Hi
Anything odd going on with the EFC voltage before / after holdover?
Bob
> On Jun 20, 2019, at 1:05 PM, Dan Rae via time-nuts
> wrote:
>
> I have an elderly 3801A with some 182,000 hours on the clock, which if my
> arithmetic is correct means over twenty years of operation. Since it has
ns with
> u-blox 6 GPS receivers - Application Note" that makes interesting reading.
>
> Many thanks
> Dave
>
>
> On 20/06/2019 00:19, Bob kb8tq wrote:
>
> Hi
>
> On a second to second basis, the 10 MHz will be off by < +/- 0.02 ppm.
> Averaged over 24 h
Hi
Which is why I asked about the EFC ….. they *should* start complaining when the
EFC gets close to limit.
How close? No idea. Are there other parameters it monitors? No idea.
The (useless) heater box around the 10811 in the Z3801 can be opened up. Inside
is a fairly normal 10811. On the
Hi
Cheapest and easiest is to use a power splitter. Ones from Mini Circuits that
are
rated to work at 10 MHz can be had for $20 or less. At some point you run out
of power ….
Building a splitter from NC7SZ125’s is not a all that crazy as a DIY project.
You
can get a dozen or so outputs and
Hi
Given the relatively low cost of a GPS based “Stratum 1” NTP, it’s not real
clear
why (at the end of the paper) they go off and “exchange emails individually
with the
organizations that run stratum 1 servers, as well as negotiate permission to
use them.”
to source the root time for the
Hi
A lot depends on just how long your “frequency” samples are. If the GPS is good
to
a nanosecond, you are at 1x10^-11 at 100 seconds. It’s a rare crystal based
GPSDO
that will hold closer than that frequency wise.
The FLL is non peaking so that’s going to help things a bit as well.
Bob
>
Hi
On most commercial designs a “time reset” is done when coming out of holdover
to take
care of the PLL issue. This provision for this is detailed in most OEM specs.
If you watch
most of the eBay surplus GPSDO’s as they do their thing, you can see them do a
“hop”
when this happens.
Bob
> On
Hi
Welll … ummm ….. e ….
With things like time re-synch going on, the only thing you should drive a
clock with
is the PPS output. You can go on pretty much forever and ever with a FLL and
still have
a good PPS out.
Bob
> On Jun 23, 2019, at 10:44 PM, Hal Murray wrote:
>
>
>
Hi
Digikey now shows the uBlox F9T in stock (250 pieces worth). The F9P also is
back in stock.
Pricing is identical on both parts. No eval kits for the F9T showing yet. The
F9P eval (C099-F9P)
is still listed at $50 more than the single piece price for a F9P module (and
you get a free USB
is very much
> like ground plane and reflective.
>
> ---
> (Mr.) Taka Kamiya
> I'm stuck in a wormhole Hello, worms!
>
> On Tuesday, April 30, 2019, 5:01:05 PM EDT, Bob kb8tq
> wrote:
>
> Hi
>
> You very much
Hi
You very much do *not* want to put a ground plane on one of the modern survey
antennas.(Chinese or US or Canadian or …) The better ones are very explicit
about this. They are optimized to sit on a pole in free air. Anything else and
the
pattern is degraded. ( = multipath gets worse)
Bob
mparison will be very interesting.
>
> Thanks for your reply.
>
> ---
> (Mr.) Taka Kamiya
> I'm stuck in a wormhole Hello, worms!
>
>
> On Tuesday, April 30, 2019, 6:28:11 PM EDT, Bob kb8tq wrote:
>
>
> Hi
>
working well.
>
> I’ve included a couple of pics of the mounting below. This is what can happen
> when a contractor enjoys a good challenge. :)
>
>
>
>
>
>
>
>> On Jan 27, 2019, at 05:28, Bob kb8tq mailto:kb...@n1k.org>>
>> wrote:
>>
>
Hi
There normally is a “survey in” process on a GPSDO. The location then gets used
to
help out the timing solution. If you move the antennas “far enough” (how far
very much depends
on the design) the device goes back into survey mode. While doing that, the
timing
may be less than ideal.
Bob
yone know the price of the Excelitas device? No, I'm not interested in
> purchasing one, just curious. I assume it is hair-curling expensive.
>
>
> On Monday, May 6, 2019, Bob kb8tq wrote:
>
>> Hi
>>
>> Ummm ….. e ….. the Efratom Rb’s use an integrated lamp p
us two approach. One of many:
http://www.excelitas.com/Downloads/DTS_Frequency_Standards_RAFS.pdf
<http://www.excelitas.com/Downloads/DTS_Frequency_Standards_RAFS.pdf>
Bob
> On May 6, 2019, at 3:23 PM, Ed Palmer wrote:
>
>
>
> On 2019-05-06 10:00 AM, Bob kb8tq w
.
Bob
> On May 6, 2019, at 9:51 PM, jimlux wrote:
>
> On 5/6/19 3:54 PM, Bob kb8tq wrote:
>> Hi
>> Back a while ago it was in the “over a million dollars” range. Like
>> anything that
>> is designed for space use, the price is meaningless until you sort thro
Hi
Helium is still a pretty good thermal conductor at low pressures. The reason
you backfill is thermal. Neon (or other heavy atom gasses) are relatively poor
thermal conductors.
Getters are wonderful as long as they don’t outgas. Turns out that is not as
simple a thing to “fix” as you might
Hi
Well, given the price, running it in a thermal-vac chamber would not
significantly increase
the charges to your credit card :)
Bob
> On May 7, 2019, at 3:23 PM, Poul-Henning Kamp wrote:
>
>
> In message , Bob kb8tq writes:
>
>> In terms of “I do
Hi
If you talk to the engineers who design these gizmos, after about 15 minutes of
their presentation,
they come up with the point that the 1 pps lock setup isn’t quite what you
might think. Yes, in some
cases there are hints about this in the doc’s. In other cases …. not so much.
They design
Hi
If ADEV was a “narrowband” measure, you would be correct. Unfortunately ADEV
looks at a
wide range of frequencies so doing a single point analysis can be misleading.
However the general
conclusion is often correct in the case of simple noise processes.
One way to “get better” is to look
Hi
I’m sure they are good cells. The gotcha is “which one is it?”. A normal Rb has
multiple
cells doing different things. You … umm… errr … need a set of cells ….
Bob
> On May 5, 2019, at 5:32 PM, ed_pal...@sasktel.net wrote:
>
> I've seen lots of weird stuff on ebay, but I never thought I'd
HI
I suspect that as long as the 1050 has been around …. there are mulitple
versions of the schematics.
I doubt there ever *was* a service manual. It likely was a “factory repair
only” sort of device.
Bob
> On May 4, 2019, at 5:53 PM, Jeff Kruth via time-nuts
> wrote:
>
> Hello!
> Does
Hi
….. a little elaboration …..
If you *don’t* terminate the main distribution line, it effectively acts as a
great big antenna. It
floods the lab area (or production floor or building …) with 10 MHz. I
unfortunately have a lot
of empirical data to back this up.
It’s also worth using a
Hi
Just to confirm - it seems to be broken from here as well.
Bob
> On Apr 27, 2019, at 7:31 AM, AC0XU (Jim) wrote:
>
> Does anyone know how to obtain the NRL Canvas (clock analsis) software? The
> widely published link
>
> https://goby.nrl.navy.mil/canvas/
>
> appears to be broken.
nce of Justice" Both MLK
> and Albert Einstein
>
> ________
> From: time-nuts on behalf of Bob kb8tq
>
> Sent: Saturday, May 4, 2019 5:00 PM
> To: Discussion of precise time and frequency measurement
> Cc: Jeff Kruth
> Subject: Re: [t
Hi
Anything is possible. Working out exactly what happened and what needs to be
done
to fix it might be a bit involved. A maser is a pretty complicated piece of
gear.
The best bet is to dig out the manuals and go through the troubleshooting
process in
them. Plan for it taking a bit of time
Hi
The purpose of coax is to shield the signal. The outer portion of the cable
acts to protect the inner part from stray signals in the environment. In a
normal
system, the outer braid is connected to ground. It is no different than a lot
of audio
cabling in that respect.
Energy flow is
ject is only done if
> the spec is met, and of course the spec can go on being as tight as you want.
> You could spend your whole life on it.
>
> glen
> On 25/06/2019 1:16 PM, Bob kb8tq wrote:
>> Hi
>>
>> In a GPSDO, an FLL can be done with no “cycle slips” betwee
Hi
> On Jul 11, 2019, at 9:37 AM, Leo Bodnar wrote:
>
>> Well part of it comes from designing, testing, and manufacturing a few
>> thousand OCXO designs over the years. We likely built 10’s of millions of
>> OCXO’s over the time I was doing / managing that.
> It might be just my personal
Hi
The whole clock error / orbit error thing can be corrected after the fact with
data from
various agencies. It impacts survey work at least as much as timing. Looking at
it that
way, it does not really present a hard limit.
The “what’s the frequency limit?” question depends on just what
noise setups *is* done. It’s just not very practical.
Bob
> On Jul 10, 2019, at 3:49 AM, Leo Bodnar wrote:
>
>> From: Bob kb8tq
>> Drive power on an OCXO will pretty much always be below a milli-watt. A
>> typical design will be in
>> the range of 1/1
Hi
One of the gotcha’s if you are in the US is that the most often seen “alternate
brand” of Maser comes out of Russia. Depending on the phase of the moon and
just what the rule book says this week, you may well not be able to bring one
into the country.
Back when things were a bit more
Hi
> On Jul 10, 2019, at 4:26 PM, Hal Murray wrote:
>
>
>> Would someone please expand on what the practical frequency calibration limit
>> might be?
>
> That's not quite a well formed question yet. You need to say something about
> the time scale. What are you trying to calibrate?
>
>
idn’t, the design
task would simply be to have a low noise follower amp. There have been designs
published in a
lot of places for amps that are 50 db better than the noise of any OCXO at 1 Hz
offset.
Bob
>
> Leo
>
>>> From: Bob kb8tq
>> It depends a lot on the off
Hi
There is nothing on the spec sheet that leaps out as “obviously better” than
the
T-Bolt’s that we all know and love. Indeed you *will* get support, a warranty,
and
a unit that has 10 to 20 years less wear and tear.
Bob
> On Jul 11, 2019, at 3:22 PM, Chris Burford wrote:
>
> I'm on the
for maximum Q in a 5 or 10 MHz OCXO. Practical package
size for the resonators is as much a part of it as anything else. ( = that’s
about as
big a package as anybody is tooled to do an OCXO crystal in )
Bob
> On Jul 12, 2019, at 4:24 AM, Leo Bodnar wrote:
>
> From: Bob kb8tq
>>>&g
Hi
If you do go the TEC route, plan on a fairly big power source :). There is a
Wenzel doc on doing a TEC based enclosure using a couple of die cast
boxes. The pictures don’t show what they used to drive the beast so part of
it would still be up to you. My search skills and their web site are
Hi
Airlines tend to have issues with various battery types as well. Not clear
what the rules are on “powered up in the hold” are. My guess is that ground
transportation gets the nod pretty quickly.
TEC’s are good for some limited temperature delta and then you need to go to
cascaded “layers”
Hi
Ok, if it’s a “heat only” design, how about a dewar flask? They aren’t the most
rugged items
out there so some sort of padded enclosure would be needed. The real question
is:
Does a “single end” design impact your ability to use the resistor? Put another
way - do you need
to hit both ends
on the bottom of the unit ….. again, no real information.
Bob
> On Jul 12, 2019, at 7:11 PM, Bruce Griffiths
> wrote:
>
> Figure 5 in http://www.wenzel.com/wp-content/uploads/Sub-pico-Multiplier.pdf
> ??
> Bruce
>> On 13 July 2019 at 05:23 Bob kb8tq wrote:
>>
>>
Hi
There are an enormous number of combinations and permutations to the whole
GNSS timing question.
1) Does your multi band receiver only track GPS L2C? ( = is it like a F9T or
F9P)
If so, the number of GPS stats will be smaller and performance will not be as
good
as it might be.
2) Are
Hi
Running and shielding a 10 MHz standard signal is never easy. Ground loops
here or there are highly likely to exist and create all sorts of issues. In
some
setups, -10 to -20 dbm is not an uncommon result ( = fix the termination on
your Spectracom system …). Getting below -90 is actually
Hi
One alternative, if you only need two lines is to write a parser just for them.
There’s not a whole lot to the protocol and the uBlox doc’s are pretty good at
describing it. Yes, it’s a binary protocol so there will be a bit of this and
that
involved.
Bob
> On Jul 13, 2019, at 5:16 PM,
nar wrote:
>
> Correction on all Ublox receivers including F9P is done at navigation rate
> which can be set as high as 20Hz.
> Leo
>
>> From: Bob kb8tq
>> Frequency of any GNSS output on the F9P is limited by the accuracy of the
>> time pulse.
>
Hi
As far as the coax goes, termination is a good idea. As far as the signal goes
… maybe not so much ….
Using 5V logic as an example:
If you build up a driver that has a 50 ohm source impedance, you have a (so
far) do-able project. The
output delivered into a light load could be the same as
Hi
If the data is GPS referenced it is not at all uncommon to see a roughly 24
hour pattern in
the data. Ionospheric changes are one significant contributor. The further down
into the
mud you get, the more other things pop up (multipath repeating with the same
constalation
….)
Bob
> On
e 24 hour measurement duration?
>
> I have attached a screen capture that will hopefully make its way through for
> viewing.
>
> Thanks,
>
> Chris
>
> On 07/02/19 11:50:10, Bob kb8tq wrote:
>> Hi
>>
>> The difference in seconds between the start phase
a while and measuring ADEV for
> a week on the sellers premises.
>
> glen
>
>
> On 1/07/2019 7:09 AM, Bob kb8tq wrote:
>> Hi
>>
>> Based on several replacements on a “high performance” 5071 …. 6 to 7 years
>> of 24/7/365 seems to
>> be about
Hi
You will see used tubes for sale from time to time. That’s about the only
“cheap” way to
re-tube your dead Cs standard. It’s very much a gamble any time you buy one.
There
is no guarantee you are getting anything better than what you already have.
There is nobody out there doing “real”
Hi
Well here’s another twist and turn in the F9T availability saga. The F9T
modules are now up on the
uBlox site for $199 and 3-5 day delivery. The RCB-F9T board with an F9T mounted
on it is also up
on the site for $247.50. More or less the board is a “Sparkfun” clone in a more
or less
Hi
The whole “phase here vs phase there” thing was at the heart of the papers the
power guys started presenting back in the late 1980’s …. At least back then the
data
was between points a lot further spread out than both sides of a valley.
Bob
> On Jul 7, 2019, at 5:39 PM, jimlux wrote:
>
>
Hi
Whatever they are doing to create an output is being done modulo the internal
TCXO period.
That gets you down to a +/- 4 ns error on either the F9T or the F9P. They can
do that however
often they like, it’s still a very coarse correction as far as I’m concerned.
What matters is how
Hi
My solution is to kidnap Mark’s pet goldfish and hold it captive until the
specific device
is incorporated into LH …. :). In the case of expensive or rare gear lending
out a
device might get things going faster than the goldfish maneuver ….
Bob
> On Jul 14, 2019, at 4:06 AM, Hal Murray
Hi
All of the divide by 2 stuff and the frequency counter on the input would make
more
sense with a DFF as a mixer. It also might explain the use of a 3V CMOS signal
as
the “standard input”.
It may all be in an FPGA.
One thing missing in the info - can the LO be tuned at all? If not, you
Hi
With any DMTD, the offset between the LO and the DUT is a critical part of the
resolution. Without much info on the LO, it is not very easy to work out just
what
they might or might not be doing.
That said, with “normal” offset frequencies, a filpflop would be challenged to
hit
the sort of
Hi
My advice: Pull out the nicads and run the device on a normal UPS if you
actually need
power backup. When the UPS bites the dust … replace it. Much easier than keeping
the batteries in these devices happy.
Bob
> On Apr 24, 2019, at 11:53 AM, Roy Thistle
> wrote:
>
> Hi Time Nuts:
>
>
Hi
The “fix” for this (adding 3 more bits) was worked out and announced back in
2004. The new
generation of sats will be transmitting a longer week number. The gotcha is
that the old sats
are still up there doing their thing. They are built in a way that you can’t
just shoot a firmware
patch
Hi
I don’t really see anything in your plots that looks like it correlates with
temperature.
You may have processed it out with some of your fitting and regression stuff.
There *is* something going on with he red line. What it is … very unclear. Best
guess
would be a bum solder joint
Hi
Well *maybe* they came from Oscilloquartz. They could easily have come from
somebody
else and been rejects because of that …..
Bob
> On Apr 25, 2019, at 5:36 PM, Dan Rae via time-nuts
> wrote:
>
> On 4/25/2019 1:13 PM, Bob kb8tq wrote:
>> Pretty much all of these OC
> On Apr 17, 2019, at 8:45 AM, Greg Troxel wrote:
>
> Bob kb8tq writes:
>
>> I have never seen any manufacturer recommend SBAS for improved timing. The
>> simple answer seems to be that the reference system does not have time
>> sources
>> in it
---
> (Mr.) Taka Kamiya
> I'm stuck in a wormhole Hello, worms!
>
>On Monday, July 1, 2019, 9:35:49 AM EDT, Bob kb8tq wrote:
>
> Hi
>
> There are a lot of posts back in the archives about various things on Cs
> sta
Hi
The difference in seconds between the start phase and the end phase divided by
the number
of seconds duration gives you the parts in whatever of the error.
If you see 1us ( = 1x10^-6 seconds) of change in a second, you are off by 1
ppm (or 1x10^-6).
If you see 1 us of change in 1,000
Hi
With all the rain in the spring, you could easily have better local grounding.
Bob
> On Jun 29, 2019, at 10:15 AM, Tim Shoppa wrote:
>
> Interestingly enough, compared to my initial testing last winter, my ES100
> is suddenly much more likely to acquire and track WWVB in broad daylight.
>
Hi
The “normal” approach is to stabilize the inner wall and cross section (= open
tube)
of the dewar. Often this is done with a metal “plug”. It may or may not extend
to the
bottom of the dewar. A lot depends on fiddly little details about how much heat
you are generating in the circuitry
Hi
There are a lot of dewar / vacuum flasks on eBay in a wide variety of
shapes and sizes. Some get into the proper combination of affordability,
size and shape. There does not appear to be a constant supply of any
one version so it is very much shop and see.
Dewar based OCXO’s go way back ( in
Hi
You can run a controlled experiment where you simply change the pressure.
Crystals
are indeed pressure sensitive. It’s one of the reasons welded packages became
more
popular for OCXO’s ( welded crystal package inside a welded OCXO package means
less pressure change onto the crystal package).
Hi
Could you? Sure you could.
Should you? How much do you feel like rewriting all the driver software from
scratch?
Do you really want to rewire things to fit to the Raspberry pinout? That’s
either a fairly
simple PCB or a whole bunch of wires.
The main benefits would be the bigger RAM on
Hi
The cheapest approach for phase noise is probably to use a single RPD-1 mixer
plus preamp and feed the
output into a sound card. Total cost should be under $100. Yes, it’s a DIY sort
of project rather than a “buy
it and use it” sort of thing.
Bob
> On Aug 22, 2019, at 8:55 AM, Anton
Hi
There are a few folks around who have done boards. The circuit is simple
enough that point to point wiring on perf board works pretty well. ( = mixer
plus opamp after it).
Bob
> On Sep 5, 2019, at 12:19 PM, Peter Vince wrote:
>
> On Thu, 5 Sep 2019 at 19:00, Bob kb8
Hi
Assuming Mark’s data is at 10 MHz and 1 second then 0.0002 Hz is 20 ppt. That
number
can be compared directly against data presented for a variety of other devices.
By far the
best way to do the comparison would be to take data over a range of tau’s and
look at the
resulting plot. That way
HI
Assuming 0.01 Hz at 6 GHz is the resolution, that comes out to 1.6 ppt. That’s
roughly
10X better than the noise level that Mark reported on the FA1. Given that
resolution is not
the same as noise and 10 seconds may well be 10X better than 1 second, it’s not
at all clear
how the two data
Hi
The gotcha with putting anything on top of a GPS antenna is that it impacts the
phase
shift from the sat’s. How important that is gets quickly into just how picky
you happen to be.
Bob
> On Sep 6, 2019, at 11:07 AM, Nick Sayer via time-nuts
> wrote:
>
> I’m late to the party, but my
Hi
Ummm ….. e ……
The divisors run down to an output port. There has to be a filter at that port
to
knock down the noise and make the loop close properly. When you multiply the
divisors by three, you cut the frequency at that port by three. You also have a
significant impact on the control
Hi
A lot depends on what your end use is and what you have to work with. There are
Altera FPGA boards that have built in PLL’s that will accept a 5 MHz input. You
can
generate just about anything with them. 10 and 25 MHz (plus 1 pps) with
multiple
outputs of each would be pretty easy. Phase
> U400 is the same MC145190 which is doing the division. So it sounds like
> they're compensating for some of the effects by configuring the phase
> detector differently depending on the divisor values.
>
>
> On Fri, Sep 13, 2019 at 11:00 AM Bob kb8tq wrote:
>
>> Hi
>
Hi
What are you really trying to do here?
If it’s a “from scratch” atomic standard, then you just aren’t going to get
there. Sorry about that ...
If it’s a wall clock sync’d to an external radio service then indeed you
might get there.
In-between those two lie tings like buying eBay telecom
figuring the phase
> detector differently depending on the divisor values.
>
>
> On Fri, Sep 13, 2019 at 11:00 AM Bob kb8tq wrote:
>
>> Hi
>>
>> Ummm ….. e ……
>>
>> The divisors run down to an output port. There has to be a filter at that
>>
Hi
The TBolt does code phase to lock up the OCXO. Effectively its best guess error
is zero once the control loop
closes. That also means the average error is also zero. Since it’s yanking the
OCXO *and* guessing at the error,
separating those two numbers can get a bit tangled up. One of the
Hi
You are not going to get useful phase noise data out of a normal DMTD ….
The DMTD is targeted at ADEV and similar long term / high accuracy
measurements. If a DMTD “makes it” to a 10 Hz beat note that is about
as far as most people take it.
Bob
> On Sep 16, 2019, at 10:41 AM,
Hi
Based on the papers I have seen, there is no “magic” shape that can be ignored.
Part of the issue is that the cover is going to be in the near field of the
antenna.
As noted in another post, the impact is more complex than a simple delay. (
consider
that signals bounce off the cover
Hi
You probably are not going to find the Nano’s on the used market.
The last one I worked with was very much a pre-production unit and
that was only a few years back.
Indeed if you are simply looking for a lab clock, the miniature Rb’s may
not be the best choice. Their stability is generally
Hi
Why not just grab the “lock” signal and use that to disable your existing
10 MHz output? That sounds like a lot less work.
Bob
> On Sep 18, 2019, at 3:08 AM, David C. Partridge
> wrote:
>
> Having seen the recent discussion of the NB3N502 and other PLLs for
> frequency multiplication.
Hi
An antenna is pretty much an antenna so it will still work on the “new” WWVB
signal. The receiver
portion of the setup will indeed have issues with the new signal. The rest of
the setup would still
work with an alternate approach to the receiver.
Bob
> On Sep 8, 2019, at 10:55 AM, bill
Hi
If that’s the objective then the correct answer is: “none of the above” :)
For a low noise microwave chain, you want to go as high as you can with a
crystal oscillator in the first step. That gets you into the 100 to 200 MHz
range
as the first step up from your low frequency standard.
Hi
The 8405 is a fine device and with working probes can be very useful to have
around. Without the
probes .. not so much. Since they have been around since the 1960’s, the probes
may have seen
quite a bit of wear and tear.
For comparing standards, an RPD-1 and a DVM will kind of / sort of do
Hi
With anything like this a very real question is “what am I trying to do?”.
Generally it involves
getting time from device A to device B. The next layer of the onion is “how
accurate is device
A?” and “how good does device B need to be?”. If the source is only good to 0.1
seconds, there
Hi
Pretty much the same “no” as on the input circuits on the 5335 …. ( best to
avoid +5V on a 5335 input with the attenuator set to 1X ….)
Bob
> On Jul 29, 2019, at 7:42 AM, Jim Palfreyman wrote:
>
> So that's a "no" I'm guessing.
>
> :-(
>
> Jim
>
>
> On Sun, 21 Jul 2019 at 17:38, Jim
Hi
There are a lot of “stock” programs out there that will handle this sort of
“wrap” process. The obvious gotcah is porting them to accept the output
of the device.
Bob
> On Jul 29, 2019, at 5:35 AM, tim...@timeok.it wrote:
>
>
> Hal,
>
> I thank you for the answer, but I'm not a
Hi
Assuming we are still talking about a test instrument that needs to handle a
variety of levels
and a range of frequencies, the 6957 is probably as good as anything.
With a “full up” Collins style circuit, you very much need to optimize for a
specific input.
Change that and you change the
Hi
Keep in mind that all those designs date “way back” in terms of OCXO design.
The whole issue of pressure sensitivity really was not well understood /
accepted
until the mid 1990’s. Up to that point the whole “is it pressure or something
else”
thing was very much a hot topic.
In terms of
Hi
If you look at any sort of “TimeNut” sort of level of detail, every unit
in the batch will be different.
Bob
> On Aug 1, 2019, at 3:05 AM, Clint Jay wrote:
>
> I'd imagine the effort required to characterise a TCXO to that level and
> add the monitoring hardware/software would put the
JF2DKG
>
>
> On Saturday, July 20, 2019, 11:02:19 AM EDT, Bob kb8tq
> wrote:
>
> Hi
>
> If you are buying them on eBay, it is not at all clear which OCXO your A or B
> will show up
> with. The 10811’s get swapped back and forth with earlier units in a lot o
Hi
It’s a pretty good guess that a device from that era ran a “downconverter” head
end.
They had a full RF front end out at the antenna and fed some sort of IF
frequency
back to the unit. Various outfits had approaches to how to do it. The net
result is that
the head end is pretty specific to
Hi
If you are buying them on eBay, it is not at all clear which OCXO your A or B
will show up
with. The 10811’s get swapped back and forth with earlier units in a lot of
used gear. One
might *think* it’s a one way exchange, but I’ve seen it go both ways.
If you lock the counter to an
Hi
There seems to be a firmware update for the F9P. It is a bunch of minor looking
bug fixes. They also changed the ordering code to reflect the new firmware. That
may get Digikey to obsolete the old part and put up a new one.
Various doc’s have also been updated at the same time.
Hi
Having played with both, there are differences in how the P and the T do
things. Both do a better job on
timing than single band modules do. The T has multiple pps outputs and *should*
handle logging (at a
fairly coarse resolution) an input pps on two inputs.
Both will handle external
Hi
Positive aging on a crystal is not at all unusual. If your device dates to the
1970’s,
it’s had a *lot* of time to age. Aging up a couple ppm over 40 years is not at
all
unusual ….
There are a variety of methods out there to double the frequency. The diode
“rectifier”
doublers are
nglish VK1XX
> wrote:
>
> fine business.
>
> thanks for the insight.
>
> The dual band L1, L2 is a certain plus. At a price Hard to ignore the
> benefits certainly for apps that can afford it.
>
> I'll report back...
>
> cheers
>
>
> On 18/07/2019 7
Hi
The simple answer is that your clock is locked directly to a set of time
sources built
into the GPS satellites. Those sources are corrected by ground stations via
comparison
to NRL and NIST (and indirectly other sources as well). The various ground
reference
time systems get measured and
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