Steve Rooke wrote: > Bruce, > > But the sampling interval is still 1 sec and you can see by my notes > that I explicitly give this on the command line for adev1.exe. > > 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.
> 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.
