[time-nuts] HP5065A pressure compensation

Hi Corby, I an looking your Pressure Compensation for the HP5065A ad I have a question about the preliminary adjustment of R3. Can you give me the alignment procedure you have used?. I suppose you have used the Pressure chamber looking at the frequency offset. thanks, Luciano

Re: [time-nuts] wifi with time sync

On Fri, January 13, 2017 10:59 am, Bob Camp wrote: > 1588 is a "less than a microsecond" sort > of approach that does indeed get down to nanosecond > sort of levels. This could be similar. There was talk of adding a wireless profile into 1588 either as an addendum or as part of PTPv3. I suspect

Re: [time-nuts] Thermal effects on cables --> ADEV

I think you might be overthinking their point, that if you plan to use an xDEV as a measure for state of health, don't use years worth of data. Otherwise it could be days before the xDEV visually changes. On Fri, Jan 13, 2017 at 11:04 AM, Bob Camp wrote: > Hi > > There’s an

Re: [time-nuts] Thermal effects on cables --> ADEV

That IS interesting.. It reads to me that the advice is to keep a "moving 300 pt ADEV" when continously monitoring a (pair of) frequency source in e.g a VLBI site - the reason for limiting it to 300 pts being that much more than that is likely to average out potential issues.. Does that make

Re: [time-nuts] Thermal effects on cables --> ADEV

Hi That’s the way I read what they are saying. More or less: Keep the number of samples above 100, but below 300. Bob > On Jan 13, 2017, at 12:30 PM, Ole Petter Rønningen > wrote: > > That IS interesting.. It reads to me that the advice is to keep a "moving 300 > pt

Re: [time-nuts] wifi with time sync

Can we please stop talking about pings? Bob Camp wrote on Fri, 13 Jan 2017 at 15:12:38 -0500 in : > I’m sure you are right about the response time. Right now the > variation is running almost 3 ms at one sigma on a ping so there is >

Re: [time-nuts] wifi with time sync

Even with the long and variable ping time, time sync can work. The reason it can work is that time is not re-sync'd in one "ping" but time sync is an on-going process that occurs over a period as long as hours. Think about adjusting the rate of a clock by hand. The computer (NTP) can (and does)

Re: [time-nuts] wifi with time sync

Bob Camp wrote on Fri, 13 Jan 2017 at 15:35:19 -0500 in : > What standard protocol would you recommend I run from the command > line on my computer to get a quick estimate of the timing lag and > variablilty on my particular WiFi

Re: [time-nuts] wifi with time sync

Hi What standard protocol would you recommend I run from the command line on my computer to get a quick estimate of the timing lag and variablilty on my particular WiFi connection? Bob > On Jan 13, 2017, at 3:25 PM, John Hawkinson wrote: > > Can we please stop talking about

Re: [time-nuts] wifi with time sync

Hi That *assumes* that NTP is installed on the laptop. Bob > On Jan 13, 2017, at 3:45 PM, Chris Albertson > wrote: > > Short answer: See man page for ntpq > > Longer... > > First run NTP then after some time (15 minute to an hour) at the command > line time type

Re: [time-nuts] wifi with time sync

Hi Ok. so I bring up NTP on the laptop against a server on the other side of the country and install NTP on the laptop. I get all of the jitter and offset of my cable modem plus the network issues between here and who know where. If I want to know the specific delay issues just on the WiFi

Re: [time-nuts] Thermal effects on cables --> ADEV

Mark, Ole, Yes, averaging can both enhance precision but also destroy information. In many cases too much data is a bad thing. The solution is to add another dimension to the plot. Stable32 does this with DAVAR (dynamic Allan variance). TimeLab has a multi- "trace" feature. Both of these break

Re: [time-nuts] wifi with time sync

On Fri, January 13, 2017 11:40 am, Bob Camp wrote: > The ping response is anywhere from 2 ms out to 400 ms. Most of > the time it's in the 3 to 9 ms range. Simply taking that > down to < 1 us would be a really big deal. I doubt that the response time will get that low, rather the time sync will

Re: [time-nuts] wifi with time sync

Hi I’m sure you are right about the response time. Right now the variation is running almost 3 ms at one sigma on a ping so there is a lot to do simply to get the accuracy anywhere near 1 us. Bob > On Jan 13, 2017, at 2:35 PM, Chris Caudle wrote: > > On Fri, January

Re: [time-nuts] wifi with time sync

To add to this I'd be curious in knowing about easy PC based ways to measure network latencies / delays with microsecond accuracy vs millisecond accuracy. The tools I used to use at work were generally designed for use on networks where millisecond resolution measurements made sense as a

Re: [time-nuts] wifi with time sync

Hi It just so happens that I’m trying to track down an issue with my WiFi as I type this. My *guess* is that there is a dropout going on. The only easy way I can see to get a round trip time with a high data rate is to run ping. It’s the only tool that gives me something that is fast enough to

Re: [time-nuts] wifi with time sync

Short answer: See man page for ntpq Longer... First run NTP then after some time (15 minute to an hour) at the command line time type "ntpq -p" "ntpq" will query NTP for timing statistics. It will report the average delay between the local computer and the set of reference clocks (other

Re: [time-nuts] wifi with time sync

they were really short on hard details about this new technology. the *WiFi alliance* website only shows this off-site article link I found under NEWS:

[time-nuts] Thermal effects on cables --> ADEV

I recently made a change in Lady Heather's satellite signal maps to help with a very similar issue. Before, the maps were based upon the accumulated average value of the sat signals at each point in the sky. Now, every 24 hours, the signal level averages are reset to their current average and

Re: [time-nuts] wifi with time sync

I saw this article too -- is anyone aware of something with more technical details? For example, where in the protocol stack does it work? Is it specific to 802.11 or general purpose ethernet? Speaking as someone who has a primary hobby of the development of super low cost time sync algorithms

Re: [time-nuts] wifi with time sync

Hi Just for reference, I happen to be running a ping over my local WiFi to one of the switches on the LAN. The ping response is anywhere from 2 ms out to 400 ms. Most of the time it’s in the 3 to 9 ms range. Simply taking that down to < 1 us would be a really big deal. Bob > On Jan 13,

Re: [time-nuts] wifi with time sync

Hi I probably should have added that I already know that the switch will do sub 1 ms LAN pings all day long with the near zero load that it’s running. Sorry about that. Now, there certainly are OS level things on my laptop that will muck up pings. Unfortunately they also get into a number of

Re: [time-nuts] wifi with time sync

Hi A lot depends on how much “less than a microsecond” the chip sets really deliver in the real world. If they get down into the sub 100 ns range (which they might), it’s a very useful thing for relaying GPS data from a roof antenna down to an NTP server in the basement. 1588 is a “less than a

Re: [time-nuts] Thermal effects on cables --> ADEV

You are certainly justified to be cautious of only using an xDEV for state of health. I don't know what GPS does for example to mark SV's as healthy or not healthy. On Fri, Jan 13, 2017 at 1:11 PM, Bob Camp wrote: > Hi > > I do agree with their point that systematics will get

Re: [time-nuts] Thermal effects on cables --> ADEV

Hi I do agree with their point that systematics will get buried in giant data blocks. What I’m not quite as sure of is the utility of even 300 sample blocks to spot systematic issues. Bob > On Jan 13, 2017, at 1:08 PM, Scott Stobbe wrote: > > I think you might be

Re: [time-nuts] wifi with time sync

> On Jan 13, 2017, at 09:40, Bob Camp wrote: > > Just for reference, I happen to be running a ping over my local WiFi to one > of the switches > on the LAN. The ping response is anywhere from 2 ms out to 400 ms. Most of > the time it’s > in the 3 to 9 ms range. Simply taking

Re: [time-nuts] wifi with time sync

> What standard protocol would you recommend I run from the command line on my > computer to get a quick estimate of the timing lag and variablilty on my > particular WiFi connection? I'd use ping. But you said "quick estimate". My wifi is crappy enough that its noise swamps everything

Re: [time-nuts] wifi with time sync

On Fri, Jan 13, 2017 at 8:45 PM, Chris Albertson wrote: > Short answer: See man page for ntpq > > Longer... > > First run NTP then after some time (15 minute to an hour) at the command > line time type "ntpq -p" > > "ntpq" will query NTP for timing statistics. It will

Re: [time-nuts] wifi with time sync

It’s a little more complicated than that. A switch’s main cpu is like a host with rx coalesce set to 100. And there are a surprising number of things that trigger the main cpu beyond management functions. Multicast is a good example. The amount of load on the main cpu can be quite variable, and

Re: [time-nuts] hm H Maser

Hydrogen maser in radio astronomy to sync worldwide systems: http://flip.it/rmbdRQ (Lifted from the Albany, NY astronomy group). -- Gary Woods O- K2AHC Public keys at home.earthlink.net/~garygarlic, or get 0x1D64A93D via keyserver fingerprint = E2 6F 50 93 7B C7 F3 CA 1F 8B 3C C0 B0 28

Re: [time-nuts] wifi with time sync

On Fri, January 13, 2017 3:17 pm, Bob Camp wrote: > It just so happens that I'm trying to track down an issue with my WiFi > as I type this. This is getting off topic for time-nuts very quickly, but use bufferbloat and "make wifi fast" as search phrases. The guy who did a lot of the work on

Re: [time-nuts] wifi with time sync

On 1/13/17 2:19 PM, Chris Caudle wrote: On Fri, January 13, 2017 3:17 pm, Bob Camp wrote: It just so happens that I'm trying to track down an issue with my WiFi as I type this. This is getting off topic for time-nuts very quickly, well, wireless distribution of accurate time is, I think, on

Re: [time-nuts] wifi with time sync

On Fri, Jan 13, 2017 at 3:35 PM, Bob Camp wrote: > Hi > > What standard protocol would you recommend I run from the command line on > my computer > to get a quick estimate of the timing lag and variablilty on my > particular WiFi connection? If I wanted to do this I would use

Re: [time-nuts] Thermal effects on cables --> ADEV

I think their advice was to limit the ADEV calculation for some tau to 300 bins. The standard error on estimating the standard deviation is ~ +- 5% for 200 samples. So loosely speaking in the neighborhood of 100-300 bins the resulting adev will have an rms uncertainty of roughly 5%. So limiting

Re: [time-nuts] hm H Maser

An entire room kept near to absolute zero with a simple door access???Unlikely, likely the writer is unfamiliar with science/engineering. Bruce On Saturday, 14 January 2017 11:39 AM, Gary Woods wrote: Hydrogen maser in radio astronomy to sync worldwide

[time-nuts] wifi with time sync

While probably not tight enough for time nuts use, there is a new WiFi technology shown at CES that provides time sync between nodes to allow audio to be simulcast over many locations. the info (in short form) is here for those interested:

Re: [time-nuts] wifi with time sync

On Fri, Jan 13, 2017 at 1:11 PM, Bob Camp wrote: > Hi > > Ok. so I bring up NTP on the laptop against a server on the other side of > the country and install > NTP on the laptop. I get all of the jitter and offset of my cable modem > plus the network > issues between here and who

Re: [time-nuts] wifi with time sync

If there is a modern microwave oven with a switching power supply, or a cordless telephone around, you might want to look there. The old linear supply ovens were easy to deal with because they presented a strong CW signal that drifted around as voltage, load, and temperature changed. The

Re: [time-nuts] Thermal effects on cables

On 1/12/17 10:52 PM, Ole Petter Ronningen wrote: Hi, all The question of phase shifts in cables pops up every now and then on this list - I stumbled across a good table of measured phase shifts with temperature in different cable types in this paper:

Re: [time-nuts] Thermal effects on cables --> ADEV

Hi There’s an interesting comment buried down in that paper about limiting ADEV to < 300 samples per point. Their objective is apparently to better highlight “systematic errors”. I certainly agree that big datasets will swamp this sort of thing. I’m not quite sure that I’d recommend ADEV to