Sinewave

[crio]

Hi Jerry,

                    i got the toolkit problem fixed Thank you very much.

Remember u told me that the sine wave that i see in the ni5640R IQ output is jus the NCO's output and u sent a wave form example for me......

Now i know how to generate a sine wave by jus giving a lookup table to the FIFO and looping it..... but my question is is there a possibility to elminate the other waves that shows up .... i mean to say that i am jus trying to change few codes of ni5640R IQ output program..... i am now generating a sine wave in the correct range but those distoreted waves and the false sine of NCO still exits wat do i do to eliminate it???

Thank you

Valli

[JerryAL]

Hi Valli

Unfortunately, you can not disable the NCO in the DACs. 

Theoretically, you can get just a sine wave out of the DAC.  The easiest method is to use an IQ waveform in the “I”s are all 1.0s, and the “Q”s are all 0.0s.  This will just generate the configured NCO frequency.

Another method is to generate the NCO frequency with an offset.  Basically, the IQ waveform in this case will just be simple sine waves, 90 degrees apart and of the same amplitude (1.0).  The frequency of these sine waves will be the offset of the NCO.

You should be able to use the VI I sent you to simulate what you want your IQ waveforms in the hardware to do.  If you are not sure what you are going to get, you should simulate your code on the computer before putting it in the hardware.  I do this for a lot of the code I write.

Jerry

[crio]

Hey Jerry,
     i Understand that the ni5640R IQ program will generate a waveform

QAM 256
Symbol Rate = 500 KHz
PN Sequence 9
Filter: Raised Cosine
Filter alpha: 0.5
Filter Length: 8
Samples per symbol: 2

  according to the above specification. But the signal generated seems like a burst i mean the system goes to ideal state (nosignal generation) between cycles, is there a possibility in this ni5640R IQ program that i can eliminate that ideal state output and generate a continuous signal like it is generated in the single tone mode ?????

Take care
Valli