On 10/05/2013 01:03 AM, Jim Lux wrote: > On 10/4/13 2:54 PM, Alan Melia wrote: >> Jim it may not be helpful but had you thoughtof expanding the >> exponential as the first few terms of an infinite series to see if it >> simplifies fitting? > > Hmm.. > > So the tradeoff is "fit polynomial with higher order" (because the > polynomial basically is the first few terms of a Taylor expansion for > exp(x)). My DC and linear term in X basically add to the terms for > the exponential. > vs > linearize the data by taking the log of each point, then fit a > straight line. > > Without grinding through a benchmark, I have to believe that > calculating the various powers of the inputs to do a least squares has > to be computationally lighter load than doing log, and then exp > > > I'll try attaching a plot of some sample data. Oh, I/Q data, in that case recording the state of your tracking loop helps a lot. Also, the rate of your exponential should be fairly well known, so you could do a linear least square with that.
Your tracking-loops dynamics is a significant hint to after the fact compensate for the lock-in behavior. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
