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Found 15 results

  1. Hi, I am am able to compute the FFT using IP core block available in Vivado 2017. However, whatever is the sample rate of input signal to FFT IPcore, the frequency resolution of the FFT is fixed by clock frequency of the FFT. Example Frequency resolution = sampling frequency/number of samples DDS compiler generates sinusoidal frequency 976.56Hz at a clock freq of 1MHz,therefore the sample rate is 1Ms/s. this signal is given as input to the FFT IPcore 9.0 which is clocked at 5MHz with number of samples as 65536. therefore, Expected frequency resolution = 1MHz/65536, however
  2. Hi, I am using Xilinx XADC IP core for FFT operation and I have a couple of questions on the XADC sampling rate. Question 1) I would like to have the sampling rate at 1 MSPS but for a 100 MHz clock the XADC actual conversion rate is 961.54 KSPS. Same is for 50 MHz. I realized that for 104 MHz of DCLK clock the conversion rate is 1000 KSPS but implementing this clock from clocking wizard IP resulted in timing failure during implementation. (This is another problem if you have any inputs on how to tackle it) So I settled for 100 MHz clock and expected a 961.54 KSPS sampling r
  3. Hello, this is my first post in this forum. Im working on a project which I should sample data from ADC (ADS5463), and then fft the sampled data and see the results. The sampling clock is 400MHz and my FPGA working with DRY clock coming from the ADC which is 200MHz (fs/2). Im sampling the data with DDR interface using Lattice IP (GDDRX1_RX.SCLK.Aligned Interface), which sampling 12 bit DDR data into a bus of 24 bit (there the 11:0 bits is positive edge data and 23:12 is the negative edge data). Next Im storing this data into 2 FIFOs, one for the positive edge data and another for th
  4. i enter 5V in FFT so maybe the result are just on impulse signal. but actuality my result have unexpected -'128 signals' (263~390 cnt ) why does -128 apear. and how to disapear unexpected value (-128)
  5. Hello sir, I have implemented FFT of sine wave using "FFT IP core". It gives me exact frequency of the input. But when i tried to implement IFFT of that output using "FFT IP core with configuration value 8000H", output is not again sine wave in time domain. Could you please help me to sort this out? Thanks and regards
  6. renesas_an1560_making_noise_measurements_pgs_1-3.pdfI have a noise test setup that is measuring the en noise of jfets and is gaining it by 1000x to the AD2. What tools exist in the AD2 - likely either scope with FFT or the SA where I can get reported the rms voltage value over frequency and the number of samples taken for the RMS. I don't want pk-pk as it requires more work and samples to be meaningful to the analog circuit designer - me. Please provide a best practice method as I am struggling at this time. An alternate can be to move to another piece of test equipment if this is
  7. Hi, I use WaveForm 3.11.5 and I would like to be able to import a previously exported Scope FFT, Impedance Analyzer and Network Analyzer data. The exports work fine, and it's pretty good for working with other tools that can handle .csv. On the other hand, it would be great to have the ability to import these values later to compare them with the ones we are measuring. I could imagine it as a new reference type, so we could import even multiple files, name them and choose colors for them. What do you think, @attila? Regards, Andras
  8. Hi, I'm having some little trouble with WF. It's complex software so maybe missing something, but may be actual problems, two of them: 1) Wfm math in FFT window is acting little different than expected. I'm doing 0-50MHz sine sweep with ext gen on some filter and would like to see normalized response graph. For that I first create Ref 1 trace using Peak Hold Continuous. Then create filter response trace. Now try to get final plot using Math 1. No desired result since it calculates on current values, not the PHC plots! 2) Persistence window is not taking into account interpolation
  9. Hello, I am getting successfully data from an accelerometer and I then I want to calculate the frequency of a vibrating object where the accelerometer is placed at. As you can observe in the attached VI after I obtain the accelerometer measurements I use data queue function in order to collect a certain amount of data(200), in order to have enough samples for my FFT. Then I use build waveform function and at the end filter and spectral measurements vi. But unfortunately I do not thing that I get the frequency I want.And that means not only that the x axis in waveform graph is not
  10. Hi, I'm working on a WaveForms script which would be able to generate chart with the frequency profile of a liquid. For this, I need to use a Wavegen and a Scope: first I need to set the generator to a certain frequency and then I'd like to check the power of that signal on the scope. Between the probes of the generator and the scope there will be the liquid I would like to test. I created a basic script to step from 1 Hz to 150 Hz, check that signal with the scope, repeat this loop 5 times, and calculate the min, max and average values at each frequency. Although the script w
  11. Hi, I am trying to compute FFT of a synthesized square wave of frequency 100Hz. The 100Hz signal has to be sampled at 1kHz. So, I kept the clock frequency of FIFO, FFT_IPcore and other blocks at 1ms. I have attached the screenshot of the design file and simulation results. From the simulation output, it can be observed that the buffer stores for 512 samples and the un-buffer after 512*1ms. But, there is no output from the FFT block. I would like to know whether my approach is correct or I am committing any mistake in the way the blocks have to be integrated. Help much app
  12. Weevil

    FFT

    Hi all, i started to do a FFT from exact one sine wave with the XFFT(9.0). This works for the 32bit input signal, but for the 16bit input signal it seems not to work. By doing the FFT i would expect one peak in the frequency spectrum like i get in in the following picture: XFFT settings: - Architecture Choice -> Pipelined, Streaming I/O - Transform Lenght -> 256 - Scaling Options -> Scaled - Input Data Width -> 16 -> input signal from DDS 32bit - Input Data Width -> 8 -> input signal from DDS 16bit For generating a sine wave i
  13. Hello, For a project in one of my courses my adviser asked me to find a way to control the sample rate and record length in the Analog Discovery in order to understand how to use the FFT module. Thank you, cjobi247
  14. Hello all, I am trying the measure a variable frequency signal, is it possible to create a custom scope channel that will display the most prominent frequency? If a scope channel is not possible, is there a way to continuously log the frequency over time? Currently, I am only able to get one frequency reading per acquisition using the logging tool and exporting the 'measurements' source.
  15. Hello everybody! Since I was sharing this image with others, I thought I'd share it here at Digilent as well. The attached image shows the frequency response of several FFT windows, including the well-known rectangle and Hanning windows. The blue window is one I've put together, but haven't shared the FPGA source code used to implement it. I challenge anyone to do better. Oh, and one other comment ... all but the Hanning window can be used in an invertible FFT process. Dan