looking for DAQ that measures PPM tia sal22

[ratullloch_delthis]

Greetings all

I'm looking for a DAQ that will measure PPM (particles per million) over time, can anyone recomend one?

tial sal22

 

[Bob Masta]

On Thu, 02 Dec 2010 15:36:33 GMT, ratullloch_delthis
<ratullloch_delthis@gmail.com> wrote:

Greetings all

I'm looking for a DAQ that will measure PPM (particles per million) over time, can anyone recomend one?

tial sal22

Could you elaborate on exactly what you want to do?

Best regards,


Bob Masta

DAQARTA v5.10
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
DaqMusic - FREE MUSIC, Forever!
(Some assembly required)
Science (and fun!) with your sound card!

 

[Martin Brown]

On 03/12/2010 13:26, Bob Masta wrote:

On Thu, 02 Dec 2010 15:36:33 GMT, ratullloch_delthis
ratullloch_delthis@gmail.com> wrote:

Greetings all

I'm looking for a DAQ that will measure PPM (particles per million) over time, can anyone recomend one?

Not really clear here what you are asking for.
DACs output voltages, and ADCs measure them.

Old Solatron 7060 voltmeter secondhand, provided you don't want absolute
calibration will just about do it on the 10v range (as will some of the
later models but they are usually more expensive).

It is actually rather hard to get ppm low noise ADCs to behave reliably
at 6 sig figs and you need reference gear to qualify and calibrate it.

Regards,
Martin Brown

 

[Bob Masta]

On Fri, 03 Dec 2010 13:37:28 +0000, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote:

On 03/12/2010 13:26, Bob Masta wrote:
On Thu, 02 Dec 2010 15:36:33 GMT, ratullloch_delthis
ratullloch_delthis@gmail.com> wrote:

Greetings all

I'm looking for a DAQ that will measure PPM (particles per million) over time, can anyone recomend one?

Not really clear here what you are asking for.
DACs output voltages, and ADCs measure them.

Old Solatron 7060 voltmeter secondhand, provided you don't want absolute
calibration will just about do it on the 10v range (as will some of the
later models but they are usually more expensive).

It is actually rather hard to get ppm low noise ADCs to behave reliably
at 6 sig figs and you need reference gear to qualify and calibrate it.

Depending on what he really wants, the OP may want to look
into averaging methods. I have a series of articles on
synchronous waveform signal averaging, starting at:

<http://www.daqarta.com/tm01.htm>

The articles are about recovering a repeating waveform that
is buried in noise, but the noise reduction and bit
resolution principles apply equally to simpler measurements,
if that's what the OP is looking for.

Basically, for every doubling of the number of samples
averaged, the noise goes down by 3 dB and the resolution is
increased by 1 bit. Note that this assumes that any drift
in the ADC is of much longer duration than the thing you are
looking for.

Interestingly, you can make an "ADC" that has only a *single
bit* and get high-resolution results using averaging. Here
you actually use noise (either in the signal being measured,
or deliberately added as "dither") to improve the
resolutiuon. See:

<http://www.daqarta.com/tm07.htm>

Best regards,


Bob Masta

DAQARTA v5.10
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
DaqMusic - FREE MUSIC, Forever!
(Some assembly required)
Science (and fun!) with your sound card!

 

[ratullloch_delthis]

I'm just looking for a DAQ that can measure PPM
http://en.wikipedia.org/wiki/Concentration

They have portable versions but I'm looking for a DAQ version so I can export data to a text file over time.
http://www.sunstoneherbals.com/tds3.htm