DVICO Fusion 5 HDTV tuner - Page 2

Cliff:
--connected to the same Silver Sensor using a splitter to both cards--

That's not such a swell idea.

Why is that? I have two tuners attached to the same antenna using a splitter and I haven't seen a difference with or without the splitter in terms of reception.

I am going to add my two bits here, 'cause I may have one of these cards soon.

I thought the major difference was the better rejection of multipath, not better sensitivity.

I was of the opinion that multipath (echos in the signal) were more likely to be a problem with strong signals, not weak ones where the echo may fall beneath reception threshold.

I was hoping that some of the issues with cable might be poor terminated splitters, and the new multipath correction might deal with that.

'course, if I could pull in LA OTA from ~300mi away I would be pleased, but still....

Allen

Anytime a signal is split, it cuts the signal strength by half. For example, a 100 Watts signal going into a spliter, the signal strength of each output of the splitter will be 50 Watts. If the same signal is split by four times, then signal strength of each output would be 25 Watts. You may not see the difference probably because the source of your signal is already strong.

Allen, yes, MP distortion occurs when the tuner/demodulator cannot distinguish between the direct and reflected signals, because they are of comparable strength (whether both are weak or strong). The test that Cliff did of rotating the antenna would have the effect of changing the relative strengths of the direct and reflected components reaching both tuners, so that if they had markedly different MP-rejection behavior he would have seen them lose signal lock differently. That's not what he found.

Right...and if the signal is split by a factor of 2 the signal to noise ratio would ideally be decreased by a factor of the square root of 2. I'm not sure what matters more for digital reception - S or S/N, but I think it's the latter.

I believe the S/N ratio will stay the same. Both the signal and the noise strength will get reduced by the same factor, therefore the ratio should not change.

You are correct that it is the SNR that matters the most. Both tested cards need between 16 and 17 dB SNR for a good lock.

The SNR does not stay the same. Man made noise does not decrease with reduced signal level, unless the source of the noise is also reduced.

Great report Cliff, but if I might suggest some additional test ideas.

First, techically I think to make sure the tuners are acting identically as you claim, you should reverse the cables to each one, just on the off chance that one cable is better than the other. Then your testing would be pure scientology!

Second (and the real reason for this post), if I'm not mistaken, multipath issues would show up better without the splitter, since the MP signal would be slightly stronger (or at least I believe I know attenuators reduce FM multipath interference). So, you might want to devise some sort of independent tests you can do with each card in a relatively short timeframe. I'm not sure whether walking around your SS would result in multipath interference, or what you'd need to do.

Steve,

The Fusion QT was fairly even with the MDP-130.

hope this is correct place...will the new fusion 5th gen run in a xp pro 64 bit enviroment

--xp pro 64 bit enviroment--

Not with the current drivers.

ok thought it would be fun....just will put it next to my myhd120

--So, you might want to devise some sort of independent tests you can do with each card in a relatively short timeframe. --

Outdoor antenna = more strength = more multipath. Multipath looks like poor strength, no way of telling the diff without more testing. Just about impossible to test for multipath rejection unless you know it is there.

If you take a splitter, split your incoming signal into two different lengths of cable, then recombine them (a splitter run backwards should do - if not, then I can do some reading in the ARRL handbook for a combiner) you have made a controlled amount of multipath. An attenuator in one of the lines makes even better control. If you wanted real scientology, then you would chose a set of attenuators so you could make any attenuation and then find the threshold... and vary the differential lengths of the cables to find the equalization window.

lots of work, I know. Could be fun, though.

(this should be a "learning" dodad - remember how the high speed modems deal with line non-idealities by screaming at each other to listen for the echos/pass band behavior? Is there something in the manual/card about "training" it for the multipath in your environment? Perhaps it knows the format of the broadcast and deconvolves that? The upshot/implication of this speculation is that the tuner might get "better" over time - and I don't know if that time is short or long enough to complicate testing)

Allen

So the F5 don't know it's own strength or is it a bad/normal/good strength meter (based)?

I have a Windows utility that can analyze the multipath from the Nxt2000 demodulator chip. The chart shows the amount of +/- signal caused by MP and also shows the actual locked signal and time variation of each signal.

After ATI purchased NextWave they stopped releasing the demodulator API for newer chips so I can no longer check the MP.

Ray,

The scale factor can be adjusted by the manufacturer. MIT believes that it is better to have MyHD display a lower signal strength while still being able to lock and decode the signal than have a higher SS and not be able to lock on the signal.

You would think that a SS of 50% should display a video image.

It's good to see someone still believes in the scientologic method ...

But for those who already have the Fusion 5 and who want to do the experiment, can MCE use it standalone, or do you need to have another (NTSC) tuner card installed?

ALso, any input on whether the Fusion 5 has a hardware MPEG encoder?

Thanks in advance

No hardware. It's all software.

I tried it and the F5 does not work standalone. Also, any thought s on QAM reception? I'm not getting any digital stations. I expected to get at least the locals. Right now I'm dissapointed with the results because I had a early F3 that was known not to be very good at decoding QAM and still in the same boat.

I can say using my radio shack antenna down in my basement allows me to receive all my locals channels with 80% or higher reception. Any suggestions for a nice outdoor omni directional antenna? I have a tower right now with a very directional antenna on top, don't know what it is though.

I'd suggest getting an antenna from Antennas Direct. They have a 90 day money back guarantee in case your reception doesn't improve. This forum doesn't allow me to post the website, so just type the name in Google.

The best Omni-directional model they have is the DB-8, which they rate at 70 miles.

"I use pure scientology principals for this test.


I didn't know you were from L.A."


FWIW, the Scientology HQ is in Clearwater, Florida....

Thanks, I'll give it a shot.

I'm sort of waiting to the answers to two questions before deciding whether to buy one of these:

1) Does its 5th gen LG chip really make it have better ATSC (multipath) reception than my current F3Q, or maybe even the MyHD 130? (doesn't really sound like it so far, but maybe)

2) Does it work okay with unencrypted QAM cable, assuming strong signal.

Cmon guys, need more (and better) reports here.

- Tom

I'm not sure why their aren't any reports about QAM, but I can guess.
My cable company (Adelphia) won't tell whether or not they offer unencrypted QAM support. In order for me to recieve HDTV they want me to spend $20/month extra for basic digital cable, $17/month to rent an HD reciever and a $25 installation fee. With these ridiculous prices, I'm not willing to find out. Especially since the only HD channels they offer besides the free local channels are HBO and Showtime.

That is why I'm sticking with an antenna for now.



On the other hand the FusionHDTV5 was just released. It will take time for others to get it. QAM reports should come pretty soon.

Tom, based on the head-to-head tests that Cliff reported between this card and the MDP-130, it seems to me highly unlikely that there is a tangible difference between them in either sensitivity or MP rejection. At least, I'm sufficiently satisfied that I'm not about to venture a hundred bucks for the experiment. OTOH, if somebody wants to send me a card to test here in (ahem) real MP hell, aka S.F. Peninsula canyons, I'll be happy to provide another head-to-head test result (and I'd even return the card).

revgen--

I'm not sure what your concern is...even the F3 cards receive QAM OK, limited only by the buggy sw. And the F5 has essentially the same sw, so what's the rant about? If you want QAM with stable sw, get an MDP-130.

(BTW, it's "eye before ee, except after cee." )

The rant was directed at my cable company, not the card.


I didn't mean to offend the spelling bee champ.