> If you are fairly deep inside a building, GPS isn’t going to get there. WWVB likely > will make it to an internal location.
Interesting thought. I wonder if anyone has tested WWVB reception in a deep underground location such as a sub sub level in a building or parking garage? Wayne On Mon, Dec 31, 2018 at 5:29 PM Bob kb8tq <[email protected]> wrote: > Hi > > If you are fairly deep inside a building, GPS isn’t going to get there. > WWVB likely > will make it to an internal location. > > If you are convinced that WWVB is un-jamable and that GPS is easily > jammed, WWVB > would be more robust. > > That’s about it. > > Bob > > > On Dec 31, 2018, at 7:56 PM, Wayne Holder <[email protected]> > wrote: > > > > 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 <[email protected]> > 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, [email protected] > >>> wrote: > >>> > >>>> time-nuts Digest, Vol 173, Issue 44 > >>>> Message: 7 > >>>> Date: Mon, 31 Dec 2018 04:04:22 -0800 > >>>> From: "Tom Van Baak" <[email protected]> > >>>> To: "Discussion of precise time and frequency measurement" > >>>> <[email protected]> > >>>> Subject: Re: [time-nuts] More ES100 WWVB Measurements > >>>> Message-ID: <96BB388753294278A9CDE96C1EA7D9AE@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 > >>>> ****************************************** > >>> _______________________________________________ > >>> time-nuts mailing list -- [email protected] > >>> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >>> and follow the instructions there. > >>> > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > >> > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
