Re: [time-nuts] Precision DACs

As a clarification, the AD5791 is the minimum implementation of a DAC, it's merely a resistor array with SPI controllable switches. (But an impressive set of resistors, no doubt. Maybe with a dash of secret sauce in digital calibration). The only guaranteed specs for the AD5791 are at DC,

Re: [time-nuts] The home time-lab

On 7/25/16 6:55 AM, Bob Camp wrote: Hi If you go back far enough in time …. there is another alternative: Big rectifier bank, turning AC into DC, often off of multiple phases or sources. Big DC motor running into a fairly large flywheel. AC generator (or in some cases

Re: [time-nuts] controlling instruments using USB

here is what the author has to say https://joeyh.name/code/alien/ On Mon, Jul 25, 2016 at 7:33 PM, Pete Lancashire wrote: > Never tried this Alien convert RPM to DEB > > https://www.howtoforge.com/converting_rpm_to_deb_with_alien > > > > On Mon, Jul 25, 2016 at 6:02 PM,

Re: [time-nuts] controlling instruments using USB

Have you looked at alien to convert the rpm to a deb? https://www.google.com/#q=alien+package+conversion > Semi-off-topic.. > > I've got a bunch of Keysight/Agilent/HP instruments with USB interfaces > that I want to control from Python. On Mac and PC, the PyVisa library > works great

Re: [time-nuts] controlling instruments using USB

Never tried this Alien convert RPM to DEB https://www.howtoforge.com/converting_rpm_to_deb_with_alien On Mon, Jul 25, 2016 at 6:02 PM, jimlux wrote: > Semi-off-topic.. > > I've got a bunch of Keysight/Agilent/HP instruments with USB interfaces that > I want to control

[time-nuts] GPS receiver time message offsets to 1PPS

Heather will take either time format, but requests the receiver to send T2 format. I originally thought the SCPI receivers would be right on time due to my original measurements of their message jitter, but when I started measureing the actual message arrival times... surprise, surprise,

Re: [time-nuts] GPS receiver time message offsets to 1PPS

hol...@hotmail.com said: > Here are the results of measuring the difference between the time code in a > GPS receiver time message and the arrival time of the last byte of the > message. Negative values mean that the receiver sends the timing message > after the 1PPS pulse that it describes. The

[time-nuts] controlling instruments using USB

Semi-off-topic.. I've got a bunch of Keysight/Agilent/HP instruments with USB interfaces that I want to control from Python. On Mac and PC, the PyVisa library works great (either the one with the NI back end or the python only back end ) But, on Ubuntu, there's no way to install the NI

Re: [time-nuts] The home time-lab

On Mon, 25 Jul 2016 12:28:52 -0500 David wrote: > I have never seen one which did not use a class-D output with L-C > filtering. Total efficiency is in the 84 to 92 percent range. Actually, the better ones have 3 level or 5 level inverters (or even more). Ie their output

Re: [time-nuts] GPS receiver time message offsets to 1PPS

Yo Mark! On Mon, 25 Jul 2016 22:51:01 + Mark Sims wrote: > Here are the results of measuring the difference between the time > code in a GPS receiver time message and the arrival time of the last > byte of the message. Negative values mean that the receiver sends > the

Re: [time-nuts] Precision DACs

On Sun, 24 Jul 2016 23:48:05 -0400 Scott Stobbe wrote: > I doubt the AD5791 does much better than 16 bits operating at 1 Msps, when > you include glitch energy, noise, and distortion. What makes you think so? Yes, if you are using the full 500kHz bandwidth then the

Re: [time-nuts] Precision DACs

On Sun, 24 Jul 2016 19:17:29 -0500 David wrote: > There *has* to be a better way to do this. Maybe we could build a > wooden badger ... What? Has the wooden rabbit failed? As I said, I looked into this some time ago and I couldn't come up with any "easy" way to build a

[time-nuts] GPS receiver time message offsets to 1PPS

Here are the results of measuring the difference between the time code in a GPS receiver time message and the arrival time of the last byte of the message. Negative values mean that the receiver sends the timing message after the 1PPS pulse that it describes. The table also shows the standard

[time-nuts] [LEAPSECS] Leap second to be introduced at midnight UTC December 31 this year

And somebody paid well over 10 times the market rate to lease server space that was one building closer to the NYSE computers. My idea to put an end to this bogo-trading nonsense is to add a random delay to all the trades. > Someone recently built a new fiber route

Re: [time-nuts] [LEAPSECS] Leap second to be introduced at midnight UTC December 31 this year

I'd be interested to know how 10ns less latency is useful. AFAIK, a high speed trading system consists of multiple processing nodes, which certainly could have a 10ns accurate time reference eg via PTP, but latency and jitter would limit time stamping of transactions to the microsecond level.

Re: [time-nuts] [LEAPSECS] Leap second to be introduced at midnight UTC December 31 this year

We've been dealing with speed of light issues for over 20 years in the financial world. And telecom. Someone recently built a new fiber route from Chicago to NY because it was just a touch shorter. The distances are down to hundredths of a ms. > On Jul 25, 2016, at 17:41, Bob Camp

Re: [time-nuts] The home time-lab

Brooke wrote: But a relay switched UPS, like mine, does nothing to the line waveform, so the Sola offers a lot of improvement. Since the Sola does not help getting a sine waveform, it may be better to put it on the input since that might make dropout detection more reliable? Instead of

Re: [time-nuts] [LEAPSECS] Leap second to be introduced at midnight UTC December 31 this year

A second here or there is a very big deal to those of us in the financial and database worlds. Aside from the well known instances involving electronic trading I have customers fighting over cabinet positions and cable lengths to place processors closer to disk drives and on switch paths

Re: [time-nuts] [LEAPSECS] Leap second to be introduced at midnight UTC December 31 this year

Hi In these days of computers trading with computers, the whole issue of “who did what when” can result in major money trading hands. I’m sure that at some point the financial markets will have to deal with light speed issues and geography if they have not already. Bob > On Jul 25, 2016,

Re: [time-nuts] Symmetricom Power On Counter

Hi Maybe it only has a 20 year life if you power it up 50% of the time :) Somehow I doubt that it only has a 10 year “power on” life. Bob > On Jul 25, 2016, at 3:55 PM, Skip Withrow wrote: > > Hello Time-Nuts, > > I just ran a Symmetricom X72 for 10 days to check the

[time-nuts] [LEAPSECS] Leap second to be introduced at midnight UTC December 31 this year

Apple's new file system timestamps files with nanosecond resolution. A lot of Linux file systems also do that now. The nanosecond ain't what it used to be... I can imagine people wanting picosecond timestamps in the near future. Who knows, maybe we'll have something like NTP compensating

[time-nuts] Venus838LPx-T opinions?

I have a Z3812A that I added back in the GPS receiver and modified it (moving 6 zero ohm resistors) to work as a standalone GPS. Basically it's now a stand-alone Z3811. I have Lady Heather working with it now. The hack of using the RS-422 output to directly drive a RS-232 serial port does

Re: [time-nuts] The home time-lab

Charles, I can't speak for Brooke, but I have to point out that each of us has different needs when it comes to powering our lab.  For myself, if I lose power, that's OK.  I'm retired selling a few GPSDOs here and there and working on some other stuff, so I don't need a 24/7 operation.  What

[time-nuts] Symmetricom Power On Counter

Hello Time-Nuts, I just ran a Symmetricom X72 for 10 days to check the rate of the Pwr HRS counter. At one point I thought I did this with an SA.22c and found a discrepancy between actual number of hours run and the counter increment. I can report that the X72 does appear to count hours

Re: [time-nuts] The home time-lab

The reason they call it a modified sine wave is that it is a square wave with the same peak and RMS voltages as a sine wave. Since the RMS value of a (bipolar) square wave is equal to its peak value, it has to include parts at zero or a lower voltage. Some inverters use additional voltage steps

Re: [time-nuts] The home time-lab

kb...@n1k.org said: > If you go back far enough in time …. there is another alternative: >Big rectifier bank, turning AC into DC, often off of multiple phases > or sources. >Big DC motor running into a fairly large flywheel. >AC generator (or in some cases DC

Re: [time-nuts] The home time-lab - APC Smart UPS 700

I let an older, well-aged GPSDO warm up overnight and then I ran a test with the UPS.  Attached were the PRS*, the GPSDO, and the 5370A.  I didn't notice anything when I removed power.  I did notice about a 450ps phase spike when I plugged the UPS back in some 640 seconds later.  But that was

Re: [time-nuts] The home time-lab

Or the current version: Large AC motor driving a LARGE flywheel with an AC (and/or -48VDC) generator on the other side feeding a very large battery plant. If mains drops more than 1/2 cycle it connects the turbine and starts it up. We had a 5MW one at $OLD_GIG for feeding our supercomputer

Re: [time-nuts] Venus838LPx-T opinions?

Hi Mark, If you are ever interested in playing with the Lucent boxes (Z3811, Z3812) I would be glad to send you a working system to play with. Sure would like to use LH with it. 73, Bill, WA2DVU Cape May, NJ -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On

Re: [time-nuts] The home time-lab

Hi Chris: The APC RS1500 uses what they call modified sine wave, but I call modified square wave, i.e. it's a square wave with a couple of parts that are at zero volts. Don Lancaster promoted "Magic Sinewaves" where a pulse modulated waveform drives an H-bridge. The leading and trailing edges

Re: [time-nuts] [LEAPSECS] Leap second to be introduced at midnight UTC December 31 this year

Hi > On Jul 25, 2016, at 10:21 AM, Martin Burnicki > wrote: > > Bob, > > Bob Camp wrote: >> Hi >> >> The practical problem with any change to leap seconds is transition from >> what we have >> to the “new system”. Anything other than dropping them altogether

Re: [time-nuts] The home time-lab

I have never seen one which did not use a class-D output with L-C filtering. Total efficiency is in the 84 to 92 percent range. These days they also include power factor correction on their line input so they can be used to apply power factor correction to any load. Refurbished ones are

Re: [time-nuts] The home time-lab

Hi Bill: I have links to the Sola patents at: http://www.prc68.com/I/Sola_CVS.html#Patents The 1939 patent shows a single gap and the resonant circuit, but the current patent (number on Sola xformer label) shows two gaps and the resonant circuit. They specify up to a 3 ms dropout restoration

Re: [time-nuts] The home time-lab

Charles is correct and most data centers and metrology laboratories operate from power produced by large versions of these systems i.e. From 50KW to megawatts generally backed by one or more generators to carry facility when utility power is not available Content by Scott Typos by Siri > On

Re: [time-nuts] The home time-lab

Yes, "ferroresonant" is also called CVT. Typically rather than buying just the transformer you buy a box that has one in it but also some other components to clip spikes (some MOVs) and and LC low pass filter. I know it seems a saturated core might produce a non-sine wave but current CVTs have

Re: [time-nuts] [LEAPSECS] Leap second to be introduced at midnight UTC December 31 this year

Bob, Bob Camp wrote: > Hi > > The practical problem with any change to leap seconds is transition from what > we have > to the “new system”. Anything other than dropping them altogether involves a > *lot* of > coordination. You pretty much have to pick a date and bring everything onto > the

Re: [time-nuts] The home time-lab

Hi If you go back far enough in time …. there is another alternative: Big rectifier bank, turning AC into DC, often off of multiple phases or sources. Big DC motor running into a fairly large flywheel. AC generator (or in some cases DC generators) running off of the

Re: [time-nuts] The home time-lab

Chris wrote: I've never thought UPS were a good idea for anything but a computer that needs to shut down gracefully. For your use you need something that cleans up the AC mains power. A proper "online" (or "double conversion") UPS does just that. It always provides cleanly-generated

Re: [time-nuts] NCOCXO anyone?

Hi A typical double oven design runs about 10 mw or so in the circuitry in the inner oven. The “stuff” inside the outer oven likely doubles that number. The rest of the circuit is put outside the outer oven to reduce heat rise. There could be another 40 mw in that part of the circuit.

Re: [time-nuts] Precision DACs (was: NCOCXO anyone?)

The AD5791 specifications under various conditions are all roughly consistent; 20 bits at DC, 16 bits at 10 ksps based on SFDR, and 12 bits at 1 Msps for large code changes. Its intended application is DC where its 1 Msps update rate applies for code steps of 500 or smaller and settling time will

Re: [time-nuts] The home time-lab

But then you may find that you can NEVER finish a test. The AC line is typically full of transients. I've never thought UPS were a good idea for anything but a computer that needs to shut down gracefully. For your use you need something that cleans up the AC mains power. The best ones have a

Re: [time-nuts] The home time-lab

you could bring the horse to the well. On 7/24/2016 7:36 PM, Bill Hawkins wrote: Years ago I knew exactly how Sola regulators worked. That has faded, but what remains is that the regulation was done by varying the saturation of the core. That's why there is a slot in the laminations. I

Re: [time-nuts] The home time-lab

On Thu, Jul 7, 2016 at 6:54 PM, Bob Stewart wrote: > So, since I need to power the 5370 (preferably both) I'm looking at a deep > cycle battery, a charger, and an inverter? At this point in the process, a > power line monitor is looking like a good solution. At least it would

Re: [time-nuts] Precision DACs (was: NCOCXO anyone?)

I doubt the AD5791 does much better than 16 bits operating at 1 Msps, when you include glitch energy, noise, and distortion. On Saturday, 23 July 2016, Attila Kinali wrote: > On Fri, 22 Jul 2016 12:15:25 -0500 > David > wrote: > > > If you