[time-nuts] More ES100 WWVB Measurements

[Brooke Clarke]

Hi Joseph:

Thanks for the patent link.  I've added it to my WWVB phase modulation info at:
https://prc68.com/I/Loop.shtml#La_Crosse_UltrAtomic

-- 
Have Fun,

Brooke Clarke
https://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.

-------- Original Message --------
> On Mon, 31 Dec 2018 12:00:02 -0500, time-nuts-request at lists.febo.com
> wrote:
>
>>   time-nuts Digest, Vol 173, Issue 44
>> Message: 7
>> Date: Mon, 31 Dec 2018 04:04:22 -0800
>> From: "Tom Van Baak" <tvb at LeapSecond.com>
>> To: "Discussion of precise time and frequency measurement"
>> 	<time-nuts at lists.febo.com>
>> Subject: Re: [time-nuts] More ES100 WWVB Measurements
>> Message-ID: <96BB388753294278A9CDE96C1EA7D9AE at pc52>
>> Content-Type: text/plain;	charset="UTF-8"
>>
>> Hi Graham,
>>
>> That's very nice work. And you have uncovered several unusual effects
>> in the ES100. Bugs? Features? If we time nuts keep up the good work
>> to evaluate this chip, we are likely at some point to get an
>> informative response from the guys who designed it. They read
>> time-nuts.
> I didn't see this mentioned, but I think I have found the relevant US
> patent application: US20130051184A1, Real-time clock integrated circuit
> with time code receiver, method of operation thereof and devices
> incorporating the same, Oren Eliezer et al, Oren Eliezer et al, filed
> 2013-02-28.
>
> .<https://patents.google.com/patent/US20130051184>
>
> Found this by chasing stuff from the EverSet website:
> .<http://everset-tech.com/wp-content/uploads/2014/11/ReceiverRadioClocks.pdf>.
>
> Joe Gwinn
>
>   
>> So now both you and Tim have observed the off-by-one-second (or
>> off-by-N-seconds) effect in the ES100. I wonder if this explains why
>> some of my ES100-based La Crosse 1235UA Ultratomic wall clocks are
>> off by a second sometimes.
>>
>> My main question: in your "Time Plot.PNG" plot, what is the cause of
>> the sawtooth pattern? The points are almost all on a clear negative
>> slope, though bounded by roughly +/- 75ms. Looking on the far left, I
>> see a time drift of +50 ms to -25 ms over an hour, which is
>> equivalent to a -20 ppm frequency offset; about -2 seconds/day.
>>
>> Do you think this is due to the 16 MHz onboard xtal? If so, how about
>> changing the temperature of the eval board by a lot (say, several
>> tens of degrees) for an extended time (say, 4 hours) and see if the
>> sawtooth slope changes convincingly.
>>
>> Also, just to be sure, can you put a known independent timing signal
>> (e.g., GPS/1PPS) into your complex BeagleBone Black / Debian 9.4 /
>> ntpd time server / Python 3 / Excel stack to establish the validity
>> of your measurement methodology? Very likely you did it right, but I
>> always cringe when I hear "Linux" or "NTP" and "precise time" in the
>> same sentence. Yes, sorry, forgive me; I grew up in the "trust, but
>> verify" generation [1]. It applies pretty well to metrology also ;-)
>>
>> /tvb
>>
>> [1] https://en.wikipedia.org/wiki/Trust,_but_verify
>>
>>
>> End of time-nuts Digest, Vol 173, Issue 44
>> ******************************************
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