[time-nuts] More ES100 WWVB Measurements

Tue Jan 1 20:34:55 UTC 2019

Hi Wayne:

DST.

GPS has no bits for Daylight Savings.  As far as I know only WWV and WWVB have those bits.
So for a clock displaying local time WWVB is the way to go.

-- 
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 --------
> While reading this thread and pondering whether to buy and fool around with
> an ES100-based module from Universal Solder, I suddenly found myself
> wondering if there was any advantage to using the time received from WWVB
> vs just using an inexpensive GPS receiver.  The ES100  module costs about
> $70, but I can get a GPS receiver, with antenna, for far less than that and
> I've had no trouble receiving GPS signals indoors with most modern receiver
> modules.
>
> I suppose the low power requirements of the ES100 might be an advantage
> when building battery powered clocks to mount on the wall, but it seems
> like some of the newer, ultra low power GPS modules intended for use in
> smart watches could also work in a battery-powered wall clock, especially
> if the receiver was only powered on a few times a day to update the time.
>
> And, finally, if GPS modules are (or will some become) a suitable
> replacement for WWVB receiver modules, do we really need WWVB in the modern
> age?  Perhaps there's some critical advantage to using WWVB to get the time
> but, offhand, I cannot think of it.  What am I missing?
>
> Wayne
>
> On Mon, Dec 31, 2018 at 4:30 PM Brooke Clarke <brooke at pacific.net> wrote:
>
>> 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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