Re: [time-nuts] OXCO Spurious Output at Line Frequencies

Just to clarify - AC motors are either synchronous or induction. Induction motors must slip away from line frequency to develop the magnetic field they need to carry a load. The name plate speed is for rated load and the number of magnetic poles in the rotor. A 2 pole motor spins near line

[time-nuts] OXCO Spurious Output at Line Frequencies

A friend on mine once worked on projects to build very sensitive magnetometers (submarine detection and space probes). Their test lab was in the middle of a square mile of land selected for its low magnetic residue properties. The building was made completely (of carefully selected) wood...

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

I can't seem to get the line related spurs much below -170dBc/Hz for the fundamental and -180dBc/Hz for the line frequency related harmonics. Everything was bolted down to a 12mm thick aluminium slab. Avoiding an Earth loop by isolating the Timepod Ch0 and CH2 inputs from the aluminium plate

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

Hi ummm …… errr ….. yes. If you mount the OCXO that drives an 800 MHz FM narrowband transmitter in the middle of a wall panel on the rack, you *can* measure the rotation speed of the blowers. That’s not a guess, that’s empirical knowledge :) Bob > On Jul 12, 2016, at 8:24 PM, Hal Murray

Re: [time-nuts] GPS for Nixie Clock

Hi Hal, I've done NTP before, I wanted to do this with GPS since I have never done a GPS implementation before. Xerox Alto, wow that brings back memories! My dad worked at Xerox in Palo Alto for 20 years in the 70s and 80s. He primarily worked on the D machines but I did get to use an Alto a

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

kb...@n1k.org said: > All of those motors in the building are rotating at line frequency. You > don’t just have an electromagnetic field. You can have an acoustic / > vibration field as well. Probably not a big deal, but it’s there …. Most of the medium sized motors run at slightly

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

Hi Bottom line: This is why you often see spur specs stated with a lower frequency limit (like 250Hz) or an exclusion for line related spurs. One really fun one not (yet) mentioned: All of those motors in the building are rotating at line frequency. You don’t just have an electromagnetic

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

Bob the VLF guys in Europe can receive the 60Hz signal over here! so you probably needed a test site on the far side of the Moon :-)) Alan G3NYK - Original Message - From: "Bob Camp" To: "Discussion of precise time and frequency measurement" Sent:

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

On 7/12/16 3:44 AM, Martyn Smith wrote: Hello, I have a customer who is measuring the phase noise of my 10 MHz ultra-low phase noise frequency standard. He is seeing spurious signals at line frequencies (50 and 100 Hz as we are in Europe) at a level around -130 dBc. My opinion is that it's

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

Hi The “practical” solution often is to ship it to an office of the same company that happens to have 60 Hz power. The spur moves to 60 / 120 / 180 and they move on with their evaluation. I have also played the “let’s do it with batteries" approach. Screen rooms were of little benefit.

Re: [time-nuts] GPS for Nixie Clock

DHCP is handy to provide the IP address and specify which NTP server to use. Using DHCP I don't need to setup all the network settings for my project. The NTP packet parser itself is really small and doing its duty very well. Using such setup, it gives me flexibility to choose the different

Re: [time-nuts] GPS for Nixie Clock

t...@patoka.org said: > In addition, even MCU has not enough resources to handle TCP/IP, DHCP and > NTP, it is some solutions available to outsource it to dedicated chips. I > was using WIZ5100 (assembled as a modules) with great success. NTP is pretty simple. If you are willing to take a

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

I retired in 1999 so it's been a long time since I used one, but I don't recall ever seeing a device measured using an HP 3048 system that didn't exhibit line frequency (and harmonic) spurs. See the "live" plots at the end of this page: http://hpmemoryproject.org/news/3048/hp3048_01.htm Wes

Re: [time-nuts] GPS for Nixie Clock

I've used the wiznet module, these days I'd consider the esp8266, powerful little module that can be had for a couple of dollars complete with WiFi capabilities and enough GPIO to interface GPS and some sort of serial nixie interface. On 12 Jul 2016 20:11, "Vlad" wrote: > > In

Re: [time-nuts] GPS for Nixie Clock

In addition, even MCU has not enough resources to handle TCP/IP, DHCP and NTP, it is some solutions available to outsource it to dedicated chips. I was using WIZ5100 (assembled as a modules) with great success. Regards, Vlad On 2016-07-12 12:01, Chris Albertson wrote: What kind of micro

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

Unless your DUT is in a mu-metal enclosure, I wouldn't say observing the same results while battery powered provides any conclusive statement as to whether or not its the DUT. The terminals around a crystal are pretty high impedance at line frequencies. On Tue, Jul 12, 2016 at 6:44 AM, Martyn

[time-nuts] More FE405B data

Hi, I posted an AD plot of a good FE405B back on Jun 7th. A plot just completed today after an additional month of running is essentially the same. I did however measure the aging rate and it is currently 1.15X10-11th per day! Cheers, Corby ___

Re: [time-nuts] A different way to think about time dilation?

Using Google I find this idea is all over theInternet and quite common. That motion in 4-space is always at c. Or more specifically motion in four space for a body at rest in 3-space is v = (dx, dy, dz, dt/t) = (0, 0, 0, c) for a photon trading along x axis it is v = (c, 0, 0, 0) and that |(c,

Re: [time-nuts] GPS for Nixie Clock

What kind of micro processor are you using to run the Nixie tube clock? If that processor could run NTP you would not need GPS. But of course you could always do both. GPS requires a view of the sky and maybe that is not available in a multi story building unless near a window. NTP would be

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

Hi Martyn, For such measurement you may shield your DUT and instruments. Ever using a shielded room which might not be easy for everyone or using shielded tents. You can find them made custom for 600-1000€ depending on the size. I've just ordered two of them from a company in netherlands

Re: [time-nuts] OXCO Spurious Output at Line Frequencies

Hi, I agree with you. Some HP spectrum analyzer have  internal 50 and 100 Hz spurs down to -80dBc due the fan as described in the manual. It can be the spurs are from the test set and/or connection cables. If your oscillator is battery powered you can be sure the spurs are not from the source.

[time-nuts] OXCO Spurious Output at Line Frequencies

Hello, I have a customer who is measuring the phase noise of my 10 MHz ultra-low phase noise frequency standard. He is seeing spurious signals at line frequencies (50 and 100 Hz as we are in Europe) at a level around -130 dBc. My opinion is that it's impossible to get much better than that.