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LOCAL OSCILLATOR PICKED UP ON QSD

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  • Frank
    Hello, I m curious to know on how good a QSD rejects signals generated by the CMOS counter ICs. On the softrock40 v.40, I placed a long wire on the parallel L1
    Message 1 of 18 , Jun 22, 2007
      Hello,
      I'm curious to know on how good a QSD rejects signals generated by the
      CMOS counter ICs.

      On the softrock40 v.40, I placed a long wire on the parallel L1 C21
      input and was hoping to pick up a 7.056Mhz signal I generated with a
      separate circuit placed about a foot away. I checked the antenna with
      a 10x probe and saw nearly a 1Vpp 7.056Mhz signal. Each AND gate is
      producing a pulse of 1/(4* 7.056MHz) width and 1/7.056MHz period, so
      isn't quite normal to pick it up at detection in forms of a A
      Cos(theta) DC offset output, where theta is the difference in phase
      between the antenna input and a particular QSD switch?


      Now, I just assembled the softrock40 a day ago and I don't have any
      experience with zero IF based receivers. Do zero IF receivers work at
      all unless the receiver circuitry is very well shielded with a
      metallic box with the input signal traveling into the circuit with a
      coaxial cable fed by a distant antenna? What is the common
      installation of a functional softrock40?

      Frank
    • w7qjq
      ... the ... a ... with ... so ... at ... a ... Frank, I do not understand your first paragraph at all (???). Regards the second paragraph, The SoftRock
      Message 2 of 18 , Jun 22, 2007
        --- In softrock40@yahoogroups.com, "Frank" <transistortoaster@...>
        wrote:
        >
        > Hello,
        > I'm curious to know on how good a QSD rejects signals generated by
        the
        > CMOS counter ICs.
        >
        > On the softrock40 v.40, I placed a long wire on the parallel L1 C21
        > input and was hoping to pick up a 7.056Mhz signal I generated with
        a
        > separate circuit placed about a foot away. I checked the antenna
        with
        > a 10x probe and saw nearly a 1Vpp 7.056Mhz signal. Each AND gate is
        > producing a pulse of 1/(4* 7.056MHz) width and 1/7.056MHz period,
        so
        > isn't quite normal to pick it up at detection in forms of a A
        > Cos(theta) DC offset output, where theta is the difference in phase
        > between the antenna input and a particular QSD switch?
        >
        >
        > Now, I just assembled the softrock40 a day ago and I don't have any
        > experience with zero IF based receivers. Do zero IF receivers work
        at
        > all unless the receiver circuitry is very well shielded with a
        > metallic box with the input signal traveling into the circuit with
        a
        > coaxial cable fed by a distant antenna? What is the common
        > installation of a functional softrock40?
        >
        > Frank
        >


        Frank, I do not understand your first paragraph at all (???).

        Regards the second paragraph, The SoftRock receivers do not require
        shielding nor do they require a "distant antenna". My un-shielded
        Rx v6.2 works well laying on one edge of my workbench amid a tangle
        of other projects.
        What they DO require for proper operation is a connection to BOTH
        terminals of the antenna connector. Hanging a wire on just one
        terminal won't do it. You need rf current flowing thru the input
        network (and thus the primary of T1) and you won't get that with
        just one wire no matter how long it is. One wire is fine so long as
        you provide an rf ground to the other terminal (it matters not which
        terminal is "hot" and which is "ground" since the input circuit is
        floating (ref to DC)).

        73, Sid W7QJQ
        Oklahoma
        a
      • Frank
        ... Sid, Thanks for your response. In the first paragraph, I am saying that the digital circuitry itself generates a 7.056MHz signal while the qsd is trying to
        Message 3 of 18 , Jun 22, 2007
          >
          > Frank, I do not understand your first paragraph at all (???).
          Sid,
          Thanks for your response.

          In the first paragraph, I am saying that the digital circuitry itself
          generates a 7.056MHz signal while the qsd is trying to receive a weak
          signal at 7.056Mhz. Wouldn't the digital circuitry be a very strong
          interferer?

          Exactly what antenna do you use?
          Frank
        • Chris Albertson
          ... I think the 7.056MHz signal when mixed with a 7.056MHz LO comes out as 0.000Hz (DC) and 14.112Mhz.(sum and difference) the DC would be blocked by a
          Message 4 of 18 , Jun 22, 2007
            --- Frank <transistortoaster@...> wrote:


            > In the first paragraph, I am saying that the digital circuitry itself
            > generates a 7.056MHz signal while the qsd is trying to receive a weak
            > signal at 7.056Mhz. Wouldn't the digital circuitry be a very strong
            > interferer?

            I think the 7.056MHz signal when mixed with a 7.056MHz LO comes out
            as "0.000Hz" (DC) and 14.112Mhz.(sum and difference) the DC would be
            blocked by a capacitor and the 14Mhz is way above the low pass filter's
            cut off.



            Chris Albertson
            Home: 310-376-1029 chrisalbertson90278@...
            Office: 310-336-5189 Christopher.J.Albertson@...



            ____________________________________________________________________________________
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          • Bill Dumke
            Chris, What happens in practice is that a large spike will be seen in the middle of the +/- 24 kHz or +/- 48 kHz tuning range, depending on the sound card and
            Message 5 of 18 , Jun 22, 2007
              Chris,

              What happens in practice is that a large spike will be seen in the
              middle of the +/- 24 kHz or +/- 48 kHz tuning range, depending on the
              sound card and ground loops. (The sampling rate of the sound card
              determines the frequency range coverage you will get. The Delta 44 uses
              96 kHz sampling so you get roughly 96 kHz of tuning range with that
              card.) In the SoftRock 40 it was possible to isolate the antenna ground
              from the PC board ground by cutting a few traces with a Dremel tool.
              When I did this with my 40 meter ground mounted vertical antenna, the
              noise spike disappeared. But I was using the Delta 44 sound card, which
              is a very good sound card.. So even though there was a minor hole in
              the coverage at the zero frequency, SSB signals right on top of the zero
              frequency are still perfectly readable. In the SoftRock 40 this was at
              approximately 7.058 MHz RF.

              In the RXTX v. 6.2, I believe there is no way to break the ground loop
              through the antenna ground, so I am sure you you will see a small spike
              there again depending on the performance of the sound card at or near DC
              and the grounding of your antenna.
              .
              However, I would think an external transformer could still be used to
              break the ground loop if desired, or possibly a balanced dipole could be
              used as well to break the loop, and consequent 60 Hz pickup.

              I haven't built mine yet, so I don't know how bad a problem it is with
              the RXTX v6.2.

              Bill wa9pwr
            • w7qjq
              ... Yes, It does act as an interferer, but as Bill explains, it is not all that bad in practice. Just think of it as a fairly strong AM carrier. I have not
              Message 6 of 18 , Jun 23, 2007
                --- In softrock40@yahoogroups.com, "Frank" <transistortoaster@...>
                wrote:

                > In the first paragraph, I am saying that the digital circuitry itself
                > generates a 7.056MHz signal while the qsd is trying to receive a weak
                > signal at 7.056Mhz. Wouldn't the digital circuitry be a very strong
                > interferer?
                >
                > Exactly what antenna do you use?
                > Frank

                Yes, It does act as an interferer, but as Bill explains, it is not all
                that bad in practice. Just think of it as a fairly strong AM carrier.

                I have not yet built my RxTx kit... I have only the 40 m Rx (with a
                homebrew plug-in front-end for 80 m). I usually use a long-wire and
                GND for listening (looking). Even some hook-up wire run across the
                room AND a ground connection receives well.

                73, Sid W7QJQ
                Oklahoma
              • Frank
                Chris, Thanks for your response. The DC gains on the op amps in http://www.amqrp.org/kits/softrock40/SoftRock40_v4.0.gif are determined by the R16/R14 and
                Message 7 of 18 , Jun 23, 2007
                  Chris,
                  Thanks for your response. The DC gains on the op amps in
                  http://www.amqrp.org/kits/softrock40/SoftRock40_v4.0.gif

                  are determined by the R16/R14 and R15/R13 ratios, which come out to
                  500. With the output swing limited to 4V, the input DC offset relative
                  to Vcc/2 can't be more than 2V/500=4mV. This circuit has been used
                  successfully by a lot of people , so I would have to assume that there
                  cannot be a DC component more than 4mV at the integration capacitor.


                  Frank

                  > I think the 7.056MHz signal when mixed with a 7.056MHz LO comes out
                  > as "0.000Hz" (DC) and 14.112Mhz.(sum and difference) the DC would be
                  > blocked by a capacitor and the 14Mhz is way above the low pass filter's
                  > cut off.
                  >
                  >
                  >
                  > Chris Albertson
                  > Home: 310-376-1029 chrisalbertson90278@...
                  > Office: 310-336-5189 Christopher.J.Albertson@...
                  >
                  >
                  >
                  >
                  ____________________________________________________________________________________
                  > Choose the right car based on your needs. Check out Yahoo! Autos
                  new Car Finder tool.
                  > http://autos.yahoo.com/carfinder/
                  >
                • Frank
                  ... I suppose we are best shifting the sdr operation frequency such that the reception signal of interest has its whole spectrum is entirely outside. I guess
                  Message 8 of 18 , Jun 23, 2007
                    --- In softrock40@yahoogroups.com, "w7qjq" <sbjknox@...> wrote:
                    >
                    > --- In softrock40@yahoogroups.com, "Frank" <transistortoaster@>
                    > wrote:
                    >
                    > > In the first paragraph, I am saying that the digital
                    > > circuitry itself generates a 7.056MHz signal while the qsd is
                    > > trying to receive a weak
                    > > signal at 7.056Mhz. Wouldn't the digital circuitry be a very strong
                    > > interferer?
                    > >
                    > > Exactly what antenna do you use?
                    > > Frank
                    >
                    > Yes, It does act as an interferer, but as Bill explains, it is not all
                    > that bad in practice. Just think of it as a fairly strong AM carrier.

                    I suppose we are best shifting the sdr operation frequency such that
                    the reception signal of interest has its whole spectrum is entirely
                    outside. I guess that people who have had the chance to play with this
                    more than me do that.
                    Frank
                  • Chris Albertson
                    ... Given the direct conversion design I think you can t do that. Ok you could ignore the near DC part of the output or just program the software not to show
                    Message 9 of 18 , Jun 23, 2007
                      > I suppose we are best shifting the sdr operation frequency such that
                      > the reception signal of interest has its whole spectrum is entirely
                      > outside. I guess that people who have had the chance to play with
                      > this more than me do that.

                      Given the direct conversion design I think you can't do that. Ok
                      you could ignore the near DC part of the output or just program
                      the software not to show it to you. But you gain nothing that
                      way.

                      What you need to truely get rid of the LO signal is a multiple
                      conversion design. There is no reason not to build a double
                      conversion SDR other the added complexity.

                      Yu can go the other way too. No conversions. There are a
                      few SDR projects that directly sample the antenna without
                      any down conversion first but for that you need a ADC that
                      can sample at many megasamples per second. Sound cards
                      do at best just under 200K SPS.

                      One cheap way to do SDR on the 160, or maybe 80M band
                      is to hook an antenna up to a "TV Card" as TV input cards digitize
                      the video signal at 12 to 16 MSPS, but only 6 to 10 bits.
                      Still good enough t directly sample the voltage on the feed line
                      without any down conversion.

                      Chris Albertson
                      Home: 310-376-1029 chrisalbertson90278@...
                      Office: 310-336-5189 Christopher.J.Albertson@...



                      ____________________________________________________________________________________
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                    • Bill Dumke
                      Chris, The SoftRock series of radios are NOT direct conversion, at least in the usual sense of the term used in Ham Radio, where one tunes to a single station
                      Message 10 of 18 , Jun 23, 2007
                        Chris,

                        The SoftRock series of radios are NOT direct conversion, at least in the
                        usual sense of the term used in Ham Radio, where one tunes to a single
                        station with a VXO or VFO. These are SDR, Software Defined Radios. The
                        software is used to tune quite a chunk of spectrum, either a little less
                        than 48 kHz for a 48 kHz sampling sound card or a little less than 96
                        kHz for a 96 kHz sampling sound card. The little (I would guess about
                        100 Hz or so) that is lost in the center of the passband is
                        insignificant. All of the tuning is done in the software. You don't
                        need a VFO with this type of rig. And it gives crystal frequency
                        stability allowing many digital modes to be used as well as SSB or CW
                        with good dynamic range as well. Passband filtering is also done by the
                        software. Rocky, for example, can be continuously varied from about 20
                        Hz at the narrowest to 2700 Hz max, without the ringing you get in most
                        hardware audio filters.. The kits from Tony are also very inexpensive.
                        And they do work well.

                        Bill wa9pwr
                      • k5nwa
                        ... I ll have to disagree with you, a direct conversion receiver goes from RF to base band which is exactly what you do with a SoftRock, what you do with the
                        Message 11 of 18 , Jun 23, 2007
                          At 05:39 PM 6/23/2007, you wrote:

                          >Chris,
                          >
                          >The SoftRock series of radios are NOT direct conversion, at least in the
                          >usual sense of the term used in Ham Radio, where one tunes to a single
                          >station with a VXO or VFO. These are SDR, Software Defined Radios.
                          >Bill wa9pwr

                          I'll have to disagree with you, a direct conversion receiver goes
                          from RF to base band which is exactly what you do with a SoftRock,
                          what you do with the audio afterwards does not qualify or disqualify
                          from it being a direct conversion radio. There are a few direct
                          conversion receivers from many years ago that had dual receivers with
                          a Quadrature LO to get binaural reception (I and Q audio).

                          You can take the audio from one of your binaural receivers and feed
                          it to SDR software and it would work the same as a SoftRock. The
                          using of switches does not make it work any different, the switches
                          are taking the place of diodes use in a typical DBM but they are more
                          efficient and take a lower power LO while being able to handle very
                          large input signals.

                          Actually you could take two NE602 Gilbert cell mixers, feed the
                          clocks in quadrature and you would have a more sensitive mixer since
                          the NE602 is a mixer with gain, and your software would not know the
                          difference from a SoftRock.

                          A computer does give you extra capabilities but it does not change
                          how the radio hardware work.


                          Cecil
                          K5NWA
                          www.softrockradio.org www.qrpradio.com www.hpsdr.com

                          "Blessed are the cracked, for they shall let in the light."
                        • Lawrence
                          ... From: k5nwa Subject: Re: [softrock40] Re: LOCAL OSCILLATOR PICKED UP ON QSD ... It must depend on how you define direct conversion. I have always
                          Message 12 of 18 , Jun 23, 2007
                            ----- Original Message -----
                            From: "k5nwa"
                            Subject: Re: [softrock40] Re: LOCAL OSCILLATOR PICKED UP ON
                            QSD


                            > I'll have to disagree with you, a direct conversion
                            > receiver goes
                            > from RF to base band which is exactly what you do with a
                            > SoftRock,
                            > what you do with the audio afterwards does not qualify or
                            > disqualify
                            > from it being a direct conversion radio. There are a few
                            > direct
                            > conversion receivers from many years ago that had dual
                            > receivers with
                            > a Quadrature LO to get binaural reception (I and Q audio).

                            It must depend on how you define direct conversion. I have
                            always understood it to mean converting directly to the
                            required audio frequency. That would only be the case with
                            SDR if the nominal carrier frequency, for SSB, was the same
                            as the injection frequency or the multiple being used.

                            If the injection was, for example, 20 kHz away from the
                            carrier, then we have to convert that again down to the
                            final audio frequency making it double conversion. Obviously
                            the second IF is very low and, although about 20 kHz in this
                            example, can be anything up to the limit imposed by the
                            sound card.

                            A SoftRock Rx board could be used as part of a direct
                            conversion receiver but would need a VFO instead of the
                            crystal controlled oscillator for the injection. To phase
                            out the unwanted sideband and to filter out the rest of the
                            spectrum could be done in the computer or by using
                            "conventional" analogue circuits.

                            The SDR is therefore double conversion, according to my
                            definition, with the second IF existing entirely within the
                            computer.

                            73, Lawrence GJ3RAX
                          • Lawrence
                            ... From: Lawrence Subject: Re: [softrock40] Re: LOCAL OSCILLATOR PICKED UP ON QSD ... It is late at night here and I got myself a bit confused with my
                            Message 13 of 18 , Jun 23, 2007
                              ----- Original Message -----
                              From: "Lawrence"
                              Subject: Re: [softrock40] Re: LOCAL OSCILLATOR PICKED UP ON
                              QSD


                              > If the injection was, for example, 20 kHz away from the
                              > carrier, then we have to convert that again down to the
                              > final audio frequency making it double conversion.
                              > Obviously
                              > the second IF is very low and, although about 20 kHz in
                              > this
                              > example, can be anything up to the limit imposed by the
                              > sound card.

                              It is late at night here and I got myself a bit confused
                              with my definition. I should not have said "double
                              conversion" or said "second IF". It does convert to a single
                              IF that is within the computer before further processing to
                              recover the audio output. It is equivalent to a superhet
                              radio even if the IF is a virtual one.

                              Hope I got it right this time.

                              73, Lawrence GJ3RAX
                            • Frank
                              ... Or we can say that the softrock40 *can be used as a* near zero IF recevier. Frank
                              Message 14 of 18 , Jun 24, 2007
                                > The SDR is therefore double conversion, according to my
                                > definition, with the second IF existing entirely within the
                                > computer.
                                >
                                > 73, Lawrence GJ3RAX
                                >


                                >It does convert to a single IF that is within the computer
                                > before further processing to recover the audio output. It is
                                > equivalent to a superhet radio even if the IF is a virtual one.
                                >
                                > 73, Lawrence GJ3RAX

                                Or we can say that the softrock40 *can be used as a* near zero IF
                                recevier.
                                Frank
                              • Lawrence
                                ... From: Frank Subject: [softrock40] Re: LOCAL OSCILLATOR PICKED UP ON QSD ... Yes. It does use an IF even though it is very low in comparison with
                                Message 15 of 18 , Jun 24, 2007
                                  ----- Original Message -----
                                  From: "Frank"
                                  Subject: [softrock40] Re: LOCAL OSCILLATOR PICKED UP ON QSD


                                  > Or we can say that the softrock40 *can be used as a* near
                                  > zero IF
                                  > recevier.
                                  > Frank

                                  Yes. It does use an IF even though it is very low in
                                  comparison with "conventional" radios. That is then
                                  converted again to the required output. It is not quite
                                  direct conversion although it could be used that way.

                                  73, Lawrence GJ3RAX
                                • k5nwa
                                  ... I guess we will have to agree to disagree. As far as a standard definition is concerned the radio stops at the board audio connectors, what you do after
                                  Message 16 of 18 , Jun 24, 2007
                                    At 10:21 AM 6/24/2007, you wrote:

                                    > > The SDR is therefore double conversion, according to my
                                    > > definition, with the second IF existing entirely within the
                                    > > computer.
                                    > >
                                    > > 73, Lawrence GJ3RAX
                                    > >
                                    >
                                    > >It does convert to a single IF that is within the computer
                                    > > before further processing to recover the audio output. It is
                                    > > equivalent to a superhet radio even if the IF is a virtual one.
                                    > >
                                    > > 73, Lawrence GJ3RAX
                                    >
                                    >Or we can say that the softrock40 *can be used as a* near zero IF
                                    >recevier.
                                    >Frank
                                    I guess we will have to agree to disagree.

                                    As far as a standard definition is concerned the radio stops at the
                                    board audio connectors, what you do after that is added on
                                    accessories. The SoftRock hardware is still a dual direct conversion
                                    receivers no matter what you do afterwards and it will work as such
                                    at a fixed frequency(no computer necessary) unless you use a DDS to
                                    move around, it is just like a RockMite bound to one frequency.

                                    If I take a old Collins radio and add a audio DSP filter is the
                                    Collins a DSP rig? The answer is no, it's just an external accessory.
                                    What I do to a radio outside of it's audio output has no bearing on
                                    what the radio itself is.

                                    Words have meanings, and if one one wants to change the meaning of
                                    words just to make oneself feel better then confusion will
                                    reign. Left is right, up is down, if that is what you want then
                                    there is not much I can do other than to steer clear of it.

                                    So go at it, I'm out of here.


                                    Cecil
                                    K5NWA
                                    www.softrockradio.org www.qrpradio.com www.hpsdr.com

                                    "Blessed are the cracked, for they shall let in the light."
                                  • Lawrence
                                    ... From: k5nwa Subject: Re: [softrock40] Re: LOCAL OSCILLATOR PICKED UP ON QSD ... Just to take the anaolgy a bit further, a SoftRock receiver board is more
                                    Message 17 of 18 , Jun 24, 2007
                                      ----- Original Message -----
                                      From: "k5nwa"
                                      Subject: Re: [softrock40] Re: LOCAL OSCILLATOR PICKED UP ON
                                      QSD


                                      > As far as a standard definition is concerned the radio
                                      > stops at the
                                      > board audio connectors, what you do after that is added on
                                      > accessories.

                                      Just to take the anaolgy a bit further, a SoftRock receiver
                                      board is more like the converters that I used to used to
                                      convert 2 m or 70 cms to 10 m. The converter could not be
                                      used in isolation and neither can the SoftRock. It just
                                      happens to use a computer as the tuneable IF rather than a
                                      radio receiver. The wider the bandwidth of the sound card,
                                      or future equivalent, the higher the potential IF is.


                                      > If I take a old Collins radio and add a audio DSP filter
                                      > is the
                                      > Collins a DSP rig? The answer is no, it's just an external
                                      > accessory.
                                      > What I do to a radio outside of it's audio output has no
                                      > bearing on
                                      > what the radio itself is.

                                      That is not quite the same analogy as the Collins Rx can be
                                      used by itself. The DSP filter takes AF input and then gives
                                      you AF output after processing it.

                                      73, Lawrence GJ3RAX
                                    • Terry
                                      ... conversion ... accessory. ... Sorry to not but I would like to follow this if I could. Who says the radio stops at an audio connector? I must
                                      Message 18 of 18 , Jun 24, 2007
                                        --- In softrock40@yahoogroups.com, k5nwa <k5nwa@...> wrote:
                                        >
                                        > At 10:21 AM 6/24/2007, you wrote:
                                        >
                                        > > > The SDR is therefore double conversion, according to my
                                        > > > definition, with the second IF existing entirely within the
                                        > > > computer.
                                        > > >
                                        > > > 73, Lawrence GJ3RAX
                                        > > >
                                        > >
                                        > > >It does convert to a single IF that is within the computer
                                        > > > before further processing to recover the audio output. It is
                                        > > > equivalent to a superhet radio even if the IF is a virtual one.
                                        > > >
                                        > > > 73, Lawrence GJ3RAX
                                        > >
                                        > >Or we can say that the softrock40 *can be used as a* near zero IF
                                        > >recevier.
                                        > >Frank
                                        > I guess we will have to agree to disagree.
                                        >
                                        > As far as a standard definition is concerned the radio stops at the
                                        > board audio connectors, what you do after that is added on
                                        > accessories. The SoftRock hardware is still a dual direct
                                        conversion
                                        > receivers no matter what you do afterwards and it will work as such
                                        > at a fixed frequency(no computer necessary) unless you use a DDS to
                                        > move around, it is just like a RockMite bound to one frequency.
                                        >
                                        > If I take a old Collins radio and add a audio DSP filter is the
                                        > Collins a DSP rig? The answer is no, it's just an external
                                        accessory.
                                        > What I do to a radio outside of it's audio output has no bearing on
                                        > what the radio itself is.
                                        >
                                        > Words have meanings, and if one one wants to change the meaning of
                                        > words just to make oneself feel better then confusion will
                                        > reign. Left is right, up is down, if that is what you want then
                                        > there is not much I can do other than to steer clear of it.
                                        >
                                        > So go at it, I'm out of here.
                                        >
                                        >
                                        > Cecil
                                        > K5NWA
                                        > www.softrockradio.org www.qrpradio.com www.hpsdr.com
                                        >
                                        > "Blessed are the cracked, for they shall let in the light."
                                        >
                                        Sorry to not <snip> but I would like to follow this if I could.

                                        Who says the "radio" stops at an audio connector? I must have missed
                                        that definition in school, especially if there is video or other
                                        signals involved. And, even if this "definition" holds true, you are
                                        NOT given "audio" at the SoftRock line out terminals. As LF people
                                        know, just because a signal is in the traditional "audio" frequency
                                        range, that does not make the signal "audio" to humans.

                                        In my opinion, the radio stops and accessories begin once you are
                                        given a replica of the transmitted/relayed information. This means
                                        that if some intelligence is "modulated" onto a carrier, the radio
                                        does not stop until the "demodulated" signal is reovered. For CW,
                                        this can be a little confusing, but for AM, SSB, etc, I think that
                                        should be obvious.

                                        The audio output of a SoftRock is NOT the demodulated, or original
                                        signal. It still takes more processing to recover the original
                                        intelligence.

                                        If you could hook the "audio" from a SoftRock to a speaker and hear
                                        the original intelligence or essence, then I would agree. But, you
                                        can't. It requires further demodulation first.

                                        Therefore, regardless of the frequency, the signal from the softrock
                                        is not "audio". It is a low-frequency IF that requires further
                                        processing to recover the original modulated signal.

                                        At least, that's my opinion. So there (hi hi).
                                        Terry
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