Help regarding generating I & Q components of the data

[sandeep palreddy]

Hi there,

I am having a hard time generating the I and Q components for a signal. I am using the "chirp pattern" function to generate a chirp from frequency  0 to 20MHz. To generate I and Q components, i have to some how create a 90 degree phase shift between the I and Q data, this is where i am having problem. The "chirp pattern" function doesn't

 have any input terminal for "phase" so i dont know how to create 90 degree phase shift between the I and Q data. I am attaching the VI i made with this question, please have a look at it and let me know what i need to do .(The circled portion in the VI is where i am generating the I and Q components of the chirp, but i am unable to create 90 degree phase shift between them, so i think the I and Q componets that i am generating are the same instead of being in 90 degree out of phase)

Any help regarding this will be grately appreciated.

Thanks,

Sandeep.

[david uang]

Hi,

   What do you mean by 90 degree phase shift? as you are dealing with baseband data. Do you mean delay by half of the symbol?

david

[sandeep palreddy]

Hey David,

I was also trying to generate I and Q components of a sinusoidal signal and i was able to do it by putting a 90 degree phase shift between them, and i know we cannot generate the I and Q components of a chirp by doing that (as we have bunch of frequncies not one). I was thinking about one sinusoidal signal (one frequency) when I typed the question, thats why everything got mixed up. My real question is, how can i generate I and Q components of a chirp by using "chirp pattern" function. Any help regarding this will be grately appreciated. By the way have a look at the VI i posted in my qustion (on the top of your first reply) and could you please tell me what i need to do or change (In the circled portion of the VI) to generate I and Q components of a chirp using "chirp pattern" function?

Thanks in advace david for looking at my question.

Thanks,

Sandeep.

[Mauricio Capistran-Garza]

Hello Sandeep,

A chirp waveform is one in which the amplitude remains constant but the frequency increments linearly. If the frequency increments linearly that means that the phase increments exponentially. With that in mind, I've created a simple VI to generate a baseband chirp signal. Take a look at the attached screenshot, it should get you started. You will still have to figure out how to configure it so the chirp start and end frequency are the ones you want.

- Mauricio

[sandeep palreddy]

Thanks a ton david. This should help me with what i want to do.

Thanks,

Sandeep.

[sandeep palreddy]

Hi Mauricio,

Thanks for you fast reply.

Thanks,

Sandeep.

Message Edited by sandeep palreddy on 08-15-2007 10:10 AM