Re: [time-nuts] Measuring coax temperature coefficient with a TICC

A table of a bunch of rg6 catv permutations, http://www.texcan.com/media/import/pdf/Electronic_Cable_RG6_RG59.pdf At least on this list if it has a solid copper core, it also has a copper braid shield. I'm sure there is many more permutations out there. On Wed, Apr 19, 2017 at 7:00 PM Will

Re: [time-nuts] OCXO Soft-Start

ht work fine nine times out of ten or 99 out of 100. > On the > odd time out, something goes poof ! > > Bob > > > On Apr 12, 2017, at 11:40 PM, Scott Stobbe <scott.j.sto...@gmail.com> > wrote: > > > > Bob, Rick, my use of modes vs overtones was loose, you guys are spot

[time-nuts] OCXO Soft-Start

Hello, I wanted to see if I could soft-start a used OCXO (Trimble 34310) during warm-up. By default with an appropriately rated 12 VDC supply, the OCXO starts the heater at about 8 W, and eventually settles down to 2 W for 20-25 degC ambient temperature. Figure Attached. The good news is it does

Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork crystal specs

The trim method that stands out from memory for generic RTC chips is to cycle stall or double clock, x cycles every 60 seconds. Yielding 0.5 ppm trim resolution. On Sun, Apr 9, 2017 at 7:45 AM, Tim Shoppa wrote: > I've had only a few different cars over the past 25 years but

Re: [time-nuts] Line Frequeny Stablity

I would guess the tightest control loop is on the generator stator field windings, with mechanical control being secondary. Definitely a lot of poles and zeros to worry about. On Wed, Apr 5, 2017 at 9:01 AM, jimlux wrote: > On 4/4/17 2:28 PM, Thomas D. Erb wrote: > >>

Re: [time-nuts] TAPR TICC boxed

ion delay dispersion (both vs common mode and vs overdrive) > also need to be considered along with the comparator jitter. > > > Bruce > > and overdrive (both vs overdrive and vs input common modeOn 01 April 2017 > at 15:34 Scott Stobbe <scott.j.sto...@gmail.com> wrote: &g

Re: [time-nuts] TAPR TICC boxed

Also for interest the 53131a schematic is available at http://bee.mif.pg.gda.pl/ciasteczkowypotwor/HP/53131.pdf HP used a low input bias current bjt opamp, the Lt1008 to bias/dc servo a custom JFET buffer driving an AD96687 comparator. On Fri, Mar 31, 2017 at 10:34 PM Scott Stobbe <scott.j.

Re: [time-nuts] TAPR TICC boxed

Fwiw, for a precision comparator you'll probably want a bipolar front end for a lower flicker corner and better offset stability over cmos. For high-speeds the diffpair is going to be biased fairly rich for bandwidth. So you will more than likey have input bias currents of 100's of nA to uA on

Re: [time-nuts] PLL performance?

Neat Project. I don't know if it will come up for you but optical or hall rotary encoders are notorious for jitter. While a generic IC comparator may have an open loop-gain of 100 dB, creating the mechanical equivalent is not so easy. Hall/optical have a softer switch on/off curve. Depending what

Re: [time-nuts] Bye-Bye Crystals

I would be careful to get an all analog tcxo. The digi-trim ones while may have a decent total error band over temperature can hop up and down in 100 ppb steps when the temperature straddles two points on its temp comp table. On Wed, Mar 15, 2017 at 7:06 PM Bob Camp wrote: > Hi

Re: [time-nuts] Bye-Bye Crystals

Not only that. Good luck finding a datasheet with *any* analog specifications for its internal oscillator. Here are the pins for an external crystal. The microchip PICs are nice, they give you the goldilocks selection for drive level a little cool, a little hot, maybe just right. On Tue, Mar 14,

Re: [time-nuts] time/sampling behavior of RTL-SDR

I bought one awhile back from a company called NooElec as more of a novelty item than anything. But I can say it runs quite hot and if you tune to the 3rd harmonic of a 10 MHz reference it takes a while to thermally stabilize. In hindsight spending the extra 3-4 dollars for one with a TCXO would

[time-nuts] Fwd: Dusty 53131A

Recently the fan in my 53131 has been making a pretty awful sound, so its time to replace it. When I disassembled the counter I found the trim cap had turned into a fur ball. Not that it really matters since it runs on an external reference, but its interesting to see if the dust has any effect.

Re: [time-nuts] HP5328A + NI GPIB-ENET/1000

If your counter is showing up in the NI device tree, you should be pretty close to getting it working. I haven't used a 5328A, but I suspect the command you have shown above is sample code for a basic program, the actual HPIB command may just be a 'T'. On Thu, Feb 23, 2017 at 1:37 AM, James

Re: [time-nuts] Vintage Frequency Measurement

Neat bit of kit. Was it common to get IMD with harmonics out of the vibrator power supply, and end up on tuning in on the wrong frequency? On Wed, Feb 15, 2017 at 2:28 AM, Robert Atkinson via time-nuts < time-nuts@febo.com> wrote: > Hi,Sorry if I caused confusion by calling the SCR/BC221 a

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

Something like this would make a great NTP server. https://www.digikey.com/products/en?keywords=P0286-ND Too bad they didn't include a PTP 1588 capable PHY... On Tue, Feb 14, 2017 at 12:33 PM, Chris Albertson wrote: > Here is a something that could work. It has a

Re: [time-nuts] Vintage Frequency Measurement

On Mon, Feb 13, 2017 at 6:41 PM, Bob Camp wrote: > > > I think what you would find is that it *is* a fairly normal AT cut and the > data book > that came with the instrument plotted out the data for the specific > crystal in > the device. The usable temperature range was fairly

Re: [time-nuts] Vintage Frequency Measurement

On Sun, Feb 12, 2017 at 8:39 AM, Dan Rae <dan...@verizon.net> wrote: > On 2/11/2017 10:08 PM, Scott Stobbe wrote: > >> I was inspired recently coming across a Lampkin 105 frequency meter, as to >> how frequency measurement was done before counters. >> >> Cert

[time-nuts] Vintage Frequency Measurement

I was inspired recently coming across a Lampkin 105 frequency meter, as to how frequency measurement was done before counters. Certainly zero-beating a dial calibrated oscillator, would be one approach. Is there a standout methodology or instrument predating counters?

Re: [time-nuts] Sub-ps delay line

I would also advise you take a look at how well you can maintain your system impedance, say 50 Ohms. For example, I have seen about 100's ps phase difference on a 10 MHz reference, using one BNC female-female coupler versus another, a small part is due to TOF, but most of that is due to subtle

Re: [time-nuts] Dropbox is cool, but...

I've had similar results with LTSpice, by default it tosses the simulations results to the current working directory. Fortunately, you can tell LTSpice to use a specific temp folder for simulation results. On Sun, Feb 5, 2017 at 7:42 PM, Didier Juges wrote: > Yes, I noticed

Re: [time-nuts] Distribution amplifier (again!) - now mostly ok but has gain peaking

Nice project. The gain peaking is more than likely from your high speed opamp. Parasitic capacitance on the inverting terminal from routing and the input capacitance of the opamp itself, adds another pole to your opamps loopgain, burning phase margin. A small compensation cap across the top leg

Re: [time-nuts] Thermal effects on cables

A google search for digiwave turned up cheap coax at walmart. I don't know how well copper clad steel holds up in the kHz, low MHz. On Mon, Jan 23, 2017 at 5:01 PM, Bob Camp wrote: > Hi > > Back a long time ago the people I was working with spent time looking > at the impedance

Re: [time-nuts] purpose of time of day display units

There is a lot to be said about a tool that just works. In the advent of a piece of gear failing whether that be a firmware bug or a cooling fan, or more severe, having a known diagnostic tool during that time is priceless (well maybe not priceless but extremely nice to have). On Sun, Jan 22,

Re: [time-nuts] 10MHz to 25MHz

, Jan 19, 2017 at 7:06 PM Bob Camp <kb...@n1k.org> wrote: > Hi > > > > > > > On Jan 19, 2017, at 3:03 PM, Scott Stobbe <scott.j.sto...@gmail.com> > wrote: > > > > > > Wouldn't crystal drive level be one of the important specifications for &

Re: [time-nuts] 10MHz to 25MHz

Wouldn't crystal drive level be one of the important specifications for far out phase noise? On Thu, Jan 19, 2017 at 1:33 PM, Bob Camp wrote: > HI > > A lot of your evaluation of the term “better” will depend on your intended > use. One of the limits on phase noise > is the

Re: [time-nuts] Thunderbolt Harmonics

Harmonic traps are another avenue to explore since the frequency is "fixed" at well below ppm. Which leaves the fundamental untouched. On Wed, Jan 18, 2017 at 5:21 AM, Charles Steinmetz wrote: > Rhys wrote: > > I was looking at the output of my Trimble Thunderbolt GPSDO

Re: [time-nuts] time-nuts Digest, Vol 150, Issue 36

Temperature sensor (Perry Sandeen) > >> 12. Who has a hm H Maser? (Perry Sandeen) > >> 13. Who has a hm H Maser? (Perry Sandeen) > >> 14. TICC update? (Scott Newell) > >> 15. R

Re: [time-nuts] Low CostTemperature sensor

Thermometry based on Diode leakage current wouldn't be impossible I suppose, you might loose some hair in the process. The signal levels on the opamp are goofed too. On Tue, Jan 17, 2017 at 4:19 AM Charles Steinmetz wrote: > Tom wrote: > > > > > That article has a major

Re: [time-nuts] time transfer over wifi

Pretty much every wifi transceiver is adc sampled so the frames are "timestamped", but the adc sample time may not get pushed up. The rtt/tof for the large umbrella of localization applications, I would imagine will be impented even farther back in the rx chain. On Sun, Jan 15, 2017 at 11:42 AM

Re: [time-nuts] time transfer over wifi

Here is a ti app note with timestamping hardware wl8 but ordinary ap's with no special protocol just timestamping the beacon frame. http://www.ti.com/lit/an/swaa162a/swaa162a.pdf On Sun, Jan 15, 2017 at 10:06 AM jimlux wrote: > Returning to the OP > > "A TimeSync

Re: [time-nuts] wifi with time sync

Yes, it will be interesting to see how well wifi rtt/tof does indoors with plenty of multipath. But for sure sub microsecond. On Sat, Jan 14, 2017 at 6:32 PM Bob Camp <kb...@n1k.org> wrote: > Hi > > > > > > > On Jan 14, 2017, at 5:29 PM, Scott Stobbe <

Re: [time-nuts] wifi with time sync

I don't think wifi is ever going to be a real-time system, as it shares the ether with all other ISM devices. That said even 1 ms of variation is still 4 orders of magnitude greater than the actual time of flight. The precision time aspect will most certainly be done in hardware, even if it's

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] Thermal effects on cables --> ADEV

matics 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 <scott.j.sto...@gmail.com> > wrote: > > > >

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] General questions about making measurements with time interval counter.

The pesudo code for the Adev is quite easy to interpret. For a frequency record of N samples For each tau=M samples Reshape(N/M,M) Mean Diff Rms End On Thu, Jan 12, 2017 at 4:11 PM Bob Stewart wrote: > Hi Bob, > > OK, like Bugs Bunny, I'll venture out on the

Re: [time-nuts] σ vs s in ADEV

I could be wrong here, but it is my understanding that Allan's pioneering work was in response to finding a statistic which is convergent to 1/f noise. Ordinary standard deviation is not convergent to 1/f processes. So I don't know that trying to compare the two is wise. Disclaimer: I could be

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

gt; the 5071. It > is the same thing on an Rb. > > So, your basic math is correct about a normal DDS. In this case you are in > the > PPT rather than PPB range due to the multiplication. > > Bob > > > > On Jan 9, 2017, at 10:40 AM, Scott Stobbe <scott.j.sto...@gmail.co

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

A 32-bit DDS synthesizing at 1/5 Fs, yields a tuning resolution of ~ 1 ppb. So, I would imagine a slightly lower frequency is programmed into the DDS and the c-field is trimmed to yield a higher precision. If the new synthesized tone you wish to generate is an integer number of DDS codes you could

Re: [time-nuts] Temperature (environmental) sensors

The good news is if the dataloger you get has a mems pressure sensor, you will have a high precision temperature sensor, whether or not the product software provides that resolution to you is another matter. In addition to the piezo-resistive bridge being mechanically sensitive to diaphragm

Re: [time-nuts] WWVB Simulator

Fwiw, an xor gate would make a simple bpsk modulator, carrier input A modulation B, B is low A is buffered, when B is high, carrier is inverted (180 degree phase shift). On Mon, Jan 2, 2017 at 7:20 PM David wrote: > I see generally how it should work but did not draw out a

Re: [time-nuts] Using GPSDO as a Refrence for Protable Amateur Radio Microwave Operations

would beat the 10 MHz. It’s a good bet that if > a 2.5 MHz cold weld > SC with a 30 mm blank diameter existed, it would beat either one of them > (Q would be much higher). > Given the cost of coming up with that part …. not going to happen. > > Bob > > > On Dec 22, 2016, at 3:26

Re: [time-nuts] Using GPSDO as a Refrence for Protable Amateur Radio Microwave Operations

Well for the same Q a competing oscillator will still take a 20 dB phase noise increase for every frequency decade you scale up to. If Q*f is approximately constant, you take another 20 dB hit in phase noise from degraded Q, totaling 40 dB/decade. Compared to 20 dB/decade plus the noise introduced

Re: [time-nuts] u-blox LEAH M8F

There was an interesting comment in the Lea-m8f datasheet, "In strong signal clear-sky applications the best time pulse consistency between neighbouring receivers is achieved when using a single GNSS because of the small time offsets between different GNSS systems. " On Thu, Dec 22, 2016 at 8:01

Re: [time-nuts] u-blox timing modules

The LEA-M8F is a complete GPSDO in module, the TCXO is EFC steered, no sawtooth needed. On Wed, Dec 21, 2016 at 8:30 PM, Bob Camp wrote: > Hi > > Ummm…. because you need a 30.72 MHz reference in a 4G base station rather > than the > TCXO that normally is in the uBlox modules. You

Re: [time-nuts] 1PPS users?

Part of the reason 1PPS needs to be so clean is because you are continuously integrating phase noise of the LO (hopefully an OCXO). While 10 uS is pretty trivial off a gps receiver. Without gps, 10 us over 24 hrs with a plane jane AT-cut crystal subject environmental dynamics becomes ludicrous.

Re: [time-nuts] Totally unrelated, but..

jim...@earthlink.net> wrote: > On 12/7/16 4:20 PM, Scott Stobbe wrote: > >> Yes, the short hand I like to use is 4 nV*sqrt(R/1000). >> >> 2 nV/rthz off a bandgap is pretty darn impressive, that includes a delta >> vbe gained up ~10x. >> >> On Wed, Dec 7

Re: [time-nuts] Totally unrelated, but..

oughly 0.9 nV at room > > temperature. The previously mentioned 2 nV is equivalent to about 250 ohms. > > > > Bob > > > > > On Dec 7, 2016, at 6:58 PM, Scott Stobbe <scott.j.sto...@gmail.com> > wrote: > > > > > > You can buy opamps off the

Re: [time-nuts] Totally unrelated, but..

You can buy opamps off the shelf with an input referred noise less than a 50 ohm resistor to build up a preamp (of course you can build up something even lower with discretes, but then it's a time commitment over a basic opamp preamp) Even if your regulator is low noise if it's running with low

Re: [time-nuts] Switching regulator replacement for 7805

FWIW, you can snub the switch node to dampen parasitic ringing in exchange of a loss in efficiency of a couple percent. I'm pretty sure I have seen this outlined in a few app notes. On Mon, Dec 5, 2016 at 1:22 PM, jimlux wrote: > On 12/5/16 9:13 AM, Dan Kemppainen wrote: >

Re: [time-nuts] Switching regulator replacement for 7805

in 4 mV just on half a bondwire. Equivalently a 10 uF MLCC should be able to hit 10 mOhms at 2 MHz before hitting its SRF. On Sun, Dec 4, 2016 at 5:58 PM, Attila Kinali <att...@kinali.ch> wrote: > On Sun, 4 Dec 2016 16:22:02 -0500 > Scott Stobbe <scott.j.sto...@gmail.com> wrote: &

Re: [time-nuts] Switching regulator replacement for 7805

If you wanted to be nutty you wouldn't go PWM at all, just like fractional-N sythns don't just mash 2 divider values. You would sigma-delta modulate your power stage. I don't know if you can buy one COTS, but there are plenty of papers on rolling your own. On Sun, Dec 4, 2016 at 4:09 PM, Attila

Re: [time-nuts] HP53131A RS232 question

econd … I guess that is so close to > 5.0 seconds and so far from 1. seconds that it > explains the issue > > Bob > > > On Dec 3, 2016, at 2:01 PM, Scott Stobbe <scott.j.sto...@gmail.com> > wrote: > > > > Well, that's only true

Re: [time-nuts] Best Chance GPS module

Hi Lewis, Here is a sample data-point related to processor load, on the RPI 2. Stepping from Idle to full load on 4 cores resulted in a temp rise near the XO of approximately 14 degC, and correspondingly the XO shifted 3.6 PPM. On Sat, Dec 3, 2016 at 10:29 AM, MLewis

Re: [time-nuts] HP53131A RS232 question

Well, that's only true if your counter has zero dead-time... I know you know this, 1 second gate time will give slightly less than 1 Sa/S. On Fri, Dec 2, 2016 at 1:15 PM, Bob Camp wrote: > Hi > > With a 1 second gate time, you will get one data output per second with the >

Re: [time-nuts] HP53131A RS232 question

I have a HP53131A and don't have this issue, the only thing I can think of is that you have the cables swapped i.e. the start edge on ch2 and stop edge on ch1. I have firmware REV:3703, If there are any settings you want me to try I am happy to help. On Sat, Dec 3, 2016 at 12:47 PM,

Re: [time-nuts] RPi/ beagle bone-like computer without video

As far as I know Matlab is x86 only, of course you can generate c code from Matlab but that has its own challenges. On Fri, Dec 2, 2016 at 2:14 PM jimlux wrote: > On 12/2/16 10:08 AM, David J Taylor wrote: > > From: jimlux > > > > We're processing several thousand samples,

Re: [time-nuts] RPi/ beagle bone-like computer without video

As much as it pains me to recommend them some of the iot modules sound like a good fit, like the Intel atom one. On Fri, Dec 2, 2016 at 12:13 PM jimlux wrote: > On 12/2/16 8:51 AM, Attila Kinali wrote: > > On Fri, 2 Dec 2016 08:05:17 -0800 > > jimlux

Re: [time-nuts] RPi/ beagle bone-like computer without video

Having a full blown os is nice when all the processor is responsible for is house keeping and storage. You also get plenty of RAM for buffering prior to writing to persistent storage, like an SD card. That said I have found SD cards to be fusy, at least the microchip FAT libraries. And write cycle

Re: [time-nuts] Thunderbolt Schematic

If the unit is low on amplitude, there isn't likely much more than a buffer amp between the ocxo and 10 MHz output. On Tue, Nov 29, 2016 at 7:54 PM Bob Camp wrote: > Hi > > There is no schematic for the TBolt available. Based on Trimble’s approach > to keeping > all their IP

Re: [time-nuts] Excel logarithmic function (was Thermal impact on OCXO)

ata has the aging between 1 and 10 years more > like 1/sqrt(t) If I just have a brief look on the aging graph. > > > > Lars > > > > *Från: *Scott Stobbe <scott.j.sto...@gmail.com> > *Skickat: *den 19 november 2016 04:11 > > Hi Lars, > > > > I ag

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

rient wants for > one of > their machines. One suggestion: If you *do* go with the HP solution, > running the > attenuator up and down to simulate fast fades (think urban canyon) will > fry the generator > in about 30 days … I have empirical data …. > > Bob > > >

Re: [time-nuts] Do reflections up/down the antenna cable cause a problem with GPS?

I haven't used one personally but a spirent gps simulator would let you do a try it and see. It will be interesting to see if out of the growing sdr community an open source gps simulator emerges. On Mon, Nov 21, 2016 at 1:01 PM Dr. David Kirkby (Kirkby Microwave Ltd) <

Re: [time-nuts] How phase stable is rg59 or alternate coax

When I first took a look at some of the coax datasheets I couldn't find anything. I was able to find the following paper "phase stability of typical navy radio frequency coaxial cables" http://www.dtic.mil/dtic/tr/fulltext/u2/628682.pdf I attached the table from the last page. They estimate RG59

[time-nuts] How phase stable is rg59 or alternate coax

If you had 30 ft of rg59 outdoors seeing maybe 10 degC swings everyday, would the propagation time be stable to ps? ns? On Sun, Nov 20, 2016 at 7:04 PM Hal Murray wrote: > > Is that even a sensible question? Is there a better way to phrase it? > > > The problem I'm

Re: [time-nuts] Excel logarithmic function (was Thermal impact on OCXO)

Hi Lars, I agree with you, that if there is data out there, it isn't easy to find, many thanks for sharing! Fitting to the full model had limited improvements, the b coefficient was quite large making it essentially equal to the ln(x) function you fitted in excel. It is attached as

Re: [time-nuts] Thermal impact on OCXO

erature and warmup > that *do* have trends to them. They will lead you off into all sorts of dark > holes fit wise. > > Bob > >> On Nov 16, 2016, at 6:48 PM, Scott Stobbe <scott.j.sto...@gmail.com> wrote: >> >> A few different plots. I didn't have an intuitive

Re: [time-nuts] Thermal impact on OCXO

','on','TolFun',1e-12, 'TolX', 1e-12); [Aest,resnorm, e, o] = lsqcurvefit(Fage,Ainit,ts,F_pn,[],[],options); On Thu, Nov 17, 2016 at 8:24 AM, Attila Kinali <att...@kinali.ch> wrote: > On Tue, 15 Nov 2016 23:58:31 -0500 > Scott Stobbe <scott.j.sto...@gmail.com> wrote: > >>

Re: [time-nuts] Thermal impact on OCXO

t messes up > the fit. If you fit it without > the +1, the fit is *much* easier to do. The result isn’t quite right. > > Bob > > >> On Nov 15, 2016, at 11:58 PM, Scott Stobbe <scott.j.sto...@gmail.com> wrote: >> >> Hi Bob, >> >> Do you r

Re: [time-nuts] Thermal impact on OCXO

time constant (and > will ultimately > die out). You may not be able to separate the 25 year curve from the 3 > month > curve with only 3 months of data. > > Bob > > > On Nov 13, 2016, at 10:59 PM, Scott Stobbe <scott.j.sto...@gmail.com> > wrote: > > &

Re: [time-nuts] precision timing pulse

If you are trying to avoid writing code, the 74hc might be worth taking a look at. On Tue, Nov 15, 2016 at 3:00 PM Chuck / Judy Burch wrote: > > I'm building a laboratory scintillation counter that uses my HP 5335a > counter as a read-out. The FREQ mode gives only

Re: [time-nuts] Thermal impact on OCXO

On Mon, Nov 7, 2016 at 10:34 AM, Scott Stobbe <scott.j.sto...@gmail.com> wrote: > Here is a sample data point taken from http://tycho.usno.navy.mil/ptt > i/1987papers/Vol%2019_16.pdf; the first that showed up on a google search. > > Year Aging [PPB] dF/dt [PPT/Da

Re: [time-nuts] quartz drift rates, linear or log

Those are wonderful plots :) I vaguely recall that a 1ppm frequency shift is approximately equivalent to the mass transfer of one molecular layer of a crystal. So at some point your counting atoms if there was no noise, thermal disturbance, mechanical disturbance... On Sat, Nov 12, 2016 at 5:00

Re: [time-nuts] Need some wisdom from the cesium beam tube gurus out there

If you want sub degree precision, you will need to make your connections to dissimilar metals on an isothermal boundary, a terminal block is better than clips in free air. On Fri, Nov 11, 2016 at 8:28 AM, Bob Camp wrote: > Hi > > > On Nov 11, 2016, at 8:02 AM, jimlux

Re: [time-nuts] How to get PPS from ublox mini-PCI GPS to APU2 SoC serial port for ntpd

When 1PPS is implemented as a time mark signal narrow width (versus 1 Hz 50% duty cycle) and you time stamp both edges, you can always tell which is supposed to be the leading edge. Either the assert and deassert are close together in the correct case or far apart when using incorrect polarity.

Re: [time-nuts] How to get PPS from ublox mini-PCI GPS to APU2 SoC serial port for ntpd

FWIW, the 16450 uart can interrupt on any modem line change, whether it be rising or falling. On Wed, Nov 9, 2016 at 11:41 AM, Chris Albertson wrote: > On Tue, Nov 8, 2016 at 11:08 PM, Hal Murray > wrote: > > > > > g...@rellim.com said: > > >

Re: [time-nuts] How to get PPS from ublox mini-PCI GPS to APU2 SoC serial port for ntpd

Just make sure you get a board with more than one Rx/Tx pair, unless you are happy with two boards; one for Rx/Tx and one for PPS. On Wed, Nov 9, 2016 at 2:08 AM, Hal Murray wrote: > > g...@rellim.com said: > > Who cares if the PPS is inverted? > > Good point. I wasn't

Re: [time-nuts] Thermal impact on OCXO

gt; with such arcane matters as holdover, aging, and generating the time from > the OCXO. The learning curve has been a bit steep. > > Bob > > - > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/

Re: [time-nuts] Thermal impact on OCXO

Another nice plot! It looks like after 2am you see temperature swings of 1.5 degF roughly every 30 minutes? Correspondingly, the EFC line which is nominally ~2.8vdc sees swings of +-50 uV? On Monday, 7 November 2016, Bob Stewart wrote: > Hi guys, > First of all, thanks for the

Re: [time-nuts] Thermal impact on OCXO

Typo, "Aging [PPM]" should read "Aging [PPB]". On Mon, Nov 7, 2016 at 10:34 AM, Scott Stobbe <scott.j.sto...@gmail.com> wrote: > Here is a sample data point taken from http://tycho.usno.navy.mil/ > ptti/1987papers/Vol%2019_16.pdf; the first that showed up on a go

Re: [time-nuts] Thermal impact on OCXO

C string that might be controversial, > but I don't see that it would be a candidate for the symptoms of aging. > > > > Bob > > --------- > > AE6RV.com > > > > GFS GPSDO list: > > groups.

Re: [time-nuts] HP 5275A

You could try heating the transistor and bushing then give the to5 a shot of cold spray or supper duster hoping it will shrink enough to slide out. On Sunday, 6 November 2016, Adrian Godwin wrote: > Slightly off-topic, as this is a general repair question. But it's a TIC. >

Re: [time-nuts] I love the smell of tantalum in the morning

In the case of the rt7 (or knife soldering tips for other brands) you get a fine point that easily handles 30-32 awg wire, and the edge of the tip is a little over 100 thou long, so for parts 0805 and smaller you just lay the edge along the side of the component and heat both pads and swipe it to

Re: [time-nuts] I love the smell of tantalum in the morning

I would not recommend purchasing soldering tweezers without trying them first. They are not easy to control solder application when mounting a component. I do really like the Weller rt7 knife tip. On Sunday, 6 November 2016, Adrian Godwin wrote: > SMD parts aren't going

Re: [time-nuts] Thermal impact on OCXO

would be a candidate for the symptoms of aging. > > Bob > > > - > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > > > -- > *From:* Scott Stobbe <scott.j.sto...@gmail.com> > *To:* Bob Stewar

Re: [time-nuts] Thermal impact on OCXO

ut 4.5PPT? > > Bob > > - > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > > > > > -- > *From:* Scott Stobbe <scott.j.sto...@gmail.com> > *To:* Bob Stewart <b...@evoria.net>; Discussion of preci

Re: [time-nuts] I love the smell of tantalum in the morning

For through hole parts sure, but I would not recommend that on SMD parts, the copper foil of a little pad is pretty easy to tear off and it's a royal pain if you have to mount a device missing some of its landing pads. On Sat, Nov 5, 2016 at 4:37 PM, Tom Miller wrote:

Re: [time-nuts] Thermal impact on OCXO

I think that's a nice plot, it looks like you have stepped 160 LSB over 7 days or roughly 1 LSB per hour. With a 20bit dac you are trimming maybe 1 ppt/LSB to 4 ppt/LSB? In allan devation terms, the case of 1ppt/LSB, solely due to drift, you're at 1E-12 at 3600*sqrt(2) = 5000 s, in the case of

Re: [time-nuts] Thermal impact on OCXO

Sounds like you already realized this. Phase is the integral of frequency and the derivative of phase (phase rate) is frequency. So if you go from nominal frequency - slow - nominal or equivalently nominal frequency - fast - nominal the phase integrates up/down. It would be a little more

Re: [time-nuts] Man with too many clocks.

I'm not sure if there is a reason counters don't let you digitally calibrate beyond that, the 10 MHz ref out on the rear panel would still be out of cal. On Fri, Nov 4, 2016 at 1:48 PM, Bob Camp wrote: > Hi > > The only practical way to set the 10811 or 10544 is with a >= 10 turn

Re: [time-nuts] Thinking outside the box a super reference

You will also share the same challenges as Touchstone semi did, no one wanted to stick their neck out to design in a little startup. On Thu, Nov 3, 2016 at 7:49 PM, Bob Camp wrote: > Hi > > Not many people have had exposure to Rb’s or Cs standards actually being > built. That

Re: [time-nuts] Man with too many clocks.

Bob has stated this, but perhaps not emphasized that, when you sample the phase of a 10 MHz clock once a second, you are essentially folding the 20 millionth nyquist band down to baseband. So you can alias any integer multiple of 1 Hz as if it were 10 MHz, i.e. 10 MHz + 1Hz will hold phase to 1 Hz

Re: [time-nuts] How to get PPS from ublox mini-PCI GPS to APU2 SoC serial port for ntpd

The signals on the DB9 connector are at RS232 levels, your GPS module is likely 3V3 CMOS, you will need to make a level translator if you wish to use a standard PC RS232 serial port. On Thu, Nov 3, 2016 at 12:58 PM, STR . wrote: > Hello again list and Paul, > > The USB and

Re: [time-nuts] Man with too many clocks.

You can also use your counter to directly measure your GPS receiver's 1PPS, which ends up being the error of your internal timebase. (plus the error in your 1PPS) On Thu, Nov 3, 2016 at 8:20 AM, Peter Reilley wrote: > I am the proverbial man with too many clocks and I

Re: [time-nuts] our favorite topics

So, the elephant *is* in the room, how majestic. Thanks for taking the time to list some sample books/papers. A lot of general communications systems/RFIC books certainly acknowledge phase noise and the results because of its presence, but I don't know how many have an in depth discussion of ways

Re: [time-nuts] our favorite topics

I found Frerking's "Crystal Oscillator Design and Temperature Compensation" to be a fruitful read. It's free on the archive, https://archive.org/details/CrystalOscillatorDesignTemperatureCompensation . Are there any recommendations for one or more book(s) that are definitely worth skimming

Re: [time-nuts] Opening an Isotemp OCXO

I wounder if originally the designer was hoping to use all 8 wire or'd inputs to lower the input referred noise during midscale transition. Then backed out later for some reason. On Fri, Oct 28, 2016 at 1:03 PM, Scott Stobbe <scott.j.sto...@gmail.com> wrote: > Could also be a qu

Re: [time-nuts] Opening an Isotemp OCXO

Could also be a quirk about the 74S30 that gives it better phase noise over a basic buffer. On Friday, 28 October 2016, jimlux <jim...@earthlink.net> wrote: > On 10/28/16 9:13 AM, Scott Stobbe wrote: > >> The OCXO82-59 datasheet lists 12V supply, 5V clock out, could also be a

Re: [time-nuts] Opening an Isotemp OCXO

The OCXO82-59 datasheet lists 12V supply, 5V clock out, could also be a blown regulator in your ocxo, if it is indeed a 12v model. On Friday, 28 October 2016, Poul-Henning Kamp wrote: > > In message <10a3ea7d-37f0-51bc-2470-35645d767...@comcast.net >

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