/Systems_And_Devices_Files/Linearity.pdf
http://www.arl.army.mil/arlreports/2007/ARL-TR-4235.pdf

FCC A/74 provides Guidelines for Tuner performance, including how strong the Undesired (U) signals levels SHOULD be tolerated above the Desired (D) signals level for Adjacent Channel, as well as a group of so-called "Taboo" Channels that are in Next-Adjacent (N=2) and further away channel locations. The CECB Coupon Converter Boxes made these Guidelines MANDATORY...but manufacturers are NOT required to follow them in any of their other products. It was NOT easy for CECB's to meet these and other specs, so they represent the State-Of-The-Art (in 2006) and it is unlikely newer equipment has significantly better tolerance to IMD:
http://www.ntia.doc.gov/legacy/dtvcoupon/DTVmanufacturers.pdf

FCC OET TR-05-1017 (Nov2005) reported on tests conducted on DTVs & STBs bought in 2005-2006, including Sensitivity, Noise Figure and Multipath Tolerance using RF Field Captures (cited in ATSC A/74)...but did NOT address any IMD issues:
http://transition.fcc.gov/oet/info/documents/reports/TR-05-1017-ATSC-reception-testing.pdf

FCC OET 07-TR-1003 (Mar2007) reported on additional tests conducted on DTVs & STBs bought in 2005-2006, including IMD desensitization due to ONE and TWO strong interfering channels. Figure 5-9 on (sequential) pg63 shows a susceptibility of a Desired Channel just above Sensitivity for a wide range of "Taboo" channels, not just Adjacent (N+/-1) and Next-Adjacent (N+/-2). Many have very high susceptibility as many as 7 and 14-15 channel positions (Ch44-45) higher than the desired channel (Ch30). For example with (non-EMI) Sensitivity= -85 dBm, D/U = -55 to -65 dB corresponds to Undesired Pwr(dBm)= -30 to -20 dBm.

Table 9-6 on pg102 summarized results for TWO interfering channels for a variety of separations between Desired (D) and Undesired (U) with channel separations N and K. Undesired signal levels that caused readily visible interference ("TOV") occurred over the range of U = -24 to -42 dBm when Desired signal was 1 dB above sensitivity threshold without interference. With a 10-12 dBd Gain Antenna (e.g. CM4221HD 4-Bay) and say 6 dB downlead Loss, Tuner could "Overload" with TVFool calculated (worst case) levels as low as Pwr(dBm) = -36 dBm (-42 dBm +12 - 6)....although most channel separations would be in the range of Pwr(dBm) = -25 dBm.
http://www.fcc.gov/oet/info/documents/reports/DTV_Interference_Rejection_Thresholds-03-30-07.pdf

Charles Rhodes of TV Technology magazine had several articles on this subject and the related DTV/LTE EMI issues, including:
http://www.tvtechnology.com/news/0110/fcc-dtv-receiver-tests-confirm-concerns-about-intermodulation-interference-/185330
http://www.tvtechnology.com/digital-tv/0148/solving-dtv-wireless-broadband-interference-problems/210841
http://www.tvtechnology.com/digital-tv/0148/does-dtv-interference-from-taboo-channels-exist/214566
http://www.tvtechnology.com/digital-tv/0148/test-results-for-dtv-dtv-interference-from-%E2%80%98uhf-taboo-channels/215231
http://www.tvtechnology.com/digital-tv/0148/testing-interference-on-uhf-taboo-channels/217257
http://www.tvtechnology.com/distribution/0099/g-interference-to-uhf-dtv/210181 [EMI to/from nearby LTE Cell Towers & Phones]

FCC OET 9TR1003 (Oct2009) reported on tests conducted on numerous CECB Coupon Converter Boxes including IMD desensitization due to TWO strong interfering channels. Table 2-7 on pg31 summarized these results for a variety of separations between Desired (D) and Undesired (U) with channel separations N and K. Readily visible interference ("TOV") occurred over the range of D/U Ratio of -40 to -60 dB for a "weak" desired signal level of -68 dB (nearly 20 dB ABOVE sensitivity). Unfortunately, they did NOT test at Desired signal level just above sensitivity...but from the preceding test results, the D/U Ratio can be expected to be slightly higher. So worse case, multiple Undesired signal levels in the ballpark of -25 dBm (give or take) CAN result in desensitization on weak channel positions.
http://www.fcc.gov/oet/info/documents/reports/9TR1003-ConverterBoxTestReport.pdf

Unfortunately, the ONLY Tuner tested using Double-Conversion was the first ever, specially built and tweaked "Grand Alliance" ATSC Prototype, rather than the usual Single-Conversion Super-hetereodyne design. So none of these tests provide insight into how well CURRENT Double-Conversion Tuners perform, such as the Microtune Integrated Tuner Chip....could be better....or could be worse under some conditions (as I suspect).
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post #13 of 13 Old 02-07-2013, 05:13 AM - Thread Starter
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Thanks all for your input. I'll post my results once I get a "real" antenna. smile.gif
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