b...@baylorhill.com said:
> Where does pin three (P1) connect. I may have trashed both units. Are
> schematics available.
I don't know of any schematics. I would take it apart and see if anything is
connected to any of the other pins on those connectors. Or measure the
resistance from the
kb...@n1k.org said:
> If I had not already calibrated the local standard against a nearby chain â¦
> no way to figure out which data was correct.
Isn't the ground wave shorter and hence gets there sooner? Couldn't you use
that to calibrate an uncalibrated local standard?
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kb...@n1k.org said:
> the signal shows up over many 10âs of KHz of bandwidth each side of 100
> KHz.
What does the spectrum look like? Is that even a reasonable question for
that sort of signal?
How well do typical old/analog spectrum analyzers work on that sort of
signal? (as compared
anders.e.e.wal...@gmail.com said:
> I see around 150-200ps skew which I tried to tune a bit with wires and 0R
> resistors - without very much success.. any ideas for improving this - or
> just leave it at 200ps skew?
I don't have the numbers handy, but that's ballpark of an inch of trace on a
kb...@n1k.org said:
> â¦.. errr ⦠would not that be the *right* end of the ADEV curve? â¦..:)
Argh. Thanks for the correction.
I got time and frequency swapped in my head, probably because I was thinking
of the noise vs frequency plots that he showed.
> Back in the 1980âs these guys
way way way left.
Ray Weiss was the speaker at the Stanford Physics Colloquium today. In case
you don't recognize the name, he is one of the leaders of the LIGO project
that detected gravity waves about a year ago.
He's a good speaker with a neat topic. He spent a lot of time giving credit
ke9h.gra...@gmail.com said:
> So a learning curve to get up on KiCad and, for me, an issue migrating ten
> years personal library of component foot-prints.
The Eagle files are store in simple text. If there isn't already an Eagle to
KiCad translator, I'd expect one soon.
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jim...@earthlink.net said:
> 3) It's a crude visual check - your eye/brain is pretty good at catching a
> change in the pattern of blinky lights. IN this situation, you'd expect
> all the displays to change simultaneously.
Is there a term similar to "eye candy" for geeks?
Many years ago, I
> Still, the question arises: are there any affordable alternatives?
kikad
http://kicad-pcb.org/
I haven't done any serious work with it. When I looked 5 or 10 years ago, it
was good enough to make some very nice big, complicated boards. (I don't
know how much effort went into them.)
It
hol...@hotmail.com said:
> On the chip with the "MX" marking on it, what f/w version does it show
> (usually v5.02 or v5.10)? I have a couple of CM3's configured for TAIP
> output, but I have the programs for switching them to TSIP or NMEA.
Does the which-protocol get saved away someplace or
jebponso...@gmail.com said:
> Though nominally made of copper and zinc, common brass often shows residual
> ferro magnetism because it is "recovered" metal and is contaminated with
> iron. That brass must never be used in a magnetic instrument have been known
> for a very long time.
What do
kb...@n1k.org said:
> Ok, what I see is that every few hours, I get a ârogue delayâ on a single
> ping. How would NTP help me spot a single transit with a 250 ms round trip
> and identify the time it occured? Keep in mind that NTP is going to
> throttle back to a very low level of âchatâ
> What standard protocol would you recommend I run from the command line on my
> computer to get a quick estimate of the timing lag and variablilty on my
> particular WiFi connection?
I'd use ping. But you said "quick estimate".
My wifi is crappy enough that its noise swamps everything
Or batch to batch?
If I get a unit of type A and another of type B and run some tests and conclude
that A is better, will you get the same results if you try to repeat my tests?
Will we get the same results if we swap units, that is run my tests at my
location and with my setup using your
g...@rellim.com said:
> Care to recommend any that have SMA connectors? I have found that a 3dB
> difference in antenna can degrade my data quality, it would be interesting
> to see how the 3dB loss of the splitter affects thins.
There are 2 options for splitters. One is to use cable-TV
g...@rellim.com said:
>> The Adafruit receiver outputs NMEA format data. The lat/lon values
>> are sent as dddmm.mm format (ddd=degrees, mm.mm=minutes) This
>> restricts the resolution of the values.
> Yes, easy to see the quantization in the Adafruit plot.
Something doesn't look quite
g...@rellim.com said:
>> In my case (the original post) there can be no multipath difference,
>> same antenna and done at the same time.
> There sure can be. The GPS birds are moving in orbit. At certain points in
> the sky their signal may be bouncing off a nearby steel building and into
>
preilley_...@comcast.net said:
> The curious thing are the excursions. Rather than being noise like, some
> follow a distinct path. But this is only over a few seconds so it seems
> unlikely that they are caused by weather conditions. ...
I've seen similar quirks when a non-timing unit
jim...@earthlink.net said:
> I'm kind of curious about their "UI".. hold CapsLock? how does this device
> manifest itself to the host computer? I saw a mention of HID, so it is
> emulating a keyboard?
I have a couple of the non-Gold versions. Plastic with a push button. They
have one
time-nuts@febo.com said:
> A PC can certainly generate a lot of frequencies. But if you want to use the
> audio channels at 60KHz there is a little problem. There is a brick wall
> filter in the audio channel set at about 25 KHz.
The filters I'm familiar with in audio gear scale with the
> Did the utility replace the damaged equipment?
A friend lived in a building when the city crew working on a transformer put
440 on the line. It blew out all the electronics in 12 condos - mostly TVs.
I think toasters and refrigerators were OK. There wasn't any question that
the city was
kb...@n1k.org said:
> They sell a lot of 24 bit audio DACâs into that sort of gear. Team them up
> with some DSP and you get all sorts of interesting data. The âone numberâ
> that counts is the fundamental â¦.
DAC?
There is a big market for high resolution ADCs in that area - one in
time-nuts@febo.com said:
> I have come up with a ridiculously simple WWVB simulator that simulates both
> the AM modulation and the BPSK modulation.
Did you consider software?
Is the audio on a Raspberry Pi fast enough?
I haven't looked at any details, but you can get ARM CPUs for ballpark
Here is data from a system using Google's NTP servers.
http://users.megapathdsl.net/~hmurray/time-nuts/leap/ntp-goog-leap.png
The Offset is the view from another system. The drift is from the system
itself.
Google said 13.9 uSec/sec. That matches the step in the drift.
Note the overshoot
tract...@ihug.co.nz said:
> The 'landline' networks also have significant (and variable) latency. ISTR
> measuring a maximum of around 400/500 mSec some years ago on a WN-CH digital
> link. Minimum over the test period of a week was nearer 250 mSec a few days
> later.
How can they get a delay
m...@alignedsolutions.com said:
> Are there "leap second" test sets that non time nuts could use to generate
> leap second events during pre commissioning tests ? (I'm envisioning some
> form of NTP server that could generate leap second events on command ?)
There is a file of leap seconds.
time-nuts@febo.com said:
> Do they add the leap second at the same moment in time throughout the world,
> or are the clocks here in NZ running 13 hours and 1 second ahead of those in
> the UK for half of Jan 1st?
It's added at the end of the last day of a month, UTC.
That makes if 4PM local
gha...@gmail.com said:
> No NTP was running.
What software told the kernel that there was going to be a leap second at the
end of the day?
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The nice thing about the APC units is that they are close to free if you are
already going to purchase a UPS.
I agree that something like the Dranetz 658 would be better, but a quick peek
at eBay shows prices far beyond what I'm willing to pay.
> What's the sample rate on your APC UPS?
I
> I had LH on a ks24361. I think it displayed :00 for 2 seconds (my attempt to
> record it failed). The autocapture (attached) was a little too early. I
> guess this is because LH is polling the receiver every second and the actual
> content depends on what the receiver replies and when it does
att...@kinali.ch said:
> After that, it's just some simple math of calculating the difference between
> the position of the stars and where you would have expecteded them at the
> time when the picture has been taken.
You will probably have to correct for the distortion of the lens. That is a
Is everybody setup to watch it and collect lots of data?
Anybody have a list of tools/toys for collecting data?
An old favorite:
www.cl.cam.ac.uk/~mgk25/time/leap/test/timelog.c
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petervince1...@gmail.com said:
> It seems to me that the major problem with the leap-second is the inability
> of current computer operating systems to represent it, and this is due to
> their using a second count since 1970 rather than writing it out as we would
> by hand.
Your suggestion
> on start up i have an odd behavior.
> 0, 1.99881895E+07
> 0, 1.99881912E+07
> 0, 1.99881757E+07
> 7, 1.99881856E+07
> 17, 1.99881878E+07
> 27, 1.99881900E+07
> What do you think?
Looks like you are expecting readings every 10 seconds but it's sending a few
samples
preilley_...@comcast.net said:
> I would like to get better than the +-10 nS that the better receivers
> provide.
A GPSDO generally avoids the sawtooth offset.
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drkir...@kirkbymicrowave.co.uk said:
> I assume it wont start until it has tracked sufficient number of satellites.
There is a chicken-egg problem with getting started. The satellites tell you
where they are, but you need to know where they are and where you are in
order to calculate the
b...@evoria.net said:
> So, if an NTP user can get his time fix directly from a noisy receiver, who
> actually needs a time-accurate, low jitter 1PPS pulse?
Most kernels have an option to capture a time stamp from a PPS signal at
interrupt time. That is much more accurate than the timing you
kb...@n1k.org said:
>> the cool thing about those parts is that their PSRR extends
>> up to several MHz. A lot of LDOs have good PSRR to kHz.
> Which to bring it back to noise in radios â¦.. could be the issue there. The
> device isnât oscillating, itâs just not blocking the crud from
ch...@chriscaudle.org said:
> Mark has explained previously on the list, but it is actually kind of
> convoluted. The command to set the position does not accept enough numeric
> precision to accurately set the position which was determined from
> long term averaging...
What does the chop-off
tsho...@gmail.com said:
> I have some long (24 hour) WAV files and will see if I can come to any
> determination about the offset and spread of the sampling rate. e.g. if the
> sampling rate nominally 44100, how precise is that in my PC's hardware? I
> would bet this is tied to a crystal in the
walt...@sphere.bc.ca said:
> After re-working the lab I have my Z3801A in, I realized there's no windows
> computers left anywhere near there. Is there any monitoring software that
> will run on my 16.04 Ubuntu Linux machines?
Depending on what you want, your best bet may be to wait for the
kb...@n1k.org said:
> The navigation solution is something you must have before you can begin to
> get a timing solution.
That sounds like a 2 step process: where, then when. Does it work that way?
I thought you got where and when at the same time - you couldn't get where
without also
tn1...@nic.fi said:
> I wonder what this stupid "leap smear" will do to NTP driftfiles. ...
There was a report on that area mentioned here a while ago.
As long as the smearing is slow enough, the client servers easily track the
drift. There is a bump in their drift, but it's not a problem for
jim...@earthlink.net said:
> I'm looking for a small linux single board - similar to RPi or Beaglebone
> Black, but don't need the HDMI, or video stuff.
Don't limit your search to things that doen't have what you don't need. It
may be cheaper to get a high volume part and ignore the sections
w1...@earthlink.net said:
> Any other software out there for the "Z-Box" besides SatStat (clock works,
> nothing else) or
What are you looking for?
I have a python hack that displays the status screen every N seconds and logs
a bunch of parameters so you can feed them to gnuplot or the tools
tract...@ihug.co.nz said:
> I thought it may be a reference supply for the EFC pin- with a 12.03 volt
> supply the unknown pin measures at 2.803 volts-which is usefully above the
> required EFC voltage ( ~2.4 volts) to bring it on frequency.
> But does anyone have some hard data on this
p...@phk.freebsd.dk said:
> I think the installation manual for Trimbles timing products say you can use
> either 75 or 50 Ohm cable...
I think they suggest using RG-6, the classic cable TV and/or satellite dish
cable. It's widely available at low cost.
The loss due to impedance mismatch is
Is that even a sensible question? Is there a better way to phrase it?
The problem I'm trying to avoid is that the weather and the satellite
geometry change over time so I can't just collect data for X hours, switch to
the other antenna or move the antenna to another location, collect more
rich...@karlquist.com said:
> I would have thought (just guessing) that peak to peak output current would
> be equal to Iout Full Scale, but it appears to be only half of that.
> Can anyone clarify this?
Don't overlook a bug in the data sheet.
The data sheet for the actual part at
t...@leapsecond.com said:
> Arduino probably uses compiled code, external libraries, and interrupts so
> that also is a no-no for precise time.
There are two parts to the Arduino ecosystem. One is low cost hardware. The
other is a software package that is easy for non-wizards to use.
I'd be
ch...@chriscaudle.org said:
> but once you get to most of the ARM processors it is harder to make them
> deterministic because of caches.
There are many ARM SOC chips that are half way between an Arduino and a
Raspberry Pi. They have GPIO and various serial ports and counter/timers.
They
albertson.ch...@gmail.com said:
> I'm wondering why everyone seems to be assuming a PIC is the right processor
If you want cycle-accurate timing, one approach is to count cycles. If you
have an assembly level background, the PIC is as good as any small chip.
Yes, it's a pain to get started
ciandjabu...@gmail.com said:
> How do I get a pulse to start with a push button and then stop for example
> 500 or 10,000 seconds later?
How about another PIC?
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kb...@n1k.org said:
> Yes, the FE-405 uses a DDS and a cleanup. Inside the cleanup loop the DDS
> spurs come straight through. Since the FE-405 compensates for all sorts of
> things, the DDS moves around a lot. Even a one bit change on a DDS will move
> spurs around. With an ever changing DDS,
garygar...@earthlink.net said:
> I was kinda wondering about that. Isn't H the escape artist of the periodic
> table?
I think that's helium. They way they get it commercially is to start with
gas wells that have lots of it. I think some of them are 4%. Then they just
push it through
cdel...@juno.com said:
> I just went ahead and got the short section from McMaster Carr. Want to make
> sure it's right if I'm at 400+ PSI with Hydrogen for years at a time!!!
How much hydrogen does a maser use? How big is the tank?
Does it leak through cracks or migrate through metal?
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t...@leapsecond.com said:
> The PIC's I use have essentially no jitter. If they generate a 1PPS the edge
> and the pulse width are perfect, down to picoseconds. The talk about "other
> stuff" and "priority" and "number of compares" and "ambiguity" is worrisome.
> It sounds like a design or coding
albertson.ch...@gmail.com said:
> If using the PPS for timing and the PPS is inverted you will have to measure
> the delay length an account for in the config file.
Or use the falling edge rather than the rising edge.
Most instrumentation has a knob/button/whatever to select which direction to
drkir...@kirkbymicrowave.co.uk said:
> I was looking to give a talk about frequency measurements to my amateur
> radio club. Whilst I am sure that those at the club will only use a
> commercial frequency counter, I thought it sensible to mention a large
> number of ways, as I think that would
g...@rellim.com said:
> Who cares if the PPS is inverted?
Good point. I wasn't paying attention to the PPS only context in the
subject. I keep forgetting which way is best for PPS. Fortunately, all the
software I've used knows how to handle inverted PPS.
The original message in this
stry...@hotmail.com said:
> Would this do the trick? - http://www.banggood.com/8-Channel-Logic-Level-Tran
> slator-Converter-Bi-Directional-Module-p-1023173.html
Not likely.
The normal RS-232 level shifter chip includes an inverter. (No good reason,
just historical, but with a long history.)
kb...@n1k.org said:
> Yes, thatâs a bit of a long winded reply ⦠sorry about that.
It was also valuable. Thanks.
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jim...@earthlink.net said:
> tweezers to remove
> single iron to install
> use a orange stick to hold the part down while you solder each end.
How many hands does that take?
I normally use one to hold the iron and the other to apply solder.
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t...@leapsecond.com said:
> Having not done SMT before, how should I do it with minimal risk to the
> very precious PCB. Or, what equipment should I use this as a good excuse
> to buy?
If you can get at it, 2 soldering irons, one on each end, works reasonably
well. When both ends are melted,
> At 12 hours of holdover...
> I think I'll need a lot more understanding of the impact of aging vs
> temperature
At that timescale, I'd expect aging to be lost in the noise.
How are you calibrating things?
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I would put a scope on the TX line from the Z3801A and power cycle it. I'm
pretty sure it prints out the version string on power up.
Have you checked the power supplies? Or looked for old electrolytics?
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petervince1...@gmail.com said:
> Sorry Don, I beg to differ. The effects are often not noticeable in these
> days of digital television, but the noise-floor can definitely be seen to
> rise dramatically on a spectrum analyser.
Right. But I think that's because the sun is lining up with the
> it did when my Z3801A did a false leap-second at the end of September.
Was there a similar problem/opportunity at the end of Oct? Should we watch
at the end of Nov (last chance for a while)?
What did the Z3801A do? Was the bug in the Z3801A or in an ancient version
of ntpd without the fix
kb...@n1k.org said:
> The only practical way to set the 10811 or 10544 is with a >= 10 turn pot on
> the EFC. I never have worked out just why there are so many instruments that
> donât have a pot on the EFC.
How would temperature effect that? For that matter, how does temperature
effect
> To enjoy the links, replace CS-tube with CS_tube in the links.
Worked for me without the edit and didn't work with that change.
(Skip may have fixed the web site names? Or maybe there is something
interesting going on.)
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> http://cache.nxp.com/documents/data_sheet/BFG135.pdf?pspll=1
The usual suppliers say that it's no longer available. What do you
use/suggest these days?
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> Any freeware out there to decode WWVB or any of the other standards out
> there? Using an audio card and pc?
The low cost WWVB receivers put out an on/off signal which can be wired up to
a modem control signal.
Many many years ago, I found some software that decoded that. Or tried to.
I
nsa...@kfu.com said:
> That single-chip version is going to have a *LOT* less (and less variable)
> latency than an SDR.
Latency isn't an issue as long as it is known so that you can correct for it.
Has anybody measured the jitter through SDR and/or tried to reduce it? I'd
expect that even
stewart.c...@gmail.com said:
> I hope this is not too blatantly commercial for this list
Looks good to me. Thanks.
Are the specs for extracting timing from Iridium available without NDA or $$$?
Page 6 shows several hardware boards/boxes. The NooElec NESDR Mini 2 USB Stick
seems like the
tsho...@gmail.com said:
> I'm all for a diversity of systems - putting all our eggs in the GPS basket
> seems unwise (and I maintain WWV receivers hooked to NTP at home!)
What is available in the way of WWV receivers? Anybody got a summary handy?
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i...@iliaplatone.com said:
> sorry, no attachment, this mail contains two images, one is the previous
> attempt, the second (IMG_003.JPG) was taken at 5us/div, 1v/div with a
> different oscilloscope setup.
The first one looks like you are triggering on noise or runt pulses. What
does it look
i...@iliaplatone.com said:
> These events are random photon arrivals (converted to 5vTTL pulses), their
> rate was measured using the pulse width of the smaller detected, which was
> 5~10 uS during an observation in low-light environment. The photon arrival
> and pulse width were random with a
> full disclosure: there were a couple of outlier external clocks I threw out,
> one with a 38 ms offset and the other with a 112 ms offset).
That's not uncommon. It happens more often when the server is farther away
and there are more opportunities for strange network routing.
The NIST
> Here's another way to do it for a wall clock display... set up an
> oscillator/divider (or even a 555 timer) to generate a frequency close to,
> but faster than 65536 Hz.Setup a 16 bit counter clocked by that signal.
> When the 1PPS signal arrives, start the counter. After 65536 pulses
davidwh...@gmail.com said:
> I think a PIC might be fast enough to DDS it. The output bandpass filter
> will cure a lot of sin. Using a dedicated switched capacitor filter would
> be fun but more expensive.
There are two parts to a DDS like setup. One is the math for the DDS and
then
> 1. Does anyone know of a device that will take a 1PPS GPS timing signal and
> generate a 32.768 kHz sine wave output ? I have big digital clock that uses
> an 8 bit micro processor and an external 32.768 crystal. Obviously the
> external crystal is awful for accuracy.
I don't know of any
jim...@earthlink.net said:
> What I need is that really boring single camera watching from a single
> viewpoint with a high resolution counter in the field of view. The "big
> countdown clock" at KSC doesn't show fractions of a second.
What's the technology for that clock? I'll guess that was
jg...@zianet.com said:
> What about this scenario - the GPSDO has a fixed position on initial
> powerup, but then it is moved periodically or even continuously, without
> updating the GPS coordinates. The distance from the original coordinates
> could be anywhere from close by, to across the
gmx.tallahas...@gmail.com said:
> the offset of the leontp device from the other clocks has consistently been
> in the 9.5 -10.5 range. since I'm measuring all three sources from the
> same (EL7) computer, I would expect that the offset of the leontp unit to
> converge to be in the close
time-nuts@febo.com said:
>> Nick, thanks for your detailed reply. Would you happen to have a photo of
>> the "spring looking things?" I am not entirely sure I have one of those
>> included with the kit that came with the scope.
> I donât have a picture, but the Internet does:
> Whether they actually met it, then pulled the interference supression parts
> off the board as a "cost reduction" as is common in no-name computer power
> supplies, or whether it never met it to begin with, is for you to speculate.
I only watched the first part of the video.
I'm surprised
t...@westwood-tech.com said:
> I was going to post my ntp output and ask for an opinion, then this
> discussion popped up. It would appear that asymmetric delays are the exact
> explanation for what I am seeing. Is that a reasonable assumption? It does
> seem to be rather consistent throughout
t...@leapsecond.com said:
> No, not narrow pulses. Do not use the trailing edge of a 1PPS. This is more
> about 1 Hz from a stable frequency standard, not 1PPS from a noisy GPS
> receiver.
I think we are discussing two different things.
Your setup would work if the pulse-under-test is
t...@leapsecond.com said:
> 1) My *work-around* is to adjust the REF 1PPS by tens of microseconds, or
> even 500 ms. That avoids running into sign changes and skipped samples when
> a TIC gets near zero. This works really well for stable clocks where 500 ms
> drift is next to impossible.
How
> They get counterfeited a *lot*.
Is that true for relatively obscure things like the Prologix GPIB controllers
that aren't high volume?
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jim...@earthlink.net said:
> I happen to use the ethernet one, but I would imagine the USB one also
> works fine. I've had more trouble with non-standard USB devices (e.g. not a
> disk drive, keyboard, mouse, or serial port) on Linux than on Windows or
> Mac OSX - but I don't know what the
albertson.ch...@gmail.com said:
> The problem is harder then most people think. To avoid jumps in time either
> forward or backwards the software must be something that runs continuously
> and monitors your clock vs. one or more reference clocks. Logically there
> is no other way.
I think it
j99har...@gmail.com said:
> Unless the oscillator is still warming up, 5 minutes or even 60 is way too
> short a time to look at aging. For aging, you will want to look at the
> change in DAC values over several days at least.
I think it's worse than that. You have to hold the temperature
time-nuts@febo.com said:
> Thatâs kind of why Iâm going down the road of multiple samples - to see if
> thereâs anything to it.
I would hack up some way to grab a clump (say 10) of samples and print them
out where you can capture them on a PC and analyze them.
I'd start by looking with
albertson.ch...@gmail.com said:
> But I use a set of five different servers all controlled by different
> organizations and they are geographically distributed. Also some of these
> are randomly elected "pool" servers. So even I don't know who I will ask
> for time. How could anyone corrupt
david-tay...@blueyonder.co.uk said:
> You can use a GPS puck or equivalent with PPS output to get the sort of
> accuracy you need. ..:
PPS output is only half the battle. You also have to get it into the system
that needs it.
A modem control signal on an old fashioned serial port (not USB)
> Is there a pinout posted somewhere for the Lucent box RS422 D sub 9
> connector?
It's in the mail archives. Google for something like >time-nuts RS422 pinout<
If you are interested in timing, you want the PPS signal too. (It won't be
great over USB, but it might be fun to play with. You
bruce.griffi...@xtra.co.nz said:
>> It is possible to check the output level without an oscilloscope ?
> Only with a clasical (diode detector) RF probe (they're still available) or
> an RF power meter.
How about a diode, small cap, and a DC meter? (and a few clip leads)
It won't give an
> For a low duty cycle pulse, the ac coupled signal will be approximately the
> same as if it were dc coupled. Not sure I follow what you mean. There will
> be only one rising edge for a narrow pulse ac coupled, as the falling edge
> occurs much quicker than the HPF time constant.
If there is
g...@rellim.com said:
> APC UPS can't handle the longer runtime, but never had a problem with any
> version of CyberPower.
There are two parameters for UPS boxes. One is the power the electronics can
handle. The other is the amount of energy the batteries can hold.
I think some of the
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