On Fri, 30 Apr 2021 19:54:36 +0300, upsidedown@downunder.com wrote:>On Fri, 30 Apr 2021 08:45:30 -0700, jlarkin@highlandsniptechnology.com >wrote: > >>On Fri, 30 Apr 2021 08:07:10 +0300, upsidedown@downunder.com wrote: >> >>>On Tue, 27 Apr 2021 12:35:17 -0700, John Larkin >>><jlarkin@highland_atwork_technology.com> wrote: >>> >>>>What's a good way to make a, say 2 or 3 GHz sinewave oscillator? I >>>>don't need extreme accuracy, and I'd like maybe 1 volt p-p. >>>> >>>>I was thinking a cheap MMIC with PCB delay line feedback. >>>> >>>>MiniCircuits VCOs are around $20, which isn't bad. >>>> >>>>The output would go into a PWM modulator and then an AC-coupled >>>>communications channel. >>> >>>hat are you trying to do ? >>> >>>Are you trying to transfer a very broad band DC based _analog_ signal >>>(say DC .. 500 MHz) over an AC link (say 2 GHz). >> >> >>That, or just ship a single-bit logic level over a telecom type link. >>It's just a shower musing, not serious yet. >> >>> >>>Why not simply frequency module a VCO ? Why PWM ? >>> >> >>FM is more work on both ends. Commercial VCOs have pitiful modulation >>bandwidths, kilohertz not gigahertz. PWM can be arbitrarily fast. >> >>For the logic level case, we'd want it to be fast with low jitter. >>Whatever modulation scheme is used, the time jitter should be a >>fraction of the "carrier" period. > >What about phase shifting keying (PSK) ?How can you DC couple PSK?> >Just invert the output from the oscillator at input signal change. Of >course, you have to establish the initial state somehow to be able to >decode current state from only phase changes. > >To always know the state, you could use return to zero coding, i.e. a >carrier at 0 degrees, a 0->1 transition as +90 degree phase change and >1->0 input change as -90 degrees phase shift (QPSK). > >Also take look at Manchester coding. >Manchester is phase ambiguous! A long string of 1's looks just like a long string of 0's. And the decode is clock synchronous, so has massive jitter when shipping an arbitrary signal. PSK ditto. I want to modulate, not encode. AM/OOK won't work when the receiver has AGC.
GHz oscillator
Started by ●April 27, 2021
Reply by ●April 30, 20212021-04-30
Reply by ●April 30, 20212021-04-30
fredag den 30. april 2021 kl. 19.04.03 UTC+2 skrev John Larkin:> On Fri, 30 Apr 2021 19:54:36 +0300, upsid...@downunder.com wrote: > > >On Fri, 30 Apr 2021 08:45:30 -0700, jla...@highlandsniptechnology.com > >wrote: > > > >>On Fri, 30 Apr 2021 08:07:10 +0300, upsid...@downunder.com wrote: > >> > >>>On Tue, 27 Apr 2021 12:35:17 -0700, John Larkin > >>><jlarkin@highland_atwork_technology.com> wrote: > >>> > >>>>What's a good way to make a, say 2 or 3 GHz sinewave oscillator? I > >>>>don't need extreme accuracy, and I'd like maybe 1 volt p-p. > >>>> > >>>>I was thinking a cheap MMIC with PCB delay line feedback. > >>>> > >>>>MiniCircuits VCOs are around $20, which isn't bad. > >>>> > >>>>The output would go into a PWM modulator and then an AC-coupled > >>>>communications channel. > >>> > >>>hat are you trying to do ? > >>> > >>>Are you trying to transfer a very broad band DC based _analog_ signal > >>>(say DC .. 500 MHz) over an AC link (say 2 GHz). > >> > >> > >>That, or just ship a single-bit logic level over a telecom type link. > >>It's just a shower musing, not serious yet. > >> > >>> > >>>Why not simply frequency module a VCO ? Why PWM ? > >>> > >> > >>FM is more work on both ends. Commercial VCOs have pitiful modulation > >>bandwidths, kilohertz not gigahertz. PWM can be arbitrarily fast. > >> > >>For the logic level case, we'd want it to be fast with low jitter. > >>Whatever modulation scheme is used, the time jitter should be a > >>fraction of the "carrier" period. > > > >What about phase shifting keying (PSK) ? > How can you DC couple PSK? > > > >Just invert the output from the oscillator at input signal change. Of > >course, you have to establish the initial state somehow to be able to > >decode current state from only phase changes. > > > >To always know the state, you could use return to zero coding, i.e. a > >carrier at 0 degrees, a 0->1 transition as +90 degree phase change and > >1->0 input change as -90 degrees phase shift (QPSK). > > > >Also take look at Manchester coding. > > > Manchester is phase ambiguous! A long string of 1's looks just like a > long string of 0's. And the decode is clock synchronous, so has > massive jitter when shipping an arbitrary signal. > > PSK ditto. I want to modulate, not encode. > > AM/OOK won't work when the receiver has AGC.wouldn't your pwm be OOK?
Reply by ●April 30, 20212021-04-30
On Fri, 30 Apr 2021 10:03:52 -0700, John Larkin <jlarkin@highland_atwork_technology.com> wrote:>On Fri, 30 Apr 2021 19:54:36 +0300, upsidedown@downunder.com wrote: > >>On Fri, 30 Apr 2021 08:45:30 -0700, jlarkin@highlandsniptechnology.com >>wrote: >> >>>On Fri, 30 Apr 2021 08:07:10 +0300, upsidedown@downunder.com wrote: >>> >>>>On Tue, 27 Apr 2021 12:35:17 -0700, John Larkin >>>><jlarkin@highland_atwork_technology.com> wrote: >>>> >>>>>What's a good way to make a, say 2 or 3 GHz sinewave oscillator? I >>>>>don't need extreme accuracy, and I'd like maybe 1 volt p-p. >>>>> >>>>>I was thinking a cheap MMIC with PCB delay line feedback. >>>>> >>>>>MiniCircuits VCOs are around $20, which isn't bad. >>>>> >>>>>The output would go into a PWM modulator and then an AC-coupled >>>>>communications channel. >>>> >>>>hat are you trying to do ? >>>> >>>>Are you trying to transfer a very broad band DC based _analog_ signal >>>>(say DC .. 500 MHz) over an AC link (say 2 GHz). >>> >>> >>>That, or just ship a single-bit logic level over a telecom type link. >>>It's just a shower musing, not serious yet. >>> >>>> >>>>Why not simply frequency module a VCO ? Why PWM ? >>>> >>> >>>FM is more work on both ends. Commercial VCOs have pitiful modulation >>>bandwidths, kilohertz not gigahertz. PWM can be arbitrarily fast. >>> >>>For the logic level case, we'd want it to be fast with low jitter. >>>Whatever modulation scheme is used, the time jitter should be a >>>fraction of the "carrier" period. >> >>What about phase shifting keying (PSK) ? > >How can you DC couple PSK? > > >> >>Just invert the output from the oscillator at input signal change. Of >>course, you have to establish the initial state somehow to be able to >>decode current state from only phase changes. >> >>To always know the state, you could use return to zero coding, i.e. a >>carrier at 0 degrees, a 0->1 transition as +90 degree phase change and >>1->0 input change as -90 degrees phase shift (QPSK). >> >>Also take look at Manchester coding. >> > >Manchester is phase ambiguous! A long string of 1's looks just like a >long string of 0's. And the decode is clock synchronous, so has >massive jitter when shipping an arbitrary signal. > >PSK ditto. I want to modulate, not encode. > >AM/OOK won't work when the receiver has AGC.In analog TV (with negative video modulation) uses maximum power to transmit the synch pulses. As soon as the TV-receiver has achieved line sync, only the maximum amplitude synch pulse is gated into the AGC circuit. The variable intensity video doesn't affect the AGC. You could use the same principle.
Reply by ●April 30, 20212021-04-30
On Fri, 30 Apr 2021 10:09:59 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>fredag den 30. april 2021 kl. 19.04.03 UTC+2 skrev John Larkin: >> On Fri, 30 Apr 2021 19:54:36 +0300, upsid...@downunder.com wrote: >> >> >On Fri, 30 Apr 2021 08:45:30 -0700, jla...@highlandsniptechnology.com >> >wrote: >> > >> >>On Fri, 30 Apr 2021 08:07:10 +0300, upsid...@downunder.com wrote: >> >> >> >>>On Tue, 27 Apr 2021 12:35:17 -0700, John Larkin >> >>><jlarkin@highland_atwork_technology.com> wrote: >> >>> >> >>>>What's a good way to make a, say 2 or 3 GHz sinewave oscillator? I >> >>>>don't need extreme accuracy, and I'd like maybe 1 volt p-p. >> >>>> >> >>>>I was thinking a cheap MMIC with PCB delay line feedback. >> >>>> >> >>>>MiniCircuits VCOs are around $20, which isn't bad. >> >>>> >> >>>>The output would go into a PWM modulator and then an AC-coupled >> >>>>communications channel. >> >>> >> >>>hat are you trying to do ? >> >>> >> >>>Are you trying to transfer a very broad band DC based _analog_ signal >> >>>(say DC .. 500 MHz) over an AC link (say 2 GHz). >> >> >> >> >> >>That, or just ship a single-bit logic level over a telecom type link. >> >>It's just a shower musing, not serious yet. >> >> >> >>> >> >>>Why not simply frequency module a VCO ? Why PWM ? >> >>> >> >> >> >>FM is more work on both ends. Commercial VCOs have pitiful modulation >> >>bandwidths, kilohertz not gigahertz. PWM can be arbitrarily fast. >> >> >> >>For the logic level case, we'd want it to be fast with low jitter. >> >>Whatever modulation scheme is used, the time jitter should be a >> >>fraction of the "carrier" period. >> > >> >What about phase shifting keying (PSK) ? >> How can you DC couple PSK? >> > >> >Just invert the output from the oscillator at input signal change. Of >> >course, you have to establish the initial state somehow to be able to >> >decode current state from only phase changes. >> > >> >To always know the state, you could use return to zero coding, i.e. a >> >carrier at 0 degrees, a 0->1 transition as +90 degree phase change and >> >1->0 input change as -90 degrees phase shift (QPSK). >> > >> >Also take look at Manchester coding. >> > >> Manchester is phase ambiguous! A long string of 1's looks just like a >> long string of 0's. And the decode is clock synchronous, so has >> massive jitter when shipping an arbitrary signal. >> >> PSK ditto. I want to modulate, not encode. >> >> AM/OOK won't work when the receiver has AGC. > >wouldn't your pwm be OOK?No. It would be a fixed frequency continuous square wave of modulated duty cycle. That does DC coupled transmission of an asynchronous analog or logic-level baseband signal. The duty cycle can't get extreme or the optical receivers get unhappy. 40/60 % seems conservative for a typical telecom rosa. I might look into duty cycle modulation over an ethernet type path, twisted pairs with magnetics. The Shannon-type math is beyond me here, so I'll just Spice it.
Reply by ●April 30, 20212021-04-30
fredag den 30. april 2021 kl. 19.51.58 UTC+2 skrev John Larkin:> On Fri, 30 Apr 2021 10:09:59 -0700 (PDT), Lasse Langwadt Christensen > <lang...@fonz.dk> wrote: > > >fredag den 30. april 2021 kl. 19.04.03 UTC+2 skrev John Larkin: > >> On Fri, 30 Apr 2021 19:54:36 +0300, upsid...@downunder.com wrote: > >> > >> >On Fri, 30 Apr 2021 08:45:30 -0700, jla...@highlandsniptechnology.com > >> >wrote: > >> > > >> >>On Fri, 30 Apr 2021 08:07:10 +0300, upsid...@downunder.com wrote: > >> >> > >> >>>On Tue, 27 Apr 2021 12:35:17 -0700, John Larkin > >> >>><jlarkin@highland_atwork_technology.com> wrote: > >> >>> > >> >>>>What's a good way to make a, say 2 or 3 GHz sinewave oscillator? I > >> >>>>don't need extreme accuracy, and I'd like maybe 1 volt p-p. > >> >>>> > >> >>>>I was thinking a cheap MMIC with PCB delay line feedback. > >> >>>> > >> >>>>MiniCircuits VCOs are around $20, which isn't bad. > >> >>>> > >> >>>>The output would go into a PWM modulator and then an AC-coupled > >> >>>>communications channel. > >> >>> > >> >>>hat are you trying to do ? > >> >>> > >> >>>Are you trying to transfer a very broad band DC based _analog_ signal > >> >>>(say DC .. 500 MHz) over an AC link (say 2 GHz). > >> >> > >> >> > >> >>That, or just ship a single-bit logic level over a telecom type link. > >> >>It's just a shower musing, not serious yet. > >> >> > >> >>> > >> >>>Why not simply frequency module a VCO ? Why PWM ? > >> >>> > >> >> > >> >>FM is more work on both ends. Commercial VCOs have pitiful modulation > >> >>bandwidths, kilohertz not gigahertz. PWM can be arbitrarily fast. > >> >> > >> >>For the logic level case, we'd want it to be fast with low jitter. > >> >>Whatever modulation scheme is used, the time jitter should be a > >> >>fraction of the "carrier" period. > >> > > >> >What about phase shifting keying (PSK) ? > >> How can you DC couple PSK? > >> > > >> >Just invert the output from the oscillator at input signal change. Of > >> >course, you have to establish the initial state somehow to be able to > >> >decode current state from only phase changes. > >> > > >> >To always know the state, you could use return to zero coding, i.e. a > >> >carrier at 0 degrees, a 0->1 transition as +90 degree phase change and > >> >1->0 input change as -90 degrees phase shift (QPSK). > >> > > >> >Also take look at Manchester coding. > >> > > >> Manchester is phase ambiguous! A long string of 1's looks just like a > >> long string of 0's. And the decode is clock synchronous, so has > >> massive jitter when shipping an arbitrary signal. > >> > >> PSK ditto. I want to modulate, not encode. > >> > >> AM/OOK won't work when the receiver has AGC. > > > >wouldn't your pwm be OOK? > No. It would be a fixed frequency continuous square wave of modulated > duty cycle. That does DC coupled transmission of an asynchronous > analog or logic-level baseband signal.so the ~2GHz it self have varying duty cycle? not ~2GHz on/off ?> > The duty cycle can't get extreme or the optical receivers get unhappy. > 40/60 % seems conservative for a typical telecom rosa. I might look > into duty cycle modulation over an ethernet type path, twisted pairs > with magnetics.I guess with two pairs you could send the carrier on one pair to demodulate the other pair at the far end
Reply by ●April 30, 20212021-04-30
On 30/04/2021 16:45, jlarkin@highlandsniptechnology.com wrote:> On Fri, 30 Apr 2021 08:07:10 +0300, upsidedown@downunder.com wrote: > >> On Tue, 27 Apr 2021 12:35:17 -0700, John Larkin >> <jlarkin@highland_atwork_technology.com> wrote: >> >>> What's a good way to make a, say 2 or 3 GHz sinewave oscillator? I >>> don't need extreme accuracy, and I'd like maybe 1 volt p-p. >>> >>> I was thinking a cheap MMIC with PCB delay line feedback. >>> >>> MiniCircuits VCOs are around $20, which isn't bad. >>> >>> The output would go into a PWM modulator and then an AC-coupled >>> communications channel. >> >> hat are you trying to do ? >> >> Are you trying to transfer a very broad band DC based _analog_ signal >> (say DC .. 500 MHz) over an AC link (say 2 GHz). > > > That, or just ship a single-bit logic level over a telecom type link. > It's just a shower musing, not serious yet. > >> >> Why not simply frequency module a VCO ? Why PWM ? >> > > FM is more work on both ends. Commercial VCOs have pitiful modulation > bandwidths, kilohertz not gigahertz. PWM can be arbitrarily fast. > > For the logic level case, we'd want it to be fast with low jitter. > Whatever modulation scheme is used, the time jitter should be a > fraction of the "carrier" period. > > This problem is similar to the Shannon sampling theorem. A bandlimited > signal can be sampled at some rate and reproduced perfectly from the > sampled values. The trick is to have the modulation scheme be > continuous and bandlimited such as to eliminate the jitter of the > modulation/demod scheme. > > Wideband FM gets mathematically messy too. Ugly sidebands. > > PWM would be fairly easy to generate and detect. I've tested some 10 > GBPS tosa/rosa optical links and they do transmit PWM, to various > extents. Of course they go bonkers at extreme duty cycles. > > > > >How about a very fast logic gate (or string of gates) moderated by a delay line. Make one a NOR or NAND and that gets the PWM input? piglet
Reply by ●April 30, 20212021-04-30
Am 30.04.21 um 19:03 schrieb John Larkin:> On Fri, 30 Apr 2021 19:54:36 +0300, upsidedown@downunder.com wrote:>> What about phase shifting keying (PSK) ? > > How can you DC couple PSK?BPSK is: Ring mixer like MCL IE-500 RF port: input LO port: output IF port: modulation in Demodulation / bit sclicing happens in Squaring or Costas loop. Gerhard
Reply by ●April 30, 20212021-04-30
On Fri, 30 Apr 2021 11:10:12 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>fredag den 30. april 2021 kl. 19.51.58 UTC+2 skrev John Larkin: >> On Fri, 30 Apr 2021 10:09:59 -0700 (PDT), Lasse Langwadt Christensen >> <lang...@fonz.dk> wrote: >> >> >fredag den 30. april 2021 kl. 19.04.03 UTC+2 skrev John Larkin: >> >> On Fri, 30 Apr 2021 19:54:36 +0300, upsid...@downunder.com wrote: >> >> >> >> >On Fri, 30 Apr 2021 08:45:30 -0700, jla...@highlandsniptechnology.com >> >> >wrote: >> >> > >> >> >>On Fri, 30 Apr 2021 08:07:10 +0300, upsid...@downunder.com wrote: >> >> >> >> >> >>>On Tue, 27 Apr 2021 12:35:17 -0700, John Larkin >> >> >>><jlarkin@highland_atwork_technology.com> wrote: >> >> >>> >> >> >>>>What's a good way to make a, say 2 or 3 GHz sinewave oscillator? I >> >> >>>>don't need extreme accuracy, and I'd like maybe 1 volt p-p. >> >> >>>> >> >> >>>>I was thinking a cheap MMIC with PCB delay line feedback. >> >> >>>> >> >> >>>>MiniCircuits VCOs are around $20, which isn't bad. >> >> >>>> >> >> >>>>The output would go into a PWM modulator and then an AC-coupled >> >> >>>>communications channel. >> >> >>> >> >> >>>hat are you trying to do ? >> >> >>> >> >> >>>Are you trying to transfer a very broad band DC based _analog_ signal >> >> >>>(say DC .. 500 MHz) over an AC link (say 2 GHz). >> >> >> >> >> >> >> >> >>That, or just ship a single-bit logic level over a telecom type link. >> >> >>It's just a shower musing, not serious yet. >> >> >> >> >> >>> >> >> >>>Why not simply frequency module a VCO ? Why PWM ? >> >> >>> >> >> >> >> >> >>FM is more work on both ends. Commercial VCOs have pitiful modulation >> >> >>bandwidths, kilohertz not gigahertz. PWM can be arbitrarily fast. >> >> >> >> >> >>For the logic level case, we'd want it to be fast with low jitter. >> >> >>Whatever modulation scheme is used, the time jitter should be a >> >> >>fraction of the "carrier" period. >> >> > >> >> >What about phase shifting keying (PSK) ? >> >> How can you DC couple PSK? >> >> > >> >> >Just invert the output from the oscillator at input signal change. Of >> >> >course, you have to establish the initial state somehow to be able to >> >> >decode current state from only phase changes. >> >> > >> >> >To always know the state, you could use return to zero coding, i.e. a >> >> >carrier at 0 degrees, a 0->1 transition as +90 degree phase change and >> >> >1->0 input change as -90 degrees phase shift (QPSK). >> >> > >> >> >Also take look at Manchester coding. >> >> > >> >> Manchester is phase ambiguous! A long string of 1's looks just like a >> >> long string of 0's. And the decode is clock synchronous, so has >> >> massive jitter when shipping an arbitrary signal. >> >> >> >> PSK ditto. I want to modulate, not encode. >> >> >> >> AM/OOK won't work when the receiver has AGC. >> > >> >wouldn't your pwm be OOK? >> No. It would be a fixed frequency continuous square wave of modulated >> duty cycle. That does DC coupled transmission of an asynchronous >> analog or logic-level baseband signal. > >so the ~2GHz it self have varying duty cycle? not ~2GHz on/off ?Right. It shouldn't be difficult. OOK has the long-term receive threshold problem.> >> >> The duty cycle can't get extreme or the optical receivers get unhappy. >> 40/60 % seems conservative for a typical telecom rosa. I might look >> into duty cycle modulation over an ethernet type path, twisted pairs >> with magnetics. > >I guess with two pairs you could send the carrier on one pair to demodulate >the other pair at the far endAM with synchronous demodulation? PWM only needs one channel and a lowpass filter to demodulate.
Reply by ●April 30, 20212021-04-30
On Fri, 30 Apr 2021 20:44:36 +0300, upsidedown@downunder.com wrote:>On Fri, 30 Apr 2021 10:03:52 -0700, John Larkin ><jlarkin@highland_atwork_technology.com> wrote: > >>On Fri, 30 Apr 2021 19:54:36 +0300, upsidedown@downunder.com wrote: >> >>>On Fri, 30 Apr 2021 08:45:30 -0700, jlarkin@highlandsniptechnology.com >>>wrote: >>> >>>>On Fri, 30 Apr 2021 08:07:10 +0300, upsidedown@downunder.com wrote: >>>> >>>>>On Tue, 27 Apr 2021 12:35:17 -0700, John Larkin >>>>><jlarkin@highland_atwork_technology.com> wrote: >>>>> >>>>>>What's a good way to make a, say 2 or 3 GHz sinewave oscillator? I >>>>>>don't need extreme accuracy, and I'd like maybe 1 volt p-p. >>>>>> >>>>>>I was thinking a cheap MMIC with PCB delay line feedback. >>>>>> >>>>>>MiniCircuits VCOs are around $20, which isn't bad. >>>>>> >>>>>>The output would go into a PWM modulator and then an AC-coupled >>>>>>communications channel. >>>>> >>>>>hat are you trying to do ? >>>>> >>>>>Are you trying to transfer a very broad band DC based _analog_ signal >>>>>(say DC .. 500 MHz) over an AC link (say 2 GHz). >>>> >>>> >>>>That, or just ship a single-bit logic level over a telecom type link. >>>>It's just a shower musing, not serious yet. >>>> >>>>> >>>>>Why not simply frequency module a VCO ? Why PWM ? >>>>> >>>> >>>>FM is more work on both ends. Commercial VCOs have pitiful modulation >>>>bandwidths, kilohertz not gigahertz. PWM can be arbitrarily fast. >>>> >>>>For the logic level case, we'd want it to be fast with low jitter. >>>>Whatever modulation scheme is used, the time jitter should be a >>>>fraction of the "carrier" period. >>> >>>What about phase shifting keying (PSK) ? >> >>How can you DC couple PSK? >> >> >>> >>>Just invert the output from the oscillator at input signal change. Of >>>course, you have to establish the initial state somehow to be able to >>>decode current state from only phase changes. >>> >>>To always know the state, you could use return to zero coding, i.e. a >>>carrier at 0 degrees, a 0->1 transition as +90 degree phase change and >>>1->0 input change as -90 degrees phase shift (QPSK). >>> >>>Also take look at Manchester coding. >>> >> >>Manchester is phase ambiguous! A long string of 1's looks just like a >>long string of 0's. And the decode is clock synchronous, so has >>massive jitter when shipping an arbitrary signal. >> >>PSK ditto. I want to modulate, not encode. >> >>AM/OOK won't work when the receiver has AGC. > >In analog TV (with negative video modulation) uses maximum power to >transmit the synch pulses. > >As soon as the TV-receiver has achieved line sync, only the maximum >amplitude synch pulse is gated into the AGC circuit. The variable >intensity video doesn't affect the AGC. You could use the same >principle.Video, like encoded digital data, has continuous activity and known levels (black and white, for instance) to feed back on for AGC. A DC signal might be 0 for six weeks. Can't AGC on zero. Even digital data needs algorithms, like 8b10b or something, to ensure lots of activity for AGC and phase locking.
Reply by ●April 30, 20212021-04-30
On Fri, 30 Apr 2021 20:43:08 +0200, Gerhard Hoffmann <dk4xp@arcor.de> wrote:>Am 30.04.21 um 19:03 schrieb John Larkin: >> On Fri, 30 Apr 2021 19:54:36 +0300, upsidedown@downunder.com wrote: > > >>> What about phase shifting keying (PSK) ? >> >> How can you DC couple PSK? > >BPSK is: Ring mixer like MCL IE-500 > >RF port: input >LO port: output >IF port: modulation in > >Demodulation / bit sclicing happens in Squaring or Costas loop. > >GerhardI don't want to send clocked digital data, I want to send an analog level. Suppose the input to the transmitter (IF port here) is +0.5 volts. That makes a carrier of some amplitude and phase. The receiver gets that carrier. The channel has attenuation. How does the receiver know it's supposed to output +0.5 volts? It could guess the phase wrong and output -0.5 volts. Or not know the channel attenuation and output +7 volts. If it sees an invariant sine wave for six weeks, or at powerup, is the signal positive or negative?
