On Tue, 16 Oct 2012 18:59:01 -0700, josephkk wrote:> On Fri, 12 Oct 2012 12:02:48 -0500, Tim Wescott <tim@seemywebsite.com> > wrote: > >>On Fri, 12 Oct 2012 12:08:46 +0200, Jeroen Belleman wrote: >> >>> On 2012-10-12 11:04, Robert Baer wrote: >>>> Vladimir Vassilevsky wrote: >>>>> "Tim Wescott"<tim@seemywebsite.com> wrote: >>>>>> How commonly do you see PLL designs referred to as "type I", "type >>>>>> II", "type III", etc.? Do the terms make sense to you? >>>>> >>>>> IMO this terminology is used only in Gardner's book; there is no >>>>> universal >>>>> meaning. >>>>> It is about P, PI, or PII control loop. Remnants of old times, when >>>>> they used to mix the details of implementation with the type of the >>>>> transfer function. >>>>> >>>>>> I'm writing a report; don't want to either baffle with bullshit nor >>>>>> leave >>>>>> out handy terms... >>>>> >>>>> Since nobody is going to read it anyway, why would that matter? >>>>> >>>>> Vladimir Vassilevsky >>>>> DSP and Mixed Signal Consultant >>>>> www.abvolt.com >>>>> >>>>> >>>> Do not know but my wild uneducated guess is that "P" stands for >>>> regular feedback as in a standard op-amp circuit, "PI" stands for >>>> first derivative (eg: "P dot") and "PII" stands for second derivative >>>> (eg: "P double dot"). >>>> >>>> >>>> >>> 'I' stands for an Integral term, not a derivative one. >>> >>> I think that PLL designs should be classified by the number of >>> significant poles and zeroes of their transfer functions. This 'type' >>> business only introduces an extra layer of obscurity. >> >>Both the number of poles (order), and the number of nekkid integrators >>(type) have relevance in telling you how the loop is going to behave. >> >>It's not obscurity if you know what it means. > > Then it becomes your job as author to clarify the use consistently and > extensively. > > ?-)Which is exactly what I did. -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
PLL Terminology Question
Started by ●October 11, 2012
Reply by ●October 17, 20122012-10-17
Reply by ●October 20, 20122012-10-20
On 2012-10-14, Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:> Speaking of which, while I have it fresh on me mind, I've been wondering > how one of those cheap laser diodes would behave in PV or PR mode andnot sure how receptive they are.> would they survive another laser of equal type pointed into them?they should do, I've never seen one with a warning against pointing it at a mirror. -- ⚂⚃ 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Reply by ●October 20, 20122012-10-20
In comp.dsp Jasen Betts <jasen@xnet.co.nz> wrote:> On 2012-10-14, Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:>> Speaking of which, while I have it fresh on me mind, I've been wondering >> how one of those cheap laser diodes would behave in PV or PR mode and> not sure how receptive they are.>> would they survive another laser of equal type pointed into them?> they should do, I've never seen one with a warning against pointing it at a > mirror.Most lasers don't like seeing their own reflection, though it normally won't hurt them, but it does interfere with the LASER action. Mostly a problem on an optical bench, though. Now, pointing one at a phase conjugate mirror is a different question. Actually, any shiny object near a phase conjugate mirror can get interesting. http://en.wikipedia.org/wiki/Nonlinear_optics#Optical_phase_conjugation In the DSP sense, consider a device that, given a sequence of samples, returns the sequence in the opposite order. (And, I believe, for complex samples the complex conjugate.) -- glen
