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Multiple soft rock receivers on one computer?

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  • n6rk
    Just joined the group. I would like to connect 4 to 6 SoftRock receivers to individual antennas and do some kind of diversity receiver. A couple of questions
    Message 1 of 19 , Apr 1 10:08 AM
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      Just joined the group. I would like to connect 4 to 6 SoftRock
      receivers to individual antennas and do some kind of diversity
      receiver. A couple of questions arise. First, can I use a hardware
      image rejection filter ahead of the SoftRock, and thereby only have
      to digitize I (and not Q)? This halves the number of sound card
      inputs required. Second, how many independent input channels
      (with their own A/D's) do the Delta 44 and Delta 66 cards have?
      I can't penetrate the marketing literature that assumes you are
      doing music recording and want to mix the inputs together and then
      digitize. I would like to believe the Delta 66 actually has 6
      independent inputs allowing 6 SoftRocks using I only. Can I run
      multiple instances of Rocky? To bring out the audio, I would probably
      use some cheap sound card(s). It seems to be very easy to get lots of
      DAC's on a card intended to do surround sound.

      73 Rick N6RK
    • Bill Dumke
      Rick, If you are going to use a hardware rejection filter ahead of the SoftRock, it would have to be a crystal filter of some kind or other to get any decent
      Message 2 of 19 , Apr 1 3:53 PM
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        Rick,

        If you are going to use a hardware rejection filter ahead of the
        SoftRock, it would have to be a crystal filter of some kind or other to
        get any decent image rejection. If you need to do that, why bother
        using the SoftRock?

        Using the SoftRock as it is with Rocky 1.41 and first doing an IQ
        calibration with a sweep generator (Here I use the DDS part of the
        DDS-60 with step attenuators to set the level.), I can regularly achieve
        over 70 dB of image rejection measured.

        Using a crystal filter, the audio quality would be degraded back to what
        it would be in a superhet with a crystal filter. Also you would be
        stuck with some leakage from the other sideband near the DC frequency
        point, the center frequency. And also some extra loss which would raise
        the noise figure of the unit.

        A better alternative would be a quadrature phase shift network on the
        audio outputs. Something like the polyphase network is difficult to
        build because a lot of very tightly hand matched resistors and
        capacitors are required. The best performance I have seen on this is
        about 60 or 70 dB image rejection for 7 poles. But that requires some
        work. You can do the same thing with op amps like Dan Tayloe did in his
        NC2030 transceiver with an op amp 90 degree phasing network, but he only
        used two poles in each leg, so his image rejection would not be anywhere
        near as good. With an audio quadrature network, you would only have one
        audio channel per SoftRock and the audio would still be better than what
        you would get with a crystal filter if properly designed and built.
        But this would limit your bandpass to only one audio channel, maybe 3
        kHz tops. You could drive something like the Mixw2 software directly
        with image rejection, but you wouldn't be able to tune over as wide a
        range as with Rocky and the SoftRock directly, where you can get 90+ kHz
        tuning range with a 96 kHz sampling rate sound card like the Delta 44
        without needing any VFO.

        The Delta 44 only has two stereo inputs. Each one of the 1/4" plugs is
        only a mono connection. You need some special cables to get the
        SoftRock stereo output into the Delta 44. I bought mine at about
        $135.00 a while back.

        Ain't much that is free in this world.

        Bill WB5TCO

        n6rk wrote:

        > Just joined the group. I would like to connect 4 to 6 SoftRock
        > receivers to individual antennas and do some kind of diversity
        > receiver. A couple of questions arise. First, can I use a hardware
        > image rejection filter ahead of the SoftRock, and thereby only have
        > to digitize I (and not Q)? This halves the number of sound card
        > inputs required. Second, how many independent input channels
        > (with their own A/D's) do the Delta 44 and Delta 66 cards have?
        > I can't penetrate the marketing literature that assumes you are
        > doing music recording and want to mix the inputs together and then
        > digitize. I would like to believe the Delta 66 actually has 6
        > independent inputs allowing 6 SoftRocks using I only. Can I run
        > multiple instances of Rocky? To bring out the audio, I would probably
        > use some cheap sound card(s). It seems to be very easy to get lots of
        > DAC's on a card intended to do surround sound.
        >
        > 73 Rick N6RK
        >
        >
        >
        >
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      • Bill Dumke
        Correction: 80+ kHz Tuning Range avoiding the aliasing at the ends of the band. Bill
        Message 3 of 19 , Apr 1 4:11 PM
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          Correction: "80+ kHz Tuning Range" avoiding the aliasing at the ends
          of the band.

          Bill

          Bill Dumke wrote:

          >Rick,
          >
          >If you are going to use a hardware rejection filter ahead of the
          >SoftRock, it would have to be a crystal filter of some kind or other to
          >get any decent image rejection. If you need to do that, why bother
          >using the SoftRock?
          >
          >Using the SoftRock as it is with Rocky 1.41 and first doing an IQ
          >calibration with a sweep generator (Here I use the DDS part of the
          >DDS-60 with step attenuators to set the level.), I can regularly achieve
          >over 70 dB of image rejection measured.
          >
          >Using a crystal filter, the audio quality would be degraded back to what
          >it would be in a superhet with a crystal filter. Also you would be
          >stuck with some leakage from the other sideband near the DC frequency
          >point, the center frequency. And also some extra loss which would raise
          >the noise figure of the unit.
          >
          >A better alternative would be a quadrature phase shift network on the
          >audio outputs. Something like the polyphase network is difficult to
          >build because a lot of very tightly hand matched resistors and
          >capacitors are required. The best performance I have seen on this is
          >about 60 or 70 dB image rejection for 7 poles. But that requires some
          >work. You can do the same thing with op amps like Dan Tayloe did in his
          >NC2030 transceiver with an op amp 90 degree phasing network, but he only
          >used two poles in each leg, so his image rejection would not be anywhere
          >near as good. With an audio quadrature network, you would only have one
          >audio channel per SoftRock and the audio would still be better than what
          >you would get with a crystal filter if properly designed and built.
          >But this would limit your bandpass to only one audio channel, maybe 3
          >kHz tops. You could drive something like the Mixw2 software directly
          >with image rejection, but you wouldn't be able to tune over as wide a
          >range as with Rocky and the SoftRock directly, where you can get 90+ kHz
          >tuning range with a 96 kHz sampling rate sound card like the Delta 44
          >without needing any VFO.
          >
          >The Delta 44 only has two stereo inputs. Each one of the 1/4" plugs is
          >only a mono connection. You need some special cables to get the
          >SoftRock stereo output into the Delta 44. I bought mine at about
          >$135.00 a while back.
          >
          >Ain't much that is free in this world.
          >
          >Bill WB5TCO
          >
          >n6rk wrote:
          >
          >
          >
          >>Just joined the group. I would like to connect 4 to 6 SoftRock
          >>receivers to individual antennas and do some kind of diversity
          >>receiver. A couple of questions arise. First, can I use a hardware
          >>image rejection filter ahead of the SoftRock, and thereby only have
          >>to digitize I (and not Q)? This halves the number of sound card
          >>inputs required. Second, how many independent input channels
          >>(with their own A/D's) do the Delta 44 and Delta 66 cards have?
          >>I can't penetrate the marketing literature that assumes you are
          >>doing music recording and want to mix the inputs together and then
          >>digitize. I would like to believe the Delta 66 actually has 6
          >>independent inputs allowing 6 SoftRocks using I only. Can I run
          >>multiple instances of Rocky? To bring out the audio, I would probably
          >>use some cheap sound card(s). It seems to be very easy to get lots of
          >>DAC's on a card intended to do surround sound.
          >>
          >>73 Rick N6RK
          >>
          >>
          >>
          >>
          >>------------------------------------------------------------------------
          >>YAHOO! GROUPS LINKS
          >>
          >> * Visit your group "softrock40
          >> <http://groups.yahoo.com/group/softrock40>" on the web.
          >>
          >> * To unsubscribe from this group, send an email to:
          >> softrock40-unsubscribe@yahoogroups.com
          >> <mailto:softrock40-unsubscribe@yahoogroups.com?subject=Unsubscribe>
          >>
          >> * Your use of Yahoo! Groups is subject to the Yahoo! Terms of
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        • Bill Tracey
          Got a SoftRock V7 beta built and checked out today - looks pretty good. MDS of -112 dbm with a Delta 44 and -109 dbm with an Extigy. Pics and PowerSDR spec
          Message 4 of 19 , Apr 1 4:52 PM
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            Got a SoftRock V7 beta built and checked out today - looks pretty
            good. MDS of -112 dbm with a Delta 44 and -109 dbm with an Extigy. Pics
            and PowerSDR spec shots @
            http://ewjt.com/kd5tfd/sdr1k-notebook/sr40/sr7/index.html

            Cheers,

            Bill (kd5tfd)
          • John H. Fisher
            Beautiful job, Bill, as always :-) Thanks for sharing :-) ... -- Regards, John ========================================================= email:
            Message 5 of 19 , Apr 1 5:15 PM
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              Beautiful job, Bill, as always :-) Thanks for sharing :-)

              Bill Tracey wrote:
              > Got a SoftRock V7 beta built and checked out today - looks pretty
              > good. MDS of -112 dbm with a Delta 44 and -109 dbm with an Extigy. Pics
              > and PowerSDR spec shots @
              > http://ewjt.com/kd5tfd/sdr1k-notebook/sr40/sr7/index.html
              >
              > Cheers,
              >
              > Bill (kd5tfd)
              >
              >
              >
              --
              Regards,
              John

              =========================================================
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            • Bill Tracey
              I think there are a number of approaches one could take here -- simple diversity would allow one to pick the receiver with the strongest signal and use it.
              Message 6 of 19 , Apr 1 5:23 PM
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                I think there are a number of approaches one could take here -- simple
                diversity would allow one to pick the receiver with the strongest signal
                and use it. Cooler would be to combine the output of all the receivers
                together with the correct phase relationship to get some gain out of having
                all of the antennas. To do this I think one would need to clock all the
                SoftRocks from a single oscillator and clock all the A/D converters from a
                single master clock and do a little software to combine the signals with
                correct phase relationship. Beyond my DSP capabilities at the moment, but
                maybe someday. Certainly within the realm of possibilities.

                I'd not plan on doing something like this with off the shelf sound
                cards. There's currently some work going on to build an FPGA based USB
                connected hi quality sound card for SDR as part of the High Performance SDR
                project (http://hpsdr.org/index.html). The A/D D/A board for this guy is
                known as the Janus baord ( http://hpsdr.org/janus.html ). At the moment
                it's a 4 channel in 4 channel out configuration similar to the Delta
                44. Adding additional A/D converters on the input side to deal with
                multiple receivers should not be terribly difficult.

                All of this stuff is in the very early prototype stages. Don't know if
                there's anyone on the HPSDR crew currently thinking of multiple RX
                configurations .... if not we probably should think of such a configuration.

                Cheers.

                Bill (kd5tfd)


                At 12:08 PM 4/1/2006, n6rk wrote:
                >Just joined the group. I would like to connect 4 to 6 SoftRock
                >receivers to individual antennas and do some kind of diversity
                >receiver. A couple of questions arise. First, can I use a hardware
                >image rejection filter ahead of the SoftRock, and thereby only have
                >to digitize I (and not Q)? This halves the number of sound card
                >inputs required. Second, how many independent input channels
                >(with their own A/D's) do the Delta 44 and Delta 66 cards have?
                >I can't penetrate the marketing literature that assumes you are
                >doing music recording and want to mix the inputs together and then
                >digitize. I would like to believe the Delta 66 actually has 6
                >independent inputs allowing 6 SoftRocks using I only. Can I run
                >multiple instances of Rocky? To bring out the audio, I would probably
                >use some cheap sound card(s). It seems to be very easy to get lots of
                >DAC's on a card intended to do surround sound.
                >
                >73 Rick N6RK
              • Tony Parks
                Very good Bill! Thanks for making the performance data measurements on the v7.0 SoftRock and sharing the nice pictures. All of the v7.0 kit orders have been
                Message 7 of 19 , Apr 1 7:09 PM
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                  Very good Bill! Thanks for making the performance data measurements on the
                  v7.0 SoftRock and sharing the nice pictures.

                  All of the v7.0 kit orders have been filled with most of the kits in the
                  mail. Those not in the mail are packed and will go out on April 3.

                  Several orders for built v7.0 receivers will be filled in the next tens
                  days.

                  After filling all orders and setting aside the kits for the build orders, I
                  find I have still three v7.0 kits that can be sold. If you would like one
                  of the three kits, check with me before placing a PayPal order and I will
                  let you know if one of the kits can be yours. I am asking $20 for a v7.0
                  SoftRock kit which includes postage costs.

                  73,
                  Tony KB9YIG

                  ----- Original Message -----
                  From: "Bill Tracey" <kd5tfd@...>
                  To: <softrock40@yahoogroups.com>
                  Sent: Saturday, April 01, 2006 7:52 PM
                  Subject: [softrock40] SoftRock V7 beta pics and spectum shots


                  > Got a SoftRock V7 beta built and checked out today - looks pretty
                  > good. MDS of -112 dbm with a Delta 44 and -109 dbm with an Extigy. Pics
                  > and PowerSDR spec shots @
                  > http://ewjt.com/kd5tfd/sdr1k-notebook/sr40/sr7/index.html
                  >
                  > Cheers,
                  >
                  > Bill (kd5tfd)
                  >
                  >
                  >
                  >
                  >
                  > Yahoo! Groups Links
                  >
                  >
                  >
                  >
                  >
                  >
                • FRANCIS CARCIA
                  Bill, What do you consider MDS. We should work to a standard like 3 dB increase in audio or 10 dB S+N/N also I see you have 10 KHz selected. How much does mds
                  Message 8 of 19 , Apr 2 5:37 PM
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                    Bill,
                    What do you consider MDS. We should work to a standard like 3 dB increase in audio or 10 dB S+N/N also I see you have 10 KHz selected. How much does mds improve with CW filter selected? frank WA1GFZ (waiting for santa to arrive) 

                    Tony Parks <raparks@...> wrote:
                    Very good Bill!   Thanks for making the performance data measurements on the
                    v7.0 SoftRock and sharing the nice pictures.

                    All of the v7.0 kit orders have been filled with most of the kits in the
                    mail.  Those not in the mail are packed and will go out on April 3.

                    Several orders for built v7.0 receivers will be filled in the next tens
                    days.

                    After filling all orders and setting aside the kits for the build orders, I
                    find I have still three v7.0 kits that can be sold.  If you would like one
                    of the three kits, check with me before placing a PayPal order and I will
                    let you know if one of the kits can be yours.  I am asking $20 for a v7.0
                    SoftRock kit which includes postage costs.

                    73,
                    Tony KB9YIG

                    ----- Original Message -----
                    From: "Bill Tracey" <kd5tfd@...>
                    To: <softrock40@yahoogroups.com>
                    Sent: Saturday, April 01, 2006 7:52 PM
                    Subject: [softrock40] SoftRock V7 beta pics and spectum shots


                    > Got a SoftRock V7 beta built and checked out today  - looks pretty
                    > good.  MDS of -112 dbm with a Delta 44 and -109 dbm with an Extigy.  Pics
                    > and PowerSDR spec shots @
                    > http://ewjt.com/kd5tfd/sdr1k-notebook/sr40/sr7/index.html
                    >
                    > Cheers,
                    >
                    > Bill (kd5tfd)
                    >
                    >
                    >
                    >
                    >
                    > Yahoo! Groups Links
                    >
                    >
                    >
                    >
                    >
                    >


                  • FRANCIS CARCIA
                    Rick, I m using a Racal RA6830 as a front end for SDR. The Racal has dual 20 KHz roofing filters. I plan to run it against the soft rock 6 on 75 meters soon. i
                    Message 9 of 19 , Apr 2 5:47 PM
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                      Rick,
                      I'm using a Racal RA6830 as a front end for SDR. The Racal has dual 20 KHz roofing filters. I plan to run it against the soft rock 6 on 75 meters soon. i am not limited to a small section of a band since the SDR (I) is at the 455 KHz second IF frequency.
                      frank WA1GFZ

                      n6rk <richard@...> wrote:
                      Just joined the group.  I would like to connect 4 to 6 SoftRock
                      receivers to individual antennas and do some kind of diversity
                      receiver.  A couple of questions arise.  First, can I use a hardware
                      image rejection filter ahead of the SoftRock, and thereby only have
                      to digitize I (and not Q)?  This halves the number of sound card
                      inputs required.  Second, how many independent input channels
                      (with their own A/D's) do the Delta 44 and Delta 66 cards have?
                      I can't penetrate the marketing literature that assumes you are
                      doing music recording and want to mix the inputs together and then
                      digitize.  I would like to believe the Delta 66 actually has 6
                      independent inputs allowing 6 SoftRocks using I only.  Can I run
                      multiple instances of Rocky?  To bring out the audio, I would probably
                      use some cheap sound card(s).  It seems to be very easy to get lots of
                      DAC's on a card intended to do surround sound.

                      73 Rick N6RK




                    • Bill Dumke
                      Also I was wondering how you even did it? Here with my SoftRock 40 and Rocky 1.41, when I connect it to a 50 Ohm load, rather than the antenna with a lot of
                      Message 10 of 19 , Apr 2 5:52 PM
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                        Also I was wondering how you even did it? Here with my SoftRock 40 and
                        Rocky 1.41, when I connect it to a 50 Ohm load, rather than the antenna
                        with a lot of atmospheric noise on 40 meters, I see a lot of spurious
                        signals throughout the whole Rocky bandpass. It appears the digital ALC
                        in Rocky is causing this. If you turn it the ALC on the front panel of
                        Rocky it still does this, although the audio level heard in the speakers
                        can now be adjusted manually in that case. Did you find a clean "hole"
                        somewhere to get the reading.

                        Please describe the test system you were using and how you did it.

                        I wish Rocky could be modified to use just a fixed DSP gain as a
                        setting, so that Sun and sky noise measurements could be made to check
                        the receiver noise temperature of the VHF/UHF & microwave receive
                        systems. This is NOW important with SoftRock v7.0 which is intended for
                        VHF converters.

                        Bill WB5TCO

                        FRANCIS CARCIA wrote:

                        > Bill,
                        > What do you consider MDS. We should work to a standard like 3 dB
                        > increase in audio or 10 dB S+N/N also I see you have 10 KHz selected.
                        > How much does mds improve with CW filter selected? frank WA1GFZ
                        > (waiting for santa to arrive)
                        >
                        > */Tony Parks <raparks@...>/* wrote:
                        >
                        > Very good Bill! Thanks for making the performance data
                        > measurements on the
                        > v7.0 SoftRock and sharing the nice pictures.
                        >
                        > All of the v7.0 kit orders have been filled with most of the kits
                        > in the
                        > mail. Those not in the mail are packed and will go out on April 3.
                        >
                        > Several orders for built v7.0 receivers will be filled in the next
                        > tens
                        > days.
                        >
                        > After filling all orders and setting aside the kits for the build
                        > orders, I
                        > find I have still three v7.0 kits that can be sold. If you would
                        > like one
                        > of the three kits, check with me before placing a PayPal order and
                        > I will
                        > let you know if one of the kits can be yours. I am asking $20 for
                        > a v7.0
                        > SoftRock kit which includes postage costs.
                        >
                        > 73,
                        > Tony KB9YIG
                        >
                        > ----- Original Message -----
                        > From: "Bill Tracey" <kd5tfd@...>
                        > To: <softrock40@yahoogroups.com>
                        > Sent: Saturday, April 01, 2006 7:52 PM
                        > Subject: [softrock40] SoftRock V7 beta pics and spectum shots
                        >
                        >
                        > > Got a SoftRock V7 beta built and checked out today - looks pretty
                        > > good. MDS of -112 dbm with a Delta 44 and -109 dbm with an
                        > Extigy. Pics
                        > > and PowerSDR spec shots @
                        > > http://ewjt.com/kd5tfd/sdr1k-notebook/sr40/sr7/index.html
                        > >
                        > > Cheers,
                        > >
                        > > Bill (kd5tfd)
                        > >
                        > >
                        > >
                        > >
                        > >
                        > > Yahoo! Groups Links
                        > >
                        > >
                        > >
                        > >
                        > >
                        > >
                        >
                        >
                        >
                        > ------------------------------------------------------------------------
                        > YAHOO! GROUPS LINKS
                        >
                        > * Visit your group "softrock40
                        > <http://groups.yahoo.com/group/softrock40>" on the web.
                        >
                        > * To unsubscribe from this group, send an email to:
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                        > <mailto:softrock40-unsubscribe@yahoogroups.com?subject=Unsubscribe>
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                      • Bill Tracey
                        Actually the spectrum screen shots do not match the MDS measurement -- they were for a -54 dbm input, just trying to show the level of spurs and gunk I m
                        Message 11 of 19 , Apr 2 6:07 PM
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                          Actually the spectrum screen shots do not match the MDS measurement -- they
                          were for a -54 dbm input, just trying to show the level of spurs and gunk
                          I'm seeing.

                          The MDS definition I'm using is 3 db above the noise floor in a 500 hz
                          bandwidth, The measurement is done as follows:

                          Connect SoftRock and sound card. Apply -60 dbm signal from signal
                          generator approx 12 khz above osc freq of SoftRock. Null image, calibrate
                          level. Set PowerSDR for CW mode, 500 hz bandwidth. Turn off RF on signal
                          generator. Note avg singal strength reading on S Meter - call this
                          measurement A. Turn on signal generator - adjust level until avg signal
                          strength on S meter reads 3db above measurement A. Note amplitude level on
                          signal generator - this is what I call MDS.

                          Signal generator I'm using is an HP 8656b -- it's not been calibrated in a
                          few years,. however does seem to be accurate for level when compared to an
                          Elecraft XG2 which is the closest thing I've got to a calibrated level.

                          Credit for the methodology of doing the measurement goes to Phil Harman -
                          VK6APH who explained to me how to do it.

                          Cheers,

                          Bill (kd5tfd)

                          At 07:37 PM 4/2/2006, you wrote:
                          >Bill,
                          >What do you consider MDS. We should work to a standard like 3 dB increase
                          >in audio or 10 dB S+N/N also I see you have 10 KHz selected. How much does
                          >mds improve with CW filter selected? frank WA1GFZ (waiting for santa to
                          >arrive)
                        • Bill Dumke
                          Bill, So the PowerSDR software will allow for a fixed system gain, by turning off the AGC? That makes it more appropriate for us weak signal types, as opposed
                          Message 12 of 19 , Apr 2 6:16 PM
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                            Bill,

                            So the PowerSDR software will allow for a fixed system gain, by turning
                            off the AGC?

                            That makes it more appropriate for us weak signal types, as opposed to
                            the current version of Rocky, for looking at Sun to Sky noise temperature.

                            The method you used looks good to me.

                            Bill WB5TCO

                            Bill Tracey wrote:

                            > Actually the spectrum screen shots do not match the MDS measurement --
                            > they
                            > were for a -54 dbm input, just trying to show the level of spurs and gunk
                            > I'm seeing.
                            >
                            > The MDS definition I'm using is 3 db above the noise floor in a 500 hz
                            > bandwidth, The measurement is done as follows:
                            >
                            > Connect SoftRock and sound card. Apply -60 dbm signal from signal
                            > generator approx 12 khz above osc freq of SoftRock. Null image,
                            > calibrate
                            > level. Set PowerSDR for CW mode, 500 hz bandwidth. Turn off RF on
                            > signal
                            > generator. Note avg singal strength reading on S Meter - call this
                            > measurement A. Turn on signal generator - adjust level until avg signal
                            > strength on S meter reads 3db above measurement A. Note amplitude
                            > level on
                            > signal generator - this is what I call MDS.
                            >
                            > Signal generator I'm using is an HP 8656b -- it's not been calibrated
                            > in a
                            > few years,. however does seem to be accurate for level when compared
                            > to an
                            > Elecraft XG2 which is the closest thing I've got to a calibrated level.
                            >
                            > Credit for the methodology of doing the measurement goes to Phil Harman -
                            > VK6APH who explained to me how to do it.
                            >
                            > Cheers,
                            >
                            > Bill (kd5tfd)
                            >
                            > At 07:37 PM 4/2/2006, you wrote:
                            > >Bill,
                            > >What do you consider MDS. We should work to a standard like 3 dB
                            > increase
                            > >in audio or 10 dB S+N/N also I see you have 10 KHz selected. How much
                            > does
                            > >mds improve with CW filter selected? frank WA1GFZ (waiting for santa to
                            > >arrive)
                            >
                            >
                            >
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                          • Bill Dumke
                            Bill, Which version of PowerSDR were you using? Also have you tried the same measurement on a SoftRock 40 or any of the other SoftRock versions? It would be
                            Message 13 of 19 , Apr 2 6:23 PM
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                              Bill,

                              Which version of PowerSDR were you using?

                              Also have you tried the same measurement on a SoftRock 40 or any of the
                              other SoftRock versions?

                              It would be interesting to see what results you have on the other bands
                              to compare the SoftRock v7.0 performance.

                              Bill WB5TCO

                              Bill Dumke wrote:

                              >Bill,
                              >
                              >So the PowerSDR software will allow for a fixed system gain, by turning
                              >off the AGC?
                              >
                              >That makes it more appropriate for us weak signal types, as opposed to
                              >the current version of Rocky, for looking at Sun to Sky noise temperature.
                              >
                              >The method you used looks good to me.
                              >
                              >Bill WB5TCO
                              >
                              >Bill Tracey wrote:
                              >
                              >
                              >
                              >>Actually the spectrum screen shots do not match the MDS measurement --
                              >>they
                              >>were for a -54 dbm input, just trying to show the level of spurs and gunk
                              >>I'm seeing.
                              >>
                              >>The MDS definition I'm using is 3 db above the noise floor in a 500 hz
                              >>bandwidth, The measurement is done as follows:
                              >>
                              >>Connect SoftRock and sound card. Apply -60 dbm signal from signal
                              >>generator approx 12 khz above osc freq of SoftRock. Null image,
                              >>calibrate
                              >>level. Set PowerSDR for CW mode, 500 hz bandwidth. Turn off RF on
                              >>signal
                              >>generator. Note avg singal strength reading on S Meter - call this
                              >>measurement A. Turn on signal generator - adjust level until avg signal
                              >>strength on S meter reads 3db above measurement A. Note amplitude
                              >>level on
                              >>signal generator - this is what I call MDS.
                              >>
                              >>Signal generator I'm using is an HP 8656b -- it's not been calibrated
                              >>in a
                              >>few years,. however does seem to be accurate for level when compared
                              >>to an
                              >>Elecraft XG2 which is the closest thing I've got to a calibrated level.
                              >>
                              >>Credit for the methodology of doing the measurement goes to Phil Harman -
                              >>VK6APH who explained to me how to do it.
                              >>
                              >>Cheers,
                              >>
                              >>Bill (kd5tfd)
                              >>
                              >>At 07:37 PM 4/2/2006, you wrote:
                              >>
                              >>
                              >>>Bill,
                              >>>What do you consider MDS. We should work to a standard like 3 dB
                              >>>
                              >>>
                              >>increase
                              >>
                              >>
                              >>>in audio or 10 dB S+N/N also I see you have 10 KHz selected. How much
                              >>>
                              >>>
                              >>does
                              >>
                              >>
                              >>>mds improve with CW filter selected? frank WA1GFZ (waiting for santa to
                              >>>arrive)
                              >>>
                              >>>
                              >>
                              >>
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                            • FRANCIS CARCIA
                              I prefer to monitor recovered audio with an RMS volt meter. fc Bill Dumke wrote: Bill, So the PowerSDR software will allow for a fixed
                              Message 14 of 19 , Apr 2 6:31 PM
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                                I prefer to monitor recovered audio with an RMS volt meter.
                                fc

                                Bill Dumke <billd@...> wrote:
                                Bill,

                                So the PowerSDR software will allow for a fixed system gain, by turning
                                off the AGC?

                                That makes it more appropriate for us weak signal types, as opposed to
                                the current version of Rocky, for looking at Sun to Sky noise temperature.

                                The method you used looks good to me.

                                Bill WB5TCO

                                Bill Tracey wrote:

                                > Actually the spectrum screen shots do not match the MDS measurement --
                                > they
                                > were for a -54 dbm input, just trying to show the level of spurs and gunk
                                > I'm seeing.
                                >
                                > The MDS definition I'm using is 3 db above the noise floor in a 500 hz
                                > bandwidth, The measurement is done as follows:
                                >
                                > Connect SoftRock and sound card. Apply -60 dbm signal from signal
                                > generator approx 12 khz above osc freq of SoftRock. Null image,
                                > calibrate
                                > level. Set PowerSDR for CW mode, 500 hz bandwidth. Turn off RF on
                                > signal
                                > generator. Note avg singal strength reading on S Meter - call this
                                > measurement A. Turn on signal generator - adjust level until avg signal
                                > strength on S meter reads 3db above measurement A. Note amplitude
                                > level on
                                > signal generator - this is what I call MDS.
                                >
                                > Signal generator I'm using is an HP 8656b -- it's not been calibrated
                                > in a
                                > few years,. however does seem to be accurate for level when compared
                                > to an
                                > Elecraft XG2 which is the closest thing I've got to a calibrated level.
                                >
                                > Credit for the methodology of doing the measurement goes to Phil Harman -
                                > VK6APH who explained to me how to do it.
                                >
                                > Cheers,
                                >
                                > Bill (kd5tfd)
                                >
                                > At 07:37 PM 4/2/2006, you wrote:
                                > >Bill,
                                > >What do you consider MDS. We should work to a standard like 3 dB
                                > increase
                                > >in audio or 10 dB S+N/N also I see you have 10 KHz selected. How much
                                > does
                                > >mds improve with CW filter selected? frank WA1GFZ (waiting for santa to
                                > >arrive)
                                >
                                >
                                >
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                                >
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                              • FRANCIS CARCIA
                                -109 dBM MDS is not that great for above 20 meter work. I wonder if the op amp gain needs to increase. Does the background noise come up on the spectrum
                                Message 15 of 19 , Apr 2 6:42 PM
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                                  -109 dBM MDS is not that great for above 20 meter work. I wonder if the op amp gain needs to increase. Does the background noise come up on the spectrum display when the V7 is connected without an antenna. Do you know what level input saturates the sound card making spure. IE dynamic range? I use a pair of HP8640Bs myself.
                                  I like to see a mds lower than -125 dBm above 14 MHz. I usually set a RA6830 to -130 dBM and that has just enough MDS for 10 meters. Might need a preamplifier...fc

                                  Bill Tracey <kd5tfd@...> wrote:
                                  Actually the spectrum screen shots do not match the MDS measurement -- they
                                  were for a -54 dbm input, just trying to show the level of spurs and gunk
                                  I'm seeing.

                                  The MDS definition I'm using is 3 db above the noise floor in a 500 hz
                                  bandwidth,  The measurement is done as follows:

                                  Connect SoftRock and sound card.  Apply -60 dbm signal from signal
                                  generator approx 12 khz above osc freq of SoftRock.   Null image, calibrate
                                  level.  Set PowerSDR for CW mode, 500 hz bandwidth.  Turn off RF on signal
                                  generator.  Note avg singal strength reading on S Meter - call this
                                  measurement A.  Turn on signal generator - adjust level until avg signal
                                  strength on S meter reads 3db above measurement A.  Note amplitude level on
                                  signal generator - this is what I call MDS.

                                  Signal generator I'm using is an HP 8656b  -- it's not been calibrated in a
                                  few years,. however does seem to be accurate for level when compared to an
                                  Elecraft XG2 which is the closest thing I've got to a calibrated level.

                                  Credit for the methodology of doing the measurement goes to Phil Harman -
                                  VK6APH who explained to me how to do it.

                                  Cheers,

                                  Bill (kd5tfd)

                                  At 07:37 PM 4/2/2006, you wrote:
                                  >Bill,
                                  >What do you consider MDS. We should work to a standard like 3 dB increase
                                  >in audio or 10 dB S+N/N also I see you have 10 KHz selected. How much does
                                  >mds improve with CW filter selected? frank WA1GFZ (waiting for santa to
                                  >arrive)



                                • Bill Tracey
                                  PowerSDR does allow you to turn off the AGC and set a fixed gain - although I did not do that on this these measurements and don t think it matters as I
                                  Message 16 of 19 , Apr 2 9:45 PM
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                                    PowerSDR does allow you to turn off the AGC and set a fixed gain - although
                                    I did not do that on this these measurements and don't think it matters as
                                    I believe the signal strength is computed before the AGC is applied. Next
                                    time I do some measurements I'll play around and see if the AGC setting
                                    makes any difference.

                                    Regards,

                                    Bill (kd5tfd)


                                    At 08:16 PM 4/2/2006, Bill Dumke wrote:
                                    >Bill,
                                    >
                                    >So the PowerSDR software will allow for a fixed system gain, by turning
                                    >off the AGC?
                                    >
                                    >That makes it more appropriate for us weak signal types, as opposed to
                                    >the current version of Rocky, for looking at Sun to Sky noise temperature.
                                    >
                                    >The method you used looks good to me.
                                    >
                                    >Bill WB5TCO
                                  • Ross Stenberg
                                    In looking through the archives, I m confused to the MDS of v4 5,6,and 7 as measured with the same methodology. Does anyone have those figures? Thanks and 73,
                                    Message 17 of 19 , Apr 3 9:45 AM
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                                      In looking through the archives, I'm confused to the MDS of v4 5,6,and 7 as measured with the same methodology. Does anyone have those figures?
                                       
                                      Thanks and 73,
                                      Ross K9COX
                                       


                                    • KD5NWA
                                      It s going to vary according to what sound card, and the bit resolution you take the measurement with. ... Cecil Bayona KD5NWA www.qrpradio.com I fail to see
                                      Message 18 of 19 , Apr 3 10:51 AM
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                                        It's going to vary according to what sound card, and the bit resolution you take the measurement with.

                                        At 11:45 AM 4/3/2006, you wrote:
                                        In looking through the archives, I'm confused to the MDS of v4 5,6,and 7 as measured with the same methodology. Does anyone have those figures?
                                         
                                        Thanks and 73,
                                        Ross K9COX
                                         




                                        YAHOO! GROUPS LINKS




                                        Cecil Bayona
                                        KD5NWA
                                        www.qrpradio.com

                                        I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ...

                                      • Ross Stenberg
                                        Thanks, but how about all versions used with the same 24 bit, good dynamic range, low noise, quality sound card such as the Delta 44 or similar; or any such
                                        Message 19 of 19 , Apr 3 12:41 PM
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                                          Thanks, but how about all versions used with the same 24 bit, good dynamic range, low noise, quality sound card such as the Delta 44 or similar; or any such card as long as we are comparing apples to apples?


                                          From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of KD5NWA
                                          Sent: Monday, April 03, 2006 12:51 PM
                                          To: softrock40@yahoogroups.com
                                          Subject: Re: [softrock40] MDS of various versions

                                          It's going to vary according to what sound card, and the bit resolution you take the measurement with.

                                          At 11:45 AM 4/3/2006, you wrote:
                                          In looking through the archives, I'm confused to the MDS of v4 5,6,and 7 as measured with the same methodology. Does anyone have those figures?
                                           
                                          Thanks and 73,
                                          Ross K9COX
                                           




                                          YAHOO! GROUPS LINKS




                                          Cecil Bayona
                                          KD5NWA
                                          www.qrpradio.com

                                          I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ...

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