Personally I do not see any reason why you could not use a decent graphics card as arbitrary wave form generator

card as arbitrary wave form generator.

I had this idea, too. But I think a problem could be a continuous signal. Is it possible to set VSync and HSync to 0? If you can do this, then with a modern GPU you could generate 3 complex analog signals on the fly (using even trigonometric functions), with more than 100 MHz samplerate and 8 bit resolution, for the price of a graphics card.

--
Frank Buss, http://www.frank-buss.de
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card as arbitrary wave form generator.

directly.

shit equipment,

in the category

Ok.

You see, in the US and some parts of the free world, you are allowed to make quotes like that.

But hold on, the end of the year is coming. That may all chance !

Jamie

card as arbitrary wave form generator.

Pixel clocks maxed out at 150 Mhz last I looked (several years ago) and getting past the horizontal and vertical blanking could be tricky but if you can swing it by setting the limits to the pixel counts it sounds really neat.

shit equipment,

in the category

Where are video cards manufactured?

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card as arbitrary wave form generator.

directly.

shit equipment,

in the category

I did some testing of graphics flat-panel displays in the OLD days. Suggest you try this.

You can write a simple program to set any pixel to any value you like. Write a program that puts steps, sine, triangle, arbitrary waveforms on a line of display.

Dig out your scope and decide if the waveform quality meets your needs.

Then think about what you're gonna do with it. How you're gonna amplify the signal, offset it, program it, protect it from destruction and how big/heavy the system is gonna be.

If all that looks reasonable, you can start thinking about how the chips work and whether you can make a continuous waveform out of it.

Figure the cost, including the cost of your time. Compare that to a commercial solution and some quality time with a paying customer.

I bet you'll abort somewhere around the middle of all that.

I did this almost 20 years ago. At that time, the transient response out of a video card wasn't anything to write home about. Jitter was atrocious. I didn't have a spectrum analyzer at the time. That view would be interesting too.

I expect it's better now.

On a sunny day (Sun, 29 Apr 2012 13:03:25 +0200) it happened Frank Buss wrote in :

card as arbitrary wave form generator.

I think all that is required is that you can write to the DACs directly. Sort of DMA to it from video RAM.

On a sunny day (Sun, 29 Apr 2012 07:15:23 -0400) it happened Jamie wrote in :

card as arbitrary wave form generator.

TV directly.

Chinese shit equipment,

are in the category

I am on a slow link right now, whats in that video?

On a sunny day (29 Apr 2012 11:28:53 GMT) it happened Jasen Betts wrote in :

card as arbitrary wave form generator.

Chinese shit equipment,

are in the category

Dont you know ;-)?

On a sunny day (Sun, 29 Apr 2012 05:05:34 -0700) it happened mike wrote in :

card as arbitrary wave form generator.

TV directly.

Chinese shit equipment,

are in the category

I am not exactly new to video, I have designed graphics cards. I build one for myself too. In the times you were talking about.

A 10x amp to 300MHz was already easy just a few $ in the seventies with some BFY90 transistors, somebody from Tek published the diagram (vertical amp) in a popular electronics magazine in those days, these days you can look the service manuals up on ebay. So now you have a 10Vpp or 20Vpp amp to 300MHz in 50Ohm, (and not milli Hertz Jamie) for 10$. Not counting the batteries, but most have some 78xx or even some walwarts.

Modern graphics cards have very powerful GPUs that are just super powerful vector processing units in one way, and can do a large part of the signal generation if you play it clever I think.

card as arbitrary wave form generator.

directly.

shit equipment,

in the category

-Lasse

On a sunny day (Sun, 29 Apr 2012 06:41:27 -0700 (PDT)) it happened " snipped-for-privacy@fonz.dk" wrote in :

card as arbitrary wave form generator.

TV directly.

Chinese shit equipment,

are in the category

Right, that is the one.

card as arbitrary wave form generator.

IMHO I think it is sufficient to program no horizontal and vertical blanking periods. The memory is already transferred to the DACs continuously. The clock control doesn't need to be fine grained. By changing the length of the waveform (size of the image) you should be able to create any frequency.

The real problem is that in a short while you won't be able to find videocards with DACs :-)

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

as arbitrary wave form generator.

directly.

shit equipment,

in the category

A lot of the Chinese equipment is quite good, and the prices are amazing. We just got a Rigol 4-channel 1 GHz scope and it's excellent.

There are wonderful gadgets on ebay, too. I recently bought a Gertsch Synchro Standard for $150, some nice synchros, and four HP RPN calculators. ebay is like a toy store. I have what is theoretically about a half million dollars worth of Tek sampling scopes and heads, mostly from ebay, bought for a few percent of the cost of new stuff. There's lots of interesting microwave, optical, and other exotic gear. It's worth buying some of this stuff just to take apart and see how it's built.

The graphic card ARB is a good idea, but the software has to come from somewhere. I was wondering if the video sync pulses can be disabled. This guy suggests not.

--

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

On a sunny day (Sun, 29 Apr 2012 15:42:42 GMT) it happened snipped-for-privacy@puntnl.niks (Nico Coesel) wrote in :

card as arbitrary wave form generator.

I got an AGP Gforce2 from ebay last year for a few Euro to fix an old Linux PC, that way I did not have to upgrade xfree and OS. Probably there will be many cards with VGA out for a long time on ebay.

On a sunny day (Sun, 29 Apr 2012 10:08:40 -0700) it happened John Larkin wrote in :

card as arbitrary wave form generator.

directly.

shit equipment,

in the category

Yes some is good.

Yes, I have some good stuff from ebay too. Here is an article in German about cheap 3 axis Chinese stepper divers from ebay:

those are not so good... They have optocouplers, but are not optically insulated, the optos have as function to stretch the input pulses.... :-) Still if you need a stepper diver then it is a cheap solution.

That is a very nice application, he actually says some cards allow you to set the sync to zero, I think he is mainly looking at the Linux driver and one of the X configure programs (xrandr). I do not see him modify drivers? That would be the first place to look. For example for my old Nvidia Gforce2 with VGA out I have the sources for 'rivatv' that adds video input, and you can learn a lot from the open source video drivers too. But indeed it ultimately depends on what the hardware allows, plenty of space for tinkering I think. The advantage of using a PC is that you can talk to that stuff so easily.

...

I remember reading about doing this about 10-15 years ago. Maybe Circuit Cellar, or maybe "here". Or maybe rec.radio.homebrew.

Markus Kuhn (sp?), the computer crypto expert at one of the Oxbridge universities (who used to hang out here, too) did some stuff where he turned a VGA type video display into a secret spread spectrum transmitter that worked by adding calculated dither onto the display data, demonstrating one means of sending information out of supposedly secure computers. Do you really know what your screen saver is doing?

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

ics card as arbitrary wave form generator.

tion

the TV directly.

Chinese shit equipment,

you are in the category

om ebay:

..

I read the tale of someone trying to fix one of those somewhere, there are numerous other problems with it like power supply sequencing that violates the datasheet and blows the driver etc.

-Lasse

as arbitrary wave form generator.

You can, I am quite sure.

I'll bet there are CUDA apps written already.

After all, Seti and a host of other distributed computing engines use them already.

VERY crappy sound-video "sync". Were they on the moon and the mikes on Earth (or vice-versa)?

card as arbitrary wave form generator.

HTimings 3656 3656 3664 3672 VTimings 1307 1307 1308 1309 here he has 3656 clocks (clock pulses) worth of data, 8 clocks of sync pulse and

8 clocks to the start of the next line. horizontal timings are usually constrained to multiples of 8 clock pulses by the hardware

vertical blanking is similarly set for minimal duration.

It doesn't look like he was able to set the video card for zero duration on those interruptions.

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