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Fractured Rock

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  • imitchel4you
    Hi, here s just a bit of info on the fractured rock: * tunes 80M band but can be configured for 160, 40, 20 or 20/40 etc and AM broadcast using either
    Message 1 of 14 , Sep 29, 2006
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      Hi, here's just a bit of info on the fractured rock:

      * tunes 80M band but can be configured for 160, 40, 20 or 20/40 etc
      and AM broadcast using either fundamental or harmonic sampling
      * 7 pole bandpass filter using moulded inductors
      * preamp of about 12db (but you can change it) - in my area signals
      are few and low level - also it provides the correct impedance to the
      filter , and sets the bias voltage and low impedance to the QSD
      * the LO is based on a 32bit 4th order sigma-delta modulator feeding a
      PLL with a reference frequency of 100KHz (I didn't notice any spurs
      but i've only been testing for a couple of nights) - frequency range
      is 10-20MHz
      * the QSD divides the LO by four and is a four-way commutating switch
      * the LM837 has a GBW of 25MHz and noise of less than 4nV/rtHz and is
      powered at 9V to improve dynamic range - it is a quad op-amp
      configured to offer a high impedance to all four switches
      * the LO is set by sending the decimal ascii frequency in Hz to a COM port

      Cheers, Ian
    • john sakellakis
      Hello Ian.. Your posting about the fractured rock is very interesting. Do you have any schematics to pass on? If you could email me a set, I would greatly
      Message 2 of 14 , Sep 29, 2006
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        Hello Ian..

        Your posting about the "fractured rock" is very
        interesting. Do you have any schematics to pass on?
        If you could email me a set, I would greatly
        appreciate it... 73... John

        yiannis_w8gxu@...
        ***********************************************

        --- imitchel4you <ian.mitchell@...> wrote:

        > Hi, here's just a bit of info on the fractured rock:
        >
        > * tunes 80M band but can be configured for 160, 40,
        > 20 or 20/40 etc
        > and AM broadcast using either fundamental or
        > harmonic sampling
        > * 7 pole bandpass filter using moulded inductors
        > * preamp of about 12db (but you can change it) - in
        > my area signals
        > are few and low level - also it provides the correct
        > impedance to the
        > filter , and sets the bias voltage and low impedance
        > to the QSD
        > * the LO is based on a 32bit 4th order sigma-delta
        > modulator feeding a
        > PLL with a reference frequency of 100KHz (I didn't
        > notice any spurs
        > but i've only been testing for a couple of nights) -
        > frequency range
        > is 10-20MHz
        > * the QSD divides the LO by four and is a four-way
        > commutating switch
        > * the LM837 has a GBW of 25MHz and noise of less
        > than 4nV/rtHz and is
        > powered at 9V to improve dynamic range - it is a
        > quad op-amp
        > configured to offer a high impedance to all four
        > switches
        > * the LO is set by sending the decimal ascii
        > frequency in Hz to a COM port
        >
        > Cheers, Ian
        >
        >
        >
        >


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      • imitchel4you
        Hi John, please see: http://groups.yahoo.com/group/softrock40/files/fracturedrock/fr80.pdf cheers
        Message 3 of 14 , Sep 30, 2006
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          Hi John, please see:
          http://groups.yahoo.com/group/softrock40/files/fracturedrock/fr80.pdf

          cheers


          --- In softrock40@yahoogroups.com, john sakellakis <yiannis_w8gxu@...>
          wrote:
          >
          > Hello Ian..
          >
          > Your posting about the "fractured rock" is very
          > interesting. Do you have any schematics to pass on?
          > If you could email me a set, I would greatly
          > appreciate it... 73... John
          >
          > yiannis_w8gxu@...
          > ***********************************************
          >
          > --- imitchel4you <ian.mitchell@...> wrote:
          >
          > > Hi, here's just a bit of info on the fractured rock:
          > >
          > > * tunes 80M band but can be configured for 160, 40,
          > > 20 or 20/40 etc
          > > and AM broadcast using either fundamental or
          > > harmonic sampling
          > > * 7 pole bandpass filter using moulded inductors
          > > * preamp of about 12db (but you can change it) - in
          > > my area signals
          > > are few and low level - also it provides the correct
          > > impedance to the
          > > filter , and sets the bias voltage and low impedance
          > > to the QSD
          > > * the LO is based on a 32bit 4th order sigma-delta
          > > modulator feeding a
          > > PLL with a reference frequency of 100KHz (I didn't
          > > notice any spurs
          > > but i've only been testing for a couple of nights) -
          > > frequency range
          > > is 10-20MHz
          > > * the QSD divides the LO by four and is a four-way
          > > commutating switch
          > > * the LM837 has a GBW of 25MHz and noise of less
          > > than 4nV/rtHz and is
          > > powered at 9V to improve dynamic range - it is a
          > > quad op-amp
          > > configured to offer a high impedance to all four
          > > switches
          > > * the LO is set by sending the decimal ascii
          > > frequency in Hz to a COM port
          > >
          > > Cheers, Ian
          > >
          > >
          > >
          > >
          >
          >
          > __________________________________________________
          > Do You Yahoo!?
          > Tired of spam? Yahoo! Mail has the best spam protection around
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          >
        • Jerry Flanders
          Using PowerSDR with my newly constructed 80/40 SR40 v6.1, I see a big carrier sig in the center of the range (equiv to 7056 KHz tuned freq). I assumed this
          Message 4 of 14 , Sep 30, 2006
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            Using PowerSDR with my newly constructed 80/40 SR40 v6.1, I see a big
            "carrier" sig in the center of the range (equiv to 7056 KHz tuned
            freq). I assumed this was just some kind of leakage from the LO which
            I didn't understand, but now I have discovered it stays on even when
            the SR40 is powered down (even unplugged from sound card). It also
            does not appear when I use a laptop (mono mic input) instead of the
            desktop computer (line in, stereo).

            It is big, -44dB vs nearby "grass" of -130 (SR40 off).

            It is obviously something at DC being generated in my sound card
            (cheapie Motherboard Realtek AC'97).

            Anybody know a way to null this out or reduce it short of replacing
            the sound card?

            Jerry W4UK
          • ptapon217
            Hello, Is there (will be) a kit available? If yes, I d like one. Just let me know. JEAN
            Message 5 of 14 , Oct 1, 2006
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              Hello,

              Is there (will be) a kit available? If yes, I'd like one.
              Just let me know.

              JEAN


              --- In softrock40@yahoogroups.com, "imitchel4you" <ian.mitchell@...>
              wrote:
              >
              > Hi John, please see:
              > http://groups.yahoo.com/group/softrock40/files/fracturedrock/fr80.pdf
              >
              > cheers
              >
            • imitchel4you
              Jean, right now there is no kit. I ve had some PCBs made to do the initial testing but I still need to do some more testing, particularly with sub-harmics and
              Message 6 of 14 , Oct 1, 2006
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                Jean, right now there is no kit. I've had some PCBs made to do the
                initial testing but I still need to do some more testing, particularly
                with sub-harmics and the AM broadcast band (in which there are local
                large signal levels).

                Also the microcontroller code needs a little more work to make it
                smart enough to set the up/down signal on the QSD to reverse I/Q based
                on the frequency. It would also be useful to get it to program the
                EEPROM to remember a specific frequency that it would default to at
                start up. Then it could be used as a kind of programmable softrock.

                No plans for a kit, but I would be happy to provide a PCB and
                programmed microcontroller a little later down the track. All the
                other parts are easy to get.

                Cheers, Ian

                --- In softrock40@yahoogroups.com, "ptapon217" <ptapon217@...> wrote:
                >
                > Hello,
                >
                > Is there (will be) a kit available? If yes, I'd like one.
                > Just let me know.
                >
                > JEAN
                >
                >
                > --- In softrock40@yahoogroups.com, "imitchel4you" <ian.mitchell@>
                > wrote:
                > >
                > > Hi John, please see:
                > > http://groups.yahoo.com/group/softrock40/files/fracturedrock/fr80.pdf
                > >
                > > cheers
                > >
                >
              • FRANCIS CARCIA
                Ian, I was looking at your design and it looks lik eyou are using the VCO in the 4046. I would think an external VCO would be a lot cleaner??? frank wa1gfz
                Message 7 of 14 , Oct 1, 2006
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                  Ian,
                  I was looking at your design and it looks lik eyou are using the VCO in the 4046.
                  I would think an external VCO would be a lot cleaner??? frank wa1gfz

                  imitchel4you <ian.mitchell@...> wrote:
                  Jean, right now there is no kit. I've had some PCBs made to do the
                  initial testing but I still need to do some more testing, particularly
                  with sub-harmics and the AM broadcast band (in which there are local
                  large signal levels).

                  Also the microcontroller code needs a little more work to make it
                  smart enough to set the up/down signal on the QSD to reverse I/Q based
                  on the frequency. It would also be useful to get it to program the
                  EEPROM to remember a specific frequency that it would default to at
                  start up. Then it could be used as a kind of programmable softrock.

                  No plans for a kit, but I would be happy to provide a PCB and
                  programmed microcontroller a little later down the track. All the
                  other parts are easy to get.

                  Cheers, Ian

                  --- In softrock40@yahoogro ups.com, "ptapon217" <ptapon217@. ..> wrote:
                  >
                  > Hello,
                  >
                  > Is there (will be) a kit available? If yes, I'd like one.
                  > Just let me know.
                  >
                  > JEAN
                  >
                  >
                  > --- In softrock40@yahoogro ups.com, "imitchel4you" <ian.mitchell@ >
                  > wrote:
                  > >
                  > > Hi John, please see:
                  > > http://groups. yahoo.com/ group/softrock40 /files/fractured rock/fr80. pdf
                  > >
                  > > cheers
                  > >
                  >


                • imitchel4you
                  Hi Frank, I m not sure what the phase noise is for the 4046 but the linearity is very good and varies by less than 0.4% across the tuning range. It would be
                  Message 8 of 14 , Oct 1, 2006
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                    Hi Frank,

                    I'm not sure what the phase noise is for the 4046 but the linearity is
                    very good and varies by less than 0.4% across the tuning range. It
                    would be hard to design a varicap based VCO as good as that.

                    To a large extent the phase noise will be determined by the noise on
                    the VCO input. With a sigma-delta modulator this noise is pushed well
                    away from the reference frequency and the loop filter is all that's
                    required to do a good job of filtering it. Theoretically the SD
                    modulator should push the phase noise below 100db.

                    As I've said, I'm still testing, but so far things are looking good.
                    My Tektronics TDS200 only shows noise above 50db below the fundamental
                    and the oscillator noise is below this. I'll be building a small test
                    oscillator like the XG2 to do some more testing. It'll be fun!

                    --- In softrock40@yahoogroups.com, FRANCIS CARCIA <carcia@...> wrote:
                    >
                    > Ian,
                    > I was looking at your design and it looks lik eyou are using the
                    VCO in the 4046.
                    > I would think an external VCO would be a lot cleaner??? frank wa1gfz
                    >
                    > imitchel4you <ian.mitchell@...> wrote:
                    > Jean, right now there is no kit. I've had some PCBs made
                    to do the
                    > initial testing but I still need to do some more testing, particularly
                    > with sub-harmics and the AM broadcast band (in which there are local
                    > large signal levels).
                    >
                    > Also the microcontroller code needs a little more work to make it
                    > smart enough to set the up/down signal on the QSD to reverse I/Q based
                    > on the frequency. It would also be useful to get it to program the
                    > EEPROM to remember a specific frequency that it would default to at
                    > start up. Then it could be used as a kind of programmable softrock.
                    >
                    > No plans for a kit, but I would be happy to provide a PCB and
                    > programmed microcontroller a little later down the track. All the
                    > other parts are easy to get.
                    >
                    > Cheers, Ian
                    >
                    > --- In softrock40@yahoogroups.com, "ptapon217" <ptapon217@> wrote:
                    > >
                    > > Hello,
                    > >
                    > > Is there (will be) a kit available? If yes, I'd like one.
                    > > Just let me know.
                    > >
                    > > JEAN
                    > >
                    > >
                    > > --- In softrock40@yahoogroups.com, "imitchel4you" <ian.mitchell@>
                    > > wrote:
                    > > >
                    > > > Hi John, please see:
                    > > >
                    http://groups.yahoo.com/group/softrock40/files/fracturedrock/fr80.pdf
                    > > >
                    > > > cheers
                    > > >
                    > >
                    >
                  • imitchel4you
                    Just one other general comment. I m really appreciating the comments received on this design. One simple change that I think should be made is to the resistors
                    Message 9 of 14 , Oct 1, 2006
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                      Just one other general comment. I'm really appreciating the comments
                      received on this design. One simple change that I think should be made
                      is to the resistors that set the opamp gain. I think the 1K/100K
                      combination is too high and will contribute to noise. They should be
                      reduced to 100/10K.

                      Thanks Frank, comments much appreciated!


                      --- In softrock40@yahoogroups.com, FRANCIS CARCIA <carcia@...> wrote:
                      >
                      > Ian,
                      > I was looking at your design and it looks lik eyou are using the
                      VCO in the 4046.
                      > I would think an external VCO would be a lot cleaner??? frank wa1gfz
                      >
                      > imitchel4you <ian.mitchell@...> wrote:
                      > Jean, right now there is no kit. I've had some PCBs made
                      to do the
                      > initial testing but I still need to do some more testing, particularly
                      > with sub-harmics and the AM broadcast band (in which there are local
                      > large signal levels).
                      >
                      > Also the microcontroller code needs a little more work to make it
                      > smart enough to set the up/down signal on the QSD to reverse I/Q based
                      > on the frequency. It would also be useful to get it to program the
                      > EEPROM to remember a specific frequency that it would default to at
                      > start up. Then it could be used as a kind of programmable softrock.
                      >
                      > No plans for a kit, but I would be happy to provide a PCB and
                      > programmed microcontroller a little later down the track. All the
                      > other parts are easy to get.
                      >
                      > Cheers, Ian
                      >
                      > --- In softrock40@yahoogroups.com, "ptapon217" <ptapon217@> wrote:
                      > >
                      > > Hello,
                      > >
                      > > Is there (will be) a kit available? If yes, I'd like one.
                      > > Just let me know.
                      > >
                      > > JEAN
                      > >
                      > >
                      > > --- In softrock40@yahoogroups.com, "imitchel4you" <ian.mitchell@>
                      > > wrote:
                      > > >
                      > > > Hi John, please see:
                      > > >
                      http://groups.yahoo.com/group/softrock40/files/fracturedrock/fr80.pdf
                      > > >
                      > > > cheers
                      > > >
                      > >
                      >
                    • olivier_maillard2000
                      Hello Ian, Two small questions : As I understand only 2 resistors of the group R23-26 must be inserted depending of the required division coefficient. The
                      Message 10 of 14 , Oct 3, 2006
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                        Hello Ian,

                        Two small questions :
                        As I understand only 2 resistors of the group R23-26 must be inserted
                        depending of the required division coefficient. The UpDown input of
                        the '191 is used to reverse the I and Q signal in the case where R24
                        and 25 are insterted.

                        As I see the AT2313 is used to provide the reference frequency to the
                        PLL and as frequency divider ? Is that correct ?
                        As I know on the Atmel uC the external counter clock input is gated
                        by the system clock. So the half period of the T1 input must be
                        longer than a clock period.
                        So the abolute max frequency possible on the Q1 output of the hc191
                        is 10Mhz.
                        Now the stupid question, whats is the consequence of the delay
                        introduced by this delay on the phase noise.
                        Is this eliminated by the loop filter ?

                        I have see somewhere else an interssant trick to overcome this
                        problem. The signal to divide was used to clock the CPU. So we have a
                        full synchrone divider.

                        Other question :
                        Is the source code for the AtTiny aviable ?

                        Best regards

                        Olivier HB9TOB

                        --- In softrock40@yahoogroups.com, "imitchel4you" <ian.mitchell@...>
                        wrote:
                        >
                        > Just one other general comment. I'm really appreciating the comments
                        > received on this design. One simple change that I think should be
                        made
                        > is to the resistors that set the opamp gain. I think the 1K/100K
                        > combination is too high and will contribute to noise. They should be
                        > reduced to 100/10K.
                        >
                        > Thanks Frank, comments much appreciated!
                        >
                        >
                        > --- In softrock40@yahoogroups.com, FRANCIS CARCIA <carcia@> wrote:
                        > >
                        > > Ian,
                        > > I was looking at your design and it looks lik eyou are using the
                        > VCO in the 4046.
                        > > I would think an external VCO would be a lot cleaner??? frank
                        wa1gfz
                        > >
                        > > imitchel4you <ian.mitchell@> wrote:
                        > > Jean, right now there is no kit. I've had some PCBs made
                        > to do the
                        > > initial testing but I still need to do some more testing,
                        particularly
                        > > with sub-harmics and the AM broadcast band (in which there are
                        local
                        > > large signal levels).
                        > >
                        > > Also the microcontroller code needs a little more work to make it
                        > > smart enough to set the up/down signal on the QSD to reverse I/Q
                        based
                        > > on the frequency. It would also be useful to get it to program the
                        > > EEPROM to remember a specific frequency that it would default to
                        at
                        > > start up. Then it could be used as a kind of programmable
                        softrock.
                        > >
                        > > No plans for a kit, but I would be happy to provide a PCB and
                        > > programmed microcontroller a little later down the track. All the
                        > > other parts are easy to get.
                        > >
                        > > Cheers, Ian
                        > >
                        > > --- In softrock40@yahoogroups.com, "ptapon217" <ptapon217@> wrote:
                        > > >
                        > > > Hello,
                        > > >
                        > > > Is there (will be) a kit available? If yes, I'd like one.
                        > > > Just let me know.
                        > > >
                        > > > JEAN
                        > > >
                        > > >
                        > > > --- In softrock40@yahoogroups.com, "imitchel4you"
                        <ian.mitchell@>
                        > > > wrote:
                        > > > >
                        > > > > Hi John, please see:
                        > > > >
                        >
                        http://groups.yahoo.com/group/softrock40/files/fracturedrock/fr80.pdf
                        > > > >
                        > > > > cheers
                        > > > >
                        > > >
                        > >
                        >
                      • imitchel4you
                        Hi Olivier sorry for taking so long to respond... discovered that at 100KHz ref the synthsizer was not working so well...read on ... yep you can configure to
                        Message 11 of 14 , Oct 4, 2006
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                          Hi Olivier

                          sorry for taking so long to respond... discovered that at 100KHz ref
                          the synthsizer was not working so well...read on

                          --- In softrock40@yahoogroups.com, "olivier_maillard2000"
                          <maillard@...> wrote:
                          >
                          > Hello Ian,
                          >
                          > Two small questions :
                          > As I understand only 2 resistors of the group R23-26 must be inserted
                          > depending of the required division coefficient.

                          yep you can configure to divide by an extra 2 or 4 for the lower bands

                          > The UpDown input of
                          > the '191 is used to reverse the I and Q signal in the case where R24
                          > and 25 are insterted.

                          or for 3rd harmonic sampling. a side effect of harmonic sampling is
                          that I and Q are reversed - the microcontroller can check the
                          frequency and count down instead of up so you don't have to change the
                          setting in the software

                          >
                          > As I see the AT2313 is used to provide the reference frequency to the
                          > PLL and as frequency divider ? Is that correct ?

                          yes, both, a fixed reference frequency and a programmable divider

                          > As I know on the Atmel uC the external counter clock input is gated
                          > by the system clock. So the half period of the T1 input must be
                          > longer than a clock period.
                          > So the abolute max frequency possible on the Q1 output of the hc191
                          > is 10Mhz.

                          atmel recommend clk/2.5 so the max is 8MHz

                          > Now the stupid question, whats is the consequence of the delay
                          > introduced by this delay on the phase noise.
                          > Is this eliminated by the loop filter ?

                          not stupid at all and it was a big concern for me. initially I was
                          using a reference of 100KHz. the LO locked great on the scope, but in
                          my listening peoples voices sounded somewhat distored. i then had the
                          idea of listing to the LO on my DX934 receiver and I could hear the
                          variation in the tone. a kind a warbling effect.

                          i'm not sure why but i don't think it is related to the uC essentially
                          sampling the signal but might be more due to the fact that the
                          variation of the programmable divider as a consequence of the sigma
                          delta modulator is a significat proportion of the integer value. eg if
                          the LO is 3.6MHz the integer divider will be 36, but the variation to
                          this is about +-7 which is a +-20% variation. it might also be
                          integer-N boundary spurs which occur when the fractional part is very
                          small and the output frequency is close to a multiple of the
                          comparison frequency - which can also happen on submultiples of the
                          reference frequency

                          as an experiment I set the reference frequency to 10KHz and removed
                          the fractional-N code so that it operated in the standard PLL
                          arrangment (frequency steps of 10KHz only). then the tone sounded fine
                          in the DX394 (the warbling had gone). band conditions were poor last
                          night so I didn't get much of a chance to listen to SSB signals

                          anyway I replaced the fraction-N code but with a 10KHz reference and
                          the warbling had gone (it may have been slightly distorted but it's
                          hard to tell) - but I'm still not convinced - I need to do more
                          listening (at 10KHz the integer divider is 360 and the variation is
                          now just 2%)

                          one thing to try is including an extra order (5th) in the modulator
                          and see what that sounds like

                          >
                          > I have see somewhere else an interssant trick to overcome this
                          > problem. The signal to divide was used to clock the CPU. So we have a
                          > full synchrone divider.

                          yes, but i was worried the uC would crash because the specs say the
                          clock should not vary by more that 4% (or something like that) over
                          short periods so that scared me off :-)

                          >
                          > Other question :
                          > Is the source code for the AtTiny aviable ?

                          yep, just posted it in the fracturedrock folder

                          >
                          > Best regards
                          >
                          > Olivier HB9TOB
                          >
                        • olivier_maillard2000
                          Hello, This random delay between the last pulse provided by the 191 and the arrival of the information on the phase comparator sound very bad to me. It can be
                          Message 12 of 14 , Oct 6, 2006
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                            Hello,

                            This random delay between the last pulse provided by the '191 and the
                            arrival of the information on the phase comparator sound very bad to me.
                            It can be on the worst case a whole period of the 20Mhz oscilltor.
                            Witch can be 40% of the clock of 8Mhz.

                            My sugestion is to add a D Flip-Flop (edge trigerred) between the CT1
                            output of the Atmel and the input of the phase comparator.
                            CT1 conected on the D input.
                            The D Flip-Flop will be clocked by the Output of the '191.

                            In the Atmel you divide by n-1.
                            After n-1 pulse from the '191 the output of CT1 will change with the
                            random delay.
                            At the next pulse comming from the '191 the latch will IMMADIATLY send
                            the information to the phase comparator.

                            The delay is out !

                            My second sugestion is for your reference clock.
                            My did you not use the same trick used in the dual module PLL.

                            Make the divisor between the system colock and the reference CLOCK of
                            the PLL variable.
                            The divisor of course stay also variable.

                            From the RS232 interface you send booth information of the Atmel.
                            In the main computer you have to do some math to find the ratio with
                            the smallest round divisor possible to obtian the desired frequency.

                            But all this is only my point of you and I have almost no time to
                            experiment this.
                            But building a low cost variable oscillator with common parts for the
                            soft rock in definittly a good idea.

                            73's de Olivier HB9TOB
                          • Ian Mitchell
                            Olivier, I really appreciate your suggestions. I d like to try the D-FF idea but that would require an additional IC. I d previously built a 32bit DDS driven
                            Message 13 of 14 , Oct 8, 2006
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                              Olivier, I really appreciate your suggestions. I'd like to try the D-FF
                              idea but that would require an additional IC.

                              I'd previously built a 32bit DDS driven PLL using AN AVR and a fixed
                              divisor of 256 (but not incorporated into a receiver). The DDS has an
                              equivalent clock of 2.2MHz (with the AVR at 20MHz) and generates a
                              reference frequency of between 39KHz and 78KHz via an R-2R D/A
                              converter. It also has a programmable divisor that the AVR can set to
                              divide the 10-20MHz output. So, I was able to set the output to 3.6MHz
                              and do the listening test with the DX394. And, no warbling, a very pure
                              tone it seemed.

                              I designed this circuit for use in a 0-30MHz SDR that I was hoping to
                              develop after the FR80.

                              With the current FR80 circuit I could use the second half of the 4053 to
                              get a fixed division of 64 and add the components for the A/D converter
                              to the AVR - no extra IC required. The reference frequency would need to
                              be between 156KHz and 312KHz and the equivalent DDS clock would be 2MHz
                              (one extra cycle required because the original circuit had enough SRAM
                              to move the sine table into and access that - with 2313 the table needs
                              to be program memory which takes an extra cycle access).

                              In this case there are 4x fewer samples per cycle but if it works... :-)

                              olivier_maillard2000 wrote:
                              >
                              > Hello,
                              >
                              > This random delay between the last pulse provided by the '191 and the
                              > arrival of the information on the phase comparator sound very bad to me.
                              > It can be on the worst case a whole period of the 20Mhz oscilltor.
                              > Witch can be 40% of the clock of 8Mhz.
                              >
                              > My sugestion is to add a D Flip-Flop (edge trigerred) between the CT1
                              > output of the Atmel and the input of the phase comparator.
                              > CT1 conected on the D input.
                              > The D Flip-Flop will be clocked by the Output of the '191.
                              >
                              > In the Atmel you divide by n-1.
                              > After n-1 pulse from the '191 the output of CT1 will change with the
                              > random delay.
                              > At the next pulse comming from the '191 the latch will IMMADIATLY send
                              > the information to the phase comparator.
                              >
                              > The delay is out !
                              >
                              > My second sugestion is for your reference clock.
                              > My did you not use the same trick used in the dual module PLL.
                              >
                              > Make the divisor between the system colock and the reference CLOCK of
                              > the PLL variable.
                              > The divisor of course stay also variable.
                              >
                              > >From the RS232 interface you send booth information of the Atmel.
                              > In the main computer you have to do some math to find the ratio with
                              > the smallest round divisor possible to obtian the desired frequency.
                              >
                              > But all this is only my point of you and I have almost no time to
                              > experiment this.
                              > But building a low cost variable oscillator with common parts for the
                              > soft rock in definittly a good idea.
                              >
                              > 73's de Olivier HB9TOB
                              >
                              >

                              --
                              Ian Mitchell
                              Research Services
                              University of Tasmania
                              Private Bag 1
                              Hobart, Tasmania, Australia, 7001

                              Phone (03) 6226 7457
                              Fax (03) 6226 2765

                              Intl Phone +61 3 6226 7457
                              Intl Fax +61 3 6226 2765

                              http://www.research.utas.edu.au/
                              "...for who can escape what he desires."
                              Genesis, And Then There Were Three, 1978
                            • old_newcomer
                              ... Where is the file FR80.PDF just? The FRACTUREDROCK directory is not existing. Regards
                              Message 14 of 14 , Apr 6, 2009
                              • 0 Attachment
                                --- In softrock40@yahoogroups.com, "imitchel4you" <ian.mitchell@...> wrote:
                                >
                                > Hi John, please see:
                                > http://groups.yahoo.com/group/softrock40/files/fracturedrock/fr80.pdf
                                >
                                > cheers
                                >

                                Where is the file FR80.PDF just?

                                The FRACTUREDROCK directory is not existing.

                                Regards

                                >
                                > --- In softrock40@yahoogroups.com, john sakellakis <yiannis_w8gxu@>
                                > wrote:
                                > >
                                > > Hello Ian..
                                > >
                                > > Your posting about the "fractured rock" is very
                                > > interesting. Do you have any schematics to pass on?
                                > > If you could email me a set, I would greatly
                                > > appreciate it... 73... John
                                > >
                                > > yiannis_w8gxu@
                                > > ***********************************************
                                > >
                                > > --- imitchel4you <ian.mitchell@> wrote:
                                > >
                                > > > Hi, here's just a bit of info on the fractured rock:
                                > > >
                                > > > * tunes 80M band but can be configured for 160, 40,
                                > > > 20 or 20/40 etc
                                > > > and AM broadcast using either fundamental or
                                > > > harmonic sampling
                                > > > * 7 pole bandpass filter using moulded inductors
                                > > > * preamp of about 12db (but you can change it) - in
                                > > > my area signals
                                > > > are few and low level - also it provides the correct
                                > > > impedance to the
                                > > > filter , and sets the bias voltage and low impedance
                                > > > to the QSD
                                > > > * the LO is based on a 32bit 4th order sigma-delta
                                > > > modulator feeding a
                                > > > PLL with a reference frequency of 100KHz (I didn't
                                > > > notice any spurs
                                > > > but i've only been testing for a couple of nights) -
                                > > > frequency range
                                > > > is 10-20MHz
                                > > > * the QSD divides the LO by four and is a four-way
                                > > > commutating switch
                                > > > * the LM837 has a GBW of 25MHz and noise of less
                                > > > than 4nV/rtHz and is
                                > > > powered at 9V to improve dynamic range - it is a
                                > > > quad op-amp
                                > > > configured to offer a high impedance to all four
                                > > > switches
                                > > > * the LO is set by sending the decimal ascii
                                > > > frequency in Hz to a COM port
                                > > >
                                > > > Cheers, Ian
                                > > >
                                > > >
                                > > >
                                > > >
                                > >
                                > >
                                > > __________________________________________________
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                                > >
                                >
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