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Re: Continuous Power spectrum density at 0.25 Hz resolution

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 wrote:

I do not see a circular buffer in your examples, you are just enqueuing data. You need to think about how you want to implement your buffer, it is lossy, do you want to skip adding points to it if it is busy processing, etc.

 

There are lots of other things in your example that could be fixed, but I do not know whether you just put it together for an example.

 

Attached is a real hack of the program that will get it to do what you want, but I highly suggest you just look at it to see what can be done and rethink you problem.

 

mcduff


@mcduff, really appreciate your help and thanks for taking out time to modify the program.

 

1. You are right, i have used wrong nomenclature, it's just buffer and not circular buffer. I have buffered previous 3 data blocks using shift register.

2. In your program, PSD will be calculated at every 4 second. Basically it waits for 4 seconds data to gather. Whereas I am trying to achieve continuous PSD, being calculated at 1 sec, with previous 3 seconds data from shift register.

 


Re: crc32 of a binary file

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Plus, there was someone who recently came to this thread on a Google search and complained about people suggesting searching Google as a solution.  Yet, this person hasn't come back to this thread for help, so apparently Googling WAS a solution.

Re: Continuous Power spectrum density at 0.25 Hz resolution

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Once again, I do not recommend this as a final product, but something to think about. (I added some noise to the signal)

 

mcduff

Re: Relationship between Sample Rate/Record Length and time/div on horizontal axis

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Unencumbered by any "facts" (I've not used NI-Scope nor a USB oscilloscope, but have used numerous "real" scopes, both the old "moving CRT beam" and the more modern "fast internal A/D and digital display" model.

 

So a "traditional" scope has a Time/Div setting, and there are usually 10 Divisions on the screen, so if you have it set to 1 sec, then you'll see 10 seconds of data as the beam moves (slowly) across the face of the scope.  If you need to see a Rising Edge, you set it to 0.1 msec (or less) per division and use triggering to get the rising edge in your 1 msec of display.

 

Now consider Sample Rate (Samples/sec) and Record Length.  Let's say (remember, unencumbered by the facts!) that you are going to display the Record to fit on the screen.  What is the total time represented there?  Let RL = Record Length, SR = Sample Rate, and ST = Sample Time = Full Screen time.

   ST = RL / SR.

Example -- the width of the screen is 1000 samples, and you sample at 1KHz.  It takes 1000(samples)/(1000 samples/s) = 1 second to take the data that fills the screen.  If the Screen has 10 "divisions", then 1 div = 0.1 sec.

 

You probably want to sample (speaking as a non-engineer!) 100 to 1000 times faster than the shortest time interval you are interested in seeing (this might be low by a factor of 10, but probably not by a factor of 100, and I'm happy to be corrected on this).

 

So if we are using a Digital Scope, have a display with 10 Divisions across the Screen, know the Sample Rate (SR) and Record Length (RL),

   Time/Div = (RL/SR) / .

 

Bob Schor

 

P.S. -- I love your Quote!

Re: Watlow F4T

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Update,

i have installed this driver on a win 7 machine and it works flawless. On windows 10 I have the issue as described. has anyone solved this in windows 10?

Re: Relationship between Sample Rate/Record Length and time/div on horizontal axis

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Unencumbered by any "facts" (I've not used NI-Scope nor a USB oscilloscope, but have used numerous "real" scopes, both the old "moving CRT beam" and the more modern "fast internal A/D and digital display" model.

 

So a "traditional" scope has a Time/Div setting, and there are usually 10 Divisions on the screen, so if you have it set to 1 sec, then you'll see 10 seconds of data as the beam moves (slowly) across the face of the scope.  If you need to see a Rising Edge, you set it to 0.1 msec (or less) per division and use triggering to get the rising edge in your 1 msec of display.

 

Now consider Sample Rate (Samples/sec) and Record Length.  Let's say (remember, unencumbered by the facts!) that you are going to display the Record to fit on the screen.  What is the total time represented there?  Let RL = Record Length, SR = Sample Rate, and ST = Sample Time = Full Screen time.

   ST = RL / SR.

Example -- the width of the screen is 1000 samples, and you sample at 1KHz.  It takes 1000(samples)/(1000 samples/s) = 1 second to take the data that fills the screen.  If the Screen has 10 "divisions", then 1 div = 0.1 sec.

 

You probably want to sample (speaking as a non-engineer!) 100 to 1000 times faster than the shortest time interval you are interested in seeing (this might be low by a factor of 10, but probably not by a factor of 100, and I'm happy to be corrected on this).

 

So if we are using a Digital Scope, have a display with 10 Divisions across the Screen, know the Sample Rate (SR) and Record Length (RL),

   Time/Div = (RL/SR) / .

 

Bob Schor

 

P.S. -- I love your Quote!

Re: Help Performing FFT Spectrum on Logged Data

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Not sure if this is what you are asking, but your plots in magnitude are showing the RMS amplitude, take 1/2 of your peak to peak amplitude and multiply by square root of 2 to get what you see. If you want your spectrum to display peak-to-peak amplitude or peak amplitude then you need to multiply your FFT by the appropriate constant. (Hint I told you how to go in one direction, now just reverse it for what you need.)

 

mcduff

Re: Relationship between Sample Rate/Record Length and time/div on horizontal axis

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Hmm... That makes sense and gives me something to think about tonight.

Other than cursing NI for making me go through this. I have automated several real oscilloscopes both analog and digital and they all usually had time/div as part of their horizontal vi and in the case of DSO's also had a separate vi with sample rate settings.

 

 


HTTP POSTBuffer.vi:6120001

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Hello Im trying an application where I post some data through an API (JSON) to AWS. Everything works fine in my computer (LabVIEW and executable) but in the client machine it doesn´t work, and even if I try to publish the JSON from "Postman" (a REST client) in the client machine I'm able to publish de data, but when I run the LV distributed application returns me the Error 363500 -> POSTBuffer.vi:6120001 and there is no answer in header and body. Does someone have any idea about what is happening????

 

My publishing code is really basic and the JSON string has been tested in Postman and my computer and runs ok.
HTTP_POST.png

 

Re: how to acquire data from digital output sensor LSM6DS3 using cRio 9039?

how to do that

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Một hy vọng đơn giản LABVIEW (5.1) DAQ câu hỏi từ một newbie:
Tôi cần phải kích hoạt kỹ thuật số một kênh D / A chuyển đổi của một
tín hiệu khác nhau mỗi 50 mili giây (chiều dài tín hiệu <4096 mẫu,
sử dụng PCI 6111E hội đồng quản trị trong một 400 Mhz Pentium).

Tôi tạo và lưu trữ các tín hiệu khác nhau trong một mảng 2-D và sử dụng Finite
Pulse Train.vi như là một nỗ lực đầu tiên tại một tín hiệu kích hoạt.

Các ví dụ VI và tài liệu có sẵn không làm cho nó rõ ràng như thế nào để
lặp đi lặp lại và liên tục kích hoạt chuyển đổi D / A theo thời gian. Có bất kỳ
ví dụ nào ở đó hoặc tài liệu hướng dẫn về cách thực hiện điều này không? Bất kỳ trợ giúp sẽ
được đánh giá rất nhiều !! 

Re: myRIO FIFO overflow

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The sampling frequency is 20 kHz so it takes less than a second for FPGA (I have 4 channels) to collect those data. Yes I am using two FIFO Read in RT exactly like you.

I am not doing that much processing on RT, just reading from FPGA and saving the raw data in a external memory, and sending a few number of data in each cycle for PC for processing (just to monitor how the data look like during the experiment).

How to inject drag & drop code in Python as LabVIEW??

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At present me working on software that runs on bio-instrumentation. I tough it would be great if I could program few operations seq as drag & drop from an interface, as to execute callbacks in LabVIEW process for custom orders.

For the info, I am already using PyQt5 & Designer for interface creation. Now I need an interface that allows my functions to perform custom scrips - graphically.

I use a sys that runs with RaspberryPi with the main controller, The whole app is coded with Python.

Now, how to achieve it? Some help is appreciated?? 

 

Re: Error-200077 at DAQmx

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Hi,

This error is occurring because:

1. USB multifunction I/O devices do not support hardware timed single point acquisition

2. Only PCI/PXI/PCIe/PXIe DAQ devices can support Hardware-Timed Single Point Sample Mode (HWTSP). 

 

For a complete list of supported and unsupported device, please refer to our documentation:

http://www.ni.com/product-documentation/54449/en/#toc4

 

In HWTSP, samples are acquired or generated continuously using hardware timing without a buffer. Because samples must be continuously acquired/updated and processed on a point-by-point basis, you need to use a fast, deterministic bus. The inherent latency of the USB bus itself does not provide enough determinism to allow this output mode, therefore it is not supported.

ACCESS USB IDIO-16

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Hello,

while going through the USB SSRs i came across acess usb idio-16 (16 ssr output).

i talked to their representative if it will work in labview environment who assured that it will work.

i want suggestion from you guys whether i should buy it or not as i didn't get more information on this forum and providing more channels than ni usb-6525 of ssr

http://accesio.com/?p=../usb/usb-idio-16.html#DownloadLinks 


Re: Need help with http "Content-Encoding:deflate" (decompressing data)

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There is no decompressing method available in LabVIEW. You need external tools.

The .net deflate is not working in LabVIEW since version 2014 and it is not planned to fix it...

In our Company we are actually developing a .dll that will do the job.

Good luck

Benoit

Re: List all attached devices

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here is the code you are looking for:

Benoit

Re: Query the version of MySQL ODB from LabVIEW

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Hi,

I did this once but i have only tried it on my computer, don't know if it works for others.

I have windows 10. 

/Peter

Find MySQL driver.png

Re: List all attached devices

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Hello all,

 

I have managed to get up and running using the following....

 find device.png

Iain

Re: How can i fit the Gaussian curve?

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Hi altenbach,
Thank you for your reply.
Theory behind the shape is Positron Annihilation Spectroscopy. I work with a linear positron accelerator.
The data are taken from the accelerator. Now, I'm working offline.
The accelerator has its own radiation source, There is a radiation background from the other sources like soil, electronic devices etc. And this background creates an asymmetry between the left side and the right side of the spectrum curve.
The left side of peak is high because there is background radiation. I want to get rid of it and to see the left side and the right side of the Gaussian curve equal. The level that should be is the right side of the curve. Using these formulas, I tried to reduce the background of the left side.

Please help me to fix it. Nobody helps me.

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