How to match analog input frequency in FPGA with FIFO out in computer

[Monica10975]

Dear all,

I am working on NI Crio 9039 with 9205 analog input card.

I want to perform FFT on analog signal with sampling frequency of 1MHZ.

I have designed code where I am taking analog input into FPGA target, storing data into FIFO, performing FFT and then sending real and imaginary data of FFT to computer target through DMA FIFO.

For testing purpose, I am giving normal sinewave signal.

I am able to see sine wave on computer target with same amplitude but frequency is different. It is not matching with my input frequency. FFT result is also showing different frequency

For ex. if my anaog input is 2v 1Khz, I am able to see sine wave with 2V but 10khz or something different.

I am not able to understand how to match all the loop time and sampling frequency so that I will get same frequency as input signal. How to retrieve correct frequency and correct data in FFT?

Can somebody please help me out? I tried FFT With single cycle and while loop both.

[Monica10975]

It works properly with only 50k sampling frequency and not with any other frequency but still i am not getting correct FFT results. 

Can somebody help me out to understand how to check?

[IDASYAN]

Hello,

Here is a link for Specifications Explained: C Series Modules. Read the article I'm almost sure you will find the solution.

Regards.