02-21-2012 07:52 AM
I need it because I only need high sampling rate for the first few hours. While the experiment can last several days. Therefore, if I used a very high sampling rate, there will be to much data and might consumed to much space on the computer hard disc. by having different sampling rate and block it will be more efficient.
02-21-2012 08:05 AM
In that case we need to use different criteria and averaging to reduce the sample rate and frequency.
The easiest way would be to use different files for the different sample rate but could be done with ASCII files as well as DDF not sure if you can with other types.
Which file format were you planning on using?
You really need to talk to your professor to upgrade to V12 I'm sure that your local rep would have something for Universities discounts
02-21-2012 08:25 AM
I used ASCII.
Ow, how do you use different criteria and sample averaging?
Currently I used a different file by using 3 write module. But, If I stop one of them(from writer module option or using stop module), the whole program would stop....is there anyway to stop only one of it?
yeah...I think I'll try to talk to him about that tomorrow...Is it easier to do that in V12?
02-21-2012 10:15 AM
I feel rather strongly that my proposed solution will resolve your problem, and that it's very likely to work with DASYLab V5. It's similar to an example that we included in our original Getting Started guide, and works independently of your sample rate. Your base sample rate (where you collect and display the data on the screen, before reducing it for the file) should be at least twice, and probably 5-10 times faster than the fastest storage rate. That ensures that the Generator module can actually pulse.
This is an image of the pulse signal that you specified.... The very dark at the left is the high speed, then the lighter area is the moderate speed, followed by the very slow rate. The dark lines are an artifact of the aliasing that is happening on the image, and not a reflection of the data rate.
I've attached the data file that this produced. I ran for a simulated 10 hours, so that you have a few data points at the end to show that it slowed down to one sample per hour.
My raw sample rate was 100 Hz.
02-21-2012 10:20 AM
You can find the DASYLab 6 QuickStart, which should apply to V5, at www.dasylab.com in the Downloads tab, under Information, on page 2.
DASYLab in less then 30 days (Hands-On Guide Version 6, English)
02-22-2012 02:02 AM
In my daisy lab, when I click the generator, there are several options that I have to choose (without modulation, amplitude modulation, frequency modulation, etc). Can you tell me what type of generator that you used?
the signal switch module is the same like time slice right? isn't this module only changes the chanel that I used?in which part the sample rate is altered?
I tried to see generator module under "read global variables" option. How to control the sampling rate by using global variable?
I have read the module that you reccommend to me, but I still a bit confused because in that book, they ussually adjust the sample rate based on the amplitude instead of duration.
02-23-2012 09:06 AM
If you go back to my original post,
Generator01 is generating a constant. It is an ordinary generator, without modulation.
To use Gl. Variables, you can change the Generator to read Global variables.
The constants are the desired RATE in seconds (1, 30, 3600, etc)
Arithmetic is Arithmetic 1 channel, and is doing the "Inverse" or "Reciprocal" function, 1/input
The channel value at this point is a frequency in Hz.
Signal Switch is the Time Slice module, time based. Each channel defines the duration of the step (30 minutes, 5 hours, forever = 999999 hours). It selects which input to send to the output.
The Generator00 is a FREQUENCY modulated generator, where the mode is "Pulse" or "impulse" and the amplitude is 5 (TTL High). This will create a timing signal, with a pulse at the specified RATE, using the frequency computed above.
The data reduction is done by the RELAY module. It releases one data point for each TTL High pulse that the Generator00 outputs. Otherwise, it discards the data.
The output of the Relay is the reduced data stream... no averaging or separate needed.