[time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

I did it for $25... $7 for the GPS+antenna module, $3 for an Arduino chip on a PCB with proto area from China (should have bought a lot more when they were available),$10 for a small ovenized 5V TTL output OCXO (also should have bought a lot more), and $5 for misc parts (OK, beer money

Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

Oh but thats what the marketing blurb even says. It hit me later that the thing that runs out is still the same CS oven Regards Paul WB8TSL On Mon, Mar 20, 2017 at 3:09 PM, Attila Kinali wrote: > On Sat, 18 Mar 2017 19:25:28 + > "Poul-Henning Kamp"

[time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

Attilla, You are talking about product design, development and optimization, not the production of a one-off for home use. Since performance standards are already well established, it is only necessary for the developer to test the bench built instrument against published standards and determine

Re: [time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

On Mon, Mar 20, 2017 at 4:14 PM, Mark Sims wrote: > $3 for an Arduino chip on a PCB with proto area from China (should have > bought a lot more when they were available),$10 for a small ovenized 5V > TTL output OCXO (also should have bought a lot more), and $5 for misc

Re: [time-nuts] WTB: GPSDO

Hi A good OCXO run continuously should get down to < 0.1 ppb / week. Doing a tweak every Saturday is likely enough to keep it in that range. The *big* advantage is that you have the ADEV of the OCXO without any scruffy stuff from the control loop getting in the way. If your objective is to

Re: [time-nuts] WTB: GPSDO

On 3/20/17 2:26 PM, Mark Spencer wrote: Hi: Bob's comment about adjusting an oscillator from time to time aligns well with my limited experience in the time nuts hobby.Once I realized that in practice my better OCXO's were typically more than stable enough for my intended uses things

[time-nuts] ADEV query Timelab and TICC

Yes, programs like Timelab and Stable32 are definitely the way to go for post-processing and analyzing your data in depth. Lady Heather is more of a real-time monitoring and data acquisition program. The sensitivity of ADEV to data hiccups can be a good thing. If your ADEV data goes to

[time-nuts] ADEV query Timelab and TICC

Orin sent me his data files and I ran them through Lady Heather. Attached is a screen dump showing the Time Interval Error (TIE) plot of the 1PPS signal. This is the deviation of the 1PPS signal from the expected 1 second interval. Three of the bad points are flagged (1, 2, and 3 at the

Re: [time-nuts] ADEV query Timelab and TICC

On Sun, Mar 19, 2017 at 8:03 PM, Tom Van Baak wrote: > > Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 > points). Everything looks fine with the exception of 8 glitches. These are > sometimes obvious jumps in phase, which cause massive spikes in

[time-nuts] Four hour cycle in GPS NMEA jitter

Hello time nuts, I'm working on a custom embedded Linux device, with a custom inertial reference unit, which contains a GPS module. The module is a Telit JN3, which is based on the SiRFSTAR IV I believe. I'd like to use the GPS to sync the Linux system clock. Eventually I'd like to use the

Re: [time-nuts] WTB: GPSDO

Hi: Bob's comment about adjusting an oscillator from time to time aligns well with my limited experience in the time nuts hobby.Once I realized that in practice my better OCXO's were typically more than stable enough for my intended uses things became much simpler. I also realized that I

Re: [time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

I would say that the price for a home-built time-nuts quality GPSDO is going to be significantly greater than $200.  Yes, if you are making them for sale, eventually the unit cost will get down there.  But to build one single good GPSDO, you're going to throw away a lot of prototypes on the way

Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

On Sat, 18 Mar 2017 19:25:28 + "Poul-Henning Kamp" wrote: > >The A magnet being replaced by the A laser will for the same flow from > >the cesium oven produce twice as much atoms and thus improve signal to > >noise. > > It will generate more than twice the (usable)

[time-nuts] PLL Digital Loop Filter

I'm trying to understand how to design and analyze the loop filters in a digital PLL. Specifically, because of digital processing delays, the phase offset measured at time t will only produce a change on the VCXO input at time t+T, where T is the sampling period of the digital loop. I've found

Re: [time-nuts] PLL performance?

Hi, Scott. I rarely post here, but just noticed your post. I can open the "PLL0.pdf" file, but the other files appears to be corrupted. Adobe Acrobat Reader thinks it's not really a PDF file or it's corrupted. I'm not ready to comment on the expected results yet, and would like to see the

Re: [time-nuts] Four hour cycle in GPS NMEA jitter

Hi NMEA sentences are not the best thing to use for timing. If you *do* decide to use them, configure the receiver so that one and only one sentence comes out. Any time you have more than one, you run the risk of collision in the serial buffer on the part. Next thing to do is to pick the

Re: [time-nuts] Four hour cycle in GPS NMEA jitter

Hi Trent, > But first things first. I'm just grabbing the time from NMEA sentences. > And there's quite a bit of jitter there! Clearly using the first sentence > output by the GPS is critical. I've tried to account for any time delays in > the software. I think it's the GPS module that is

Re: [time-nuts] Four hour cycle in GPS NMEA jitter

> Does this sound like something that one would expect with the NMEA output of > a non-timing GPS? Is it related to satellite orbits? Or perhaps is has > something to do with the design of the SiRFStar IV? > Remember the phone based time service? "At the tome time time will be BEEP"

[time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

The "DAC" was PWM based, but used a separate voltage regulator for the "reference". I never tried it using the USB power as the reference. The OCXO (+board) uses less than 500 mA warming up (which it does rather quickly). It's in a small hermetic package about twice the size of a standard

Re: [time-nuts] Four hour cycle in GPS NMEA jitter

Yo Chris! On Mon, 20 Mar 2017 15:19:25 -0700 Chris Albertson wrote: > I've only hear of 1 uS being broken with hardware. A Raspberry Pi can get down to a Standard Deviation of about 350 nano seconds using NTPsec.. https://blog.ntpsec.org/2017/02/01/heat-it-up.html

Re: [time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

Moin, On Mon, 20 Mar 2017 17:11:36 -0400 "William H. Fite" wrote: > You are talking about product design, development and optimization, not the > production of a one-off for home use. Since performance standards are > already well established, it is only necessary for the

Re: [time-nuts] PLL performance?

Hi. I did a 15728640Hz signal locked to a 7680Hz reference using a 74hct9046. It was ugly (I mean, individual trimming of the resistors... I assembled 20 boards). Circuit behaves more like a FLL than a PLL (if you look at both with an scope they never quite locks to each other), but it works

Re: [time-nuts] HP5061B Ion Current

https://www.febo.com/pipermail/time-nuts/2017-March/104374.html I could not figure out why the A15 Ion Current monitor would not let the cesium oven turn on with ion current under 25 uA. At the time we had no way of measuring the +3,500 ion pump supply. We bought some 200 Meg resistors and made

[time-nuts] Time Dilation tinkering

Hi, I've been mostly lurking on the list for some time now and follow with interest the many discussions. Very much at the early stages of my time-nut journey, but enjoying it so far :) I'd like to have a go at re-creating the efforts of Tom (and I gather others) in taking a clock up a

[time-nuts] HP5061B Ion Current

This is my first post. I just bought a non-working HP5061B on eBay for $350. My old boss KB7APQ in Salt Lake City and I are working on it. It came in from the Philipines in October of 2015 and was diagnosed with a bad physics package in March 2016 by AllTest in New Jersey. We initially found

Re: [time-nuts] HP5061B Ion Current

trojancow...@gmail.com said: > We will discuss our findings if there is interest. This is time-nuts. Of course there is interest. What fraction of the old/dead tubes are "gassy"? -- These are my opinions. I hate spam. ___ time-nuts mailing

Re: [time-nuts] HP5061B Ion Current

Donald welcome to the group. If a units been off a long time and it sure sounds like thats the case it may take quite a while like a month or so for the unit to remove all of the "Stuff" that has out gassed. So be patient and let the pump do its job. After it does lower and my fingers are crossed.

Re: [time-nuts] HP5061B Ion Current

Do a search of the list and a few other sites. there is a LOT of information on what challenges one can have. And a lot of the information is practical. As for as pumping a tube down, it took me pretty much a day + a whole weekend, but it did go down to what was scribbled on the door, and now

[time-nuts] PLL performance?

Hi All, I have built and tested a PLL circuit that will be used to generate a 1 MHz signal locked to a 0.5 HZ signal from a pendulum. (Details available upon request.) The circuit is a classic 4046 generating the 1 MHz signal which is fed into a 2e6 digital divider which outputs 0.5 Hz which

[time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

On Thu, 16 Mar 2017 00:06:49 -0700 Chris Albertson wrote: > I actually did use your method. I have a Rb and Thunderbolt, a pair > of freq. counters and so on.But still I wanted to see if I could > build from scratch and verify proper operation and keep the budget

Re: [time-nuts] ADEV query Timelab and TICc

The 1 PPS signal is derived from an 81 MHz clock (12 ns) on the GPS chip according to the Skytraq manual. So that would mean n * 12ns. From: time-nuts-requ...@febo.com Sent: ‎3/‎20/‎2017 9:00 AM To:

Re: [time-nuts] MAINTENANCE OF HP 5071A PRIMARY FREQUENCY STANDARDS USNO

> blockquote {padding-left: 1ex; margin: 0px 0px 0px 0.8ex; border-left: > #cc 1px solid;} p {margin: 0px;padding: 0px;} > Hello, > I'm looking for good quality copy of this paper (especially plots): > > > http://tycho.usno.navy.mil/ptti/1997papers/Vol%2029_06.pdf > > > SD Hi Slawek,

[time-nuts] MAINTENANCE OF HP 5071A PRIMARY FREQUENCY STANDARDS USNO

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Re: [time-nuts] ADEV query Timelab and TICC

All, the similar problem I have verified using the HP5065A and HP5061B 1PPS output, the dividers are pratically unusable for ADEV measurements. The 5/10MHz output of the same instruments using the TAPR divider are ok, so these dividers have some spike noise problems. It can be seen even

Re: [time-nuts] ADEV query Timelab and TICC

Many thanks for the replies on this, what was initially intended as a quick "Hello World" test seems to have become far more interesting:-) I'll forward my results to Tom as requested and see where we go from there. Nigel GM8PZR ___ time-nuts

Re: [time-nuts] ADEV query Timelab and TICC

The LTE-Lite User Manual (version 1.3) says: 2.3.7 1 PPS Module outputs The LTE-Lite SMT Module provides GPS raw 1 PPS CMOS pulse on pin 15 with sawtooth present, and a clean TCXO-generated, sawtooth-removed, UTC(GPS) phase-locked 1PPS output on pin 4. It is the pin 4 output that connects to the

Re: [time-nuts] ADEV query Timelab and TICC

I noticed with the TICC that the very high peak voltage on the 5061, 5065, etc. PPS causes trigger errors.  Putting a 50 ohm load at the TICC channel input helped a lot, or an attenuator might even be better. These HP units have a very short pulse width that peaks at something like 20v into a

Re: [time-nuts] ADEV query Timelab and TICC

Luciano, This should not happen with the hp 5065A or 5061B frequency standards. I'm glad you worked around it by using a TAPR divider, but let's see if we can figure out the actual problem. One thing to know is that the 1PPS output level from the 5061 and 5065 is *HUGE*, even up to 10 volts.

[time-nuts] ADEV query Timelab and TICC

That doesn't make much sense if you are using the PICDIV properly... the TAPR dividers use the PICDIV chip to do the dividing. The only difference between using a TAPR divider and a bare PICDIV is that the TAPR dividers have an input squarer circuit and output buffer. If you are feeding the