Return to the CurtPalme.com main site CurtPalme.com Home Theater Forum
A forum with a sense of fun and community for Home Theater enthusiasts!
Products for Sale ] [ FAQ: Hooking it all up ] [ CRT Primer/FAQ ] [ Best/Worst CRT Projectors List ] [ Setup Tips & Manuals ] [ Advanced Procedures ] [ Newsletters ]

 
Forum FAQForum FAQ   SearchSearch   MemberlistMemberlist  Photo AlbumsPhoto Albums  RegisterRegister 
 MembershipClub Membership   ProfileProfile   Private MessagesPrivate Messages   Log inLog in 
Blu-ray disc release list and must-have titles. Buy the latest and best Blu-ray titles to show off in your home theater!

(non professional) VGA card bandwidth evaluation
Goto page 1, 2  Next
 
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> Home Theater PCs
View previous topic :: View next topic  
Author Message
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Wed Nov 27, 2013 3:31 pm    Post subject: (non professional) VGA card bandwidth evaluation Reply with quote


        Register to remove this ad. It's free!
Here we are, I started a small campaign to evluate the common VGA card's output performance, there are a lot of parameters that should be considered, but for now I focus only on the rise time measurement giving a clue about the bandwidth of the actual card, if there is interest in this thread the measured parameters could be extended later of course.

The measuring theory and method
This is not a reference level measurement, but later when the number of the measured cards are growing they could give a good basis of comparision.
The best way would be to get an oscilloscope with bandwith of at least 500MHz, but that's not a cheap toy for fun experiments. So I choose the indirect way of measurement.
I have an old HP 1720A analog oscilloscope, originally it was a military item, used by the USAF, after that it still remained in the corporate sector until I bought it from a friend who bought it at their rollout. It has an advertised bandwidth of 275Mhz, has switchable 50 Ohm input, it was held in good hands, but the last calibration date is unknown, otherwise it seems to be accurate enough for hobby purposes.
The VGA cards are connected directly to the scope's BNC input with a 3m (10 feet) long, VGA-BNC cable Fujikura brand. Though the standard VGA output would require a 75 Ohm termination I used the scope's 50 Ohm internal termination, but that does not affecting the rise time of the circuit. I did this to measure with the least intervention to the original signal and to ease the measurement.
A system's bandwith is proportional to its rise time and vice versa, the used method is based on the theory of rise time of cascaded blocks, in a perfect world this would mean if I would connect an infinitely fast rising edged signal to my oscilloscope I would measure 1,27ns rise time (=0,35/275MHz, see above the wiki link).
An other example: If I connect a (flat to) 400MHz (->tr=0,87ns) VGA card to my (ideal) scope (->tr=1,27ns) that would mean an 1,54ns overall rise time, and this is actually observable on my oscilloscope since it has a 1ns/div speed, that is further divided to 5 subdivisions.

For the further calculations I difine that my scope's rise time is 1,3ns, wether it is really or not, but until the measuring rig remain the same all myl measurements will be comparable.

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Wed Nov 27, 2013 3:44 pm    Post subject: Reply with quote

Asus nVidia GeForce 7950GT 512MB (PCIe):
Measured in 800x600 with a specially breed test pattern (to ease scope triggering) otherwise this is a simple multiburst, bandwidth pattern.
There was a slight overshoot, I set the 100% level to where the signal settled,
Total measured rise time(10%-90%): slightly less than 1,6ns
solving the equation gives us: 0,93ns calculated rise time for this card which would mean a bandwidth of about 375MHz, where the advertised bandwidth is 400MHz.



GF7950.jpg
 Description:
nVidia GeForce 7950GT rise time on a HP1720A o'scope
 Filesize:  39.74 KB
 Viewed:  9479 Time(s)

GF7950.jpg



_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB


Last edited by gjaky on Wed Dec 04, 2013 12:31 pm; edited 1 time in total
Back to top
View user's photo album (1 photos)
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Wed Nov 27, 2013 3:54 pm    Post subject: Reply with quote

integrated intel GMA950 (i945GZ on a foxconn motherboard):
Measured in 1920x1080 96Hz with the same pattern as above
Total measured rise time: 2,4ns
Calculated rise time for this VGA: 1,77ns -> ~200MHz, this is about the half of the advertised 400MHz.

That's it for now, an ATI HD3650, and other nVidia cards will follow soon.



GMA950.jpg
 Description:
intel GMA950 integrated VGA rise time on a HP1720A o'scope
 Filesize:  29.99 KB
 Viewed:  9475 Time(s)

GMA950.jpg



_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB


Last edited by gjaky on Wed Dec 04, 2013 12:31 pm; edited 1 time in total
Back to top
View user's photo album (1 photos)
AnalogRocks
Forum Moderator


Joined: 08 Mar 2006
Posts: 25437
Location: Toronto, Ontario, Canada

TV/Projector: Sony 1252Q, AMPRO 4000G


PostLink    Posted: Wed Nov 27, 2013 5:26 pm    Post subject: Reply with quote

I'll be interested to see the ATi 3650, I think that's what is in my HTPC
_________________
Tech support for nothing

CRT.

HD done right!
Back to top
View user's photo album (27 photos)
fragzero



Joined: 30 Aug 2012
Posts: 344



PostLink    Posted: Wed Nov 27, 2013 5:34 pm    Post subject: Reply with quote

It might be a good idea to photograph the card, not every manufacturer uses the reference design!
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Wed Nov 27, 2013 5:56 pm    Post subject: Reply with quote

fragzero wrote:
It might be a good idea to photograph the card, not every manufacturer uses the reference design!

Of course that can be done, the above mentioned asus card is a reference design, asus didn't even bothered to remove the original nvidia sticker from the heatsink, they just put their sticker on it Razz
In the meantime I figured out maybe I can test a HDF1 soon too..

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
winny



Joined: 09 Oct 2013
Posts: 401
Location: Sweden

TV/Projector: BD808s, BG1209/2


PostLink    Posted: Wed Nov 27, 2013 8:22 pm    Post subject: Re: (non professional) VGA card bandwidth evaluation Reply with quote

gjaky wrote:
The best way would be to get an oscilloscope with bandwith of at least 500MHz


I have a 500 MHz DPO4000 at work and if you send me the test pattern, I'll gladly measure whatever card I have laying around for you. Someone with a GHz scope should be better though.
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Wed Nov 27, 2013 9:23 pm    Post subject: Re: (non professional) VGA card bandwidth evaluation Reply with quote

winny wrote:
gjaky wrote:
The best way would be to get an oscilloscope with bandwith of at least 500MHz


I have a 500 MHz DPO4000 at work and if you send me the test pattern, I'll gladly measure whatever card I have laying around for you. Someone with a GHz scope should be better though.


Sure! See the attached picture bellow, I used this at full screen in 800x600, that's about enough as we are only interested in the steepness of the rising edge.



burst2.GIF
 Description:
pattern
 Filesize:  11.59 KB
 Viewed:  9430 Time(s)

burst2.GIF



_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Wed Dec 04, 2013 12:29 pm    Post subject: Reply with quote

Reference (Sapphire) ATI Radeon HD4650 (PCIe):
Measured at 640x480
Measured rise time: 1,8ns
Calculated rise time for VGA: 1,2ns -> ~280MHz (claimed bw: 400MHz)



ATI_HD4650.jpg
 Description:
 Filesize:  35.45 KB
 Viewed:  9361 Time(s)

ATI_HD4650.jpg



_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
fragzero



Joined: 30 Aug 2012
Posts: 344



PostLink    Posted: Wed Dec 04, 2013 1:54 pm    Post subject: Reply with quote

Any chance you can test a HD6350 reference design?

Quote:
http://tiptop.lt/blog/wp-content/uploads/2010/09/amd_radeon_hd_6350.jpg


Very popular HTPC card last generation!
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Wed Dec 04, 2013 2:25 pm    Post subject: Reply with quote

fragzero wrote:
Any chance you can test a HD6350 reference design?

Quote:
http://tiptop.lt/blog/wp-content/uploads/2010/09/amd_radeon_hd_6350.jpg


Very popular HTPC card last generation!


Unfortunately, I don't have a source to borrow that card, yet.
But I have an nvidia GF6600 and GF8800 card on my list, so we'll see at least how are the generations realated to one another with the nvidia cards... Otherwise I doubt the manufacturers took much effort to make the DACs even better and better with the ongoing generations, it's like wasted wasted time for the mass market... It would be also interesting if a very recent card has any cuttings in the analog performance compared to older cards?

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Fri Dec 13, 2013 10:01 pm    Post subject: Reply with quote

ASUS GeForce 8800GTS 320Mb (G80 core, PCIe):
Measured at 800x600
Measured rise time: ~1,7ns
Calculated rise time for VGA: 1,1ns -> ~320MHz (claimed bw: 400MHz) But note the output is very similar to the GF7950GT's only with less overshoot, thus the slightly worse rise time.



GF8800GTS.jpg
 Description:
 Filesize:  47.42 KB
 Viewed:  9268 Time(s)

GF8800GTS.jpg



_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
CasetheCorvetteman



Joined: 09 Nov 2008
Posts: 6319
Location: Australia


PostLink    Posted: Sat Dec 14, 2013 2:18 am    Post subject: Reply with quote

What do you get from a GigaByte 760 GTX OC Edition?
_________________
Barco CineMAX, 120" OZ Theatre Majestic 16:9 screen, H/K AVR 7.1...

RUNCO DTV991 LC ( NEC XG 852 LC ) 100" 4:3 screen, H/K AVR 5.1...
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Sat Dec 14, 2013 10:00 am    Post subject: Reply with quote

CasetheCorvetteman wrote:
What do you get from a GigaByte 760 GTX OC Edition?

Nothing, yet... Razz

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
CasetheCorvetteman



Joined: 09 Nov 2008
Posts: 6319
Location: Australia


PostLink    Posted: Sat Dec 14, 2013 10:56 am    Post subject: Reply with quote

Thats what i have in my main rig, 650Ti in the other.

Both allow me to select Generic CRT for 3D even over HDMI.

_________________
Barco CineMAX, 120" OZ Theatre Majestic 16:9 screen, H/K AVR 7.1...

RUNCO DTV991 LC ( NEC XG 852 LC ) 100" 4:3 screen, H/K AVR 5.1...
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Sat Dec 14, 2013 12:43 pm    Post subject: Reply with quote

The "latest" nVidia card that I can borrow is a GT240, which is pretty old as well Smile
_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
CasetheCorvetteman



Joined: 09 Nov 2008
Posts: 6319
Location: Australia


PostLink    Posted: Sat Dec 14, 2013 2:28 pm    Post subject: Reply with quote

Yeah thats WAY down the order from what i have here...
_________________
Barco CineMAX, 120" OZ Theatre Majestic 16:9 screen, H/K AVR 7.1...

RUNCO DTV991 LC ( NEC XG 852 LC ) 100" 4:3 screen, H/K AVR 5.1...
Back to top
noos@xp37+



Joined: 17 Jun 2008
Posts: 464
Location: Berlin/Munich


PostLink    Posted: Sat Dec 14, 2013 6:01 pm    Post subject: Reply with quote

I use a 280gtx, and I have one for SLI/spare lying around here. With the next parcel to HU I will include it for you. Great work Gabor!
Back to top
CasetheCorvetteman



Joined: 09 Nov 2008
Posts: 6319
Location: Australia


PostLink    Posted: Sun Dec 15, 2013 12:01 pm    Post subject: Reply with quote

I have the HDMI output connected to the AVR for audio, the RGB to the projector, then the DVI goes to my 27" monitor.
_________________
Barco CineMAX, 120" OZ Theatre Majestic 16:9 screen, H/K AVR 7.1...

RUNCO DTV991 LC ( NEC XG 852 LC ) 100" 4:3 screen, H/K AVR 5.1...
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2638
Location: Budapest, Hungary


PostLink    Posted: Sun Feb 21, 2016 7:20 pm    Post subject: Reply with quote

A new approach, multiburst signal.
Just because I was at it...
nVidia Geforce 6600GT



2048_1536_60.jpg
 Description:
2048x1536 60Hz
 Filesize:  103.55 KB
 Viewed:  6678 Time(s)

2048_1536_60.jpg



1080p_72.jpg
 Description:
1080p 72Hz
 Filesize:  106.19 KB
 Viewed:  6678 Time(s)

1080p_72.jpg



1080p_60.jpg
 Description:
1080P 60Hz
 Filesize:  103.25 KB
 Viewed:  6678 Time(s)

1080p_60.jpg



_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
Display posts from previous:   
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> Home Theater PCs All times are GMT
Goto page 1, 2  Next
Page 1 of 2
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum