On 11 Dec 2014 21:52, "Bert Kehren via time-nuts"
wrote:
>
> who did you buy it from?
>
The seller was yixunhk on eBay.
That information was in the title and first line of my original post.
Dave.
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Welcome to the wonderful world of Chinese capitalism.
Don
> On Dec 11, 2014, at 6:16 PM, Dr. David Kirkby (Kirkby Microwave Ltd)
> wrote:
>
> Hi Stuart,
> Several people have contacted me about the fakes. I can't understand why
> his feedback is so good. The seller bought some calibration sta
Bob wrote:
Separate from the analysis of the voltage on the OCXO, there is
another part to this:
Ok, so why am I harping on the "need" for all this from a system standpoint ?
We've been around this track a time or two before, me frustrated with
your "make it just good enough" philosophy and
Hi Charles,
I hope you don't mind if I throw my two cents in, as this began as a question
about my GPSDO project. We had a thermal drift problem that Dan traced to the
PWM to EFC interface and resolved. The question to the list was whether there
was a regulator package that had a built-in refe
By any chance, does anyone on the list have a copy of the manual
(preferably with schematics) for an
Astrodata 5140 Time Code generator?
I would like to get this venerable NASA refugee up and running again.
Can't beat the mesmerizing glow of Nixie tubes.
I'd happily pay copying or scanning
Hi, George
look for the book "The art of electronics" from Paul Horowitz and
Winfield Hill, they describe how to design excellent electronic
circuits, including power supplies
73
Alex
On 12/11/2014 4:37 PM, xaos wrote:
I don't know if this is the right time to ask this but here goes.
I have
kb...@n1k.org said:
> I would bet the power supply is some sort of âbrickâ. That could make it a
> bit tough to replace.
Power supply bricks were quite popular 10 years ago. There were several
companies making them. Sizes and pinouts were reasonably standard. I
haven't looked recently.
Hi
Separate from the analysis of the voltage on the OCXO, there is another part to
this:
Ok, so why am I harping on the “need” for all this from a system standpoint ?
1) Adding stuff to a design that does not make it measurably better is simply a
waste of money. That’s ok if it’s your money.
Hi
> On Dec 11, 2014, at 8:20 PM, d...@irtelemetrics.com wrote:
>
>Hi Bob,
> Some numbers. Maybe you can double check my math, just to be sure I'm not
> getting something completely wrong. That is very possible, since I'm new
> here... ;)
> The DAC is moving up and down about 7.5 counts wi
Hi Bob,
Some numbers. Maybe you can double check my math, just to be sure I'm
not getting something completely wrong. That is very possible, since
I'm new here... ;)
The DAC is moving up and down about 7.5 counts with room temp
swings. 20 bit resolution at 6.6volts full scale output.
6
Hi
> On Dec 11, 2014, at 8:18 PM, Richard (Rick) Karlquist
> wrote:
>
>
>
> On 12/11/2014 4:20 PM, Bob Camp wrote:
>> Hi
>>
>> Those OCXO’s were made to the spec’s of an OEM customer. The spec’s are
>> owned by that customer and can not be released without authorization from
>> them. Anyb
Hi Stuart,
Several people have contacted me about the fakes. I can't understand why
his feedback is so good. The seller bought some calibration standards from
me which I clearly stated were damaged. I did at the time notice they left
about 25% negative or neutral feedback, so was expecting that,
On 12/11/2014 4:20 PM, Bob Camp wrote:
Hi
Those OCXO’s were made to the spec’s of an OEM customer. The spec’s are owned
by that customer and can not be released without authorization from them.
Anybody who wants to stay in the business would be a bit crazy to release
somebody else’s intelec
I have bought several items from this seller and left positive feedback
because the items arrived promptly and appeared to work. Problems only
became apparent days, weeks, or months later. But by then it was too late
to change feedback.
This seller admits to changing the firmware on a GPSDO to "up
Hi
> On Dec 11, 2014, at 7:37 PM, xaos wrote:
>
> I don't know if this is the right time to ask this but here goes.
> I have started a design for a linear power supply for the Beagleboard
>
> 5V 5-10A. Over-Voltage, short circuit and temp protection.
> Very low ripple and HF noise.
>
> I have
I don't know if this is the right time to ask this but here goes.
I have started a design for a linear power supply for the Beagleboard
5V 5-10A. Over-Voltage, short circuit and temp protection.
Very low ripple and HF noise.
I have been watching this thread and I am still not sure
what device wou
Hi
Those OCXO’s were made to the spec’s of an OEM customer. The spec’s are owned
by that customer and can not be released without authorization from them.
Anybody who wants to stay in the business would be a bit crazy to release
somebody else’s intelectual property to the public. That’s not an
Hi
Most OCXO’s will meet all spec’s with 1 to 10 mV RMS on the supply lead. That’s
mV not uV.
If the noise is flat in a 100 Hz to 100 KHz bandwidth, most will meet their
ADEV specs with a mV RMS on the EFC line. Again mV not uV.
The issue is pretty simple:
Things like an EFC or supply FM mo
All:
Anybody have a DATA SHEET on the Wenzel VCXO's mentioned here and being
sold on ebay? I went to the Wenzel site and they say oscillators in
that part number series are "proprietary", you must contact them for
"additional information".
I bought one, it got here REALLY quick, and was hop
There exists a newer generation of linear regulators with much lower noise,
designed for sensitive analog loads. Here are some representative parts. Check
Analog Devices' website for other options...
ADM7170/7171/7172
6.5 V, Ultra Low Noise, High PSRR, Fast Transient Response CMOS LDO
Doug R.
--
So I've done a lot of work in power lately and I can summarize some of this
quickly:
The lowest noise LDOs today are the TI TPSa4700/01 up to 36v/1a and about 4
uVRms noise, and the ADP7154/55 up to 5.5v and 600ma with only *0.9* uVRms
above 100hz.
Both feature great PSRR -and in the case of the
More Arduino clock and timekeeping notes:
If the part connected to the processor's XTAL1 and XTAL2 pins has 2 pins
and external capacitors it is a crystal. If it has 3 pins and no caps it is
a ceramic resonator. If you have a crystal, you can fine-tune its frequency
by replacing one of the capacit
If all the voltages and currents are odd, there is the possibility
that the measurement A/D converter or its voltage reference (if
present) is faulty...
On Thu, Dec 11, 2014 at 10:46 PM, Dr. David Kirkby (Kirkby Microwave
Ltd) wrote:
> On 11 December 2014 at 01:10, Bob Camp wrote:
>> Hi
>>
>> I
Hi
I would bet the power supply is some sort of “brick”. That could make it a bit
tough to replace.
Bob
> On Dec 11, 2014, at 4:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd)
> wrote:
>
> On 11 December 2014 at 01:10, Bob Camp wrote:
>> Hi
>>
>> I suspect that if you look closely at the b
who did you buy it from?
In a message dated 12/11/2014 4:47:02 P.M. Eastern Standard Time,
drkir...@kirkbymicrowave.co.uk writes:
On 11 December 2014 at 01:10, Bob Camp wrote:
> Hi
>
> I suspect that if you look closely at the board in the unit, it’s got
water stains on it ….
>
> Bob
I
On 11 December 2014 at 01:10, Bob Camp wrote:
> Hi
>
> I suspect that if you look closely at the board in the unit, it’s got water
> stains on it ….
>
> Bob
I suspect you might be right Bob, but I am not going to break the seal
to open it up to find out. I will be contacting the seller, to see
w
e...@telight.com said:
> If the plan is to use a three-terminal regulator after all, I'd suggest not
> using a low-dropout (LDO) type if the raw input supply is noisy - the LDOs
> usually have PNP output transistors (for positive regulators), so may tend
> to have poorer HF input ripple rejecti
I was just looking at various modern LDOs, and I see that they are
greatly improved wrt PSRR - I think the older style PNP passers have
been supplanted by new topologies that also even include MOSFETs, so
there should be plenty of choices out there.
So, I'm changing my recommendation - to avoi
jim...@earthlink.net said:
> Ah, but will the exact same single board computer be available for
> replacement in 5 years? Or will it be Rev F instead of Rev B, with "just a
> few tweaks to improve performance", but also enough that it's not "drop the
> image on it and run"
> What about 10 year
br...@lloyd.aero said:
> I want to have a good time and frequency source in my little network that I
> run. ...
> Oh, and if it has nixie tubes to display current time, umso besser! After
> all, I still need to set my old-style watch and a few mechanical
> chronographs I have kicking around.
x
Hello everyone,
If anyone is interested, I have created a HOWTO
on running a Motorola GPS receiver connected to
a CentOS 7 box via serial port (com1), with 1PPS over DCD.
Here is the documentation.
http://www.maximaphysics.com/Centos_7_GPS_Setup.html
Let me know if something does not look right
On Thu, Dec 11, 2014 at 1:22 PM, Bob Bownes wrote:
>
> If there is always a system running, why go with the bbb? I use the file
> server in the basement fed with 1pps to the non USB serial port from a
> TBolt in my office.
>
> You do have a file server in the basement don't you? :)
>
Yes, I do.
If there is always a system running, why go with the bbb? I use the file server
in the basement fed with 1pps to the non USB serial port from a TBolt in my
office.
You do have a file server in the basement don't you? :)
I suppose it would be an interesting experiment to feed an NTP server wit
On 12/11/14, 9:54 AM, Brian Lloyd wrote:
On Thu, Dec 11, 2014 at 10:46 AM, Jim Lux wrote:
Actually, I think my point was that the problems I face at JPL are
essentially identical to the problems we face at home. I'm not in the time
and frequency group (and I don't know that they actually are
Brian...
"Look, I used to leave WWV running all the time on a receiver. That
background D D D was very reassuring as I moved through the
house watching the sweep second hands ticking in time with WWV."
Based on personal experience, this strongly suggests that you weren't married
at
Hi,I would like to modify my profile, but I've lost the password. I have done
the password remind procedure, but it didn't work, no email received. Any help
please?Thanks,Antonio Iovane
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If the plan is to use a three-terminal regulator after all, I'd
suggest not using a low-dropout (LDO) type if the raw input supply is
noisy - the LDOs usually have PNP output transistors (for positive
regulators), so may tend to have poorer HF input ripple rejection
than equivalent ones with NP
On Thu, Dec 11, 2014 at 11:11 AM, Brian Lloyd wrote:
> So, I am still looking for a straight-forward, "here is a really good way
> to use a BBB coupled to a GPS 1pps to do NTP," treatise
>
Fellow time-nut Dan Drown has done this although he uses Chrony rather than
NTPd. The idea is the same but
On Thu, Dec 11, 2014 at 10:46 AM, Jim Lux wrote:
> Actually, I think my point was that the problems I face at JPL are
> essentially identical to the problems we face at home. I'm not in the time
> and frequency group (and I don't know that they actually are better off..
> although they do have
On 12/11/14, 8:11 AM, Brian Lloyd wrote:
Discussing the lifetime of NTP server hardware is all well and good but
given the thrust of this list, i.e. individual time-nuttery, I don't see it
as being too germane. Few of us have the same problems that Jim Lux has at
JPL.
Actually, I think my poin
Quoting Paul :
From the time-nut perspective what's the interest in high resolution NTP?
I mean beyond the "can I do this?" appeal.
From a practical standpoint, I don't personally have any application
that benefits from sub-1s accuracy. I'm just doing it for fun and
learning.
[]
So, I am still looking for a straight-forward, "here is a really good way
to use a BBB coupled to a GPS 1pps to do NTP," treatise. Better still if
someone is using their LTE-lite to do it. It seems like a nice little
package for the amateur time-nut for everyday time and frequency keeping.
[]
B
On Thu, Dec 11, 2014 at 10:03 AM, Paul wrote:
> On Thu, Dec 11, 2014 at 10:27 AM, Dan Drown
> wrote:
>
> > Is this better or worse than other NTP server platforms? I haven't
> tested
> > them, so I have no idea.
>
>
> Tharp says his appliance
>
> "can sustain thousands of queries per second. Ev
Discussing the lifetime of NTP server hardware is all well and good but
given the thrust of this list, i.e. individual time-nuttery, I don't see it
as being too germane. Few of us have the same problems that Jim Lux has at
JPL.
I want to have a good time and frequency source in my little network t
On 12/11/14, 7:35 AM, Paul wrote:
On Thu, Dec 11, 2014 at 9:59 AM, Jim Lux wrote:
Linux isn't a whole lot better. If you have a system you cobbled together
in 2004
In the PPS via GPIO this is an issue and you don't have to go back 10
years. There's been a major change between (I think) 3.
On Thu, Dec 11, 2014 at 10:27 AM, Dan Drown wrote:
> Is this better or worse than other NTP server platforms? I haven't tested
> them, so I have no idea.
Tharp says his appliance
"can sustain thousands of queries per second. Even under high throughput
timekeeping operations are never disrupte
On Thu, Dec 11, 2014 at 10:33 AM, Jim Lux wrote:
> Most national labs are more like time-nuts hobbyists for many of the same
> reasons.
>
> A big business (think cellphone provider) depreciates and amortizes their
> gear, so they cycle through in 3-5 years, and *build the update process
> into th
On Thu, Dec 11, 2014 at 9:59 AM, Jim Lux wrote:
> Linux isn't a whole lot better. If you have a system you cobbled together
> in 2004
>
In the PPS via GPIO this is an issue and you don't have to go back 10
years. There's been a major change between (I think) 3.8 and later
kernels which makes s
On 12/11/14, 7:04 AM, Paul wrote:
On Thu, Dec 11, 2014 at 9:45 AM, Chris Albertson
wrote:
Your logic would disqualify EVERY computer made today. What will still be
in production in 10 years?
The ones you make yourself. Or if you're a nation-state the ones you have
made to your specificat
As a test of load, I sent around 650 ntp queries per second (give or
take 20 q/s) to the BBB. CPU usage was around 87% idle. There were
no dropped packets for the 108,000 sent. Round-trip time was between
287us and 199us. Traffic was around 470kbit/s.
Assuming clients have a query rate
On Thu, Dec 11, 2014 at 9:45 AM, Chris Albertson
wrote:
> Your logic would disqualify EVERY computer made today. What will still be
> in production in 10 years?
>
The ones you make yourself. Or if you're a nation-state the ones you have
made to your specifications which include N years of sup
On 12/11/14, 6:14 AM, Brian Lloyd wrote:
On Thursday, December 11, 2014, Jim Lux wrote:
Ah, but will the exact same single board computer be available for
replacement in 5 years?
Most likely not. These days I can't imagine a manufacturer making the same
SBC or mobo board for more than a ye
On Thu, Dec 11, 2014 at 8:13 AM, Jim Lux wrote:
> Philosophically it might be a straightforward thing, but it might not be
> as easy as one might hope.
>
> Legacy support with processor boards is a real challenge.
>
Which is why you don't do it this (ot that) way. The little SoC boxes are
great
The CPU temperature as measured by the on-CPU sensor went from about
55C to about 60C.
300MHz to 1GHz, ondemand, CPU in red http://dan.drown.org/bbb/run9/temp.png
1GHz fixed, CPU in red http://dan.drown.org/bbb/run8/temp.png
For current drain, I only have numbers at the wall wart measured by
Your logic would disqualify EVERY computer made today. What will still be
in production in 10 years?
If you care a lot about reliantly you install three NTP servers on your
network. Further you make sure each server is DIFFERENT and uses a
different brand of GPS. You configure them all as peers
> Some of the Arduinos (not sure about Mini 04 but I am suspicious) use
> ceramic resonators rather than real crystals and thus may have extremely
> poor frequency stability. See here
> http://jorisvr.nl/arduino_frequency.html
> for an example.
ah!
Very intriguing material, those crystals. I wonde
On Thursday, December 11, 2014, Jim Lux wrote:
>
> Ah, but will the exact same single board computer be available for
> replacement in 5 years?
Most likely not. These days I can't imagine a manufacturer making the same
SBC or mobo board for more than a year. If you consider BBB to be the
logica
On 12/10/14, 9:45 PM, Mike Cook wrote:
Le 11 déc. 2014 à 05:47, Brian Lloyd a écrit :
On Wed, Dec 10, 2014 at 10:15 PM, Chris Albertson
wrote:
Those sub 1 u-second numbers are very good. They argue for using
the BBB as an NTP server but I wonder if it really is the best.
I think the numb
Hi
If your OCXO has a stability of +/-3x10^-10 over 0 to 60C (numbers picked to
make math easy):
6x10^-10 / 60 = 1x10^-11 per C
If the OCXO is 10X better than that (unlike) you are at 1x10^-12/C
If the room temperature swings 1 C, you get a 1x10^-11 swing in the OCXO.
Keep in mind that the
Hi
With all the NTP traffic on this list, I’d sure hope we can help out with this.
Bob
> On Dec 11, 2014, at 2:19 AM, Harlan Stenn wrote:
>
> With the permission of TVB and JRA, here's the short version.
>
> Network Time Foundation is now old enough (3 years) to qualify to be
> listed with t
Hi
> On Dec 11, 2014, at 3:35 AM, Brian Inglis
> wrote:
>
> On 2014-12-09 04:10, Mike Monett wrote:
>
>>> One very cute addition would be to pull down the NIST GPS data and
>>> use it to correct your system on an hourly / daily basis. If you
>>> do that with common view satellites, you most ce
Yeah, I suffer from time-nuts digest lag, family lag, day job lag,
among other things. So please excuse delayed responses...
The oscillator has proven to be relatively immune to 'reasonable'
changes in voltage, as would be expected. About the range of Numbers
Bob Camp has suggested, or m
Hi
> On Dec 10, 2014, at 11:12 PM, Mike Monett wrote:
>
>>> It would appear the best approach is to simply start reading the
>>> posts at the beginning and save the interesting ones.
>>
>> There are lots of interesting threads on Time Nuts ...
>
> Yes. It is very easy to get distracted.
>
>>
On 11/12/2014 04:15, Chris Albertson wrote:
Those sub 1 u-second numbers are very good. They argue for using the BBB
as an NTP server but I wonder if it really is the best. I think the
numbers that matter are measures of the close on the computers who use your
BBB as a server. In other words
Just to echo that using the PRU cores is the wrong way to go, the BBB
has a multitude of hardware timers that will give better performance for
less hassle.
Having said that, by far the Number One thing to consider is controlling
the impact of temperature changes. If you sort that, the rest is
Getting a BBB to take 10MHz refclk input (in the fashion of
http://www.febo.com/pages/soekris/)
and being able to timestamp _multiple_ PPS signals via the PRUs would
make for a pretty awesome time-nuts toy.
This is quite do-able and I posted a few weeks ago with the details of
where to poke th
On 2014-12-09 04:10, Mike Monett wrote:
One very cute addition would be to pull down the NIST GPS data and
use it to correct your system on an hourly / daily basis. If you
do that with common view satellites, you most certainly will beat
a surplus grade Cs standard.
How can we do this? The NIS
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