Re: Logging 2 million samples a second for 15 minutes

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Quoted text here. Click to load it

Do a search for 'data acquisition boards".  A few thousand dollar
board and a spare PC should exceed your requirement.

For example:
http://www.superlogics.com/specpage.asp?Items52%19
http://www.mstarlabs.com/hardware/5400/5400spec.html

--
John Popelish

Re: Logging 2 million samples a second for 15 minutes

Quoted text here. Click to load it
<snip>
Quoted text here. Click to load it

The 7/9 track digitizer I'm prototyping uses five AD9201 ten bit
two channel 20mhz converters, and a synchronous FIFO connected
to a PCI DMA IDE channel inside a PowerMac, which has several
gigabytes of SDRAM.

2 to 3gb of ram on a desktop machine isn't THAT expensive any
more.

Re: Logging 2 million samples a second for 15 minutes
On Thu, 17 Jul 2003 20:14:36 -0700, the renowned snipped-for-privacy@spies.com (Al

Quoted text here. Click to load it

SDRAM is cheap ($130-200/1G, in 1G SIMMs). Not all PeeCee motherboards
will support huge amounts of memory, of course.

unsigned char my_data[1800000000];  // ??

Best regards,
Spehro Pefhany
--
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Logging 2 million samples a second for 15 minutes
Quoted text here. Click to load it

here is a scan of the proto pcb

http://www.spies.com/aek/digitizerPCB.jpg

Re: Logging 2 million samples a second for 15 minutes
snipped-for-privacy@spies.com (Al Kossow) wrote in message
Quoted text here. Click to load it

What's the interface to the computer?  I count 50 pins on the ICD header
on the right of the board, SCSI?

Tim.

Re: Logging 2 million samples a second for 15 minutes

Quoted text here. Click to load it

IDE, used as a 16 bit DMA interface.

After a long search I decided that bog standard bus master PCI
IDE cards were the simplest way to interface moderate speed
data into current pc's.

My current favorite is the side raid66 card, which uses a documented
Highpoint HPT368 part, and has a 40 pin connector coming out the fence.

This obviously assumes the config rom has been modified so that the OS
doesn't try to touch it as a disc (not an issue on a Mac running OS9,
since the card isn't recognized)

The pcb in the picture is just a bare board, the A/D - FIFO data path
was fabbed, but the rest of the interface is wire-wrap. There is a
second FIFO prototyped on the right side for disc interface prototyping
where an A/D isn't needed.

Re: Logging 2 million samples a second for 15 minutes
On 17 Jul 2003 18:46:41 -0700, shoppa@trailing-edge.com (Tim Shoppa)

Quoted text here. Click to load it

 I just copied 13 megabytes, a directory with a bunch of files, from
my c: drive to d: in under 2 seconds, including all the Windows file
overhead. Old 700 Mhz Dell PC. So the disk stuff is in the ballpark.
You'd probably need a fancy buffered or DMA data acq card to keep
streaming the samples into RAM while the disk drivers were sputtering
to unload the stuff. I should thing some of tha data acq card vendors
would have all this worked out already.

John


Re: Logging 2 million samples a second for 15 minutes

Quoted text here. Click to load it
are

I think you know the probable answer to that. Until someone familiar with
IDE
chimes in, I'd suspect you'd need some kind of FIFO or circular buffer in
the
pipeline somewhere, so you can guarantee the storage, at the data rate, of
the
original samples.  Then if you can pull them out, at, say, 2.5 MHz with a
50ms
"hiccup", you know you'll need to have at least a:

50ms + (x/2.5Mhz) = x/2.0Mhz  // match fill time with extract time

.05s + (x/2.5M)s = (x/2.0)s // convert to seconds

.05=x/2.0M-x/2.5M  // remove seconds units

10M(.05)=5x-4x  // multiply by 10M

500,000  =  x // this is the number of bytes that satisfy the first equation

In other words, a 500kByte buffer.  Kind of like CD anti-skip protection on
automobile and sports CD players.

You could "double buffer" also, into two 500kbyte buffer, and have the
synchronous filling routine switch from one to the other when the first is
filled.  In this case, all you care is that the extractor can wait when it
has
finished reading one buffer until the next "switch".


hth

Rufus








Re: Logging 2 million samples a second for 15 minutes

Quoted text here. Click to load it

Maybe convert to 400Mbps Firewire and dump the data into a Firewire RAID
or a desktop computer?  The Oxford 911 chipset is designed to be an IDE
to Firewire bridge but it allows for custom firmware.  Ask them if the
IDE interface could be reprogrammed to take in a continuous data stream.

I'm sure the R&D would be a pain in the ass but you could mass produce
them for a few dollars each after that.

Re: Logging 2 million samples a second for 15 minutes

Quoted text here. Click to load it

I'd be looking at USB 2.0 - it's faster (480 Mbits/s), and is supported on
almost all newer computers.



Re: Logging 2 million samples a second for 15 minutes
On Sat, 19 Jul 2003 23:56:07 GMT, "Da Man"

Quoted text here. Click to load it

Is this based on experience or on reading advertizing?

In the tests i have seen so far, FireWire outperformed
USB2 by 30% in net transfer rate :-)

Regards
Klaus


Re: Logging 2 million samples a second for 15 minutes

Quoted text here. Click to load it

You could do it with a PC, a little FIFO, a shift register,  and one of
those new 60 megabits per sec
serial cards.  I've seen them even at CompUSA!

At those speeds you even have time to do a little delta data compression if
your data is amenable.  Then you don't need a very speedy disk drive at all.


Regards,


George




Re: Logging 2 million samples a second for 15 minutes

Quoted text here. Click to load it





If you don't find a better way, you might try reading it into two
independent disks, staggered.  Then later you fill in the drops in one
of them from the other.  A side benefit is you get a partial backup and
also if god-forbid some of the readings they share aren't the same then
at least you find out about it.


Re: Logging 2 million samples a second for 15 minutes

Quoted text here. Click to load it

I'd go for a PCI card and have it write samples through DMA directly
into the PC's memory.

--
Reply to nico@nctdevpuntnl (punt=.)
Bedrijven en winkels vindt U op www.adresboekje.nl

Re: Logging 2 million samples a second for 15 minutes
Quoted text here. Click to load it

This guy here is evidently the toy of choice for such applications.

http://www.measurementcomputing.com/cbicatalog/cbiproduct_new.asp?dept_id23%8&pf_id11%50

And if you van get work to pay for it, you can use it to experiment with
GnuRadio in your spare time. :)

Rob

Re: Logging 2 million samples a second for 15 minutes
You need to think USB 2.0....

Quoted text here. Click to load it


Site Timeline