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No new posts, no traffic, what's wrong ?

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  • dariusjack2006
    Message 1 of 10 , May 10, 2013
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    • Mark McCarron
      I m seeing the same thing here. Unless everyone suddenly became happy and finally read the entire user manual, I think there may be problems somewhere.
      Message 2 of 10 , May 10, 2013
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        I'm seeing the same thing here.  Unless everyone suddenly became happy and finally read the entire user manual, I think there may be problems somewhere.

        Regards,

        Mark McCarron


        To: SpectrumLabUsers@yahoogroups.com
        From: dariusjack2006@...
        Date: Fri, 10 May 2013 15:02:29 +0000
        Subject: [SpectrumLabUsers] No new posts, no traffic, what's wrong ?

         



      • Burt I. Weiner
        Both of your comments seem to be popping out on this end. I suspect that means the list is working properly. Burt, K6OQK At 08:30 AM 5/10/2013, Mark McCarron
        Message 3 of 10 , May 10, 2013
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          Both of your comments seem to be popping out on this end.  I suspect that means the list is working properly.

          Burt, K6OQK

          At 08:30 AM 5/10/2013, Mark McCarron wrote
           

          I'm seeing the same thing here.  Unless everyone suddenly became happy and finally read the entire user manual, I think there may be problems somewhere.

          Regards,

          Mark McCarron


          To: SpectrumLabUsers@yahoogroups.com
          From: dariusjack2006@...
          Date: Fri, 10 May 2013 15:02:29 +0000
          Subject: [SpectrumLabUsers] No new posts, no traffic, what's wrong ?

           



          Burt I. Weiner Associates
          Broadcast Technical Services
          Glendale, California  U.S.A.
          biwa@...
          www.biwa.cc
          K6OQK

        • michael
          Same here, am getting all the messages in this thread, maybe we have a large group of happy users. Michael D Calistoga, CA
          Message 4 of 10 , May 10, 2013
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            Same here, am getting all the messages in this thread, maybe we have a large group of happy users.

            Michael D
            Calistoga, CA
          • M. Ben Schuetz
            Hi all, I m searching for signals from 0.05 to 1 Hz using large bins, bin averaging and large FFT decimations. For the present I am using both dc and pulsed
            Message 5 of 10 , May 10, 2013
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              Hi all,

              I'm searching for signals from 0.05 to 1 Hz using large bins, bin
              averaging and large FFT decimations. For the present I am using both dc
              and pulsed test signals, the background (dc) is between -80 and -90 dB
              with the pulsed test signal between -70 and -80 dB respectively. The
              detector is a photomultiplier detecting/counting single photons. The
              background test signal is from an LED fed with a dc level. The pulsed
              test signal is also from an LED running with 100 ns pulses. Thus, both
              the background and pulsed test signals are random events following
              Poisson statistics. Pause - - -. As near as can be determined, both
              the dc and pulsed test signals are behaving as they should.

              Now the problem. The test signal is nicely detected for several
              minutes, then fades 5 to 10 dB and recovers in another minute or two.
              The fading is not periodic, but has the rough appearances of
              periodicity. Might this be happening in SL? Is there some widget in SL
              that can prevent it?

              Best from Ben
            • Mark McCarron
              So, there are two test signals, one DC and the other pulsed??? You don t mention it, but is the 10dB drop in both the DC and pulsed sources, or just one one?
              Message 6 of 10 , May 10, 2013
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                So, there are two test signals, one DC and the other pulsed???  You don't mention it, but is the 10dB drop in both the DC and pulsed sources, or just one one?

                If it is in both, then I would suspect the common point in the power supply or mains.  Possible sources:

                1.  Load coming on/off.
                2.  Thermal changes
                3.  Induction/capacitance
                4.  External RF signal

                Another factor could be something in the LEDs themselves and how they handle thermal loads.

                Regards,

                Mark McCarron

                > To: SpectrumLabUsers@yahoogroups.com
                > From: kg4lra@...
                > Date: Fri, 10 May 2013 15:17:07 -0500
                > Subject: Re: [SpectrumLabUsers] Here is a post. Fading
                >
                > Hi all,
                >
                > I'm searching for signals from 0.05 to 1 Hz using large bins, bin
                > averaging and large FFT decimations. For the present I am using both dc
                > and pulsed test signals, the background (dc) is between -80 and -90 dB
                > with the pulsed test signal between -70 and -80 dB respectively. The
                > detector is a photomultiplier detecting/counting single photons. The
                > background test signal is from an LED fed with a dc level. The pulsed
                > test signal is also from an LED running with 100 ns pulses. Thus, both
                > the background and pulsed test signals are random events following
                > Poisson statistics. Pause - - -. As near as can be determined, both
                > the dc and pulsed test signals are behaving as they should.
                >
                > Now the problem. The test signal is nicely detected for several
                > minutes, then fades 5 to 10 dB and recovers in another minute or two.
                > The fading is not periodic, but has the rough appearances of
                > periodicity. Might this be happening in SL? Is there some widget in SL
                > that can prevent it?
                >
                > Best from Ben
                >
                >
                >
                >
                > ------------------------------------
                >
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              • wolf_dl4yhf
                Hello Ben, Difficult to say if this is a software feature, or the result of an automatic gain control (hardware), or similar. Maybe a sinewave test signal with
                Message 7 of 10 , May 10, 2013
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                  Hello Ben,

                  Difficult to say if this is a software feature, or the result of an
                  automatic gain control (hardware), or similar.

                  Maybe a sinewave test signal with constant amplitude, sufficiently
                  attenuated and added to the signal into the soundcard (via resistor
                  network) can shed some light on this.
                  I had a similar effect with one of my test PCs: Even if the soundcard's
                  input is configured as 'line-in', not as 'microphone in', there is an
                  AGC active in it, which reduces the audio gain if there is noise / hum /
                  etc entering the soundcard - outside the observed frequency band (seems
                  to be a broadband rectifier which generates the control voltage for the
                  AGC).

                  All the best,
                  Wolf .

                  Am 10.05.2013 22:17, schrieb M. Ben Schuetz:
                  > Hi all,
                  >
                  > I'm searching for signals from 0.05 to 1 Hz using large bins, bin
                  > averaging and large FFT decimations. For the present I am using both dc
                  > and pulsed test signals, the background (dc) is between -80 and -90 dB
                  > with the pulsed test signal between -70 and -80 dB respectively. The
                  > detector is a photomultiplier detecting/counting single photons. The
                  > background test signal is from an LED fed with a dc level. The pulsed
                  > test signal is also from an LED running with 100 ns pulses. Thus, both
                  > the background and pulsed test signals are random events following
                  > Poisson statistics. Pause - - -. As near as can be determined, both
                  > the dc and pulsed test signals are behaving as they should.
                  >
                  > Now the problem. The test signal is nicely detected for several
                  > minutes, then fades 5 to 10 dB and recovers in another minute or two.
                  > The fading is not periodic, but has the rough appearances of
                  > periodicity. Might this be happening in SL? Is there some widget in SL
                  > that can prevent it?
                  >
                  > Best from Ben
                  >
                  >
                  >
                  >
                  > ------------------------------------
                  >
                  > Yahoo! Groups Links
                  >
                  >
                  >
                  >
                  >
                • M. Ben Schuetz
                  Mark & Wolf, Thanks for the help. Regarding Mark s question, only the pulsed signal fades significantly. The dc LED is running at 60 microwatts, while the
                  Message 8 of 10 , May 10, 2013
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                    Mark & Wolf,

                    Thanks for the help. Regarding Mark's question, only the pulsed signal
                    fades significantly.
                    The dc LED is running at 60 microwatts, while the pulsed LED is less
                    than 6 milliwatts. The pulsed signal is only 100 ns long at a rep rate
                    of 0.4 Hz. Understated, heating may not be a problem here. To clarify,
                    the received, pulsed signal is stretched to 40 us before going to the box.

                    Wolf, you may have hit on it regarding an agc in the box. The
                    individual photon pulses (for either signal) are stretched to an
                    equivalent frequency of about 25 kHz. This may be on the ragged edge,
                    or over the edge, for this sound card. I'll try stretching all the
                    pulses more and if that doesn't help, try another sound card.

                    Great input guys.

                    Best from Ben


                    On 5/10/2013 4:34 PM, wolf_dl4yhf wrote:
                    > Hello Ben,
                    >
                    > Difficult to say if this is a software feature, or the result of an
                    > automatic gain control (hardware), or similar.
                    >
                    > Maybe a sinewave test signal with constant amplitude, sufficiently
                    > attenuated and added to the signal into the soundcard (via resistor
                    > network) can shed some light on this.
                    > I had a similar effect with one of my test PCs: Even if the soundcard's
                    > input is configured as 'line-in', not as 'microphone in', there is an
                    > AGC active in it, which reduces the audio gain if there is noise / hum /
                    > etc entering the soundcard - outside the observed frequency band (seems
                    > to be a broadband rectifier which generates the control voltage for the
                    > AGC).
                    >
                    > All the best,
                    > Wolf .
                    >
                    > Am 10.05.2013 22:17, schrieb M. Ben Schuetz:
                    >> Hi all,
                    >>
                    >> I'm searching for signals from 0.05 to 1 Hz using large bins, bin
                    >> averaging and large FFT decimations. For the present I am using both dc
                    >> and pulsed test signals, the background (dc) is between -80 and -90 dB
                    >> with the pulsed test signal between -70 and -80 dB respectively. The
                    >> detector is a photomultiplier detecting/counting single photons. The
                    >> background test signal is from an LED fed with a dc level. The pulsed
                    >> test signal is also from an LED running with 100 ns pulses. Thus, both
                    >> the background and pulsed test signals are random events following
                    >> Poisson statistics. Pause - - -. As near as can be determined, both
                    >> the dc and pulsed test signals are behaving as they should.
                    >>
                    >> Now the problem. The test signal is nicely detected for several
                    >> minutes, then fades 5 to 10 dB and recovers in another minute or two.
                    >> The fading is not periodic, but has the rough appearances of
                    >> periodicity. Might this be happening in SL? Is there some widget in SL
                    >> that can prevent it?
                    >>
                    >> Best from Ben
                    >>
                    >>
                    >>
                    >>
                    >> ------------------------------------
                    >>
                    >> Yahoo! Groups Links
                    >>
                    >>
                    >>
                    >>
                    >>
                    >
                    >
                    > ------------------------------------
                    >
                    > Yahoo! Groups Links
                    >
                    >
                    >
                  • M. Ben Schuetz
                    Well I screwed that explanation up nicely. Another try. The raw signal is both the background and pulsed signal. That signal is the total photon count and
                    Message 9 of 10 , May 10, 2013
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                      Well I screwed that explanation up nicely. Another try. The raw signal
                      is both the background and pulsed signal. That signal is the total
                      photon count and each count pulse is stretched to 50 ns before going to
                      the box. The raw count can be anything from 1 kHz up to 0.5 MHz. That
                      doesn't sound like it should work, but the whole of these pulses are
                      wavelike enough that the sound card pulls the low frequency components
                      through. The other, very low rep rate signal (0.3 Hz) is sent to the
                      box as a 40 us pulse.

                      I also somewhat misstated the pulsed LED info. While the pulsed LED is
                      pulsed with 6 milliwatts of peak power, it also has an optical filter
                      that drops the output photon count to about 1/4. The neat thing about
                      this whole deal is that the number of "signal" photons during the 100 ns
                      interval is only about 25x the number of photons received during the
                      same interval from the dc LED. At 300 kHz raw count, the signal is
                      still >5dB above background and there is a lot of room for improvement.

                      It is a very interesting setup. I have used a similar detection concept
                      before, but only injected signals for test purposes. This is the first
                      time I've used real photon signals on the telescope to check it out. So
                      far, so good.

                      Ben


                      On 5/10/2013 7:11 PM, M. Ben Schuetz wrote:
                      > Mark & Wolf,
                      >
                      > Thanks for the help. Regarding Mark's question, only the pulsed
                      > signal fades significantly.
                      > The dc LED is running at 60 microwatts, while the pulsed LED is less
                      > than 6 milliwatts. The pulsed signal is only 100 ns long at a rep
                      > rate of 0.4 Hz. Understated, heating may not be a problem here. To
                      > clarify, the received, pulsed signal is stretched to 40 us before
                      > going to the box.
                      >
                      > Wolf, you may have hit on it regarding an agc in the box. The
                      > individual photon pulses (for either signal) are stretched to an
                      > equivalent frequency of about 25 kHz. This may be on the ragged edge,
                      > or over the edge, for this sound card. I'll try stretching all the
                      > pulses more and if that doesn't help, try another sound card.
                      >
                      > Great input guys.
                      >
                      > Best from Ben
                      >
                      >
                      > On 5/10/2013 4:34 PM, wolf_dl4yhf wrote:
                      >> Hello Ben,
                      >>
                      >> Difficult to say if this is a software feature, or the result of an
                      >> automatic gain control (hardware), or similar.
                      >>
                      >> Maybe a sinewave test signal with constant amplitude, sufficiently
                      >> attenuated and added to the signal into the soundcard (via resistor
                      >> network) can shed some light on this.
                      >> I had a similar effect with one of my test PCs: Even if the soundcard's
                      >> input is configured as 'line-in', not as 'microphone in', there is an
                      >> AGC active in it, which reduces the audio gain if there is noise / hum /
                      >> etc entering the soundcard - outside the observed frequency band (seems
                      >> to be a broadband rectifier which generates the control voltage for the
                      >> AGC).
                      >>
                      >> All the best,
                      >> Wolf .
                      >>
                      >> Am 10.05.2013 22:17, schrieb M. Ben Schuetz:
                      >>> Hi all,
                      >>>
                      >>> I'm searching for signals from 0.05 to 1 Hz using large bins, bin
                      >>> averaging and large FFT decimations. For the present I am using
                      >>> both dc
                      >>> and pulsed test signals, the background (dc) is between -80 and -90 dB
                      >>> with the pulsed test signal between -70 and -80 dB respectively. The
                      >>> detector is a photomultiplier detecting/counting single photons. The
                      >>> background test signal is from an LED fed with a dc level. The pulsed
                      >>> test signal is also from an LED running with 100 ns pulses. Thus, both
                      >>> the background and pulsed test signals are random events following
                      >>> Poisson statistics. Pause - - -. As near as can be determined, both
                      >>> the dc and pulsed test signals are behaving as they should.
                      >>>
                      >>> Now the problem. The test signal is nicely detected for several
                      >>> minutes, then fades 5 to 10 dB and recovers in another minute or two.
                      >>> The fading is not periodic, but has the rough appearances of
                      >>> periodicity. Might this be happening in SL? Is there some widget
                      >>> in SL
                      >>> that can prevent it?
                      >>>
                      >>> Best from Ben
                      >>>
                      >>>
                      >>>
                      >>>
                      >>> ------------------------------------
                      >>>
                      >>> Yahoo! Groups Links
                      >>>
                      >>>
                      >>>
                      >>>
                      >>>
                      >>
                      >>
                      >> ------------------------------------
                      >>
                      >> Yahoo! Groups Links
                      >>
                      >>
                      >>
                      >
                    • Mark McCarron
                      Well, that s a better explanation. I take it that this is a SETI project and you are looking for pulsed laser signals. I ve just got the USRP B100 and I will
                      Message 10 of 10 , May 10, 2013
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                        Well, that's a better explanation.  I take it that this is a SETI project and you are looking for pulsed laser signals.  I've just got the USRP B100 and I will be using it for SETI work also.  Even on a cheap antenna without any parabolic dish, picking up satellites is quite easy.  The problem is that I need a very big dish and to be honest, the entire antenna and analogue stage would need to be cryogenically frozen.  But beggars cannot be choosers.

                        I suppose you are in the same boat as the atmosphere will disperse any optical signal.  The odds of a detection are...well...astronomical when all factors are considered.  That said, the odds are worse if no one is looking.

                        From your description, it would appear that your box is converting the detection to a voltage that you are passing to your sound card.  The sound card is acting as a poor man's ADC.  In terms of the electronics inside a sound card, the signals are modified in terms of audio DSP, not just raw samples.  Different cards, will do different things to the that input to improve richness, fidelity, etc.  This will skew your results somewhat and lead to minor artifacts.

                        Then, the point I was making about your power supply is that it will not be perfect.  There will be a margin or error in the stability of its output and all circuits have different inductances and capacitances which lead to anomalies and weird spike/brownouts in rapid switching.

                        Then the LEDs themselves are not perfect and will not provide consistent output.

                        Every element in the entire chain of devices has specific tolerances that, when combined, will add up to a range of error in the dB output and detection.  I think what you were hoping for was a single major factor that would be the major source of error and it is difficult to define given the lack of experimental data.

                        My best advice maybe to filter the mains, upgrade the power supply and switch to a professional ADC.  That may stabilize the dB somewhat, but expecting a certain tolerance in that is just the way it goes.

                        Regards,

                        Mark McCarron

                        > To: SpectrumLabUsers@yahoogroups.com
                        > From: kg4lra@...
                        > Date: Fri, 10 May 2013 20:05:31 -0500
                        > Subject: Re: [SpectrumLabUsers] Fading. Trying for brevity, ending in confusion
                        >
                        > Well I screwed that explanation up nicely. Another try. The raw signal
                        > is both the background and pulsed signal. That signal is the total
                        > photon count and each count pulse is stretched to 50 ns before going to
                        > the box. The raw count can be anything from 1 kHz up to 0.5 MHz. That
                        > doesn't sound like it should work, but the whole of these pulses are
                        > wavelike enough that the sound card pulls the low frequency components
                        > through. The other, very low rep rate signal (0.3 Hz) is sent to the
                        > box as a 40 us pulse.
                        >
                        > I also somewhat misstated the pulsed LED info. While the pulsed LED is
                        > pulsed with 6 milliwatts of peak power, it also has an optical filter
                        > that drops the output photon count to about 1/4. The neat thing about
                        > this whole deal is that the number of "signal" photons during the 100 ns
                        > interval is only about 25x the number of photons received during the
                        > same interval from the dc LED. At 300 kHz raw count, the signal is
                        > still >5dB above background and there is a lot of room for improvement.
                        >
                        > It is a very interesting setup. I have used a similar detection concept
                        > before, but only injected signals for test purposes. This is the first
                        > time I've used real photon signals on the telescope to check it out. So
                        > far, so good.
                        >
                        > Ben
                        >
                        >
                        > On 5/10/2013 7:11 PM, M. Ben Schuetz wrote:
                        > > Mark & Wolf,
                        > >
                        > > Thanks for the help. Regarding Mark's question, only the pulsed
                        > > signal fades significantly.
                        > > The dc LED is running at 60 microwatts, while the pulsed LED is less
                        > > than 6 milliwatts. The pulsed signal is only 100 ns long at a rep
                        > > rate of 0.4 Hz. Understated, heating may not be a problem here. To
                        > > clarify, the received, pulsed signal is stretched to 40 us before
                        > > going to the box.
                        > >
                        > > Wolf, you may have hit on it regarding an agc in the box. The
                        > > individual photon pulses (for either signal) are stretched to an
                        > > equivalent frequency of about 25 kHz. This may be on the ragged edge,
                        > > or over the edge, for this sound card. I'll try stretching all the
                        > > pulses more and if that doesn't help, try another sound card.
                        > >
                        > > Great input guys.
                        > >
                        > > Best from Ben
                        > >
                        > >
                        > > On 5/10/2013 4:34 PM, wolf_dl4yhf wrote:
                        > >> Hello Ben,
                        > >>
                        > >> Difficult to say if this is a software feature, or the result of an
                        > >> automatic gain control (hardware), or similar.
                        > >>
                        > >> Maybe a sinewave test signal with constant amplitude, sufficiently
                        > >> attenuated and added to the signal into the soundcard (via resistor
                        > >> network) can shed some light on this.
                        > >> I had a similar effect with one of my test PCs: Even if the soundcard's
                        > >> input is configured as 'line-in', not as 'microphone in', there is an
                        > >> AGC active in it, which reduces the audio gain if there is noise / hum /
                        > >> etc entering the soundcard - outside the observed frequency band (seems
                        > >> to be a broadband rectifier which generates the control voltage for the
                        > >> AGC).
                        > >>
                        > >> All the best,
                        > >> Wolf .
                        > >>
                        > >> Am 10.05.2013 22:17, schrieb M. Ben Schuetz:
                        > >>> Hi all,
                        > >>>
                        > >>> I'm searching for signals from 0.05 to 1 Hz using large bins, bin
                        > >>> averaging and large FFT decimations. For the present I am using
                        > >>> both dc
                        > >>> and pulsed test signals, the background (dc) is between -80 and -90 dB
                        > >>> with the pulsed test signal between -70 and -80 dB respectively. The
                        > >>> detector is a photomultiplier detecting/counting single photons. The
                        > >>> background test signal is from an LED fed with a dc level. The pulsed
                        > >>> test signal is also from an LED running with 100 ns pulses. Thus, both
                        > >>> the background and pulsed test signals are random events following
                        > >>> Poisson statistics. Pause - - -. As near as can be determined, both
                        > >>> the dc and pulsed test signals are behaving as they should.
                        > >>>
                        > >>> Now the problem. The test signal is nicely detected for several
                        > >>> minutes, then fades 5 to 10 dB and recovers in another minute or two.
                        > >>> The fading is not periodic, but has the rough appearances of
                        > >>> periodicity. Might this be happening in SL? Is there some widget
                        > >>> in SL
                        > >>> that can prevent it?
                        > >>>
                        > >>> Best from Ben
                        > >>>
                        > >>>
                        > >>>
                        > >>>
                        > >>> ------------------------------------
                        > >>>
                        > >>> Yahoo! Groups Links
                        > >>>
                        > >>>
                        > >>>
                        > >>>
                        > >>>
                        > >>
                        > >>
                        > >> ------------------------------------
                        > >>
                        > >> Yahoo! Groups Links
                        > >>
                        > >>
                        > >>
                        > >
                        >
                        >
                        >
                        > ------------------------------------
                        >
                        > Yahoo! Groups Links
                        >
                        > <*> To visit your group on the web, go to:
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