Limits of PDA acquisition

[chilly_charly]

Do you know a solution to develop a data acquisition system (at leat  8 channels, optimal 16) working at 20 ks/s, on a PDA ?

I found that the compact flash proposed by NI has only 4 channels. I don't think PCMCIA cards work with last generation PDA's.

There are probably some possible adaptations of PCMCIA on Compactflash, but there the compactness of the system will be lost...

Any comment ?

[chilly_charly]

It would be nice if someone had a look to my problem.

[tst]

Looks like you're not important enough. Maybe you should contribute more to this community and then someone will help you.

[Bob_Y.]

We have looked at creating a system like this.  We were going to use a Pocket PC with with a cradle for PCMCIA cards.  We were then going to use a PCMCIA DAQ card in the cradle.  We never built the system because it turned out that it would be more expensive than our prospective customer wanted to spend.  When we were specing the system, we were having trouble finding the equipment.  There are very few of these handhelds left on the market.

Perhaps you can find one with 2 compact flash ports?  Or USB (probably draw too much power, though)?

Hope that this helps,

Bob Young

[chilly_charly]

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Bob Y. a écrit:
We have looked at creating a system like this.  We were going to use a Pocket PC with a cradle for PCMCIA cards.  We were then going to use a PCMCIA DAQ card in the cradle.  We never built the system because it turned out that it would be more expensive than our prospective customer wanted to spend.  When we were specing the system, we were having trouble finding the equipment.  There are very few of these handhelds left on the market.
Perhaps you can find one with 2 compact flash ports?  Or USB (probably draw too much power, though)?

---

Bob Y, thanks for this answer that comforts my opinion. I may have an alternative to this bottleneck : wireless data acquisition.

As anybody some experience in designing a compact and lightweight system similar to the one I need (acquisition on 8 DAQ channels (20 kS/s) and broadcast to a PDA ) ?

[EdDickens]

Hey CC,

Contact me through our "other" forum where we can discuss a possible alternative. Can't do it here.

Ed

[Sheldon_Stokes]

It's not exactly what you want, but how about the Toshiba Libretto and a USB daqpad?  IT's a lot larger, but sill a lot smaller than a traditional laptop.  It also has a PCMCIA slot if you don't want the USB DAQ.  Plus given your data rates and number of channels, you'll be filling the PDA memory pretty quickly unless you are not saving raw data.  The libretto has a 60 GB drive. 

Sheldon

[chilly_charly]

Thanks Sheldon.

Memory space should not be a big issue, since the average acquisition rate will not be maintained at 20 Ko. USB DAQ could be also a solution, but I don't kink the Libretto will be compact enough.

The system has to be "wearable". Since the original idea of having a PDA to do directly the job does not seem to be viable, we are now thinking to alternative solutions. Even a raw data recorder system, from which we could dump the data after one hour may be acceptable now ;).

Thanks for the ideas anyway. Great to receive your attention !

[Sheldon_Stokes]

For you hardware acquisition guys, have you seen gumstix?  (http://www.gumstix.com).  They are essentially gum stick sized little computers that run linux.  The really interesting part is that they are expandable with various daughter boards snapped in place.  The one that has my attention is the audio daughter card which has like 4 channels of 16 bit analog input and 4 channels of output.  I sample rate is at least 48 KHz if not 96 KHz.  You'd have to build your own pre-amp section but the audio board is $40.  The computer portion comes in a variety of flavors and even the most advanced one (with bluetooth etc) is less than $200. 

The downside is no labview, but they are really slick all the same. 

If you are looking for a straight data recorder, I found this one for a project (but I haven't ever used it).  It sounds like it might fit the bill:  http://www.microdaq.com/dataq/di-710/index.php 

It's still not quite what you want bandwidth-wise, but it's the smallest high bandwidth logger I know of.

Sheldon

Message Edited by Sheldon Stokes on 09-14-2005 03:52 PM

[aartjan]

I know of gumstix and I think it has potential, but.. there will be a lot of tinkering. Also: another device maker came out with a DAQ device for pocketPC (here), but who knows how much tinkering that will take before it works with LV PDA.  And then there was BTkit. I haven't bought one yet, but I don't know why. Btkit may work very well with labview, communicates through Bluetooth, and has a staggering 16 DIO, 8 AI and 2 AO. check it out here.
of course there are many more types of external hardware that can do the daq for you, and personally I believe Bluetooth is the way to communicate with them.