snip ..> > Hi Erik, > > I already tried this with a number of delay equal to half the order ofthe> > filter, > > is this right? > > With a Hilbert transformer of an odd number of taps, the delay needed > for alignment is available at the middle tap. But I have to remind you > again: there is no such thing as instantaneous reactive power. > Instantaneous quantities don't have phase. > > You can maintain a running sum of products accumulated for the past > period; they will be watts ans VARs. The instantaneous numbers are > meaningless until integrated. > > Jerry > -- > Engineering is the art of making what you want from things you can get. > �����������������������������������������������������������������������Right, I meant instantaneous product, I have a filter to average the reactive power. Thank Giuseppe
90 degrees phase shift
Started by ●July 1, 2005
Reply by ●July 2, 20052005-07-02
Reply by ●July 2, 20052005-07-02
"Giuseppe Sbarra" <giuseppe_sbarra@tin.it> ha scritto nel messaggio news:q9exe.101452$75.4536009@news4.tin.it...> Hi, > I'm an hold analog engineer , actually developing a DSP based application > and I need to change of 90 degrees the phase of a signal on the range of > 50 - 250 Hz aving the system a 200uSec sampling rate. > I have considered the Hilbert FIR filter but for the moment I cannot getit> to work not even reducing the sampling rate. > In particular I nedd to phase shift by 90 degrees a signal (voltage)respect> to another (current) in order to calculate the instantaneous REACTIVEpower> by a simple multiplication. > > Any suggestion would be very appreciated. > Thanks everybody >Hi everybody thanks to the support I received by the NG I have been able to discover a very stupid bug on my implementation, all I need now is the coefficients for a say 67 order Hilbert, cause my tool just reach 35, or some reference to a free tool on the net for the job. Thank you very much again. Giuseppe
Reply by ●July 2, 20052005-07-02
> > There is no possibility of a real-time RMS reading. > > JerryIt depends of the definition of real-time. If the output is permitted to lag the input, then my defintion of real-time is satisfied. If the output is not permitted to lag the input, then no sampled data system is real-time, and for that matter neither is my Fluke true RMS voltmeter. John
Reply by ●July 2, 20052005-07-02
john wrote:>>There is no possibility of a real-time RMS reading. >> >>Jerry > > > It depends of the definition of real-time. If the output is permitted > to lag the input, then my defintion of real-time is satisfied. If the > output is not permitted to lag the input, then no sampled data system > is real-time, and for that matter neither is my Fluke true RMS > voltmeter.Thanks for the correction. I wrote "real time" when I should have written "instantaneous". Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●July 3, 20052005-07-03
On Sat, 02 Jul 2005 03:48:14 GMT, Al Clark <dsp@danvillesignal.com> wrote: (snipped)>> >> >> Then, perhaps you should provide the original poster with some >> references that will help him get started. >> >> >> > >A very good discussion on hilbert transforms is in Rick Lyons' book: >Understanding Digital Signal Processing (Second Edition). It is often >available at the local Barnes & Noble or Borders as well as Amazon. > > >-- >Al ClarkHi Al, Thanks for the plug. If Giuseppe actually buys a copy of my book, I'll send him the errata. Take care Al, [-Rick-]
