What is the Current State of ATSC Tuner Development? - AVS Forum
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post #1 of 10 Old 05-13-2013, 01:32 PM - Thread Starter
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I live in an area where reception is a problem with a CM 4228/7777 so I need to get the best tuner I can find.

Where are the best tuners usually found? what kind of "appliance?"

Are Generation 8 tuners being shipped?

Are tuners made now Chip or are Can tuners still being made?

Are all Chip tuners better than any Can tuner? (Low Cost -v- Performance could make this up-side-down.)

I read comments that some generation tuners completely outperformed previous generations. Evidently this is not true of all generations. Would like to find a technical summary of the ATSC generations.

Thanks in advance,
Tom
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post #2 of 10 Old 05-13-2013, 01:59 PM
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Hmmm, STB ATSC tuners are not as prolific as they once were. Most of the ones left include a DVR. It's been years since I looked for ATSC STBs but back in the day LG made one of the best. Most major mfr HDTVs nowadays have very good ATSC tuners. How high up is your antenna? Do you have a rotor? What are you using now for an ATSC tuner?
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post #3 of 10 Old 05-13-2013, 03:28 PM - Thread Starter
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My antenna is about 8' high and I need to get it on a mast.

I do have a couple of rotors but have not installed one - I definitely have multipath distortion because minute changes in orientations produce huge changes in signal strength. (Maybe I should run a side-by-side array and narrow the lobe?

I have a Sanyo TV first model w/DVI input that has a terrible tuner compared to my CM 7000 SD Coupon Box (which is my primary ATSC tuner.)

I know there are only a couple OTA DVR's being made and don't really know which have the better tuners - it could be a Tivo for all I know.

I could settle for using my CM7k and one of my DVD w/HDD for a SD DVR function, but it would be nice to capture HD.

HTPC is the other avenue. It could very well be that those guys have really good tuners these days. I simply don't know.

Its a "cross-discipline" discussion when you talk about ATSC tuners wherever they can be found.

I also picked up Radio Shacks deepest fringe VHF/UHF antenna which is about 12' long. But I don't think I have any VHFlow channels in my area, so the 4228 should be OK.
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post #4 of 10 Old 05-13-2013, 04:38 PM
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You might want to run a TVFool report and post the results in the Local HDTV forum that is specific (or close enough) to your area. They may be able to give you some ideas on a better antenna. However, 8' is not high enough, IMO, to get reliable reception. Mine is 30' from ground (to the highest point on my single story) with a rotor (which I rarely use). Even if you get a better tuner, antenna height may still be an issue. As far as which tuner is better than the other, I think any of the newer ATSC DVRs have good tuners. I'd still get your antenna as high up as is reasonable and safe and see what happens.
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post #5 of 10 Old 05-13-2013, 08:20 PM
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The LAST publicly available comparison test of HDTV's and HD-STB was way back in 2005, but model numbers were NOT disclosed:
http://transition.fcc.gov/oet/info/documents/reports/TR-05-1017-ATSC-reception-testing.pdf
http://www.fcc.gov/oet/info/documents/reports/DTV_Interference_Rejection_Thresholds-03-30-07.pdf
The biggest disparities in performance were Sensitivity (Noise Figure) and how many of the ATSC A/74 "Field Ensembles" the different boxes could receive.
The 50 "Field Ensembles" are a set of Lab & OTA signal recordings captured during various field tests representing WORST CASE Multipath. Some of the captures are known to be damaged and hence unrecoverable. And a few may be so "bad", they'll probably never be successfully decoded:
http://www.nutune.com/attachments/article/13/sup_12_NuTune_Tech_Recommended%20Ensembles.pdf

In early 2007, CECB's (Coupon Eligible Converter Boxes) are the first (and ONLY) Tuners REQUIRED to actually MEET ATSC A/74 Receiver "Guidelines":
http://www.ntia.doc.gov/dtvcoupon/dtvmanufacturers.pdf
Here are results of comparison tests, but again, model numbers are NOT disclosed:
http://www.fcc.gov/oet/info/documents/reports/DTV_Interference_Rejection_Thresholds-03-30-07.pdf
Section 3 includes the Field Ensemble test results, showing a big improvement wrt to HDTV & HD-STB's for 2-years earlier.
NAB also sponsored a comparison test, but again model numbers were NOT disclosed in test results:
http://www.nabfastroad.org/NABSTVDigitalConverterBoxEvaluation/DigitalConverter.asp
Note that ALL CECB's had the SAME Sensitivity, give or take 1 dB, so no clear winners......or losers for that particular spec number.

And that's the last we've heard on this subject...and BTW, all of the above tests were on Single-Conversion Super-Het Tuners, except for the first-ever Prototype 1st Gen ATSC Tuner that was Double-Conversion. So we still don't know if Double-Conversion Tuners, like Microtune and a few Samsung Tuners have better or worse (my suspicion) resistance to strong out-of-band signals.

Zenith (who sold the ATSC Patent Rights to Korea) created their own "Generation" designation:
Code:
Gen     Ghost    Post-Ghost    Pre-Ghost    Dynamic 
      Amplitude   Length        Length      Speed
First    70%      10-20 us      <3 us         5 Hz  
Second   80%      40-44 us      3-5 us        8 Hz
Third    90%      40-44 us      5-10 us     10-15 Hz
Fourth   95%      40-44 us     10-20 us     20-50 Hz

From: "Advances in 8-VSB and Receiver Performance: The Digital Evolution",
Wayne C. Luplow (Zenith), at CITEL PCC II, Fortaleza, July 2002.

In 2004, LGDT3303 chip was labeled "5th Gen", pushing the Pre and Post-Ghost Lengths to +/- 50 us, an IMPORTANT improvement:
http://www.tvtechnology.com/news/0110/is-dtv-reception-problem-solved/184758

From my experience with Adaptive Equalizers for HF Communications, 20-years EARLIER, we learned that it is IMPORTANT to have an Equalizer that is TWICE the length of the maximum delay expected. When the Equalizer is initialized the first time or when recovering from a severe fade, it doesn't KNOW whether the received signal preamble signal is a Direct Path signal, or is a Delayed Path signal. The early Equalizers assumed that they were ALWAYS locking onto a Direct path signal and failed whenever the Direct path signal had momentarily faded away. A Double-Length Equalizer always puts the Preamble signal in the MIDDLE of the Equalizer, so it is ready to accept a late arriving Direct Path signal.

In early 2007, CECB "6th Gen" chips were REQUIRED to meet ATSC A/74 "Guidelines", and subsequently were head and shoulders better than earlier chips. We should hope that any HDTV or HD-STB designed since about 2008 will have equivalent "6th Gen" (and maybe slightly better) performance. FYI: I enumerated the various 6th Gen chips in the "CECB FEATURES", found in my signature line below.

Unless manufacturers disclose how much "better" they are at meeting various requirements, any claim beyond 6th Gen is pure marketing hype....or an admission that their earlier 6th Gen chips weren't quite as good as the others and had room for improvement...

BTW: I doubt that there has been much advancement in tuner technology since the 6th Gen chips.....they were THAT good....and apparently no one has any interest in reporting what's in their HDTV or HD-STB.
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post #6 of 10 Old 05-13-2013, 09:06 PM
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Excellent! Thanks holl_ands.
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post #7 of 10 Old 05-14-2013, 11:17 AM
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Although I doubt that any actual FCC "action" will come out of it, there have been calls for "better" tuner performance to further suppress out-of-band interference by adding an additional Varactor tuned RF Filter to Single-Conversion Tuners (that already use at least one Varactor RF Filter) and to also add them to Double-Conversion Tuners that usually do NOT have any input RF Tuning stages. This would reduce extended range Sensitivity a bit, but would perform better when the TV Spectrum is repacked with even higher density, reducing the likelihood of ANY extended range reception. See fol. by Dr O. Bendov, former technical lead at Dielectric Antennas, maker of most DTV broadcast antennas:
http://www.tvtechnology.com/news/0086/bendov-efficient-spectrum-use-calls-for-receiver-standards-/217637
http://apps.fcc.gov/ecfs/document/view;jsessionid=WfhDRT2TKmtGK4gXs116cvygfzHfWnZLwWPRCkn3cQRRSBLvnbny!956499833!NONE?id=7022117651
BTW: Old UHF Tuners used 3 or 4 Varactor RF Tuner stages...an artifact from the past....as if anyone ever checks.....

Rather than doing something rationale, in Feb2013 the FCC instead unloaded an entirely off-the-wall proposal: HARM CLAIM THRESHOLDS - a lawyer's dream approach to solving engineering problems:
http://www.tvtechnology.com/regulatory/0113/fcc-seeks-feedback-on-receiver-standard-alternative/219064
http://transition.fcc.gov/bureaus/oet/tac/tacdocs/WhitePaperTACInterferenceLimitsv1.0.pdf

Charles W. Rhodes has published many articles in TV Technology magazine re EMI, this one noting that Double-Conversion Tuners he has tested are more susceptible to out-of-band interference, except they're better on N+14 and N+15 (Single-Conversion Image Freqs):
http://www.tvtechnology.com/digital-tv/0148/dtv-interference-and-its-mitigation-after-repacking/217733
http://apps.fcc.gov/ecfs/document/view?id=7022112325

Charles has also postulated changes in DTV channel assignments to improve EMI between stations:
http://www.tvtechnology.com/digital-tv/0148/could-broadcastings-future-hinge-on-changes-to-oet-/218903

For more info re Single & Double-Conversion Tuners, see my earlier post(s):
http://www.avsforum.com/t/980052/atsc-converter-box-comparisons/870#post_13503331
Note that Infineon TUA6034 App Note (from 2003) shows TWO Varactor Tuned RF Filter stages.
If only we knew what is in today's tuners.......
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post #8 of 10 Old 05-14-2013, 06:39 PM
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Some tuners are still better than others. The tuner boxes from ePVision always have strong tuners, including their PHD-VRX DVR. Their newest tuner box also reportedly has a very sensitive tuner, the PHD-208. Those would probably be my current choices.
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post #9 of 10 Old 05-14-2013, 08:09 PM - Thread Starter
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holl_ands!

Wow! School is in session!

Just the juicy stuff I was looking for.

Unfortunately, I was completely unaware of the political issues regarding digital tuners.

Was NTSC tuner evolution so mired?

Thanks so much!
Tom
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post #10 of 10 Old 05-15-2013, 09:55 AM
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The Dvico Fusion HDTV7 tuner uses a 6th generation tuner (silicon as opposed to the can tuner of previous generations). Users reviewing this product claim its reception is up to 10% better and more stable than 5th generation tuners.
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