"Tauno Voipio" <tauno.voipio@notused.fi.invalid> wrote in message news:prbot2$63a$2@dont-email.me...> Computing arctangents at John's bandwidth will be sweaty, and > it's the way to detect angle modulation (FM/PM) on a SDR. >He's got big FPGAs and even bigger RAMs. Pipeline as many as needed, or just shove everything into a lookup table. :^) Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
wideband FM demodulator
Started by ●October 31, 2018
Reply by ●November 2, 20182018-11-02
Reply by ●November 2, 20182018-11-02
On Thursday, November 1, 2018 at 4:37:31 PM UTC-4, John Larkin wrote:> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), > bloggs.fredbloggs.fred@gmail.com wrote: > > >On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John Larkin wrote: > >> We're thinking of sending a wideband (say, dc to 50 MHz) signal using > >> FM. The carrier could be in the 500 MHz to 1 GHz range maybe. > >> > >> I can get the VCO. What's a good way to do the FM discriminator these > >> days? > >> > >> I could homebrew a quadrature detector, with some resonator and an XOR > >> gate or a mixer, but there must be some easier way to do it. Not being > >> an RF type, I'd appreciate suggestions. > > > >7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf > > How would I use that?Quadrature signals are mixed, and then lowpass of product is the modulating signal. The linearity is a function of ATN(k) being approximately equal to k, so the smaller the relatively deviation the better. May be better to use 1GHz carrier for 5% deviation.> > > -- > > John Larkin Highland Technology, Inc > picosecond timing precision measurement > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com
Reply by ●November 2, 20182018-11-02
On Thu, 1 Nov 2018 15:11:32 -0700 (PDT), "John Miles, KE5FX" <jmiles@gmail.com> wrote:>On Thursday, November 1, 2018 at 1:37:31 PM UTC-7, John Larkin wrote: >> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), >> bloggs.fredbloggs.fred@gmail.com wrote: >> >> >On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John Larkin wrote: >> >> We're thinking of sending a wideband (say, dc to 50 MHz) signal using >> >> FM. The carrier could be in the 500 MHz to 1 GHz range maybe. >> >> >> >> I can get the VCO. What's a good way to do the FM discriminator these >> >> days? >> >> >> >> I could homebrew a quadrature detector, with some resonator and an XOR >> >> gate or a mixer, but there must be some easier way to do it. Not being >> >> an RF type, I'd appreciate suggestions. >> > >> >7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf >> >> How would I use that? > > >That'd be your delay line, used with a mixer to recover the modulated >signal. It'll work but I'd be surprised if it's very stable.It's not characterized as a delay line. It's apparently intended to provide a 90 degree phase shift that's independent of frequency. Not the basis of an FM discriminator.> >For the case you're describing, straight FM isn't all that common. I used >an MC13155D for something similar at one point but it's gone the way of >the 12AX7 (oh, wait, you can still get those). I wonder if there's a >QAM chipset available with similar bandwidth? Something comparable to >a cable or DSL modem, but without all the DOCSIS baggage.We've been playing with pushing maybe DC-100 MHz of analog signal over a telecom-type fiber link. I was thinking of using FM, but that might become a nightmare. Brute force (merely apply money) is an ADC at one end, 8B10B coding, a 6 Gbps fiber link, and a DAC at the far end. Sampling at 300 MHz, 1.5x Nyquist, makes the filtering reasonable. I can buy pretty good VCOs for the transmit end, but their typical modulation bandwidths are low. Then there is the receiver problem. Oh well, back to connecting bricks. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●November 2, 20182018-11-02
On Fri, 02 Nov 2018 08:35:51 -0700, John Larkin wrote:> On Thu, 1 Nov 2018 15:11:32 -0700 (PDT), "John Miles, KE5FX" > <jmiles@gmail.com> wrote: > >>On Thursday, November 1, 2018 at 1:37:31 PM UTC-7, John Larkin wrote: >>> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), >>> bloggs.fredbloggs.fred@gmail.com wrote: >>> >>> >On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John Larkin wrote: >>> >> We're thinking of sending a wideband (say, dc to 50 MHz) signal using >>> >> FM. The carrier could be in the 500 MHz to 1 GHz range maybe. >>> >> >>> >> I can get the VCO. What's a good way to do the FM discriminator these >>> >> days? >>> >> >>> >> I could homebrew a quadrature detector, with some resonator and an XOR >>> >> gate or a mixer, but there must be some easier way to do it. Not being >>> >> an RF type, I'd appreciate suggestions. >>> > >>> >7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf >>> >>> How would I use that? >> >> >>That'd be your delay line, used with a mixer to recover the modulated >>signal. It'll work but I'd be surprised if it's very stable. > > It's not characterized as a delay line. It's apparently intended to > provide a 90 degree phase shift that's independent of frequency. Not > the basis of an FM discriminator. > >> >>For the case you're describing, straight FM isn't all that common. I used >>an MC13155D for something similar at one point but it's gone the way of >>the 12AX7 (oh, wait, you can still get those). I wonder if there's a >>QAM chipset available with similar bandwidth? Something comparable to >>a cable or DSL modem, but without all the DOCSIS baggage. > > We've been playing with pushing maybe DC-100 MHz of analog signal over > a telecom-type fiber link. I was thinking of using FM, but that might > become a nightmare. Brute force (merely apply money) is an ADC at one > end, 8B10B coding, a 6 Gbps fiber link, and a DAC at the far end. > Sampling at 300 MHz, 1.5x Nyquist, makes the filtering reasonable. > > I can buy pretty good VCOs for the transmit end, but their typical > modulation bandwidths are low. Then there is the receiver problem. > > Oh well, back to connecting bricks.take a look at these http://www.ti.com/interface/fpd-link-serdes/camera-serdes/overview.html The 933/934 will do 100Mhz 12 bit parallel IO. They are limited to 15M cable length though, coax or UTP. Dont know if that's a show stopper. -- Chisolm Republic of Texas
Reply by ●November 2, 20182018-11-02
On Fri, 2 Nov 2018 07:58:34 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com wrote:>On Thursday, November 1, 2018 at 4:37:31 PM UTC-4, John Larkin wrote: >> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), >> bloggs.fredbloggs.fred@gmail.com wrote: >> >> >On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John Larkin wrote: >> >> We're thinking of sending a wideband (say, dc to 50 MHz) signal using >> >> FM. The carrier could be in the 500 MHz to 1 GHz range maybe. >> >> >> >> I can get the VCO. What's a good way to do the FM discriminator these >> >> days? >> >> >> >> I could homebrew a quadrature detector, with some resonator and an XOR >> >> gate or a mixer, but there must be some easier way to do it. Not being >> >> an RF type, I'd appreciate suggestions. >> > >> >7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf >> >> How would I use that? > >Quadrature signals are mixed, and then lowpass of product is the modulating signal. The linearity is a function of ATN(k) being approximately equal to k, so the smaller the relatively deviation the better. May be better to use 1GHz carrier for 5% deviation. >Mixing fixed 90 degree sine waves makes zero. The Minicircuits part is designed for minimum phase shift vs frequency. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●November 2, 20182018-11-02
On 11/2/18 11:35 AM, John Larkin wrote:> On Thu, 1 Nov 2018 15:11:32 -0700 (PDT), "John Miles, KE5FX" > <jmiles@gmail.com> wrote: > >> On Thursday, November 1, 2018 at 1:37:31 PM UTC-7, John Larkin >> wrote: >>> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), >>> bloggs.fredbloggs.fred@gmail.com wrote: >>> >>>> On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John >>>> Larkin wrote: >>>>> We're thinking of sending a wideband (say, dc to 50 MHz) >>>>> signal using FM. The carrier could be in the 500 MHz to 1 GHz >>>>> range maybe. >>>>> >>>>> I can get the VCO. What's a good way to do the FM >>>>> discriminator these days? >>>>> >>>>> I could homebrew a quadrature detector, with some resonator >>>>> and an XOR gate or a mixer, but there must be some easier way >>>>> to do it. Not being an RF type, I'd appreciate suggestions. >>>> >>>> 7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf >>> >>> How would I use that? >> >> >> That'd be your delay line, used with a mixer to recover the >> modulated signal. It'll work but I'd be surprised if it's very >> stable. > > It's not characterized as a delay line. It's apparently intended to > provide a 90 degree phase shift that's independent of frequency. Not > the basis of an FM discriminator. > >> >> For the case you're describing, straight FM isn't all that common. >> I used an MC13155D for something similar at one point but it's gone >> the way of the 12AX7 (oh, wait, you can still get those). I wonder >> if there's a QAM chipset available with similar bandwidth? >> Something comparable to a cable or DSL modem, but without all the >> DOCSIS baggage. > > We've been playing with pushing maybe DC-100 MHz of analog signal > over a telecom-type fiber link. I was thinking of using FM, but that > might become a nightmare.Especially in the presence of facet reflections, which cause phase nonlinearities just like multipath distortion in radio. If you use FC-APC (angled physical contact) connectors, you can get the reflection down to ~1% or a bit less, which helps, but if the fibre delay is up near your deviation bandwidth there'll be nonlinearity.> Brute force (merely apply money) is an ADC at one end, 8B10B coding, > a 6 Gbps fiber link, and a DAC at the far end. Sampling at 300 MHz, > 1.5x Nyquist, makes the filtering reasonable. > > I can buy pretty good VCOs for the transmit end, but their typical > modulation bandwidths are low. Then there is the receiver problem. > > Oh well, back to connecting bricks.One of our main customers just blew up three lasers that we sent them. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●November 2, 20182018-11-02
On Fri, 2 Nov 2018 15:12:24 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 11/2/18 11:35 AM, John Larkin wrote: >> On Thu, 1 Nov 2018 15:11:32 -0700 (PDT), "John Miles, KE5FX" >> <jmiles@gmail.com> wrote: >> >>> On Thursday, November 1, 2018 at 1:37:31 PM UTC-7, John Larkin >>> wrote: >>>> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), >>>> bloggs.fredbloggs.fred@gmail.com wrote: >>>> >>>>> On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John >>>>> Larkin wrote: >>>>>> We're thinking of sending a wideband (say, dc to 50 MHz) >>>>>> signal using FM. The carrier could be in the 500 MHz to 1 GHz >>>>>> range maybe. >>>>>> >>>>>> I can get the VCO. What's a good way to do the FM >>>>>> discriminator these days? >>>>>> >>>>>> I could homebrew a quadrature detector, with some resonator >>>>>> and an XOR gate or a mixer, but there must be some easier way >>>>>> to do it. Not being an RF type, I'd appreciate suggestions. >>>>> >>>>> 7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf >>>> >>>> How would I use that? >>> >>> >>> That'd be your delay line, used with a mixer to recover the >>> modulated signal. It'll work but I'd be surprised if it's very >>> stable. >> >> It's not characterized as a delay line. It's apparently intended to >> provide a 90 degree phase shift that's independent of frequency. Not >> the basis of an FM discriminator. >> >>> >>> For the case you're describing, straight FM isn't all that common. >>> I used an MC13155D for something similar at one point but it's gone >>> the way of the 12AX7 (oh, wait, you can still get those). I wonder >>> if there's a QAM chipset available with similar bandwidth? >>> Something comparable to a cable or DSL modem, but without all the >>> DOCSIS baggage. >> >> We've been playing with pushing maybe DC-100 MHz of analog signal >> over a telecom-type fiber link. I was thinking of using FM, but that >> might become a nightmare. > >Especially in the presence of facet reflections, which cause phase >nonlinearities just like multipath distortion in radio. If you use >FC-APC (angled physical contact) connectors, you can get the reflection >down to ~1% or a bit less, which helps, but if the fibre delay is up >near your deviation bandwidth there'll be nonlinearity.Yeah, digital either works or it doesn't. The plug-in SFP things do work and are shockingly cheap.> > >> Brute force (merely apply money) is an ADC at one end, 8B10B coding, >> a 6 Gbps fiber link, and a DAC at the far end. Sampling at 300 MHz, >> 1.5x Nyquist, makes the filtering reasonable. >> >> I can buy pretty good VCOs for the transmit end, but their typical >> modulation bandwidths are low. Then there is the receiver problem. >> >> Oh well, back to connecting bricks. > >One of our main customers just blew up three lasers that we sent them.Maybe they did something wrong? After blowing up the first two, they needed a time-out. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●November 2, 20182018-11-02
On 2.11.18 20:16, John Larkin wrote:> On Fri, 2 Nov 2018 07:58:34 -0700 (PDT), > bloggs.fredbloggs.fred@gmail.com wrote: > >> On Thursday, November 1, 2018 at 4:37:31 PM UTC-4, John Larkin wrote: >>> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), >>> bloggs.fredbloggs.fred@gmail.com wrote: >>> >>>> On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John Larkin wrote: >>>>> We're thinking of sending a wideband (say, dc to 50 MHz) signal using >>>>> FM. The carrier could be in the 500 MHz to 1 GHz range maybe. >>>>> >>>>> I can get the VCO. What's a good way to do the FM discriminator these >>>>> days? >>>>> >>>>> I could homebrew a quadrature detector, with some resonator and an XOR >>>>> gate or a mixer, but there must be some easier way to do it. Not being >>>>> an RF type, I'd appreciate suggestions. >>>> >>>> 7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf >>> >>> How would I use that? >> >> Quadrature signals are mixed, and then lowpass of product is the modulating signal. The linearity is a function of ATN(k) being approximately equal to k, so the smaller the relatively deviation the better. May be better to use 1GHz carrier for 5% deviation. >> > > Mixing fixed 90 degree sine waves makes zero. The Minicircuits part is > designed for minimum phase shift vs frequency.At frequencies from 500 MHz to 1 GHz the delay is easiest with just a piece of transmission line. A full wave of 1 GHz will be about 8 inches of cable. A quarter wave is short enough to be made of stripline on the PC board. -- -TV
Reply by ●November 2, 20182018-11-02
On Friday, November 2, 2018 at 3:12:35 PM UTC-4, Phil Hobbs wrote:> On 11/2/18 11:35 AM, John Larkin wrote: > > On Thu, 1 Nov 2018 15:11:32 -0700 (PDT), "John Miles, KE5FX" > > <jmiles@gmail.com> wrote: > > > >> On Thursday, November 1, 2018 at 1:37:31 PM UTC-7, John Larkin > >> wrote: > >>> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), > >>> bloggs.fredbloggs.fred@gmail.com wrote: > >>> > >>>> On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John > >>>> Larkin wrote: > >>>>> We're thinking of sending a wideband (say, dc to 50 MHz) > >>>>> signal using FM. The carrier could be in the 500 MHz to 1 GHz > >>>>> range maybe. > >>>>> > >>>>> I can get the VCO. What's a good way to do the FM > >>>>> discriminator these days? > >>>>> > >>>>> I could homebrew a quadrature detector, with some resonator > >>>>> and an XOR gate or a mixer, but there must be some easier way > >>>>> to do it. Not being an RF type, I'd appreciate suggestions. > >>>> > >>>> 7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf > >>> > >>> How would I use that? > >> > >> > >> That'd be your delay line, used with a mixer to recover the > >> modulated signal. It'll work but I'd be surprised if it's very > >> stable. > > > > It's not characterized as a delay line. It's apparently intended to > > provide a 90 degree phase shift that's independent of frequency. Not > > the basis of an FM discriminator. > > > >> > >> For the case you're describing, straight FM isn't all that common. > >> I used an MC13155D for something similar at one point but it's gone > >> the way of the 12AX7 (oh, wait, you can still get those). I wonder > >> if there's a QAM chipset available with similar bandwidth? > >> Something comparable to a cable or DSL modem, but without all the > >> DOCSIS baggage. > > > > We've been playing with pushing maybe DC-100 MHz of analog signal > > over a telecom-type fiber link. I was thinking of using FM, but that > > might become a nightmare. > > Especially in the presence of facet reflections, which cause phase > nonlinearities just like multipath distortion in radio. If you use > FC-APC (angled physical contact) connectors, you can get the reflection > down to ~1% or a bit less, which helps, but if the fibre delay is up > near your deviation bandwidth there'll be nonlinearity. > > > > Brute force (merely apply money) is an ADC at one end, 8B10B coding, > > a 6 Gbps fiber link, and a DAC at the far end. Sampling at 300 MHz, > > 1.5x Nyquist, makes the filtering reasonable. > > > > I can buy pretty good VCOs for the transmit end, but their typical > > modulation bandwidths are low. Then there is the receiver problem. > > > > Oh well, back to connecting bricks. > > One of our main customers just blew up three lasers that we sent them.Three!? that takes a special talent. Usually when you fry one you stop and think about what you are doing. George> > Cheers > > Phil Hobbs > > > -- > Dr Philip C D Hobbs > Principal Consultant > ElectroOptical Innovations LLC / Hobbs ElectroOptics > Optics, Electro-optics, Photonics, Analog Electronics > Briarcliff Manor NY 10510 > > http://electrooptical.net > http://hobbs-eo.com
Reply by ●November 2, 20182018-11-02
On 11/2/18 3:39 PM, John Larkin wrote:> On Fri, 2 Nov 2018 15:12:24 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 11/2/18 11:35 AM, John Larkin wrote: >>> On Thu, 1 Nov 2018 15:11:32 -0700 (PDT), "John Miles, KE5FX" >>> <jmiles@gmail.com> wrote: >>> >>>> On Thursday, November 1, 2018 at 1:37:31 PM UTC-7, John Larkin >>>> wrote: >>>>> On Thu, 1 Nov 2018 12:25:10 -0700 (PDT), >>>>> bloggs.fredbloggs.fred@gmail.com wrote: >>>>> >>>>>> On Wednesday, October 31, 2018 at 12:52:08 AM UTC-4, John >>>>>> Larkin wrote: >>>>>>> We're thinking of sending a wideband (say, dc to 50 MHz) >>>>>>> signal using FM. The carrier could be in the 500 MHz to 1 GHz >>>>>>> range maybe. >>>>>>> >>>>>>> I can get the VCO. What's a good way to do the FM >>>>>>> discriminator these days? >>>>>>> >>>>>>> I could homebrew a quadrature detector, with some resonator >>>>>>> and an XOR gate or a mixer, but there must be some easier way >>>>>>> to do it. Not being an RF type, I'd appreciate suggestions. >>>>>> >>>>>> 7 bucks https://www.minicircuits.com/pdfs/QBA-07+.pdf >>>>> >>>>> How would I use that? >>>> >>>> >>>> That'd be your delay line, used with a mixer to recover the >>>> modulated signal. It'll work but I'd be surprised if it's very >>>> stable. >>> >>> It's not characterized as a delay line. It's apparently intended to >>> provide a 90 degree phase shift that's independent of frequency. Not >>> the basis of an FM discriminator. >>> >>>> >>>> For the case you're describing, straight FM isn't all that common. >>>> I used an MC13155D for something similar at one point but it's gone >>>> the way of the 12AX7 (oh, wait, you can still get those). I wonder >>>> if there's a QAM chipset available with similar bandwidth? >>>> Something comparable to a cable or DSL modem, but without all the >>>> DOCSIS baggage. >>> >>> We've been playing with pushing maybe DC-100 MHz of analog signal >>> over a telecom-type fiber link. I was thinking of using FM, but that >>> might become a nightmare. >> >> Especially in the presence of facet reflections, which cause phase >> nonlinearities just like multipath distortion in radio. If you use >> FC-APC (angled physical contact) connectors, you can get the reflection >> down to ~1% or a bit less, which helps, but if the fibre delay is up >> near your deviation bandwidth there'll be nonlinearity. > > > Yeah, digital either works or it doesn't. The plug-in SFP things do > work and are shockingly cheap. > > >> >> >>> Brute force (merely apply money) is an ADC at one end, 8B10B coding, >>> a 6 Gbps fiber link, and a DAC at the far end. Sampling at 300 MHz, >>> 1.5x Nyquist, makes the filtering reasonable. >>> >>> I can buy pretty good VCOs for the transmit end, but their typical >>> modulation bandwidths are low. Then there is the receiver problem. >>> >>> Oh well, back to connecting bricks. >> >> One of our main customers just blew up three lasers that we sent them. > > Maybe they did something wrong? > > After blowing up the first two, they needed a time-out. > >We sent one of them all connected and everything, and they disconnected it and blew it up. Or maybe they just put the FFCs in backwards, in which case it would probably have survived. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
