Does the new 811/921 have better 8vsb modules?

[Stacy A]

Does anyone happen to know if the new 811 or 921 will sport more advanced 8vsb ATSC tuners? The reason I ask is because my father-in-law just bought a Zenith OTA only ATSC tuner for his new DLP and I am floored at how sensitive his tuner is. He can pick up channels much more easily than I can, and we are both using the same antenna. I just figured the technology in his tuner is newer and better, so I'm hoping the new ATSC tuners in the 811's and 921's are better built and designed as well.

Stacy

 

[dmodemd]

Going on hearsay...

I once read somwhere that the 811 and 921 8vsb chipsets are different and that the 811 was newer than the one in the 921.

Also, Dish (Tech chat) has said that the 811 and 921 chipset is different and is why the SD/HD can be output simultaneously on the 811 but not 921. One could assume that some corners may have been cut on the 921 to simplify it and keep the costs down where the 811 may be a little better tasked for tuning. The 921 has a lot to do with dual tuning and DVRing as well. I think trying to combine all those features with off-air tuning required them to step back a generation.

It will be interesting to see any tests between them. I hope to have one of the first 811s (>>hope<&lt and can at least compare with the 6000. It is a fact the 6000 tuning is not nearly as good as other tuners in the last year at least.

There is a next generation tuning chipset called "Lynx"? which has better algorithms to handle multipathing which is the biggest problem in getting a good signal. I have that problem as well as interference from general aviation. Whenever a small plane goes over I get dropouts on my weaker channels.

Lee

 

[BarryO]

According to a Broadcom press release, the 921 uses the same BCM3510 chip as the 6000:

http://www.broadcom.com/cgi-bin/pr/prps.cgi?pr_id=PR030109

Conventional wisdom is that the Broadcom devices are very good, but the Zenith/LG boxes are the best consumer units there are.

I may end up getting the 921 and the Zenith LG HD PVR unit myself, as the 6000 cannot pick up two OTA stations at my location.

 

[Ken_F]

Barry,

The 6000 8PSK module uses the BCM4500. Are you confusing that with the BCM3510? The 6000 8-VSB module was introduced with the Nxt2000 8-VSB demod.

 

[mikeb]

The company that has a new algorithm is Linx Electronics and I think their website is http://www.linxelectronics.com/ and the device is said to be:

"LX1080TX is a "Ghost-Friendly" ATSC standard compliant receiver. In contrast to the existing solutions trying to remove multiple ghosts, LX1080TX combines the signal energies in complex multiple ghosts to deliver near optimal DTV reception performance. LX1080TX is a receiver oriented solution. It is completely compatible with the existing ATSC DTV standard, and will enhance DTV reception without any change on the transmission side. It is the first chip to support multiple transmitter environments (such as Single Frequency Network and On Channel Repeater) with the ATSC DTV standard."

It's an interesting concept to try and time shift multiple ghosts and synchronize them with the desired signal. That is extremely difficult to do. I wonder if they do a ton of FFTs to try and correlate the samples. A lot of radar and elint receivers do that for the military but they cost millions. Sample product won't be available until spring of 2004 so I doubt we will see it in product until late 2004 or 2005.

As far as the NXT2000 goes, it was discontinued as well as the NXT2002. The NXT2003 is the latest (along with NXT2004 & NXT2005) and they claim it's capable of receiving with 0dB ghosts.

 

[Guest]

Barry,

The 6000 8PSK module uses the BCM4500. Are you confusing that with the BCM3510? The 6000 8-VSB module was introduced with the Nxt2000 8-VSB demod.

Ken,

You're right. I was confusing the 6000 with the Samsung '-151 (I have both); the Samsung unit uses the same Broadcom chip as the 921. It works a little better than the NxtWave in my situation, although it still won't bring in the two problem stations.

 

[BarryO]

It's an interesting concept to try and time shift multiple ghosts and synchronize them with the desired signal. That is extremely difficult to do.

Actually, all ATSC receivers do that; yes, it is difficult to do, which is why sometimes some receivers don't work real well.

The adaptive equalizer in the receiver is what does this; technically it is implemented with something call an adative Finite Impulse Response (FIR) filter, that is set to mimic the received multipath (ghost) characteristics.

Things break down when the delay spread of significant multipath is greater than the length of the equalizer, or the multipath changes too quickly for the adaptation algorithms to keep up.

So the statement about adding all the ghosts together and summing them is marketing fluff; if they're doing anything new this doesn't describe it. OTOH If they have new techniques for handling dynamic changes in the mobile environment or of handling things like same frequency repeaters, then they may have a significant improvement.

 

[mikeb]

Interesting information Barry. I'm sure there is more to it. I saw on one website that they claim acceptable performance even with up to 0dB multipath signals. Do they improve performance by the number of taps they use?. My digital signal processing knowledge is a little rusty since that was a college course a couple of decades ago.

 

[xgrep]

Conventional wisdom is that the Broadcom devices are very good, but the Zenith/LG boxes are the best consumer units there are.

Very interesting.

Do you know anything about the Samsung tuners? I had seen some reviews of the SIR-T165 (and in fact had tried it myself). It's fairly sensitive, but I have very bad multipath, and had trouble on some channels. I haven't compared it to anything else, so don't have any info to offer. But I have a vague recollection that it uses a relatively recent Broadcom chipset.

x

 

[zmwp01]

I purchased the Zenith HDR230 OTA receiver/recorder about a month
ago and have very impressed with its performance. I connected a
Zenith Silver UHF antenna and set it on top of my equip cabinet, did
an EZ scan on the HDR230 and locked in on more digital stations than
I hoped for 8, 3 of them 720P, 4 of them 1080i, all of them having
some HD programming during primetime. The pic quality rivals HDNet
on my Sat. The recorded material is the same. It has the EPG, timeshift play,
res-record once/daily, 5.1 audio, component/RGB video.
The only downfall is 9hrs record capacity HD and 30hrs SD.
Since I rarely keep anything longer than a couple of days its fine for me.
I shopped the web and got mine new for $720. I wouldn't trade for it
anything. I sold my Samsung 160 on ebay.
Still trying to decide which to go with for Sat/DVR equip and service.

 

[hankh]

The Zenith HDV420 uses an LG3205 receiver chip.
They bill it as their "advanced receiver chip." The
nearest OTA station, to me, taking DTV seriously,
is 85 miles away. I am able to receive that station
about 50% of the time. With a higher gain antenna,
I am sure that figure would rise to 80 or so.

I am interested in finding out if the 811 will have the
kind of sensitivity I find in the Zenith receiver. Does
anyone know what chipset the 811 contains?

 

[Smith P.]

Broadcom BCM4500, same as used in 8PSK module for 6000 model.

 

[Guest]

Broadcom BCM4500, same as used in 8PSK module for 6000 model.

Looking up this chip, it appears to run the satellite receiver section. I was
refering to the OTA part of the 811 receiver. Sorry if I was confusing.