sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
FM Demodulation
Started by ●January 17, 2007
Reply by ●January 18, 20072007-01-18
Reply by ●January 18, 20072007-01-18
sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 18, 20072007-01-18
sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 18, 20072007-01-18
sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 18, 20072007-01-18
sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 18, 20072007-01-18
sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 18, 20072007-01-18
sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 18, 20072007-01-18
sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 18, 20072007-01-18
sampson164@gmail.com writes:> Randy Yates wrote: >> Gentle and Wise Readers of comp.dsp, >> >> Two ways to demodulate FM are: >> >> 1. Find the instantaneous phase (e.g., by examining the phase of the >> analytic signal) and compute the phase differences, i.e, f = dtheta/dt. >> >> 2. Lock a PLL to the FM signal and use the VCO control voltage as the >> demodulated signal. >> >> It seems to me that method 1 is much simpler. Why would anyone do FM >> demodulation via method 2? >> >> Let me state up front that I have an idea, but I'd rather get others' >> ideas first without biasing them. >> -- >> % Randy Yates % "She tells me that she likes me very much, >> %% Fuquay-Varina, NC % but when I try to touch, she makes it >> %%% 919-577-9882 % all too clear." >> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO >> http://home.earthlink.net/~yatescr > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > for details.That's it, John - that's what I was looking for. Apparently it's fairly well-known - I found it in [couch] after my original post It's apparently also known as FMFB (FM with feedback), which is referenced in both [couch] and [schwartcommtecniques]. Does anyone know how prevalent the PLL technique is in current demods (TVs, FM broadcast, etc.)? Is it pretty much standard fare now or are they somewhat unique? --Randy @BOOK{couch, title = "{Digital and Analog Communication Systems}", author = "{Leon~W.~Couch}", publisher = "Prentice Hall", edition = "fifth", year = "1993"} @book{schwartzcommtechniques, title = "Communication Systems and Techniques", author = "{Mischa Schwartz and William R. Bennett and Seymour Stein}", publisher = "IEEE Press (reissue, originally New York: McGraw-Hill 1966)", year = "1996"} -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 18, 20072007-01-18
Randy Yates wrote:> > > > The SNR threshold is lower with a PLL. Search for "Threshold Extension" > > for details. > > That's it, John - that's what I was looking for. Apparently it's > fairly well-known - I found it in [couch] after my original post It's > apparently also known as FMFB (FM with feedback), which is referenced > in both [couch] and [schwartcommtecniques]. > > Does anyone know how prevalent the PLL technique is in current > demods (TVs, FM broadcast, etc.)? Is it pretty much standard > fare now or are they somewhat unique? >Hello Randy, I remember when the PLL technique started to become popular back during the 1970s. Up until then people were using Ratio detectors and Foster Seeley Discriminators. But the PLL technique became inexpensive and it worked quite well. I figure it is the standard thing today in plain vanilla analog FM receivers. Clay
