Hello, I would like to design a signal generator. the signal as the following form : cos(cos w1).sin(w2) with w1~ 10Mhz and w2~50kHz amplitude and frequency of the signal have to be digitally controlled. I thought about DDS's (AD) to design this. What do you think about such a solution?
Thank you. y.
Depends on what the teacher wants.
Good Luck! Rich
Easy in an FPGA. Two phase accumulators, two sine lookup tables, one multiplier, all feeding a dac. I did a similar thing recently, 8 channels, 32 MHz Nyquist, but the multiply was just used as a slow gain scaler.
John
Actually, this is not a student project! I'm not familiar with us>
Thank you for yout suggestion. Yes, I was thinking about a FPGA, but I'm not familiar with this technology, since I usually work with uC's. I think I'll study this option a bit further! In fact, DDS seems not to be really done for a "real-time" modulation as I wouls like to design.
teacher wants.
You should look at the Analog Devices web site. They make several DDS chips, and some of them integrate most (or perhaps all) of what you want into one part. I assume that the function you originally posted is not quite correct, and that you want to amplitude modulate one sinusoid (high frequency) by another (much lower frequency). Or did you really mean the cosine of a cosine wave, times a sine wave?
DDS is most certainly done for real-time modulation. It's done for arbitrary modulating waveforms as well as for sinusoids or other repetitive waveforms.
Cheers, Tom
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