Re: [time-nuts] LEA-M8T

On Fri, Apr 8, 2016 at 12:06 AM, Tom Van Baak wrote: > Meanwhile it would not surprise me if each GNSS system gives a slightly > different position and a slightly different time than GPS does. One could easily imagine a system that when signals from both constellations were

Re: [time-nuts] LEA-M8T

Hi Been there / done that: The answers on position are off by 3 to 5 meters after multi day self survey. The answers on time are off by even more than that would predict. (> 20 ns but < 100 ns). Bob > On Apr 7, 2016, at 9:14 PM, Hal Murray wrote: > > >

Re: [time-nuts] LEA-M8T

Tom, On 04/08/2016 02:06 AM, Tom Van Baak wrote: Hi Bjorn, For navigation more measurements have always been prefered - that is use as many GNSS systems as all your receicers support. I would like to believe this. There's a common myth with clocks that more is always better. For example,

Re: [time-nuts] LEA-M8T

So... Back to Bob's original observation. He stated that he DID shut off all sats except GPS. So, is the LEA-8MT better or worse than the LEA-6T (or LEA-7T, if available) when only GPS is used? I wouldn't think that it would be worse, but it wouldn't be the first product that an "enhancement"

Re: [time-nuts] LEA-M8T

kb...@n1k.org said: > I agree that should be correct in principle. My observation of the modules > on the market today is that each constellation tends to create it’s own > antenna location. It would be interesting to run two units from the same antenna but using different systems and see how

Re: [time-nuts] LEA-M8T

hol...@hotmail.com said: > I've seen reports that GPS and GLONASS fixes can be off well over 50 meters > when referenced to the same map model. Was that difference stable, or does it wander over time? Was that with a good antenna, or down in the trees or an urban canyon? -- These are my

[time-nuts] LEA-M8T

Yes, they do. They seem to use different orbital, gravity, geoid, TAI, etc models. Trying to merge fixes from different systems leads to all sorts of problem, particularly at nuttery levels. I've seen reports that GPS and GLONASS fixes can be off well over 50 meters when referenced to the

Re: [time-nuts] LEA-M8T

Hi Bjorn, > For navigation more measurements have always been prefered - that > is use as many GNSS systems as all your receicers support. I would like to believe this. There's a common myth with clocks that more is always better. For example, if you have 4 cesium then adding 5 more gives you

Re: [time-nuts] LEA-M8T

HI > On Apr 7, 2016, at 10:43 AM, Björn wrote: > > For navigation more measurements have always been prefered - that is use as > many GNSS systems as all your receicers support. I agree that should be correct in principle. My observation of the modules on the market

Re: [time-nuts] Building a mains frequency monitor

A good source for what is actually going on with power line frequency is the web site of the University of Tennessee, which in partnership with Oak Ridge National Labs has a mains frequency monitoring program at http://fnetpublic.utk.edu/. The "Table Display" page shows frequency data for the

Re: [time-nuts] LEA-M8T

What Bob Camp said about PRECISION navigation and as it applies to precision time is true. Do not mix different constellations. There is direct evidence. On Thu, Apr 7, 2016 at 9:43 AM, Björn wrote: > For navigation more measurements have always been prefered - that is

Re: [time-nuts] Building a mains frequency monitor

Mark, Start with: https://en.wikipedia.org/wiki/Electrical_network_frequency_analysis and then spend some time searching. There's hundreds of technical papers and interesting details. Definitely time nut material. /tvb - Original Message - From: "Mark Sims" To:

Re: [time-nuts] LEA-M8T

For navigation more measurements have always been prefered - that is use as many GNSS systems as all your receicers support. That should be true also for common view timing. --        Björn Originalmeddelande Från: Bob Camp Datum:2016-04-07 18:41 (GMT+07:00)

Re: [time-nuts] TS 2100 Parts

If yours is the same version as mine, it has an Astec Switching Power supply. IIRC, it ends in "42". I would be more specific, but I am not where it is. ;-). I was surprised to learn that this supply is still in production by more than one vendor and is much less than $100. Swapping it out is

Re: [time-nuts] LEA-M8T

Hi Indeed, if you have not turned off the other systems for timing, you will have issues. Even for precision navigation, you need to turn them off. Until the European system goes up, there will not ba a coordinated approach between any two of the systems. Right now they each make their own

Re: [time-nuts] Does anyone have an inoperable TS2100 they'd part with?

Frequently power supplies in instruments like the TS2100 are standard off the shelf units. I would suggest googling the vendor and part number and of course checking the well known auction site In one case avocent wanted 1800 bucks to fix a terminal server with a dead PS I was able to buy a

Re: [time-nuts] Building a mains frequency monitor

My measurements show the fractional frequency deviation of the power line at my home is ~25 e-6 with a 1-second measurement and 100 loops through the calculation. I agree with Bill that a precision frequency source is not necessary. Jeremy N6WFO On Wednesday, April 6, 2016, Bill Hawkins

[time-nuts] Stanford: Hofstadter lecture, Apr 25+26: Professor Theodor W. Hänsch

How many time-nuts are there in the Bay Area? Monday Evening, general public: "Changing Concepts of Light and Matter" The lecture will lead from historical milestones to modern frontiers, including spectroscopic precision tests of fundamental physics laws, ultraprecise clocks, and ultracold

Re: [time-nuts] Building a mains frequency monitor

Transformers really are nearly noiseless. They can pick up magnetic fields but most of that is the 60Hz you are trying to measure. (the problem is normally with audio transformers picking up the 60Hz) A transformer is by far the safest way to go. I'd even go so far as to use a split bobbin type

Re: [time-nuts] Building a mains frequency monitor

bill.i...@pobox.com said: > You are looking for parts per thousand at most. Precision GPSDO 10 MHz is > overkill. That depends on the time scale you are interested in. If you want to plot the line frequency on the scale of seconds or minutes, then a junk crystal is probably good enough. If

Re: [time-nuts] Time-nuttery at EFTF-2016

Tom, On 04/07/2016 02:55 AM, Tom Van Baak wrote: One interesting poster from Justervesenet (Norways National Meterology Institute) addressed some odd characteristics of the Keysight 53230A counter and the way it process data. It have shown several problems, and part of the research was done

Re: [time-nuts] Time-nuttery at EFTF-2016

In message , "Tom Van Baak" writes: >About odd characteristics in the 53230A, please also see: > >"... Frequency Error near the Reference Frequency Harmonics" >http://cp.literature.agilent.com/litweb/pdf/5990-9189EN.pdf >Does it relate at all to

[time-nuts] Building a mains frequency monitor

And that can be very interesting... a while back I read some stories on how the NSA, police, etc could find out where an audio recording was made by correlating AC hum in the recording with logs that they had of the power grids. Apparently logging AC mains is rather popular among the spooky /

Re: [time-nuts] LEA-M8T

Hi Bob, Can't speak to jitter accuracy but the M8 series is definitely not the same receiver in the 6 series. As you probably know, M8 introduced multi-GNSS support so in addition to GPS you have Beidou and Glonass satellites. At work we've had some gnashing of teeth about the wider

Re: [time-nuts] Building a mains frequency monitor

Jay wrote: Q3: The open-ended question: How do I improve on this? I suspect the main place for improvement will be in the trigger, but I'm not sure where to go with that. Most designs I've seen involve a schmitt trigger, generally with reference voltages set by things like voltage dividers.