Re: [time-nuts] Sample R script for ADEV under Linux wanted
EFC DAC values can be directly translated into frequency (use the ADEV y form) knowing the EFC voltage/frequency relation (a simple constant most of the time). If the time stamping reveals that the sampling is exactly uniform then you can get rid of the time stamp too and simply assume that sampling interval. The reference source is your GPS receiver, not an ideal one for tau in the seconds range. On Mon, Feb 3, 2014 at 6:22 AM, Anders Wallin anders.e.e.wal...@gmail.com wrote: I recently copy/pasted/googled together this Python library: https://github.com/aewallin/allantools patches, sample datasets, and new tests are welcome! Anders On Mon, Feb 3, 2014 at 2:02 AM, Bob Stewart b...@evoria.net wrote: Subject says it all. Does anyone have a script I could use as a starting point to calculate/plot the ADEV for my GPSDO? Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sample R script for ADEV under Linux wanted
In mathematics and engineering it's common to use the word phase to mean angle, with units of degrees or radians, often modulo 360 or 2 pi. In the time frequency world, the word phase almost always refers to a time difference (time error), with units of time (seconds), and unbounded. To further complicate things, one can sometimes see wrap when measuring time error using a time interval counter on signals that are high in repetition rate or too different in frequency. The most common form of this is if you measure two slightly drifting 10 MHz signals using time interval mode; the numbers you get will always be 0 to 99 ns. In that case you have to manually unwrap the cycles to get a true time error series. This is normal. But it can be a hassle and introduce experimental ambiguity so that's why most people avoid the problem by just using lower frequencies for their comparison, like 1 kHz or 1 Hz (1PPS). Even that doesn't guarantee no wrapping in all cases. The other trick is to artificially advance the start or retard the stop channel to avoid negative numbers or wrapping. In your case, as long as you are comparing at 10 MHz and your references are not closely locked in phase your counter will give you numbers that wrap. You must take care of this before you apply the numbers to an ADEV calculation or use them to compute frequency. Computing phase deltas does not help, since a phase wrap just turns into a frequency spike. /tvb - Original Message - From: Bob Stewart b...@evoria.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, February 02, 2014 8:31 PM Subject: Re: [time-nuts] Sample R script for ADEV under Linux wanted That code, like most ADEV calculations, assumes you have phase data... In my case, the phase data wraps at each DAC change. Do I need to unwrap it, or change it to delta values? I haven't read enough about ADEV to get a feel of what I want, or what this group means when someone say ADEV of xx. I suspect that I need phase deltas from sample to sample to get the allan deviation of the phase changes? Since mine wraps, I'm not sure if an ADEV even means anything. Bob From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, February 2, 2014 10:23 PM Subject: Re: [time-nuts] Sample R script for ADEV under Linux wanted I suggest to use the TVB's http://www.leapsecond.com/tools/adev1.c C source and derive your script from it... but first, your GPSDO has to put out the time interval error samples or you have a reference and a TIC to measure your GPSDO (better this last setup). Correct. That code, like most ADEV calculations, assumes you have phase data, and so it uses the x form of the formula. If the data is period or frequency then you use the y form of the formula. See: http://www.wriley.com/paper2ht.htm for details on both equations. See also: http://leapsecond.com/tools/adev_lib.c which computes ADEV, MDEV, and HDEV from phase. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sample R script for ADEV under Linux wanted
Nice library. Thanks for checking it against Stable32 using PHASE.DAT. /tvb - Original Message - From: Anders Wallin anders.e.e.wal...@gmail.com To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, February 02, 2014 9:22 PM Subject: Re: [time-nuts] Sample R script for ADEV under Linux wanted I recently copy/pasted/googled together this Python library: https://github.com/aewallin/allantools patches, sample datasets, and new tests are welcome! Anders ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tom's Adventures of a Time Nut (Banquet Talk)
Tom you are a vary good speaker. You would have made a good teacher if you had taken that road. That was a most enjoyable hour 1 minute and 9 seconds and an unknown number of nanoseconds. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Rex r...@sonic.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, January 31, 2014 1:51 AM Subject: Re: [time-nuts] Tom's Adventures of a Time Nut (Banquet Talk) If you take the link in the original message (it is a youtube presentation), the player on that page has an option to open the video in Youtube. Anyway, it goes here: http://www.youtube.com/watch?v=MT2reYXPvGg On 1/30/2014 8:30 PM, Max Robinson wrote: Tom. Could you give us a link to the u tube version. I haven't mastered searching on u tube yet. Regards. Max. K 4 O DS. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ovenair OSC 49-38B
Date: Wed, 29 Jan 2014 21:31:36 -0600 From: dth854 dth...@airmail.net I have one of these oscilators and wanted to test it. I saw your post on time-nuts, do you still have the connection information and did you find a schematic? Thanks for any help you can give. Dave T Dave, if you download the service manual for the EIP Microwave model 545A counter, you'll have all the connections and the specs as well. The OSC 49-38B oscillator has an alternate part number of 2030010-03, and is used in the EIP 545A counter as a time base option. Download the counter manual at www.qsl.net/n/n9zia//test/EIP_545A_Service_Manual.pdf? It's about a 47 Mb download, so if you're on dialup, let me know and I'll extract the details for you. Happy downloading! Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] EFC divider resistors
To all those time-nuts (volt-nuts as well) who have been chatting about temperature controlled environments, here is my input. I found a very neat ready-built controlled oven at a number of hamfests in the southeast (Florida Alabama) that work quite well to enclose small circuits that need to be temperature controled I found them still being sold by Fair Radio (www.fairradio.com) for only $12 apiece. Schematic is included to increase their value to us hackers. Their catalog number is OSC-8004290G1. The outside dimensions of the box is 6.5x2x3.3 inches, with about 0.5 inches of insulation and inner enclosure. They were used in Army GRT-21/22 transmitters, and contain all the necessary temperature control circuitry, as well as a crystal oscillator. I bought a couple of these gems and removed the oscillator circuitry and had a nice oven assembly with enough room inside to house a lot of circuitry for just about any thing requiring close trmperature control. It's designed to run at 75C, but with a few resistor changes, the temperature can be lowered if desired. It's insulated pretty well, too. Not a power miser by any stretch, but it has lots of potential. Cheers, Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] LORAN-C Boat-Anchor
I noticed an interesting Loran-C boat-anchor on eBay: http://www.ebay.com/itm/RAYTHEON-RAYNAV-6000-LORAN-C-/230577121042?pt=Boat_Parts_Accessories_Gearhash=item35af77a712vxp=mtr It looks clearly similar to the Micrologic ML 200 I have, but I think this is a later revision. The ML 200 I have is based on the Intel 4004 - the worlds first microprocessor, but I have no idea what's inside the one on eBay. Interestingly, the ML 200 can lock on the 4-digit european GRIs but it is not much actual use to a timenut, it is mostly a boat-anchor... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TimeLab and the Adev plot
On 03/02/14 01:19, Azelio Boriani wrote: Magnus, please, can you elaborate this: A common mistake is to assume you can average it out, but that gives you a different measure which does not represent the ADEV values you are comparing with. The time between samples will scale down the relative impact of the time-noise, but not really average it. That is, have I to increase the time between samples or take samples and average them? For example, go from samples every second to samples every 2 seconds or average two samples every second to obtain a sample every 2 seconds. The last method will (apparently) increase the resolution... What I am saying in the first sentence is that taking the average of samples does not give you improved limit, but just add filtering which makes low-tau ADEV values which is biased to look better than the real ADEV for that measurement is. In the second sentence, I make the point that when you take two sample values, at various taus, you really do not average them but rather make their time stability contribution (trigger jitter and resolution) less important relative to the tau between them. This is by itself not an averaging effect. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
