You don't need the OCXO option for the 53132... you need a stable and accurate source like a GPSDO that will be your reference. Consider buying the HP53132 but also a GPSDO. Is the 162kHz transmitter the Allouis one (TDF/Syrte)?
On Sun, Jan 22, 2017 at 3:52 PM, Gilles Clement <[email protected]> wrote: > Hi, > > I am new to this list and have been following it for a while with great > interest. I am afraid I am getting contaminated with the "TN" virus… ! > > I developed a home-brewed OCXO crystal oscillator disciplined with a long > wave radio station signal (162 kHz). Its working quite well with a long term > stability that is « probably » better than 10E-8 which I am actually looking > forward to better understand. I am considering using an HP53132 counter for > this purpose, although I understand that it may not be the most recommended > approach…. > > Please find hereafter the rationale: > - The HP53132 implements a triangular averaging algorithm (Delta averaging) > in its standard frequency or period measurement mode of operation > - This feature provides a pretty high resolution (up to 0.5*10E-12 if I am > correct) which should be appropriate at least to get a first idea of the > oscillator performance > - But it comes with the drawback that an Allan Variance computed directly > from such frequency (or period) readings, would be distorted with respect to > the "standard" Allan Variance (which assumes a PI averaging instead of a > Delta averaging algorithm to compute the fractional frequencies) > - However, from the Australian paper titled : « Considerations on the > Measurement of the Stability of Oscillators with Frequency Counters » I > noticed that: > When I look at OCXO crystals oscillator stability discussions in the > literature, White Frequency, Flicker Frequency and Random Walk Frequency seem > to be the dominant noise factors considered (ex: in phase noise spectral > density graphics) > The distortion from Allan Variance to Delta Variance is limited for White > Frequency, Flicker Frequency and Random Walk Frequency noises (though it can > be several orders of magnitudes for White Phase and Flicker Phase noises) > Moreover formulas are provided in the paper to evaluate the amount of such > distortions. The impact appears to be a simple multiplier of 1.33, 1.30 and > 1.15 for the three corresponding noises, the slopes of the curves are not > impacted (i.e: tauE-1 ; tauE+0 and tauE+1) > - So the idea is the following: start with a simple bench test, reading the > standard mode of Periods measurement, calculate the "naive" Triangular > Variance from these data, identifying the noise types (according to the slope > of the curve sections), and applying the corresponding offset correction, > hopefully leading to an estimate of the "standard" Allan Variance. > - This approach would have the great advantage to be simple and cost > effective, as one can find nowadays second hand 53132’s at reasonable cost > even with the (mandatory) OCXO option. > > Comments welcomed, > Best, > Gilles. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
