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I have a system where I am sampling at 2.5MHz, and in order to achieve a spectral resolution of 100Hz I am accumulating 25,000 samples. I am transferring the samples via a FIFO in lengths of 1024. After accumulating frames in real time "continuous" I then filter, decimate by four and apply Hamming window. What I observe in the spectrum Is the correct signal, but spurs inversely related to the time it takes to accumulate a frame. When I examine The data the frame boundaries are continuous. I would expect to see these spurs if There was a discontinuity at the frame boundaries, but there is none. Can anyone suggest what I am seeing? -Kurt |
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FFT Spurs
Started by ●September 28, 2003
Reply by ●September 29, 20032003-09-29
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What do you mean by spurs? Discontinuities generally cause a rise in the background level of the power spectrum (since the FFT of an impulse is a flat spectrum. > -----Original Message----- > From: Vetter, Kurt [mailto:] > Sent: Sunday, September 28, 2003 8:44 AM > To: > Cc: 'vetterk' > Subject: [c6x] FFT Spurs > I have a system where I am sampling at 2.5MHz, and in order > to achieve a spectral resolution of 100Hz > > I am accumulating 25,000 samples. I am transferring the > samples via a FIFO in lengths of 1024. After accumulating > frames in real time "continuous" I then filter, decimate by > four and apply Hamming window. What I observe in the spectrum > Is the correct signal, but spurs inversely related to the > time it takes to accumulate a frame. When I examine The data > the frame boundaries are continuous. I would expect to see > these spurs if > > There was a discontinuity at the frame boundaries, but there > is none. Can anyone suggest what I am seeing? > > -Kurt > > _____________________________________ > Note: If you do a simple "reply" with your email client, only > the author of this message will receive your answer. You > need to do a "reply all" if you want your answer to be > distributed to the entire group. > > _____________________________________ > About this discussion group: > > To Join: Send an email to > > To Post: Send an email to > > To Leave: Send an email to > > Archives: http://www.yahoogroups.com/group/c6x > > Other Groups: http://www.dsprelated.com > ">http://docs.yahoo.com/info/terms/ > |
