Hello,
I followed the discussion not in detail, so maybe some else already give
the same information.
I would separate the signal path into smaller units and don't combine
thinks together. You can get DAQs with signal conditioning but I would
use a separate unit for that. also you get sensors with signal
conditioning. I would also separate this. Than you are more flexible in
your design and it is easy to exchange something if broken. Than the
signal path looks like that:
1. Sensor
2. Cable
3. Signal conditioning
4. Cable
5. DAQ
6. Cable
7. Control Unit
I would recommend to hold cable length as short as possible. Only
control cable to the control unit can be as long as possible, since this
this is only start the test signal.
Most force sensors will be supply a 2mV/V signal. You put it typical 10V
and get back 20mV if maximum load is applied. So not a strong signal at
all. After that you can put the signal conditioning.
This will change this into 20mA or +-10V. Chose what is best for the DAQ.
With the DAQ, I have very good experience with this one:
http://www.mccdaq.com/solutions/USB-Data-Acquisition.aspx
They have libraries for the common DAQ software like LabView. I use
Labview because Version 6.1 is for free to download.
With the cheapest unit, you have 12 Bit resolution and a sample rate of
1000 samples per second is possible. Within the software you can use a
moving average filter to reduce noise. With my latest DAQ unit, I
already tested 500kS/s and noise level was okay. But actually no need
for this rate when testing rocket engines. If you put all the neded
hardware into a nice case, than it looks like this:
http://applied-rocket-technology.com/index.php?option=com_content&view=article&id=75%3Atestand-2&catid=38%3Apruefstaende&Itemid=58&lang=en
There is no need to spent thousands of dollars to get a nice working
piece of hardware.
Greetings
Neil
Am 17.12.2015 um 10:09 schrieb Uwe Klein:
Am 16.12.2015 um 23:05 schrieb Monroe L. King Jr.:
Ok well, the budget for DAQ is $10,000
NI cDAQ-9188 and required modules/sensors/accessories.
And a good used oscilloscope. (better than anything I've got)
LeCroy preferred.
he and jup :-)
at the time I bought a Tektronix TDS420 as it better fit my budget
but the LeCroy 9374 was the better box.
for some quick and dirty stuff there are a range of DVM with serial
output around. Rather universal applyable without much hassle.
Good for background monitoring like tank levels, AC, Charging, ...
~1Hz sample rate.
uwe