[time-nuts] Frequency doubler 5/10 and distribution amplifier for Lucent KS-24361
I'm coming late to this thread from January -- but did anybody ever make the PCBs for Gerhard's 10MHz output board? I'm interested. I just got my pair of RFTG's. Philip ___ 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] Striking change in iPhone time accuracy with 8.2
On Wed, Apr 1, 2015 at 4:41 PM, Oz-in-DFW li...@ozindfw.net wrote: The phone has to keep synch within a few microseconds of the network. I suspect only the so-called baseband system needs to maintain any synchronization with the RF network and the alarm clock is only loosely coupled. I have an LTE radio in my iPAD and according to Emerald Time the alarm clock varies from .5s to .005s error. I'm sure a signifcant fraction of that is server error but it doesn't seem worth it to do more careful testing given how fussy Emerald Time can be. ___ 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] audio-visual perception of time (was: Striking change in iPhone time accuracy with 8.2)
On Wed, 1 Apr 2015 16:11:54 -0700 Chris Albertson albertson.ch...@gmail.com wrote: The key jingle experiment is detecting a phase difference between ears. I was writing about our ability to know if a sound is in time with some other sound. For example if a bass player is keeping time with a drummer. I figure we can do that to about 20 ms or maybe a little better. Actually, quite a lot better. I cannot give you any hard numbers as I dont have my perception psychology books with me and my google skills fail to locate any good website, but quoting from memory: You can assume that an average human can perceive audio-visual time differences down to 3-10ms (flash to click), with a bit training probably better. Just auditory time differences are quite a bit better, in the couple 100us range (if you can avoid temporal masking effects). But, a word of caution here: lot of the performance of the sensory system depends on the training. Most people do not train neither hearing nor seeing. They are contempt with flickering TV sets or movies where audio is delayed by 30-40ms. They do not even perceive it conciously and ignore it unconciously. But on the other side, if you have someone who trains them, you can have interesting results. For example ask one of your nices, who play first person shooters a lot, about the jerking special effects in movies. Anyways.. so much from my side on this OT. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ 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] Good references on holdover?
Hi Javier, As far as I understand in WR both references are synchronous. Why don't you try to track both references (or N references) simultanously? If you take care of the design, your performance should increase while locked and the transition from one reference to the other if you ever miss one should be smoother. Cheers, Pablo On Fri, Feb 6, 2015 at 10:21 AM, Javier Serrano javier.serrano.par...@gmail.com wrote: Dear all, We would like to start working on holdover performance for White Rabbit [1]. This is a new domain for us. Our main use case is a WR switch losing its reference because someone disconnects a fiber. We can have redundancy, but it will take some time for a switch to change over to another reference. During this time, the oscillator in that switch will be free-running. We want to minimize the phase drift during that interval, which we think should be a couple of seconds maximum. We have never worked on holdover, and I am wondering if we can do something smarter than the obvious feeding of some constant voltage to the VCXO, based on averaging during the locked state. Does anybody know of any good references on holdover? Thanks! Javier [1] http://www.ohwr.org/projects/white-rabbit/wiki ___ 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] Striking change in iPhone time accuracy with 8.2
On 4/1/2015 2:31 PM, Paul wrote: On Wed, Apr 1, 2015 at 12:33 PM, Reid Oda reid@gmail.com wrote: This seems to imply that the iPhone does get sub-second timing info from GPS. Can anyone confirm/deny this? As of iOS N where I believe N == 5 it does the equivalent of calling ntpdate every few hours if the network is available. I assume it uses the mobile system if the network is unavailable and you have a cellular radio because the devices (can) have a lot of drift. ___ 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. The phone has to keep synch within a few microseconds of the network. There was a time when operators were very sloppy about clock time and really only worried about network frequency, but most operators are now maintaining 50 ns or so at the base stations and have to maintain within 5 microseconds to meet the LTE specs. How much of this is preserved through to the user interface is anyone's guess. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] Lucent KS-24361 mystery LED resolved.
There are two LED's on the circuit board next to the power supply module. One is green blinking. I'd never seen the other one on. I needed to get them off of my bench power supply and onto a permanent supply. I tried a 24V 3A supply. They must have been cheating a little on the ratings. The voltage dropped down to about 16V when the oven heaters fired up. I noticed that the mystery LED was lit. It's red. A good guess is that it's a power fault indicator. The LED's are next to the black power supply module. A picture is attached. Also, Below is a link to some plots from Ulrich Bangert's Z38XX software of the initial day of operation. The units had about 30 minutes of run time before I got a permanent power supply, GPS Antenna and RS-422 connection set up. I thought it was interesting to see the graph of the EFC Value slowly flattening out. I guess if I was asleep for 15 years It'd probably take me a while to get going too :-) http://mesterhome.com/timenuts/gpsdo/ -- Luke Mester http://mesterhome.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.
