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Specifications for HD-3000?
PostPosted: Mon Mar 20, 2006 4:50 pm Reply with quote
dieter
 
Joined: 20 Jan 2005
Posts: 43
Location: US




I can't seem to find basic specs for the HD-300 card.
For example: what is the noise figure for the RF input?
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PostPosted: Wed Mar 22, 2006 7:35 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




And yet people continue to buy them! Smile
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PostPosted: Sun Mar 26, 2006 9:22 pm Reply with quote
Jim
 
Joined: 01 Mar 2005
Posts: 88
Location: Greater Portland ME joined jan'05




snip


Last edited by Jim on Sun Mar 26, 2006 9:47 pm; edited 1 time in total

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PostPosted: Sun Mar 26, 2006 9:26 pm Reply with quote
Jim
 
Joined: 01 Mar 2005
Posts: 88
Location: Greater Portland ME joined jan'05




nice answer scott..really dismayed unless I misunderstood, maybe I could use my hdtv rf simulator and test relative sensitivity of cards. I am surprised you are so abrupt with this person's inquiry.
I only have 5 pchdtv cards,maybe I should test them. If poster wants to risk sending me their non hdpc card to compare tuner performance I would like that....for free for benefit of free ota hdtv endevor.
But you risk sending an expensive card for testing to a complete stranger that may not have time to drop everything and pursue this. I do use safe ESD practices in my operations. People seem to frget the real world of the analog rf sending them their bitstream...noise figure, capture ratio, phase noise, all this is greek to computer newbs.. Rambling, sorry off to bed.

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PostPosted: Sun Apr 02, 2006 4:53 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




The question is why would anyone need the card's specifications unless they were going to compare it with another card's specifications (which I've never seen).
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PostPosted: Sun Apr 02, 2006 6:36 pm Reply with quote
Jim
 
Joined: 01 Mar 2005
Posts: 88
Location: Greater Portland ME joined jan'05




To see how the card's analog rf tuner box works. It could also be just as bad to have a tuner that may be too sensitive to weak signals, but goes into cross modulation, im, desensing in presence of strong signals. This would explain a lot of performance problems people have.
One example: Desensing...this is the effect of a strong station on a nearby frequency cutting down the rf agc gain of the tuned frequency. I'm not talking capture ratio effect of fm radio.
This was a problem in 70's high end audio fm tuners in say the boston area. By putting an attenuator in the antenna line, one was able to improve performance. Completely against the thoughts of consumers thinking "I must buy fm tuner with the best sensitivity possible", and overlooking other tuner specs.
Unfortunately with our cards we can not see changes on the fly with the signal..It must be perfect or system crashes. Real time strength indicators help, but not by much. We have a ways to go.

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PostPosted: Mon Apr 03, 2006 10:26 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




What exact specifications would you need to measure the card's sensitivity? Given those specifications, how would you use them?

You don't need this information to add an attenuator.
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PostPosted: Mon Apr 03, 2006 6:05 pm Reply with quote
Jim
 
Joined: 01 Mar 2005
Posts: 88
Location: Greater Portland ME joined jan'05




to compre possible performance differences. You know, I bet pchdtv just buys the tuner box from the supplier and doesn't care, as long as it works, 99.999% of its customers are not going to swayed by specs even if true specs. It would just turn into a mess of overclaimed performance.
I was just trying to help the original poster.

For stupid specifications will just muddy the waters. For example my "500 watt" sony surround receiver can put out that much power if you drive one channel at a time, measure it, then add them all together.
Total power output is less than 200 watts true power with all channels driven.

We need the equivalent of stereo review's Hirsh-Houck labs to measure real performance, and why bother? by the time someone finds this forum, they own the card. And the .001% of the ones wanting specs won't find them on the other cards either. Besides when the flag is implemented this will all be moot.

I'll drop this thread now, as the original poster is not involved it seems.

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PostPosted: Mon Apr 03, 2006 7:59 pm Reply with quote
dieter
 
Joined: 20 Jan 2005
Posts: 43
Location: US




> I bet pchdtv just buys the tuner box from the supplier and doesn't care, as long as it works,

It works? What is your secret? I see lots of postings with "it doesn't work" complaints. I would like to see the specs and/or measurements. Maybe there is a weak spot or two that needs to be worked around.

> We need the equivalent of stereo review's Hirsh-Houck labs to measure real performance

YES!!!

> the ones wanting specs won't find them on the other cards either

There are other uses for specs besides comparing one product to another.

> I'll drop this thread now, as the original poster is not involved it seems.

I've been reading the thread and hoping someone has some specs to share. And trying to figure out why Scott appears to oppose having specs since he seems to be a reasonable guy in other threads. :-)
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PostPosted: Mon Apr 03, 2006 8:48 pm Reply with quote
Jim
 
Joined: 01 Mar 2005
Posts: 88
Location: Greater Portland ME joined jan'05




I agree completely, maybe Scott is sensitive on some issues. In any case we are all ignorant in one way or another on digital tv stuff. My saying is: you are ignorant...but that just means you could be intelligent, but just not informed. I look at this as a pioneering time... like my dead audio friend, a recording guru from the late fifties doing semipro audio recording. Lots was learned in early 60's in the amateur semipro classical music fiddling around. I was just suggesting that some rf guru should be called into the pchdtv forum, not everyone in mythtv knows of pchdtv. I am aledgedy a Dragon dealer, but just have one box of theirs I am checking out. If I sell one, I'd be sure to support anyone. Within reason.
And you could build your own, all specs are on their site. It will crash with loss of signal...Not wife friendly...but is really quiet, my tivo is much noiser, and I have treasured 1080i recordings of the Olympics and HD Nova stuff all from free off the air "rabbit ears" on a windowsill.
And I can share these HD recordings..hoping one would enjoy and later contribute to the free HD pbs providers...I want free to watch contribute if you like..this should be the same for tv or music..get rid of drm join EFF.org or at least vote for political jerks that will give us freedom rather than taking it away.

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PostPosted: Mon Apr 03, 2006 10:35 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Could someone please tell me what specifications people are looking for? Please name one.

For example there are idealized labratory measurements that test an ATSC receiver for multipath rejection. These tests have been used to improve each generation of ATSC receivers and have guided engineers to design better receivers.

The problem is that there's no way to translate these results directly into how a product will perform for a customer since no multipath situation is ever as simple as the lab tests. Solving the problem can be as simple as turning an antenna one degree. Improper antenna placement will make absolutely any ATSC receiver fail 100% just like bad speakers will make a good (or bad) amplifier sound bad. Specifications will not help you here.
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PostPosted: Tue Apr 04, 2006 9:28 am Reply with quote
xyzzy
 
Joined: 12 Feb 2006
Posts: 225




Scott Larson wrote:
Could someone please tell me what specifications people are looking for? Please name one.

Programming information for the demodulator. It's not fully supported, but without programming info, there isn't much that can be done. The driver may be open source, but when the hardware is secret and no one is developing the driver, that's only worth so much.
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PostPosted: Tue Apr 04, 2006 11:20 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Since when has an instruction set been included in the specification of any product other than a microprocessor? I have a shortwave radio and a camera that have a microprocessors in them, yet the manuals don't even say which processors are in them much less how to program them. Even my computer didn't come with a description of the x86 processor that's in it.
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PostPosted: Tue Apr 04, 2006 12:12 pm Reply with quote
dieter
 
Joined: 20 Jan 2005
Posts: 43
Location: US




Scott Larson wrote:
Since when has an instruction set been included in the specification of any product other than a microprocessor? I have a shortwave radio and a camera that have a microprocessors in them, yet the manuals don't even say which processors are in them much less how to program them. Even my computer didn't come with a description of the x86 processor that's in it.


The HD-3000 is supposed to be open source.
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PostPosted: Tue Apr 04, 2006 2:48 pm Reply with quote
xyzzy
 
Joined: 12 Feb 2006
Posts: 225




Scott Larson wrote:
Since when has an instruction set been included in the specification of any product other than a microprocessor? I have a shortwave radio and a camera that have a microprocessors in them, yet the manuals don't even say which processors are in them much less how to program them. Even my computer didn't come with a description of the x86 processor that's in it.


You can that info from Intel, along with docs for their chipsets. I used them when I wrote a utility report memory ECC status for a number of different intel chipsets.

Most hardware Linux supports has documentation, or it wouldn't be supported!

The cx8800 chip on the HD3000 has docs. The eeprom has docs. The tuner has docs. It's just the demodulator, the critital non-broadcast flag component, which will probably be outlawed, that is top secret.

A broadcast flag free card isn't worth much if you lack the information to use it.
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Specifications for HD-3000?
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