"Rick Lyons" <R.Lyons@_BOGUS_ieee.org> wrote in message news:43d2ac9a.537959156@news.sf.sbcglobal.net...> On Sat, 21 Jan 2006 13:49:04 -0500, "John E. Hadstate" > <jh113355@hotmail.com> wrote: > >> >>"Rick Lyons" <R.Lyons@_BOGUS_ieee.org> wrote in message >>news:43d191ee.465595437@news.sf.sbcglobal.net... >> >>> >>> Hope some of what I wrote makes sense. >> >>Everything you wrote makes sense. You've convinced me >>that >>I need to buy your book. ;-) > > Hi John, > > Great. Then I'd be able to buy milk and > bread for my starving children. > (If ya' do buy a copy, let me know so I can > send you the errata.)Darn! Now I'll have to buy two copies so I can claim one is "professional expenses" and the other is "charity" ;-)> > By the way, I left out an important issue > in Step# 2 of my last post. (Ha, no one caught me!) > > The steps that I wrote will work but if the > C(n) = I(n) +j*Q(n) signal is not centered > at zero Hz, the FM demod output will be riding on > a DC bias. To avoid that, we should freq translate > C(n) down so it's centered at DC before we perform > the arctan operation."Re-tuning" it to baseband may offer other advantages: (a) you can then decimate to a lower sample rate corresponding to the bandwidth of your modulated carrier (b) you can apply a low-pass filter to get the effect of a band-pass filter (the LPF filters positive and negative frequencies equally). The hardware I'm working with samples, tunes to baseband, decimates and provides (I,Q) data streams without my having to do anything except set it up and receive the data.
Ways of implementing a Hilbert Transform
Started by ●January 11, 2006
Reply by ●January 21, 20062006-01-21
Reply by ●January 21, 20062006-01-21
On Sat, 21 Jan 2006 17:24:18 -0500, "John E. Hadstate" <jh113355@hotmail.com> wrote:>(snipped)>>> >>>Everything you wrote makes sense. You've convinced me >>>that >>>I need to buy your book. ;-) >> >> Hi John, >> >> Great. Then I'd be able to buy milk and >> bread for my starving children. >> (If ya' do buy a copy, let me know so I can >> send you the errata.) > >Darn! Now I'll have to buy two copies so I can claim one is >"professional expenses" and the other is "charity" ;-)Even better (Maybe there's a "charitable" income tax deduction there!)>> By the way, I left out an important issue >> in Step# 2 of my last post. (Ha, no one caught me!) >> >> The steps that I wrote will work but if the >> C(n) = I(n) +j*Q(n) signal is not centered >> at zero Hz, the FM demod output will be riding on >> a DC bias. To avoid that, we should freq translate >> C(n) down so it's centered at DC before we perform >> the arctan operation. > >"Re-tuning" it to baseband may offer other advantages: > >(a) you can then decimate to a lower sample rate >corresponding to the bandwidth of your modulated carrierGood point!>(b) you can apply a low-pass filter to get the effect of a >band-pass filter (the LPF filters positive and negative >frequencies equally).Yep>The hardware I'm working with samples, tunes to baseband, >decimates and provides (I,Q) data streams without my having >to do anything except set it up and receive the data.Sounds very convenient. [-Rick-]
Reply by ●January 21, 20062006-01-21
Michel Rouzic wrote:> Martin Eisenberg wrote:>> The output is an array of complex numbers (pairs of doubles) >> each of wich holds the real and imaginary part of one frequency >> bin. See section 4.1.1. Have you read Rick's Appendix C? > > Not for me. I use the real to real interface, so I don't have to > bother with FFTW's complex number format (plus, at the time I > implemented it I didn't even know yet what complex numbers were)Don't take it personal but I can only roll my eyes. In response to the very first followup by Jerry, you wrote this-- Michel Rouzic wrote in message <1137224174.951704.94450@g49g2000cwa.googlegroups.com>:> In other words, you only perform the hilbert transform for the I > part of the signal? cuz the signal I have to deal with has both > real and imaginary parts. If you perform the hilbert transform > on the I part of the signal, what do you do with the Q part of > the original signal?--; you implied that your signal was complex twice more, I think; and failed to contradict me when I revealed my understanding that it was in message <1137446788.324314@ostenberg.wh.uni-dortmund.de>. Now all of a sudden it's the total opposite. Does the suggestion to start over that I entered the thread with make sense to you yet? Martin -- Quidquid latine scriptum sit, altum viditur.
Reply by ●January 21, 20062006-01-21
Michel, I'm seeing your new thread after a refresh and just wanted to say that, had I found it earlier, my previous message would have ended up softer in tone. Martin -- Quidquid latine scriptum sit, altum viditur.
Reply by ●January 23, 20062006-01-23
Randy Yates <yates@ieee.org> writes:> [...] > Al Clark <dsp@danvillesignal.com> writes: >> Thoughts? > > Yeah. How about we create a "comp.dsp" site?Hello? I thought this was (as Guiness would say) "brilliant." Did I step on your toes, Al? Did you mean to say you wanted to host the web site? Sorry - I often need to put on my rubber slippers... -- % Randy Yates % "Ticket to the moon, flight leaves here today %% Fuquay-Varina, NC % from Satellite 2" %%% 919-577-9882 % 'Ticket To The Moon' %%%% <yates@ieee.org> % *Time*, Electric Light Orchestra http://home.earthlink.net/~yatescr
Reply by ●January 23, 20062006-01-23
Randy Yates <yates@ieee.org> wrote in news:u0bvt60i.fsf@ieee.org:> Randy Yates <yates@ieee.org> writes: >> [...] >> Al Clark <dsp@danvillesignal.com> writes: >>> Thoughts? >> >> Yeah. How about we create a "comp.dsp" site? > > Hello? > > I thought this was (as Guiness would say) "brilliant." Did I step on > your toes, Al? Did you mean to say you wanted to host the web site?Well, sorta, Ours would certainly be free since it would essentially be part of our developer page area. Perhaps the advantage of a site hosted by Danville is that there will always be someone to keep it updated. Al> > Sorry - I often need to put on my rubber slippers...-- Al Clark Danville Signal Processing, Inc. -------------------------------------------------------------------- Purveyors of Fine DSP Hardware and other Cool Stuff Available at http://www.danvillesignal.com
Reply by ●January 23, 20062006-01-23
Randy Yates wrote:> Randy Yates <yates@ieee.org> writes: > >>[...] >>Al Clark <dsp@danvillesignal.com> writes: >> >>>Thoughts? >> >>Yeah. How about we create a "comp.dsp" site? > > > Hello? > > I thought this was (as Guiness would say) "brilliant." Did I step on > your toes, Al? Did you mean to say you wanted to host the web site? > > Sorry - I often need to put on my rubber slippers...I have free space, Al has space; why pay? It would be worth while if needed, but it's not needed. What's the downside to going free? I think it would be worth registering a URL that's independent of an ISP so no links break if the site moves, but that's cheaper than renting space. On my site, traffic volume could get to be a problem, but that's a issue we could address later if need be. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●January 23, 20062006-01-23
Al Clark <dsp@danvillesignal.com> writes:> [...] > Randy Yates <yates@ieee.org> wrote in news:u0bvt60i.fsf@ieee.org: > Well, sorta,I didn't mean to be inconsiderate, Al. However, I do not think it is a good idea - see below.> Ours would certainly be free since it would essentially be part of our > developer page area. > > Perhaps the advantage of a site hosted by Danville is that there will > always be someone to keep it updated.I'm uncomfortable with any one person/company owning a generic resource for comp.dsp. It biases any visitor to that company/person. That's why I thought a generic comp.dsp domain would be optimum. Perhaps the domain could be arranged to be hosted as part of someone's existing site - that would be cheaper, provide the maintenance advantage, and also be unbiased. -- % Randy Yates % "My Shangri-la has gone away, fading like %% Fuquay-Varina, NC % the Beatles on 'Hey Jude'" %%% 919-577-9882 % %%%% <yates@ieee.org> % 'Shangri-La', *A New World Record*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 23, 20062006-01-23
Randy Yates wrote: ...> Perhaps the domain could be arranged to be hosted as part of someone's > existing site - that would be cheaper, provide the maintenance advantage, > and also be unbiased.Our messages crossed in transit. We're in the same bin, but I think a "courtesy of" line on the home page is due. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
