Steve Rooke wrote: > 2009/4/9 Bruce Griffiths <[email protected]>: > >> The sampling interval is indeed 1sec in the original data. >> However, if you delete every second sample the sampling interval in the >> resultant data is then 2 sec. >> > > Doesn't that imply that the data point should correspond to the whole > sampling period and not just half of it? > > The total measurement time is only deceased by 1 sec at the most if you delete every second line. The resampled data now has a sampling interval of 2 sec for the entire measurment time.
The original data samples are phase differences measured on the second every second. The resampled data are phase differences measured every 2 seconds on the corresponding second transition. > 73, > Steve > > >>> OK, I'll have a go at compiling it as it is just a command line program. >>> >>> 73, >>> Steve >>> >>> 2009/4/9 Bruce Griffiths <[email protected]>: >>> >>> >>>> Steve >>>> >>>> Therein lies your problem. >>>> adev1 defaults to a sampling interval of 1 sec. (read the C source code). >>>> TvB's documentation explicitly states that you should supply the >>>> sampling interval. (its a command line argument for adev1.c). >>>> >>>> adev1.c is a simple command line program that uses stdin and stdout so >>>> porting it to a linux command line (non graphical) program should be >>>> straightforward. >>>> You can even use redirection and pipes should you need them. >>>> >>>> You can try porting it to Scilab which is free courtesy of the French >>>> Government. >>>> >>>> >>>> Bruce >>>> >>>> Steve Rooke wrote: >>>> >>>> >>>>> Bruce, >>>>> >>>>> I set nothing, as indicated in my text, I just delete data points, IE. >>>>> a file of 400000 records now becomes 200000. I'm trying to get my head >>>>> round this as the absolute requirement for continuous data seems >>>>> unneeded. What you have to remember here is that the data set I'm >>>>> working with consists of discrete measurements of the period of each >>>>> pulse. If it was timestamps, then there would be problems. >>>>> >>>>> I don't know how much MATLAB costs but I would guess it is way out of my >>>>> budget. >>>>> >>>>> 73, >>>>> Steve >>>>> >>>>> 2009/4/9 Bruce Griffiths <[email protected]>: >>>>> >>>>> >>>>> >>>>>> Steve >>>>>> >>>>>> The data file doesn't include the time interval between samples so do >>>>>> you set this in some way? >>>>>> If so you need to set it to 1s for the unaltered data, to 2s when you >>>>>> take every 2nd sample, and 1s when you take the first 200,000 samples. >>>>>> >>>>>> In principle you could use CANVAS (available on request from USNO - >>>>>> however you may have to wait a few days while they decide whether to >>>>>> grant your request.) for such analysis in Linux but you would then need >>>>>> the Linux version of Matlab. >>>>>> Or you could request that it be compiled for Linux - a fairly simple >>>>>> task if one has the Linux version of Matlab. >>>>>> >>>>>> In principle you should be able to port the m source files to Scilab, >>>>>> but there are some subtle differences between Scilab and Matlab so this >>>>>> may take a while. >>>>>> >>>>>> Bruce >>>>>> >>>>>> Steve Rooke wrote: >>>>>> >>>>>> >>>>>> >>>>>>> Bruce, >>>>>>> >>>>>>> But how does that explain the output of Tom's adev1 program which >>>>>>> still seems to give a a good measurement at tau = 1s? >>>>>>> >>>>>>> 73, >>>>>>> Steve >>>>>>> >>>>>>> 2009/4/8 Bruce Griffiths <[email protected]>: >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>> Steve >>>>>>>> >>>>>>>> If you delete every second measurement then your effective minimum >>>>>>>> sampling time is now 2s and you can no longer calculate ADEV for tau< >>>>>>>> 2s. >>>>>>>> You can still calculate ADEV for tau = 100,000 sec. >>>>>>>> >>>>>>>> If you delete all but the first 200,000 lines then you can calculated >>>>>>>> ADEV for tau=1sec and up to tau= 25,000 sec with reasonable accuracy. >>>>>>>> >>>>>>>> You shouldn't lose sight of the fact that ADEV and OADEV are both >>>>>>>> estimates of the Allan deviation. >>>>>>>> >>>>>>>> >>>>>>>> Bruce >>>>>>>> >>>>>>>> Steve Rooke wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>> Tom, >>>>>>>>> >>>>>>>>> I understand fully the points that you have made but I have obviously >>>>>>>>> not made my point clear to all and i apologise for my poor >>>>>>>>> communication skills. >>>>>>>>> >>>>>>>>> This is what I'm getting at: >>>>>>>>> >>>>>>>>> Using your adev1.exe from http://www.leapsecond.com/tools/adev1.htm >>>>>>>>> and processing various forms of gps.dat from >>>>>>>>> http://www.leapsecond.com/pages/gpsdo-sim/gps.dat.gz. >>>>>>>>> >>>>>>>>> C:\Documents and Settings\Steve Rooke\Desktop>adev1.exe 1 <gps.dat >>>>>>>>> >>>>>>>>> ** Sampling period: 1 s >>>>>>>>> ** Phase data scale factor: 1.000e+000 >>>>>>>>> ** Total phase samples: 400000 >>>>>>>>> ** Normal and Overlapping Allan deviation: >>>>>>>>> >>>>>>>>> 1 tau, 3.0127e-009 adev(n=399998), 3.0127e-009 >>>>>>>>> oadev(n=399998) >>>>>>>>> 2 tau, 1.5110e-009 adev(n=199998), 1.5119e-009 >>>>>>>>> oadev(n=399996) >>>>>>>>> 5 tau, 6.2107e-010 adev(n=79998), 6.1983e-010 >>>>>>>>> oadev(n=399990) >>>>>>>>> 10 tau, 3.1578e-010 adev(n=39998), 3.1549e-010 >>>>>>>>> oadev(n=399980) >>>>>>>>> 20 tau, 1.6531e-010 adev(n=19998), 1.6534e-010 >>>>>>>>> oadev(n=399960) >>>>>>>>> 50 tau, 7.2513e-011 adev(n=7998), 7.3531e-011 >>>>>>>>> oadev(n=399900) >>>>>>>>> 100 tau, 4.0029e-011 adev(n=3998), 4.0618e-011 >>>>>>>>> oadev(n=399800) >>>>>>>>> 200 tau, 2.1512e-011 adev(n=1998), 2.1633e-011 >>>>>>>>> oadev(n=399600) >>>>>>>>> 500 tau, 9.2193e-012 adev(n=798), 9.1630e-012 >>>>>>>>> oadev(n=399000) >>>>>>>>> 1000 tau, 4.9719e-012 adev(n=398), 4.7750e-012 >>>>>>>>> oadev(n=398000) >>>>>>>>> 2000 tau, 2.6742e-012 adev(n=198), 2.5214e-012 >>>>>>>>> oadev(n=396000) >>>>>>>>> 5000 tau, 1.0010e-012 adev(n=78), 1.1032e-012 >>>>>>>>> oadev(n=390000) >>>>>>>>> 10000 tau, 6.1333e-013 adev(n=38), 6.1039e-013 >>>>>>>>> oadev(n=380000) >>>>>>>>> 20000 tau, 3.8162e-013 adev(n=18), 3.2913e-013 >>>>>>>>> oadev(n=360000) >>>>>>>>> 50000 tau, 1.0228e-013 adev(n=6), 1.5074e-013 >>>>>>>>> oadev(n=300000) >>>>>>>>> 100000 tau, 5.8577e-014 adev(n=2), 6.7597e-014 >>>>>>>>> oadev(n=200000) >>>>>>>>> >>>>>>>>> So far, so good. Now I delete every even line in the file which leaves >>>>>>>>> me with 200000 lines of data (400000 lines in original gps.dat file). >>>>>>>>> (awk 'and(NR, 1) == 0 {print}' <gps.dat >gps1.dat) >>>>>>>>> >>>>>>>>> C:\Documents and Settings\Steve Rooke\Desktop>adev1.exe 1 <gps1.dat >>>>>>>>> >>>>>>>>> ** Sampling period: 1 s >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>> INCORRECT!! >>>>>> sampling period is now 2s. >>>>>> >>>>>> >>>>>> >>>>>>>>> ** Phase data scale factor: 1.000e+000 >>>>>>>>> ** Total phase samples: 200000 >>>>>>>>> ** Normal and Overlapping Allan deviation: >>>>>>>>> >>>>>>>>> 1 tau, 3.0257e-009 adev(n=199998), 3.0257e-009 >>>>>>>>> oadev(n=199998) >>>>>>>>> 2 tau, 1.5373e-009 adev(n=99998), 1.5345e-009 >>>>>>>>> oadev(n=199996) >>>>>>>>> 5 tau, 6.3147e-010 adev(n=39998), 6.3057e-010 >>>>>>>>> oadev(n=199990) >>>>>>>>> 10 tau, 3.3140e-010 adev(n=19998), 3.3067e-010 >>>>>>>>> oadev(n=199980) >>>>>>>>> 20 tau, 1.7872e-010 adev(n=9998), 1.7810e-010 >>>>>>>>> oadev(n=199960) >>>>>>>>> 50 tau, 7.9428e-011 adev(n=3998), 8.1216e-011 >>>>>>>>> oadev(n=199900) >>>>>>>>> 100 tau, 4.2352e-011 adev(n=1998), 4.3265e-011 >>>>>>>>> oadev(n=199800) >>>>>>>>> 200 tau, 2.2001e-011 adev(n=998), 2.2593e-011 >>>>>>>>> oadev(n=199600) >>>>>>>>> 500 tau, 9.6853e-012 adev(n=398), 9.5441e-012 >>>>>>>>> oadev(n=199000) >>>>>>>>> 1000 tau, 5.0139e-012 adev(n=198), 5.0387e-012 >>>>>>>>> oadev(n=198000) >>>>>>>>> 2000 tau, 2.7994e-012 adev(n=98), 2.7090e-012 >>>>>>>>> oadev(n=196000) >>>>>>>>> 5000 tau, 1.4280e-012 adev(n=38), 1.2214e-012 >>>>>>>>> oadev(n=190000) >>>>>>>>> 10000 tau, 7.4881e-013 adev(n=18), 6.5814e-013 >>>>>>>>> oadev(n=180000) >>>>>>>>> 20000 tau, 7.6518e-013 adev(n=8), 3.7253e-013 >>>>>>>>> oadev(n=160000) >>>>>>>>> 50000 tau, 2.4698e-014 adev(n=2), 1.3539e-013 >>>>>>>>> oadev(n=100000) >>>>>>>>> >>>>>>>>> Obviously we don't have enough data now for a measurement of 100000 >>>>>>>>> tau but the results for the other tau are quite close, especially when >>>>>>>>> there are sufficient data points. Now this is discontinuous data, >>>>>>>>> exactly what I was trying to allude to. >>>>>>>>> >>>>>>>>> OK, so now I take only the top 200000 lines of the gps.dat file (head >>>>>>>>> -200000 gps.dat >gps2.dat) >>>>>>>>> >>>>>>>>> C:\Documents and Settings\Steve Rooke\Desktop>adev1.exe 1 <gps2.dat >>>>>>>>> >>>>>>>>> ** Sampling period: 1 s >>>>>>>>> ** Phase data scale factor: 1.000e+000 >>>>>>>>> ** Total phase samples: 200000 >>>>>>>>> ** Normal and Overlapping Allan deviation: >>>>>>>>> >>>>>>>>> 1 tau, 3.0411e-009 adev(n=199998), 3.0411e-009 >>>>>>>>> oadev(n=199998) >>>>>>>>> 2 tau, 1.4985e-009 adev(n=99998), 1.4999e-009 >>>>>>>>> oadev(n=199996) >>>>>>>>> 5 tau, 6.1964e-010 adev(n=39998), 6.2010e-010 >>>>>>>>> oadev(n=199990) >>>>>>>>> 10 tau, 3.1315e-010 adev(n=19998), 3.1339e-010 >>>>>>>>> oadev(n=199980) >>>>>>>>> 20 tau, 1.6499e-010 adev(n=9998), 1.6495e-010 >>>>>>>>> oadev(n=199960) >>>>>>>>> 50 tau, 7.1425e-011 adev(n=3998), 7.3416e-011 >>>>>>>>> oadev(n=199900) >>>>>>>>> 100 tau, 3.9940e-011 adev(n=1998), 4.0730e-011 >>>>>>>>> oadev(n=199800) >>>>>>>>> 200 tau, 2.1488e-011 adev(n=998), 2.1558e-011 >>>>>>>>> oadev(n=199600) >>>>>>>>> 500 tau, 8.4809e-012 adev(n=398), 9.0886e-012 >>>>>>>>> oadev(n=199000) >>>>>>>>> 1000 tau, 4.9223e-012 adev(n=198), 4.7104e-012 >>>>>>>>> oadev(n=198000) >>>>>>>>> 2000 tau, 2.4335e-012 adev(n=98), 2.4515e-012 >>>>>>>>> oadev(n=196000) >>>>>>>>> 5000 tau, 1.0308e-012 adev(n=38), 1.0861e-012 >>>>>>>>> oadev(n=190000) >>>>>>>>> 10000 tau, 5.9504e-013 adev(n=18), 6.1031e-013 >>>>>>>>> oadev(n=180000) >>>>>>>>> 20000 tau, 3.6277e-013 adev(n=8), 3.1994e-013 >>>>>>>>> oadev(n=160000) >>>>>>>>> 50000 tau, 1.0630e-013 adev(n=2), 1.6715e-013 >>>>>>>>> oadev(n=100000) >>>>>>>>> >>>>>>>>> Is there any Linux tools for calculating adev as I'm having to run >>>>>>>>> Windows in a VMware session? >>>>>>>>> >>>>>>>>> 73, >>>>>>>>> Steve >>>>>>>>> >>>>>>>>> 2009/4/8 Tom Van Baak <[email protected]>: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>>> Steve, >>>>>>>>>> >>>>>>>>>> You've asked a couple of questions. Let me start with this. >>>>>>>>>> >>>>>>>>>> It is true that if one were only interested in the performance >>>>>>>>>> of a pendulum (or quartz or atomic) clock for averaging times >>>>>>>>>> of one day that all you would need is a series of time error >>>>>>>>>> (aka phase) measurements made about the same time once >>>>>>>>>> a day (doesn't have to be that exact). After one week, you'd >>>>>>>>>> have 7 error measurements (=6 frequency =5 stability points) >>>>>>>>>> and this is adequate to calculate the ADEV for tau 1 day. >>>>>>>>>> This alone allows you to rank your clock among all the other >>>>>>>>>> pendulum clocks out there. Note also you get time error and >>>>>>>>>> rate error from these few data points too. >>>>>>>>>> >>>>>>>>>> As another example, suppose you have a nice HP 10811A >>>>>>>>>> oscillator and want to measure its drift rate. In this case you >>>>>>>>>> could spend just 100 seconds and measure its frequency >>>>>>>>>> once a day, or even once every couple of days. Do this for >>>>>>>>>> a month and you'd have several dozen points. If you plot >>>>>>>>>> these frequency measurements you will likely see that they >>>>>>>>>> approximately fall on a line; the slope of the is the frequency >>>>>>>>>> drift rate of the 10811. The general shape of the points, or >>>>>>>>>> the fit of the line is a rough indication of how consistent the >>>>>>>>>> drift rate is or if it's increasing or decreasing. >>>>>>>>>> >>>>>>>>>> Neither of these examples require a lot of data. Both of these >>>>>>>>>> are real-world examples. >>>>>>>>>> >>>>>>>>>> OK so far? >>>>>>>>>> >>>>>>>>>> /tvb >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> _______________________________________________ >>>>>>>>>> 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. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>> _______________________________________________ >>>>>> 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. >>>> >>>> >>>> >>> >>> >>> >> _______________________________________________ >> 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.
