The official final DTV Table Of Allotments/channel change thread - Page 242 - AVS Forum
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post #7231 of 7371 Old 12-03-2011, 07:51 AM
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Back in the 70's, Krystals were good. They were in fierce competetion with Blue Circle for the burger biz. Three inch squared burgers with real beef in a steamed bun with onions. Nowdays, the beef is the size of a postage stamp, and weighs even less. But the real charm of Krystals has to be the employees, the C minus restaurant ratings, and the often near-slum locations of the facilities. Makes McDonalds like like up-scale dinning. Now back to television.....

Wanting a strong FCC to say no to the Wireless lobby. Keep the tv broadcast band for ota television broadcasters.
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post #7232 of 7371 Old 12-03-2011, 10:19 AM
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Originally Posted by SnellKrell View Post

This thread is becoming the Food Network!

...and to think that 'lil 'ol me started this with a mention of Krystal because of Trip's move to Chattanooga. If his road trips on behalf of Luken ever take him to Corpus Christi (MAKO's HQ), even though he doesn't care for fast food, a visit to Whataburger (with HQs there) is a must.

See? I mentioned two broadcast companies in this message so it's topical!
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post #7233 of 7371 Old 12-03-2011, 10:22 AM
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I just wish that Trip would go on a diet or a hunger strike!

This is CRAP, a station in Canada!
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post #7234 of 7371 Old 12-03-2011, 10:47 AM
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Quote:
Originally Posted by SnellKrell View Post

I just wish that Trip would go on a diet or a hunger strike!

Hey, I've been on a diet since I last saw you!

I find it sad that this thread has had more activity today than in the last few weeks, and it's all completely off subject...

- Trip

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post #7235 of 7371 Old 12-03-2011, 11:48 AM
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Originally Posted by Trip in VA View Post

Hey, I've been on a diet since I last saw you!

I find it sad that this thread has had more activity today than in the last few weeks, and it's all completely off subject...

- Trip

I think that it just shows that most of us have two passions... TV (especially HDTV) and food. Is this a great country or what???

You never know where the LIMIT is until you EXCEED it... Dianne B. "Let's try that again... without the oops." (Will Smith and Jeff Goldblum in "Independence Day")
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post #7236 of 7371 Old 12-03-2011, 12:17 PM - Thread Starter
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As the starter of this thread, I have only this to say in regards to the food off-topic posts...

When are you all going to invite me for dinner?

Yeah, things are slow on the full-power OTA side of things. This is, after all, about the transition. We might be getting close to have it power down, with the next hot thread being "stations repacking after the FCC shuts off 32-51"...

Gilbert
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post #7237 of 7371 Old 12-03-2011, 12:54 PM
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Quote:
Originally Posted by sebenste View Post

Yeah, things are slow on the full-power OTA side of things. This is, after all, about the transition. We might be getting close to have it power down, with the next hot thread being "stations repacking after the FCC shuts off 32-51"...

To try to steer this back to topicality (as the guilty party), a market not too far geographically from where Trip is now located is Huntsville.

Since this thread is is about channel changes, what prevented WAFF from flash-cutting to channel 48 (where they'll end up when they build out the CP) when the transition occurred?
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post #7238 of 7371 Old 12-03-2011, 02:27 PM
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Originally Posted by sebenste View Post

As the starter of this thread, I have only this to say in regards to the food off-topic posts...

When are you all going to invite me for dinner?

Yeah, things are slow on the full-power OTA side of things. This is, after all, about the transition. We might be getting close to have it power down, with the next hot thread being "stations repacking after the FCC shuts off 32-51"...

Nah. No need to power down this thread... "Repacking"="Transition".

Although, not one we were seeking...

As far as an invite... Com'on down. Make yourself at home. We'll throw some steaks and shrimp on the grill, mesquite charcoal of course, fix some beans and some rice, wrap up a few ears of corn, stuff some jalepenos, and open a Lone Star beer for ya.

Oh, and for an added incentive, gas started selling for under $3 ($2.98/gallon) around here at most stations yesterday...

You never know where the LIMIT is until you EXCEED it... Dianne B. "Let's try that again... without the oops." (Will Smith and Jeff Goldblum in "Independence Day")
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post #7239 of 7371 Old 12-03-2011, 04:51 PM
 
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Originally Posted by sebenste View Post

As the starter of this thread, I have only this to say in regards to the food off-topic posts...

When are you all going to invite me for dinner?

Yeah, things are slow on the full-power OTA side of things. This is, after all, about the transition. We might be getting close to have it power down, with the next hot thread being "stations repacking after the FCC shuts off 32-51"...

I think in the end at most they'll take 38-51. I think someone smart will eventually convince those that vote on that having an untouchable channel 37 in the middle of 31-51 will cause issues. If they did take away 31-51 then mobile companies could use 31-36 and 38-51 they couldn't use 31-51. Well what good does only being able to use 31-36( 36 MHz ) do?
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post #7240 of 7371 Old 12-04-2011, 06:32 AM
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Originally Posted by BCF68 View Post

I think in the end at most they'll take 38-51. I think someone smart will eventually convince those that vote on that having an untouchable channel 37 in the middle of 31-51 will cause issues. If they did take away 31-51 then mobile companies could use 31-36 and 38-51 they couldn't use 31-51. Well what good does only being able to use 31-36( 36 MHz ) do?

Perhaps the wireless companies could get legislation passed to prevent extraterrestrials from using channel 37 and they could have it too. They could get the FCC to send them a Notice Of Apparent Liability for unauthorized use...

You never know where the LIMIT is until you EXCEED it... Dianne B. "Let's try that again... without the oops." (Will Smith and Jeff Goldblum in "Independence Day")
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post #7241 of 7371 Old 12-04-2011, 04:19 PM
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Quote:
Originally Posted by BCF68 View Post

I think in the end at most they'll take 38-51. I think someone smart will eventually convince those that vote on that having an untouchable channel 37 in the middle of 31-51 will cause issues. If they did take away 31-51 then mobile companies could use 31-36 and 38-51 they couldn't use 31-51. Well what good does only being able to use 31-36( 36 MHz ) do?

Having a gap at 608 to 614 MHz is no impediment at all for many reasons.

1) Most cellular spectrum in the US is paired. An unallocated block at one end of the band just means there will be an unpaired block at the other end. Unpaired blocks can be used for TDD LTE.

2) The spectrum has to be divided up for auction to allow smaller players to have a chance at bidding. The largest block is likely to be 20 MHz for a nationwide LTE Advanced network. Then lots of regional 10 MHz blocks for the smaller players.

3) LTE Advanced will have carrier aggregation to handle non-contiguous spectrum allocations. This is already a problem at 700 MHz, where the allocations were made before the LTE standard arrived on the scene. Folks like AT+T with 6 MHz blocks can't compete with Verizon's 11 MHz block. And of course, the 11 MHz block is a waste of 1 MHz (actually 2 MHz, since it's paired).

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post #7242 of 7371 Old 12-04-2011, 08:17 PM
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I cant see where will stations move from 31 -51? Low VHF stinks for digital. Handful there I am sure would want off. FCC changing from MPEG-2 to MPEG-4 or other newer codec for better effiency? Is FCC hoping that small broadcaster will sell their spectrum to Wireless Companys?
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post #7243 of 7371 Old 12-04-2011, 08:50 PM
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Stations voluntarily selling their spectrum is exactly what the FCC is counting on. That and channel sharing, in which two or more licensees share the same 6 MHz block of spectrum. To hear FCC officials, one would think that that's the answer to all TV spectrum problems.
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post #7244 of 7371 Old 12-05-2011, 09:01 AM
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Originally Posted by dhett View Post

Stations voluntarily selling their spectrum is exactly what the FCC is counting on. That and channel sharing, in which two or more licensees share the same 6 MHz block of spectrum. To hear FCC officials, one would think that that's the answer to all TV spectrum problems.

I'm not advocating channel sharing because it limits options for sub channels, but KSBW in Salinas is broadcasting NBC 1080i on 8.1 and ABC 720p on 8.2. Both pictures look far better than I imagined they could. Maybe I'm not picky enough, but I can't see any real difference between their quality and other NBC/ABC network stations. I have not yet been able to take a careful look at KSBW when there is live sports on both networks.

There is another option to increase efficiency but I wouldn't expect anyone to be enthused about it: 16 VSB. Twice the data rate at the penalty of 3 dB higher signal-to-noise. Doubling the transmitter power could make up for that but multipath issues would be worse. Of course this would require a second transition which I agree is all but off the table for the foreseeable future.

Still though, 16 VSB + MPEG-4 + 2x transmitter power + improved receiver multipath performance would equal a significant increase in bandwidth efficiency without degrading reception.

Chuck
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post #7245 of 7371 Old 12-05-2011, 09:17 AM
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Originally Posted by Calaveras View Post

Still though, 16 VSB + MPEG-4 + 2x transmitter power + improved receiver multipath performance would equal a significant increase in bandwidth efficiency without degrading reception.

Yep, and the idiots with the ties too tight around their necks, such that they can't think straight, will cram even more useless crap into the previous bandwidth, still resulting in the main HD stream to macroblock like crazy,

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post #7246 of 7371 Old 12-05-2011, 11:35 AM
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Quote:
Originally Posted by Calaveras View Post

I'm not advocating channel sharing because it limits options for sub channels, but KSBW in Salinas is broadcasting NBC 1080i on 8.1 and ABC 720p on 8.2. Both pictures look far better than I imagined they could. Maybe I'm not picky enough, but I can't see any real difference between their quality and other NBC/ABC network stations. I have not yet been able to take a careful look at KSBW when there is live sports on both networks.

There is another option to increase efficiency but I wouldn't expect anyone to be enthused about it: 16 VSB. Twice the data rate at the penalty of 3 dB higher signal-to-noise. Doubling the transmitter power could make up for that but multipath issues would be worse. Of course this would require a second transition which I agree is all but off the table for the foreseeable future.

Still though, 16 VSB + MPEG-4 + 2x transmitter power + improved receiver multipath performance would equal a significant increase in bandwidth efficiency AD degrading reception.

Chuck

Our KBMT took over NBC duties when our longtime NBC affilliate switched from NBC to FOX. KBMT downconverts NBC to 720 and runs it beside ABC, also at 720 and it too looks really good. But don't get me wrong, "repackaging" is not something I am looking forward to. And to make matters worse for us, KBTV (the now FOX affiliate) is currently broadcasting on channel 40, a channel certain to be highjacked... Plus, we are right at a mere 100 miles from Houston which will have to repackage I think it is 17 full power stations into 31 or 36 channels???!!!

In a nutshell, this sucks. Bye, bye broadcast HD.

You never know where the LIMIT is until you EXCEED it... Dianne B. "Let's try that again... without the oops." (Will Smith and Jeff Goldblum in "Independence Day")
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post #7247 of 7371 Old 12-05-2011, 02:59 PM
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Quote:
Originally Posted by Calaveras View Post

There is another option to increase efficiency but I wouldn't expect anyone to be enthused about it: 16 VSB. Twice the data rate at the penalty of 3 dB higher signal-to-noise. Doubling the transmitter power could make up for that but multipath issues would be worse. Of course this would require a second transition which I agree is all but off the table for the foreseeable future.
Chuck

The signal to noise ratio penalty for 16-VSB is approximately 13 dB. That's because adding 1 bit per symbol doesn't get you twice the bitrate. To get twice the bitrate, the 2/3 rate Trellis FEC is also removed. Without the FEC, the S/N takes a big 13 dB hit.

16-VSB is/was intended for cable systems, not over the air emission.

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post #7248 of 7371 Old 12-06-2011, 01:58 AM
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What would the S/N penalty be if a station broadcast QAM over the air? QAM on RF 2-13 would be compatible with most existing tv sets.

How can we say "the digital transition is complete" when thousands of low power stations are still broadcasting in analog?
LOW POWER ANALOG NEEDS TO DIE NOW!!!
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post #7249 of 7371 Old 12-06-2011, 04:35 AM
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Originally Posted by Desert Hawk View Post

What would the S/N penalty be if a station broadcast QAM over the air? QAM on RF 2-13 would be compatible with most existing tv sets.

Which one? 16QAM? 64QAM? 256QAM? If I remember correctly, you would also need to change from 8VSB to DVB (COFDM). That AIN'T happening.

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post #7250 of 7371 Old 12-06-2011, 07:36 AM
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Originally Posted by dr1394 View Post

The signal to noise ratio penalty for 16-VSB is approximately 13 dB. That's because adding 1 bit per symbol doesn't get you twice the bitrate. To get twice the bitrate, the 2/3 rate Trellis FEC is also removed. Without the FEC, the S/N takes a big 13 dB hit.

16-VSB is/was intended for cable systems, not over the air emission.

Ron

I guess I need some more education because going from 3 bits per symbol to 4 bits per symbol transmits twice the number of bits. Are you saying that error correcting takes up so many bits in 16 VSB that the effective data rate increase is much less than 2X?

Chuck
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post #7251 of 7371 Old 12-06-2011, 08:01 AM
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Quote:
Originally Posted by Desert Hawk View Post

What would the S/N penalty be if a station broadcast QAM over the air? QAM on RF 2-13 would be compatible with most existing tv sets.

It's my understanding that PSK modulation is very poor at handling multipath and co-channel interference therefore it's not suitable for OTA TV broadcasting. Someone can correct me if I'm wrong about this.

I do know that PSK modulation is used in some satellite applications where multipath is not an issue. At one time I tested a demodulator that demodulated BPSK through 256QAM that was used in a satellite application. They even considered expanding it to 512QAM and 1024QAM.

I personally have received BPSK transmissions from NOAA low orbiting weather satellites and it worked fine with no error correction at all. The GOES satellites use QPSK.

Chuck
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post #7252 of 7371 Old 12-06-2011, 02:14 PM
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Originally Posted by dr1394 View Post

The signal to noise ratio penalty for 16-VSB is approximately 13 dB. That's because adding 1 bit per symbol doesn't get you twice the bitrate. To get twice the bitrate, the 2/3 rate Trellis FEC is also removed. Without the FEC, the S/N takes a big 13 dB hit.

16-VSB is/was intended for cable systems, not over the air emission.

Ron

Okay. I was able to find this:

http://books.google.com/books?id=000...coding&f=false

I understand now that the spec for the data encoding to be used with 8VSB modulation includes trellis coding which uses a lot of overhead, and that the spec for the data encoding to be used with 16VSB modulation omits the trellis coding. This is done on purpose because cable systems don't suffer from co-channel analog signals or multipath so the higher SNR requirement is acceptable; i.e. the 13 dB you mentioned.

Now my question is, could a new spec be developed that included trellis coding for use with 16VSB OTA? Let's say 3/4? I imagine that it could be. Or is there something inherent to trellis coding limits it to 2/3? I don't know the math behind this.

Finally I don't understand why they say the 8VSB bit rate with trellis coding is only half of 16VSB without trellis coding. Two bits compared to 4 bits is a factor of 4. Seems like it should be 1/4. I must be missing something.

Chuck
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post #7253 of 7371 Old 12-06-2011, 02:24 PM
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Quote:
Originally Posted by foxeng View Post

Which one? 16QAM? 64QAM? 256QAM? If I remember correctly, you would also need to change from 8VSB to DVB (COFDM). That AIN'T happening.

That's right, it ain't!

If you remember the derivation of the US HDTV system, each and every applicant got one piece of the ATSC system, the "Grand Alliance". Zenith's contribution was 8 VSB. If you eliminate 8 VSB, you break the compromise that resulted in the US system.

Now, when the ATSC patents expire, perhaps we can look at DVB-T2, which uses multiple carriers, each modulated with QAM. These signals are called OFDM, and have superior multipath performance to 8 VSB, but a higher peak to average ratio, and a greater signal to noise requirement. It would be nearly impossible to replicate ATSC coverage areas using DVB-T2 unless you had multiple transmitters transmitting the same thing on the same channel.

http://en.wikipedia.org/wiki/DVB-T2
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post #7254 of 7371 Old 12-06-2011, 02:59 PM
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Originally Posted by Calaveras View Post

I guess I need some more education because going from 3 bits per symbol to 4 bits per symbol transmits twice the number of bits.
Chuck

How is 4 = 3 * 2? Increasing the bits per symbol from 3 to 4 raises the bitrate by 4/3 or 1.333. That gets us to 19.39 * 1.333 = 25.853 Mbps. Then by removing the 2/3 FEC, the bitrate is increased by 3/2 or 1.5. 25.853 * 1.5 = 38.78 Mbps. Another way to look at it is 4/3 * 3/2 = 2.

The 16-VSB numbers can be found here.

http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf

See Table 8.1

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post #7255 of 7371 Old 12-06-2011, 03:28 PM
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Quote:
Originally Posted by Desert Hawk View Post

What would the S/N penalty be if a station broadcast QAM over the air? QAM on RF 2-13 would be compatible with most existing tv sets.

For QAM-64, the required S/N is 22 to 24 dB and for QAM-256, it's about 28 to 30 dB. So at least 7 dB for QAM-64 and 13 dB for QAM-256.

But as Calaveras points out, QAM and PSK aren't very well suited to OTA transmission. A simplified explanation is that QAM and PSK both use phase modulation to carry the bits. But multipath is essentially a phase shifted version of the main signal. Therefore, with QAM and PSK, multipath directly affects the way the bits are being received. No bueno.

For QAM and PSK to work, you need to take care of the multipath (more technically called inter symbol interference or ISI) somehow. That's were multi-carrier systems like COFDM come into play.

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post #7256 of 7371 Old 12-06-2011, 03:39 PM
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Quote:
Originally Posted by Calaveras View Post

Now my question is, could a new spec be developed that included trellis coding for use with 16VSB OTA? Let's say 3/4? I imagine that it could be. Or is there something inherent to trellis coding limits it to 2/3? I don't know the math behind this.
Chuck

You can have different FEC coding rates. The most often used rates are 1/2, 2/3, 3/4, 5/6 and 7/8.

However, there's no free lunch. Any increase in bitrate in the same 6 MHz channel will require more signal to noise ratio. IMHO, it will be impossible to convince broadcasters to either increase power to maintain their coverage area or lose coverage area just to increase the delivered bitrate.

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post #7257 of 7371 Old 12-07-2011, 02:43 AM
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When I mentioned QAM I meant broadcasting OTA using the system that is currently used on U.S. cable, because on RF channels 2-13 it would be compatible with most current tv sets. I was not referring to any system currently used in Europe or elsewhere. I am vehemantly opposed to anything that means another nonbackwardcompatible transition anytime within the next 30 years minimum!

How can we say "the digital transition is complete" when thousands of low power stations are still broadcasting in analog?
LOW POWER ANALOG NEEDS TO DIE NOW!!!
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post #7258 of 7371 Old 12-07-2011, 04:36 AM
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Quote:
Originally Posted by Desert Hawk View Post

When I mentioned QAM I meant broadcasting OTA using the system that is currently used on U.S. cable, because on RF channels 2-13 it would be compatible with most current tv sets. I was not referring to any system currently used in Europe or elsewhere. I am vehemantly opposed to anything that means another nonbackwardcompatible transition anytime within the next 30 years minimum!

Not every 8VSB set has QAM in it, but every QAM set does 8VSB. Remember 8VSB IS required for digital sets. QAM is not. I have two sets that have analog and 8VSB but no QAM. 8VSB and QAM are modulation types and are not compatible to each other. It isn't as simple as swapping one for the other. There are lots of technical issues that go along with a swap like that.

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post #7259 of 7371 Old 12-07-2011, 08:40 AM
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No CECB that I'm aware handles QAM. I don't think that was even permitted.
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post #7260 of 7371 Old 12-07-2011, 09:03 AM
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Quote:
Originally Posted by dr1394 View Post

How is 4 = 3 * 2? Increasing the bits per symbol from 3 to 4 raises the bitrate by 4/3 or 1.333. That gets us to 19.39 * 1.333 = 25.853 Mbps. Then by removing the 2/3 FEC, the bitrate is increased by 3/2 or 1.5. 25.853 * 1.5 = 38.78 Mbps. Another way to look at it is 4/3 * 3/2 = 2.

The 16-VSB numbers can be found here.

http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf

See Table 8.1

Ron

I got it. I was being dense. I was confusing the number of bits with the values they represent.

Chuck
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