Mostly we don't even write the guts of those algorithms. For example,
you'd use a PID library. One line to create a PID controller object
then one line to call the PID for each phase measurement.
This goes double for, say, drawing a graph of the phase over time to
an LCD display, you'd use a gr
Hi
We are not talking about a system (like GPS) that has junk data coming in. In
this case, the phase detector gives you a very good estimate of the delta
between input and output in real time. The error trapping / shifting / multi
this and that simply isn’t needed in this case. The solution is
Bob wrote:
PHK has a roughly 6 line code snippet that does a basic PLL. Add two
more lines to check / clamp the integrator if you wish. That's 8
lines. If you want a D term (to give it an FLL component) add 2 more
lines. We're up to 10 lines.
It's just a control loop, not a full GPSDO. There
ld be a 10-turn trimpot.
From: saidj...@aol.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] LTE-Lite module and the pendulum...
Hi John,
while I can't tell you which vendors are affected and which are not (Its
like asking an angler for his secret angling spot :), I can say that most
Hi
Depending on how much you spend on a mechanical piston trimmer, the innards
will be coaxial to some tolerance. To the extent they rotate or “swing” as one
piece moves in and out of the other, the capacitance will be more linear or
less linear vs rotation of the trimmer.
What you want - a s
made the modifications I described, the DAC sits within about
10 of 27450, and that's where my units are happy. By the way, I've
got two 1.5 KVA UPS's in my shoppe, one for each clock. They'll run
for a long time on those.
Burt
>From: Said Jackson
>
>Subj
1.5 KVA UPS's in my shoppe, one for each clock. They'll run
for a long time on those.
Burt
From: Said Jackson
Subject: Re: [time-nuts] LTE-Lite module and the pendulum...
Burt,
Great insight thanks. You nailed it: out with the old oscillator and
in with one that doesn't ha
Also have this problem with capacitor-adjusted tuning. No matterhow careful
you turn, stiction causes the adjustment to jump in the direction of the turn.
Don
John Miles
>> Great insight thanks. You nailed it: out with the old oscillator and in with
>> one
>> that doesn't have that problem.
>>
>>
Hi John,
while I can't tell you which vendors are affected and which are not (Its
like asking an angler for his secret angling spot :), I can say that most low
cost TCXOs exhibit this behavior, and are thus not really suitable for
GPSDOs.
The ones we used on the LTE-Lite are quite good
> Great insight thanks. You nailed it: out with the old oscillator and in with
> one
> that doesn't have that problem.
>
> Btw the mechanical tuning issue you mentioned is essentially the same exact
> problem: even the slightest turn will make the frequency jump too high or too
> low. It can driv
I have detailed pictures if
> anyone is interested.
>
> I don't know if the above offers any input of value, or even how scientific
> it is according to "deep" Time-Nuts standards, but it's what I did.
>
> Burt, K6OQK
>
>> From: "Poul-Hennin
Hi Hal,
This behavior is called hysteresis and it is related to vendors, and related to
the chips used (or varactor diode) inside the tcxo/ocxo. It is so subtle that
most vendors are not even aware that their oscillator is doing it. Some vendors
have product lines that do it and others that don
ven how
scientific it is according to "deep" Time-Nuts standards, but it's what I did.
Burt, K6OQK
From: "Poul-Henning Kamp"
Subject: Re: [time-nuts] LTE-Lite module
In message <9bc23a13-646f-49c6-9ff9-d42fa5ec8...@aol.com>, Said
Jackson writes:
>
Hi
The proper term for this is a frequency perturbation. It’s a low amplitude
coupled resonance in the crystal. Essentially you are sweeping through another
resonance as you tune the EFC. The result is a “blip” in the tuning curve. No
they aren’t supposed to be there. Yes they do happen.
Bob
In message <9bc23a13-646f-49c6-9ff9-d42fa5ec8...@aol.com>, Said Jackson writes:
>Then at some point the crystal 'snaps' and jumps in frequency, overshooting
>the desired frequency and causing the P term to start pushing in the opposite
>direction repeating the cycle.
If your hardware do
time-nuts@febo.com said:
> The problem is that the ocxo maintains its frequency even though the EFC
> control voltage is changing. Thus phase error is accruing making the efc
> larger and larger due to the P term.
> Then at some point the crystal 'snaps' and jumps in frequency, overshooting
> th
Poul-Henning,
I mentioned yesterday about integrator windup, this problem is similar but
happens even without any I term present:
The problem is that the ocxo maintains its frequency even though the EFC
control voltage is changing. Thus phase error is accruing making the efc larger
and larger
In message <766d6811-f733-4ab2-8574-24e4606e4...@aol.com>, Said Jackson via tim
e-nuts writes:
>Thats exactly right Bob.
>
>By the time your ocxo jumps to catch up to the efc voltage, you
>have oversteered, then the process starts in reverse and the ocxo
>jumps in the opposite direction.
few weeks. I may even make changes that will keep the DAC stable when
> loading new code.
>
> Thanks!
>
> Bob
>
> From: Said Jackson
> To: Bob Stewart ; Discussion of precise time and frequency
> measurement
> Sent: Monday, October 20, 2014 7:21 PM
> Subj
recise time and frequency
measurement
Sent: Monday, October 20, 2014 7:21 PM
Subject: Re: [time-nuts] LTE-Lite module
Bob,
You are on the right track!
Large changes in EFC can cause hysteresis, meaning you go back to an initial
voltage but the crystal does not return to the exact initial fr
__
> From: Tom Van Baak
> To: Discussion of precise time and frequency measurement
> Sent: Monday, October 20, 2014 6:42 PM
> Subject: Re: [time-nuts] LTE-Lite module
>
>
> To add to Bert's note...
>
> Realize that for a GPSDO, (linear fr
_
From: Tom Van Baak
To: Discussion of precise time and frequency measurement
Sent: Monday, October 20, 2014 6:42 PM
Subject: Re: [time-nuts] LTE-Lite module
To add to Bert's note...
Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent,
almost by definiti
: Monday, October 20, 2014 6:42 PM
Subject: Re: [time-nuts] LTE-Lite module
To add to Bert's note...
Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent,
almost by definition. What matters is phase noise and short-term stability,
neither of which you can possibly fix with
here is the ADEV plot from my overnight test with the DOCXO. * * *
This was done without any loop adjustment whatsoever, same board and
software that drives the on-board TCXO. I will let the result speak
for itself,
save to say the loop, the DAC, the DAC reference, and the GPS with a pro
high-stability,
low-noise, low-drift quartz oscillators.
/tvb
- Original Message -
From: "Bert Kehren via time-nuts"
To:
Sent: Monday, October 20, 2014 4:01 PM
Subject: Re: [time-nuts] LTE-Lite module
Allow me to clarify.
I started out with 7 MV 89 one of it a total loss
Hi
Ok, so Bob took a little literary license to make a point :)
_
If you spread out past just MV 89’s you can indeed span a range from about
4x10^-13 out to 2 or 3x10^-11 for various parts you see for sale on the auction
sites. Yes you will buy a *lot* of OCXO’s and sort throug
Thanks much Charles,
just to remind everyone that the main idea of making the boards available
was to get folks a good disciplined TCXO, not to work as a development
platform to discipline external OCXOs.. Also as mentioned in the FAQ, the
typical performance plots I have been sending and a
Allow me to clarify.
I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3
month + burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12.
Only two have been tested for ADEV and are close to 1 E-12, 2X not 10 X.
Bert Kehren
In a message dated 10/20/2014 5:
Hi
The top of my list for “new NTP” would be to bring the 1588 hardware packet
time tagging into the NTP code base. There’s a pretty good base of hardware out
there that tags. It should help things on a loaded system.
Bob
> On Oct 20, 2014, at 3:41 PM, Poul-Henning Kamp wrote:
>
>
>
Hi
The problem is that there are no “magic coefficients”. What you run depends
very much on the exact OCXO you have, the environment you run it in, and the
result you are after.
For instance, Bert is after frequency stability. Tom is after the right time.
Each of them will have very different
Hi
PHK has a roughly 6 line code snippet that does a basic PLL. Add two more lines
to check / clamp the integrator if you wish. That’s 8 lines. If you want a D
term (to give it an FLL component) add 2 more lines. We’re up to 10 lines.
It’s just a control loop, not a full GPSDO. There’s not a l
Hi Brian, Bob, Charles, et. al.
Bob has a great point about the difference between a one-off in a basement
lab, and a commercial product that has to work under any circumstances,
wether flying at 50,000 feet at -56C, or in an urban canyon, or under whatever
other stress could be thrown at i
In message
, Brian Lloyd writes:
>So why not do the GPSD hardware, software, [...]
It would be a really worthwhile project in general, and it could be
made very general with very little trouble.
I would find a cheap ARM board (Olimex ?) that can support ChibiOS:
http://www.chi
In message <60CC0E034928B664249EAC88407F@pc52>, "Tom Van Baak" writes:
>> http://phk.freebsd.dk/time/20141018.html
>
>PHK,
>
>This is the best news I've heard in a long time; an overhaul of NTP!
Indeed :-)
>Instead of tweaking GPSDO algorithms or tuning parameters and
>having to wait
On Mon, Oct 20, 2014 at 6:48 AM, Bob Camp wrote:
> Hi
>
> We tend to focus on this or that enhanced feature in a piece of code. It’s
> fun to talk about. That’s not what keeps most designs from doing what they
> should. By focusing on this rather than the testing required, we set people
> up to f
> http://phk.freebsd.dk/time/20141018.html
PHK,
This is the best news I've heard in a long time; an overhaul of NTP!
One suggestion I'd like to make. You've seen the GPSDO simulator code I started:
http://leapsecond.com/tools/gpsim1.c
And you've seen the growing collection of GPS receiver and OC
Bob wrote:
We tend to focus on this or that enhanced feature in a piece of
code. It's fun to talk about. That's not what keeps most designs
from doing what they should. By focusing on this rather than the
testing required, we set people up to fail. If you start off the
project believing you m
Hi
We tend to focus on this or that enhanced feature in a piece of code. It’s fun
to talk about. That’s not what keeps most designs from doing what they should.
By focusing on this rather than the testing required, we set people up to fail.
If you start off the project believing you mostly need
Poul-Henning wrote:
PLLs are really not that hard [context: we have been discussing
all-digital PLLs ("ADPLLs")]
Yes, I know -- I have designed more than a few. I have also reviewed
more than a dozen hobbyist designs and modeled some of them, and
found that few hobbyists seem to have maste
In message <20141019233526.znmkx...@smtp11.mail.yandex.net>, Charles Steinmetz
writes:
>A proper digital filter that computes a new
>running value at least every second will be more
>complex than that, but you're right, it's not an unfathomable task.
No, it will not, a simple running
Hi
We seem to have swung from “it’s impossible, don’t even try” to “it’s trivial,
you should have it done in a few minutes” :) (Yes I know that’s *not* at all
what was said in either case. We have swung a ways though)
Yes, I can do it for less than $1 in parts. That’s not to say it’s the *rig
We did the same using a 1 KHz out of the $ 14 ubolx M7 and a Morion .
Results better than 1 E-10. Some time nuts are now assembling and testing the
same. Total cost less than $ 10 not counting OCXO or GPS. Most expensive item
is the filter capacitor.
Bert Kehren
In a message dated 10/19/2
At the low end of the spectrum, I tried to make the simplest possible
GPSDO what would still work. Assuming you have a GPS with 1PPS
output, an OCXO and a small DC power supply I was able to get the
entire parts for the controller, board, hookup wire and all for under
$5. I purposely took the lo
Hi
> On Oct 19, 2014, at 5:00 PM, Jim Lux wrote:
>
> On 10/19/14, 1:08 PM, Bob Camp wrote:
>> Hi
>>
>>> On Oct 19, 2014, at 3:35 PM, Charles Steinmetz
>>> wrote:
>>>
>>> Bob wrote (alluding also to something Poul-Henning wrote):
>>>
The phase comparison part of the PLL is pretty straigh
On 10/19/14, 1:08 PM, Bob Camp wrote:
Hi
On Oct 19, 2014, at 3:35 PM, Charles Steinmetz
wrote:
Bob wrote (alluding also to something Poul-Henning wrote):
The phase comparison part of the PLL is pretty straightforward if
you are looking at two RF frequencies. An XOR gate is one
solution, the
Bob wrote (alluding also to something Poul-Henning wrote):
The phase comparison part of the PLL is pretty
straightforward if you are looking at two RF
frequencies. An XOR gate is one solution, there
are many others. Getting something like 100 to
200 ns full scale on the phase comparator makes
With all the work around if you want very good performance use a Shera. We
have super results with a Morion, Shera and ublox M7
Bert Kehren
In a message dated 10/19/2014 4:08:32 P.M. Eastern Daylight Time,
kb...@n1k.org writes:
Hi
> On Oct 19, 2014, at 3:35 PM, Charles Steinmetz
wrote:
Hi
> On Oct 19, 2014, at 3:35 PM, Charles Steinmetz wrote:
>
> Bob wrote (alluding also to something Poul-Henning wrote):
>
>> The phase comparison part of the PLL is pretty straightforward if you are
>> looking at two RF frequencies. An XOR gate is one solution, there are many
>> others. Get
Hi
The phase comparison part of the PLL is pretty straightforward if you are
looking at two RF frequencies. An XOR gate is one solution, there are many
others. Getting something like 100 to 200 ns full scale on the phase comparator
makes the rest of the gizmo much easier. A 12 bit ADC on a MCU
In message <20141019183956.dt4ss...@smtp2o.mail.yandex.net>, Charles Steinmetz
writes:
>>Configure the LTE to emit a suitable frequency relative to the
>>OCXO and use an analog PLL to steer the OCXO's EFC.
>
Then do it digital, it's not like it's rocket science...
Take the analog phase
Poul-Henning wrote:
>zeroes). That would need to be done by changing the PLL parameters
>internal to the LTE-Lite, which are inaccessible. Without such
>reprogramming, the LTE-Light can never get the best out of an OCXO.
It certainly can and it's not even hard:
Configure the LTE to emit a su
In message <20141019155055.osmik...@smtp11.mail.yandex.net>, Charles Steinmetz
writes:
>zeroes). That would need to be done by changing the PLL parameters
>internal to the LTE-Lite, which are inaccessible. Without such
>reprogramming, the LTE-Light can never get the best out of an OC
Bill wrote:
How tough would it be to mate the 10Mhz version up to a really good 10811?
* * * I was thinking of throwing the LTE-Lite and the 10811 in a box.
Unfortunately, to get the best out of the local oscillator, the
control PLL must be carefully adjusted so that the oscillator itse
: Re: [time-nuts] LTE-Lite module
Hi Bill,
I think it makes perfect sense. But I have no idea how the units' loop
stability would be with the 10811. That kind of testing is on the plate.
You would preferably set the OCXO to a nominal tuning voltage of 1.5V using the
mechanical adjustment,
>> m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT#ht_411wt_664
>>
>> 600+ MHz cmos 3.5 volt
>>
>> Tom
>>
>>
>> - Original Message - From: "S. Jackson via time-nuts" <
>> time-nuts@febo.com>
>> To: ;
>> Sent:
gt; Sent: Saturday, October 18, 2014 5:40 PM
> Subject: Re: [time-nuts] LTE-Lite module
>
>
>
> Dave, et.al.,
>>
>> upon popular request I put together a PDF of my email describing how I
>> generated a low-phase-noise 10MHz output from the CMOS 20MHz output of the
>
Thanks for helping out Bob,
sometimes I get ahead of myself.
Dave, you can also trace the wiring on the photo I had sent of the actual
module, its more or less clearly visible under the lupe. Please note that
on that module I mounted the IC upside down, with the pins sticking up, and
bend
ber 18, 2014 5:40 PM
Subject: Re: [time-nuts] LTE-Lite module
Dave, et.al.,
upon popular request I put together a PDF of my email describing how I
generated a low-phase-noise 10MHz output from the CMOS 20MHz output of the
LTE-Lite GPSDO. Here it is.
No guarantees whatsoever guys, and it
Hi
The 20 MHz connects only to pin 3.
+3V connects to pin 4 , but not pins 2 or 3.
Pin 6 hooks only to pin 2 and nothing else.
Bob
> On Oct 18, 2014, at 8:23 PM, Dr. David Kirkby (Kirkby Microwave Ltd)
> wrote:
>
> I am sorry, but I can't follow the circuit diagram. It is not clear to me
I am sorry, but I can't follow the circuit diagram. It is not clear to me
what pins are joined, and what are not. Sometimes you have used a filled
circle to indicate lines are joined, and in another case there's a
semicircle to indicate that they are not. But on some of the others, I
don't know
Said,
How tough would it be to mate the 10Mhz version up to a really good 10811?
I have one that I acquired from Corby some time ago. I was going to spin
my own but I wont realistically get to that with everything else I have
going on. I was thinking of throwing the LTE-Lite and the 10811 in a
Hi Bill,
I think it makes perfect sense. But I have no idea how the units' loop
stability would be with the 10811. That kind of testing is on the plate.
You would preferably set the OCXO to a nominal tuning voltage of 1.5V using the
mechanical adjustment, then let the LTE Lite do the rest.
Ple
Said:
Your email "app note" was VERY clear, thanks.
You also mentioned somewhere that the synthesizer output of 10 MHz is
cleaner than most freq counters, etc., need, so I will probably just use
that for the test equipment. I will use the 20 MHz as reference for
microwave LOs, and will do the
Guys,
one last email. The board will not fit into the Hammond enclosure without
reworking the enclosure or removing the TCXO socket. We initially planned to
ship the board without the socket, now all of them will have it. The
board was designed to be used without the TCXO/Socket to fit into
Hal,
attached is the superimposed plot of the standard 20MHz TCXO Phase Noise
and the 10MHz output of my bare-bones divide by 2 flip-flop. The green trace
is the new 20MHz plot, the blue the one I had sent out yesterday at 10MHz,
both sourced from the same TCXO.
You can nicely see that
Guys,
we have been getting a good number of emails with questions that have
already been addressed in the user manual or the FAQ, see the below link. We
spent a lot of time putting the collateral together, may I please ask that
you first look into these two documents to see if your questio
Hi guys,
lots of questions, let me try to answer some of these. Bob, David, et. al,
thanks for answering some of these already!
Dave, as Bob said "it depends on your application" -- and your time frame.
Also, please check the FAQ for an answer on the external TCXO requirement,
specificall
Hi
For a lab reference, “clean” is a relative term. Most (as in every one I’ve
ever seen) instruments expect a dirty signal on the reference input. They phase
lock an internal oscillator to clean it up. Past some (unfortunately variable)
offset, the reference signal has no impact on the instrum
On 17 Oct 2014 19:33, "S. Jackson via time-nuts" wrote:
>
>
> Hello Jim,
> let me answer through Time Nuts as this may interest other parties as
> well.
> Yes, using a fast flip flop to generate 10MHz out of the 20MHz TCXO 3.0V
> CMOS output from the LTE-Lite module will preserve the phase nois
I look forward to the app note. Might be the incentive to get me to
actually USE the Express PCB software I have.
Jim
On 10/17/2014 4:40 PM, S. Jackson via time-nuts wrote:
Hi there,
I don't know how much the Wenzel units are, but if someone is not able to,
or willing to build one on
John,
I used John Miles Timepod and associated application software, now
available from Microsemi, and highly recommended. I fed the output of the DFF
directly into the timepod (via a DC-block and 33 Ohms series resistor).
The reference was an HP 58503A GPSDO which limits the noise floor of
Said,
What tool(s) did you use to generate that data and output the graph?
Thanks,
John
On Fri, Oct 17, 2014 at 6:10 PM, S. Jackson via time-nuts <
time-nuts@febo.com> wrote:
> Jim,
>
> Here is the resulting 10MHz phase noise plot from the 20MHz TCXO output:
>
>
> In a message dated 10/17/201
Some photos of the divider module I built:
In a message dated 10/17/2014 11:32:49 Pacific Daylight Time,
saidj...@aol.com writes:
Hello Jim,
let me answer through Time Nuts as this may interest other parties as
well.
Yes, using a fast flip flop to generate 10MHz out of the 20MHz TCXO
Jim,
Here is the resulting 10MHz phase noise plot from the 20MHz TCXO output:
In a message dated 10/17/2014 11:32:49 Pacific Daylight Time,
saidj...@aol.com writes:
Hello Jim,
let me answer through Time Nuts as this may interest other parties as
well.
Yes, using a fast flip flop to
Jim, et. al.,
I spent some time today and put together a Divide-by-2 circuit. Attached
are the schematics, I will send some photos in additional mails so we don't
overload the mail system.
Some comments:
* I grab the 3.0V from capacitor C6 on the eval board. That is the
low-noise filter
And lastly the entire setup as tested:
In a message dated 10/17/2014 11:32:49 Pacific Daylight Time,
saidj...@aol.com writes:
Hello Jim,
let me answer through Time Nuts as this may interest other parties as
well.
Yes, using a fast flip flop to generate 10MHz out of the 20MHz TCXO 3.0V
How much would we guess that Wenzel blue-top would run you?
Relative to the low cost GPSDO, my understanding is the Wenzel parts are
priced appropriately to their quality.
On Fri, Oct 17, 2014 at 11:32 AM, S. Jackson via time-nuts <
time-nuts@febo.com> wrote:
>
> Hello Jim,
> let me answer th
Hi there,
I don't know how much the Wenzel units are, but if someone is not able to,
or willing to build one on their own then this could be a viable
alternative.
I will look into writing a short appnote describing how a low-noise
div-by-2 can be built at home with minimal components usin
I have emailed Wenzel about pricing and whether or not they will sell
small quantities. Will advise.
Jim
wb4...@amsat.org
On 10/17/2014 2:32 PM, S. Jackson via time-nuts wrote:
Hello Jim,
let me answer through Time Nuts as this may interest other parties as
well.
Yes, using a fast flip fl
Hello Jim,
let me answer through Time Nuts as this may interest other parties as
well.
Yes, using a fast flip flop to generate 10MHz out of the 20MHz TCXO 3.0V
CMOS output from the LTE-Lite module will preserve the phase noise (actually
improve it by up to 6dB due to the 20log(n/m) noise
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