Help with "ni5640R Analog Input and Output" example with NI-5640R card

[sandeep palreddy]

Hi there,

             Using the example "ni5640R Analog Input and Output" with the NI-5640R card i want to generate a chirp from frequency 5MHz to 45MHz and plot the amplitude response as a function of frequency. I want to output this chirp into AO0 (Analog Output Port 0) output and i am connecting physically with a wire the AO0 (Analog Output Port 0) to AI0 (Analog Input Port 0) and plot the amplitude response of the wave i recieved at AI0 (Analog Input Port 0) to make sure that i am revicing what i should be. Can some one please tell me what changes i have to make to the "ni5640R Analog Input and Output" example so that i can accomplish generating the chirp for 5MHz to 45MHz.

The chirp that i will be using is of the form:

Where, fo = initial frequency = 5MHz.

and (fo+k*t/2)*t = 45MHz at the final sweep time T = SOME USER DEFINED TIME. We get the value of 'k' from this condition.

Can some one please help me with this. Any help will be grately appreciated.

Thanks,

Sandeep.

[Mauricio Capistran-Garza]

Hi Sandeep,

The max input bandwidth of PCI-5640R is 20 MHz, so you will not be able to acquire the entire 40 MHz signal with one input channel. Other than that, you should be able to generate the 40 MHz wide signal. I believe that in the "ni5640R Analog Input and Output" example, the output section works by writing a signal to a memory block in the FPGA and then repeating that buffer. If you can fit the entire waveform in the memory block then the example should work fine just by generating the Chirp waveform on the host and downloading it to the FPGA. However, if the memory block isn't big enough, you will have to modify the example such that you generate the chirp in the FPGA.

- Mauricio

[sandeep palreddy]

Hi Mauricio,

I undestand what you are saying. And i myself found that I can at once only sweep 20MHz in the range of 0 to 100Mhz. The only thing i couldnt understand and want to know is:

1) What changes should i make to the example "Ni 5640R Analog Input and Output" so that i can generate a chip from 5Mhz to 25MHz.

2) Where in the Host VI should i be making these changes to generate the chirp. (I mean, could someone be more explicit in pointng out where and what changes i shoul be doing).

Any help will be appriciated.

Thanks,

Sandeep.

[Mauricio Capistran-Garza]

Hi Sandeep,

I'm attaching a screenshot of the Host VI and I've circled the section where the data is generated. That is what you will need to update to generate a Chirp. Notice that the board takes IQ data, so you will need to generate IQ data for the Chirp.

Then, you will need to set the AO Center Frequency to 15 MHz (which is the center of your chirp) and a Symbol Rate of 25 Mz (to have enough bandwidth for the 20 MHz Chirp)

[sandeep palreddy]

Hi Mauricio,

I know that i have to generate a Chirp instead of a QAM signal (i.e, i know i have to replace the code of the QAM signal with the chirp signal in the host vi), and i know i have to set the Symbol Rate to 25 Mz (since my chirp is from 5MHz to 25MHz) and i know my center frequency = (5MHz+25MHz)/2 = 15MHz. The problem is:

I know how to generate a chirp (as there is a "chirp" function which generates a chirp), But i dont know how to generate the I and Q components of the chirp. Could you please help me with generating the I and Q components of a chirp (i.e, Can you please make a VI that generates the I and Q components of a chirp and give it to me).

Any help regarding this will be grately appreciated.

Thanks,

Sandeep.

[sandeep palreddy]

Hi Mauricio,

I know that i have to generate a Chirp instead of a QAM signal (i.e, i know i have to replace the code of the QAM signal with the chirp signal in the host vi), and i know i have to set the Symbol Rate to 25 Mz (since my chirp is from 5MHz to 25MHz) and i know my center frequency = (5MHz+25MHz)/2 = 15MHz. The problem is:

I know how to generate a chirp (as there is a "chirp" function which generates a chirp), But i dont know how to generate the I and Q components of the chirp. Could you please help me with generating the I and Q components of a chirp (i.e, Can you please make a VI that generates the I and Q components of a chirp and give it to me).

Any help regarding this will be grately appreciated.

Thanks,

Sandeep.

[bc2007]

Mauricio,

Can you attach the entire VI pls, it will help me with a  project I'm building.

Tks