Loading ...
Sorry, an error occurred while loading the content.
 

Re: [SpectrumLabUsers] New guy looking - progress

Expand Messages
  • Bill Cromwell
    ... Hi Wolf, WWV and WWVB are frequency standards. Yes, the carriers and the tones are all very accurate. When I use SSB (or CW) it moves the WWV carrier off
    Message 1 of 13 , Jun 19, 2013
      On 06/19/2013 01:28 PM, wolf_dl4yhf wrote:
      >
      > Not a good idea, because in SSB mode, the audio from the receiver
      > depends on the radio's VFO/BFO.
      > That's why I mentioned AM (because even when the AM receiver is detuned,
      > the audio frequency of a 1000.000 Hz signal will still be at 1000.000 Hz
      > at the AF output).
      > Not sure about WWV / WWVB but afaik they have very stable, calibrated
      > audio tones similar to the 1000 Hz 'test tone' transmitted by TV
      > stations before going QRT at night. Oh, those were the days.. long gone.
      >
      > Cheers,
      > Wolf .
      >
      >

      Hi Wolf,

      WWV and WWVB are frequency standards. Yes, the carriers and the tones
      are all very accurate.

      When I use SSB (or CW) it moves the WWV carrier off the zero end of the
      spectrum display. It moves the calibrator (or other signal being
      measured the same amount. So with WWV at an arbitrary 800 HZ on the
      spectrum display the signal being examined - in this case my calbrator -
      should be on 800 Hz, too. It's entirely so true that if my VFO changes
      or my BFO changes or my heterodyne oscillator changes (yes, three
      oscillators - one signal) then WWV moves on the display too. But the
      device under test moves also the exact same amount. On the R-599 the
      drift was very small and slow but observable. It was not enough to be
      distracting. In fact, I opened the receiver and aligned my crystal
      calibrator to display exactly on top of WWV's carrier. The error is now
      less than on Hz. As I approached zero I could see the sidebands on the
      WWV carrier that were created by the Crytsal calibrator diminish to the
      point of small undulating bumps on the slopes of WWV's carrier and then
      finally - completely disappear. As I watched over several hours the
      bumps would return, undulate slowly on the slopes, and then again
      disappear. There is nothing I can to about that with the present gear
      but that is much better accuracy than is needed for day to day ham
      operation.

      I am pleased with the results. I fully intend to put the tools to work
      daily here because they are more than adequate. And now that I can
      actually see fine errors I will gradually make improvements to my gear
      as I am able. I know that people who are using WSPR and techniques to
      produce signals from vapor have to be concerned about those "miniscule"
      errors. But those are not a part of my day to day operating - yet. If I
      keep playing with the tools I am sure the improvements will come and
      when I can make WSPR actually work I will certainly turn it on.

      73,

      Bill KU8H
    • sm5le
      RRR Tnx Wolf /Sven
      Message 2 of 13 , Jun 20, 2013
        RRR
        Tnx Wolf

        /Sven

        --- In SpectrumLabUsers@yahoogroups.com, wolf_dl4yhf <dl4yhf@...> wrote:
        >
        > Hi Sven,
        >
        > During all tests, the external soundcard was always better - MUCH better
        > - last not least because its temperature-dependent oscillator drift was
        > alway very predictable (decay function). All of the internal devices
        > suffer from rapid temperature changes when the PC's internal fan goes
        > on/off. Unless you have a fan-less PC, or a netbook which hardly ever
        > turns on one of the internal fans (but when doing number crunching they
        > usually have to turn on the fan sooner or later, even a netbook with an
        > Atom CPU was no exception).
        >
        > All the best,
        > Wolf .
        >
        >
        > Am 18.06.2013 16:39, schrieb Werner Karn:
        > > Sven,
        > > from my experience, that will depend on where you can best control
        > > temperature stability.
        > > BR
        > > Werner
        > >
        > >
        > > 2013/6/18 sm5le <sm5le@... <mailto:sm5le@...>>
        > >
        > > Hello Wolf
        > > Is it better to use internal soundcard "SoundMAX Digital Audio"
        > > insted of external "E-MU 0202" for best freq. accuracies and drift ?
        > > tnx /Sven
        > >
        > > --- In SpectrumLabUsers@yahoogroups.com
        > > <mailto:SpectrumLabUsers%40yahoogroups.com>, wolf_dl4yhf
        > > <dl4yhf@> wrote:
        > > >
        > > > Hello Bill,
        > > >
        > > > Without a means to monitor ("calibrate") the soundcard's
        > > sampling rate
        > > > against a reference signal,
        > > > you can expect accuracies in the range of a few ppm (parts per
        > > million).
        > > > Of course this requires measuring the soundcard's sampling rate
        > > *once*,
        > > > which can be done easily with an off-air standard like an audio
        > > tone
        > > > received in AM (not SSB!).
        > > >
        > > > After that, the accuracy depends largely on the soundcard (no big
        > > > surprise..).
        > > > The manual contains two examples of a 'good' and a 'poor'
        > > soundcard,
        > > > concering the stability of the clock source:
        > > >
        > > >
        > > http://www.qsl.net/dl4yhf/speclab/frqcalib.htm#soundcard_clock_drift_measurements
        > > >
        > > > As you can see, with the E-MU 0202 (used for the 2nd, "good"
        > > example)
        > > > the sampling rate settles to less then 0.1 ppm after > 1 hour of
        > > > warm-up. Thus, with a sufficiently large FFT (i.e. sufficient
        > > > *resolution* of the measurement), a 1 kHz audio signal can be
        > > measured
        > > > with an accuracy 0.1 milliHertz.
        > > >
        > > > Thus the accuracy of the entire system (with HF receiver /
        > > VFO+BFO +
        > > > Soundcard) is limited by the stability of the radio, not by the
        > > soundcard.
        > > >
        > > > All the best,
        > > > Wolf .
        > > >
        > > > Am 16.06.2013 15:39, schrieb Bill Cromwell:
        > > > >
        > > > > Hi,
        > > > >
        > > > > I'm a Ham radio licensee (I know not everybody here is). I
        > > have Spectrum
        > > > > Lab, Spectran, fldigi, and some other digital mode, sound card
        > > packages.
        > > > > Spectran does some of the same tricks that Spectrum Lab does
        > > (not a
        > > > > comparison) but not nearly as many. Ergo, Spectran has a smaller
        > > > > learning curve and is dramatically quicker to get into action.
        > > Spectran
        > > > > can do more for me when I get it "mastered".
        > > > >
        > > > > I have been working my way into the goodies in Spectrum Lab
        > > and I am
        > > > > ready to try calibration for general "frequency measurements".
        > > I have
        > > > > used my dual loop PLL receiver to apply signals from WWV in AM
        > > mode (no
        > > > > BFO to consider and VFO only needs to be 'close enough') to
        > > several of
        > > > > my sound card programs and they all show me that the standard
        > > tones are
        > > > > within just about 100 millihertz on the displays. I do NOT
        > > have my sound
        > > > > card or computer timebase synced to anything like a rubidium
        > > or gps
        > > > > "standard".
        > > > >
        > > > > I can look at the manuals myself to see how Spec Lab wants me
        > > to adjust
        > > > > for the sound card clock error (and the other packages, too).
        > > What kind
        > > > > of overall accuracy can I expect from Spectrum Lab under the
        > > conditions
        > > > > I have outlined? I intend to use the information I can get
        > > from Spectrum
        > > > > Lab and Spectran to correct the alignment of my duall loop PLL
        > > and BFOs
        > > > > in that (and other receivers). For the most part, being within 100
        > > > > milliHertz is overkill in most ham radio operation (never mind
        > > about
        > > > > WSPR for now). But it's always good to know the limitations.
        > > > >
        > > > > Incidentally, when I bring in the BFO the actuall PLL "VFO"
        > > frequency
        > > > > and the BFO come into play and it's definitely "out of whack".
        > > Starting
        > > > > point is sound card calibration.
        > > > >
        > > > > 73,
        > > > >
        > > > > Bill KU8H
        > > > >
        > > > >
        > > >
        > >
        > >
        > >
        >
      Your message has been successfully submitted and would be delivered to recipients shortly.