DSP on PC/104 recommendations

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I've been looking for PC/104 DSP options and am wondering if anyone has
recommendations. I have a portable, stand alone data acquisition
product that currently uses a custom system board and would like to
replace it with a PC/104 system running linux. The system records
pressure pulses (~ 1 pulse / second) in an noisy environment (pump
noise, etc.). I am interested in adding a DSP card for filtering and
freeing up the processor for user interface, networking, database, etc.

I've looked at cards from: Bittware, RTD Embedded, S&K Electronics,
Signallogic, Arius, Mango DSP, Sheldon, SystemExcelerator and Sundance.
Obviously, some of these are focused on communications or imaging and
some blow the budget, although the RTD products are < $1K. I've also
seen some non-PC/104 products that might work: dspstak from Danville
Signal Processing or DSP Stamp from Cambridge Signal Processing. I
haven't checked out PCI DSP cards - possibly they're more affordable
and could be plugged into a PC/104plus system?

Anyone have any recommendations, pointers or war stories?

Thanks,
Bill Turner


Re: DSP on PC/104 recommendations
Just curious: with such a slow speed of processing, why do you need a
DSP? I thought any processor can handle 1 pulse/second computation
without interruting its main task...

DS


Re: DSP on PC/104 recommendations

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We may be able to get away w/o a DSP - we're not using it now. But
there is a lot of noise in the system and some of it can be very close
in frequency to our signal of interest. I am thinking we may want to
use the DSP to do some frequency domain filtering, edge detection on
the pulse, etc. Plus with the new system we'll probably bump up our
sampling rate so that we can still differentiate between the signal and
noise as they get close together in frequency.

Thanks,
Bill


Re: DSP on PC/104 recommendations
Just curious: with such a slow speed of processing, why do you need a
DSP? I thought any processor can handle 1 pulse/second computation
without interruting its main task...

DS


Re: DSP on PC/104 recommendations

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The PC/104 bus is electrically ISA, not PCI, so a PCI board wouldn't help.

What sampling rates are you contemplating?  If you aren't sampling too
fast (you should be able to do 1kHz without any trouble at all, for
heaven's sake!) you should be able to do it all in one processor --
particularly if you get a processor that has MMX capabilities.  ADC
cards for PC-104 are going to have deep buffers, so you may even be able
to get away without using a real-time linux kernel.

--

Tim Wescott
Wescott Design Services
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Re: DSP on PC/104 recommendations
On Fri, 15 Apr 2005 13:35:21 -0700, Tim Wescott

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You are going to need really deep buffers if you intend to use some
Geode based boards due to the SMM issue. Many "standard" PC features
missing in the Geode, such as VGA text mode, are emulated by SMM,
causing unpredictable delays. Transmeta processors may start to
translate x86 to internal representation at some inconvenient time.

While these processors are convenient for ordinary processing, using
them for any time-critical applications require a careful evaluation.
If a large amount of real-time data needs to be captured, the input
device should have big buffers.

Paul
  

Re: DSP on PC/104 recommendations

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has
and
etc.
Sundance.
and
also
Danville
affordable
help.
too
able

We will probably sample somewhere in the kHz range (1 - 5?). Initially
we'll try it w/o the DSP since the processor will be able to handle it.
But once we add on the other user stuff (database, remote data display,
XML-RPC server, graphical reporting package) we might need the DSP to
be sure we don't miss any samples. I was looking at the DSP now to head
down the right hardware path. Some external cards interface best over
the SPI bus; possibly this implies using processor board w/ SPI support
built in?

Also, I was thinking of PC1-104 or PC/104 plus and plugging in a PCI
board. This probably doesn't make much sense from a packaging
standpoint.

Thanks for your help,
Bill Turner


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