[time-nuts] FA2 counter

[Mark Sims]

Miy FA2 came in today.   A very quick test shows that it works.  It does not 
appear to have the -0.0002 Hz freq measurement bias that the FA1 has.

The 0.1 second gate time mode is pretty useless... there appears to be  a 300 
msec dead time between measurements in 0.1 (and 10 sec) gate time modes so you 
only get a new reading every 400 msecs.  10 second gate time produces a reading 
every 10300 msecs.  1 sec gate time outputs readings every 1100 msecs (like the 
FA1).

It auto-detects the presence of an external reference... no way to manually 
switch between internal and exterrnal references.  I have not done any testing 
on the internal ref or the high freq channel.

The screen shows a LPF setting and a 50 ohm setting... no idea if these are 
switchable there is no documentation.  

The screen shows the input signal level.
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Re: [time-nuts] Two types of GPDSO / Rubidium

[Bob kb8tq]

Hi

The gotcha is that (unless you have something very exotic) there *is* no one 
standard
for the lab. You may have a device that is quite good on phase noise at some 
offsets and
horrible for long term. You might have another device that is good medium term 
and also
pretty good for close in phase noise. Since a Cs is a primary standard, it will 
always win in
the “long term / free running” category. In the disciplined category a GPSDO 
will always 
come out the winner, if you wait long enough.

So if this is headed off in many directions, first step would be to set up a 
phase noise measurement 
system. Start comparing standards. Best to start with things you have more than 
one of. First 
approximation is that they each are just a bit better than the comparison of 
the two would indicate. 
Then start cross comparing devices. Eventually you will come up with “this one 
is best at these
offsets” sort of decision. Just how good it is …. time to buy another :). Why 
start with phase noise?
it is the quickest of the measurements to do. Start with gear that will handle 
the 10 MHz sort of 
frequency you now are dealing with. Expand the range as needed. Also be sure to 
watch the 
floor of your gear vs the measurement. You might need better gear :)

Next step would be to start looking at long term drift. That might start at 1 
second or it might start
a bit longer. Again it’s a compare similar to similar at first sort of thing. 
Then start doing cross comparisons. 
If you stick with ADEV measurements, you can more easily compare to published 
data. There also is
a body of ADEV data in various posts to Time Nuts and on web sites run by Time 
Nuts. ( The same is
true of phase noise).

Test gear wise, something like the TimePod or the new “Son of TimePod” would be 
a fun device to
play with. Neither one is in the “dirt cheap” category. They don’t seem to show 
up on eBay for < $200….
That’s not in any way a knock on the retail price of either device. There are 
other pieces of gear out there
that do way less and cost way more. 

Bob

> On Sep 26, 2019, at 11:46 AM, Taka Kamiya via time-nuts 
>  wrote:
> 
> Bob, et al.
> First, current line up of timing source:OCXODOCXOEfratom Rb of various 
> kindPRS-10GPSDO of various kindDatum FTS4040/AHP5071A high-performance (DEAD 
> tube)
> Time measurement gear:HP85132AHP5335AHP5370ATIC
> 
> My first and at most problem is, I don't know which one to trust and in what 
> circumstances.  They all settle around 10E-10 to 10E-12 but since nothing 
> stands out, (like Hydrogen Maser) I have no ways of knowing if the 
> drift/error/noise I see is coming from DUT or the clock source.  I need to 
> establish "the" lab standard which everything can be compared against.
> So what's my ultimate goal?  Just that.  There is no way for me to tell if I 
> will get into microwave or something else.  Either way, having one reliable 
> standard is a must.  I am aware, there is no such thing as "the" standard.  
> Various DUT and purpose calls for different standard.  It could be OCXO or 
> Maser.  But still, I need to characterize them to know how bad/good DUT is.
> NUT case is already taken care of.  I'm a certified NUT.
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> 
> 
>On Thursday, September 26, 2019, 11:56:56 AM EDT, Bob kb8tq 
>  wrote:  
> 
> Hi
> 
> There are some “simple” answers to this:
> 
> 1) You can (and many of us do) set up to measure things yourself. For most 
> setups this means
> comparing devices, but indeed Time Nuts seem to have piles and piles of 
> devices. You can do this
> with shiny new gear (possibly for a lot of money), eBay versions of the same 
> stuff (hopefully for 
> less money) or with home brew / DIY gear. Phase noise and the various xDEV’s 
> (like ADEV) can 
> be measured this way. 
> 
> 2) You *do* need to figure out what the objective is. If it’s microwaves then 
> the test gear needs to 
> run to those frequencies. If it’s just 10 MHz then not so much. If you do 
> indeed anticipate having
> gear at the 1x10^-15 @1 sec level then your setup needs to be a bit fancier 
> than if “only” 1x10^-11 
> is what you are after. 
> 
> 3) If this is cost constrained, be realistic about the costs. It is *very* 
> easy to say “max $100” and then
> start talking about many thousands of dollars of gear. It is also easy to 
> start with a budget and have it 
> creep on and on and on. Even projects funded by national governments (with 
> far larger charge cards 
> than any of us have) hit limits in terms of costs. It is part of this at any 
> level. 
> 
> It’s easy to say that you are setting up a full lab. If so, a hydrogen maser 
> (possibly two or three of them)
> *could* be part of the mix. There *are* Time Nuts who have set up that way, 
> but very few of them. Short
> of setting up that way, you will be in a compromise situation. (Indeed even a 
> maser is a bit of a compromise
> compared to other more exotic gear). 

Re: [time-nuts] chrony vs other NTP

[Luiz Paulo Damaceno]

I think chrony is better suitable to who wants more customization options,
such as faster pooling times, better delay calibrations and advanced
filtering settings (i dont know all on Openntpd nor chrony) but with my
experience with chrony i can say that chrony is good for my usages.

Em qui, 26 de set de 2019 às 20:08, djl  escreveu:

>
> Any quick opinions re use of chrony vs other NTP implementations?
> THANKS
> Don
> --
> Dr. Don Latham  AJ7LL
> PO Box 404, Frenchtown, MT, 59834
> VOX: 406-626-4304
>
>
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Re: [time-nuts] Am I doing something wrong?

[Bob kb8tq]

Hi

If the OCXO only makes it 6x10^-10 past 10 MHz, that’s not enough for the unit
to lock properly. 40 Hz tune range looks fine so not a shorted tune line. New 
best 
guess would still be an OCXO problem. Swap it out and see what happens. The 
OCXO’s show up on eBay all the time. Who knows what shape they are in. You might
go thorugh several to get one that works right …. they are cheap ….

Bob

> On Sep 26, 2019, at 11:21 AM, Roger Rehr W3SZ  wrote:
> 
> Hi All,
> 
> Sorry I forgot to attach the freq vs DAC voltage table to the email that I 
> just sent:
> DAC V  Freq
> +5.0 9.999.961
> +0.0 9.999.985
> -3.0 9.999.998
> -3.5 10.000.000
> -3.8 10.000.001
> -4.0 10.000.002
> -4.5 10.000.004
> -5.0 10.000.006
> 
> So the oscillator is not "centered" on 10.000.000 anymore.
> 
> 73,
> Roger
> W3SZ
> 
> On 9/26/2019 1:06 PM, Roger Rehr W3SZ wrote:
>> Hi Nigel, and Bob, and Bill!
>> 
>> Thanks for the notes!  I very much appreciate your helpful comments.  I will 
>> give my responses to all of your helpful posts here.  Sorry for the delay in 
>> responses.  The reason for the delay is that my Thunderbolt is at a remote 
>> site and I can communicate with it via Lady Heather remotely, but I had to 
>> drive out to the site to do the tests with an HP 5342A frequency counter and 
>> pulse analysis of the pps port.  I drove out to the site today.
>> 
>> First, Bob and Bill,
>> 
>> 1.
>> DAC set to +0.5 V gives significant frequency errors:  HP counter reads 
>> 9.999.984 MHz and osc error as reported by LH is 1,68x,xxx.xx ppt.  
>> Interestingly, at this voltage pps error is flipping between +50 and -50.
>> 
>> The DAC voltage that minimizes both counter error and pps/osc error as 
>> reported by LH is around -3.553 V.  This is dramatically different than the 
>> setting last October when all was working well, as you know.
>> 
>> With DAC voltage -3.553 V the osc error and pps error are reduced, but they 
>> jump around quite a bit:
>> pps short-term variation is for example between about +50 and -50 and osc 
>> short term variation is between about +5000 and -5000.  HP counter reads 
>> 10.000.000 MHz.
>> 
>> Even when I have the DAC close enough to optimum that my counter reads 
>> 10.000.000 MHz and the osc error is flipping around both sides of zero, the 
>> unit stays in "Power-up" mode and the DAC voltage stays at wherever I set it 
>> (either using d>>s or &>>i and then power cycle) and does not vary.
>> 
>> 
>> 2.
>> I get a 10 usec duration +5V pulse every 1.00 seconds from the PPS port, as 
>> per specifications.  I cannot give you greater precision than that on the 
>> pulse interval.
>> 
>> 
>> Nigel,
>> 
>> I agree that something appears odd with this unit that had been running with 
>> no problems for at least a year at my location.  There have been no known 
>> system / config changes by me, although there is always the chance that I 
>> fat-fingered something when playing with the Lady Heather display at some 
>> point.
>> 
>> The receiver self identifies as a TSIP (Trimble TSIP Binary) receiver when 
>> Lady Heather starts up.  The receiver type is not specified in my cfg file, 
>> which instead has the default line /rx which as you know means auto-detect 
>> receiver type.
>> 
>> I had assumed that the "Nortel NTGS/NTBW" designation that you mention and 
>> that appears on the Lady Heather parameter display had something to do with 
>> Trimble having supplied the unit I now have to Nortel and this "Nortel 
>> NTGS/NTBW" designation being a custom ID placed in the firmware so that the 
>> unit would be "branded" as Nortel.  This supposition is consistent with line 
>> 2170 of the heather.txt file which says "Trimble telecom GPSDOs 
>> (NTBW,NTPX,NTGS,etc)".  There is also a line in the heather.pdf file that 
>> says, "Note that non-Thunderbolt GPSDOs (such as the NTBW and NTPx telecom 
>> devices) do not all support saving disciplining parameters to EEPROM and 
>> some do not allow users to change the disciplining parameters. You can use 
>> "/d" command line options for setting the PLL parameters from the command 
>> line. If you run the auto-tune command on non-Thunderbolt devices then only 
>> the satellite elevation mask (and perhaps the signal level mask) values will 
>> be set".
>> 
>> The physical unit is labeled "Trimble THUNDERBOLT", so I guess, looking at 
>> all of the data, that I have a Trimble / Nortel device.
>> 
>> But the issue of whether it is a Nortel/Trimble Thunderbolt or just a 
>> Thunderbolt wouldn't cause the current problem that I am having now in a 
>> unit that previously worked perfectly for me.
>> 
>> Just so you know that my heather.cfg file is "OK" and not responsible for 
>> any problems, here it is:
>> 
>> /9
>> /rx
>> /br=9600:8:n:1
>> /ro=1*
>> /tz=-5EST/EDT
>> /b=1
>> /tb=W3SZ
>> /gm
>> /gw=0
>> /gqw
>> /gcs-
>> /gcg
>> 
>> To further document that this issue is not a "setup" problem, I did another 
>> factory reset of the unit 

Re: [time-nuts] Am I doing something wrong?

[Bob kb8tq]

Hi

If your OCXO tunes to 10 MHz at -3.5V and it used to tune at +0.5V, it sounds 
like the tune line is shorted somewhere. 
That could be inside the OCXO or outside. If the short is “noisy”  (and that is 
not unusual) you aren’t going to get it to lock.
You need to figure out where the short is. Best guess would be inside the OCXO.

Bob

> On Sep 26, 2019, at 11:06 AM, Roger Rehr W3SZ  wrote:
> 
> Hi Nigel, and Bob, and Bill!
> 
> Thanks for the notes!  I very much appreciate your helpful comments.  I will 
> give my responses to all of your helpful posts here.  Sorry for the delay in 
> responses.  The reason for the delay is that my Thunderbolt is at a remote 
> site and I can communicate with it via Lady Heather remotely, but I had to 
> drive out to the site to do the tests with an HP 5342A frequency counter and 
> pulse analysis of the pps port.  I drove out to the site today.
> 
> First, Bob and Bill,
> 
> 1.
> DAC set to +0.5 V gives significant frequency errors:  HP counter reads 
> 9.999.984 MHz and osc error as reported by LH is 1,68x,xxx.xx ppt.  
> Interestingly, at this voltage pps error is flipping between +50 and -50.
> 
> The DAC voltage that minimizes both counter error and pps/osc error as 
> reported by LH is around -3.553 V.  This is dramatically different than the 
> setting last October when all was working well, as you know.
> 
> With DAC voltage -3.553 V the osc error and pps error are reduced, but they 
> jump around quite a bit:
> pps short-term variation is for example between about +50 and -50 and osc 
> short term variation is between about +5000 and -5000.  HP counter reads 
> 10.000.000 MHz.
> 
> Even when I have the DAC close enough to optimum that my counter reads 
> 10.000.000 MHz and the osc error is flipping around both sides of zero, the 
> unit stays in "Power-up" mode and the DAC voltage stays at wherever I set it 
> (either using d>>s or &>>i and then power cycle) and does not vary.
> 
> 
> 2.
> I get a 10 usec duration +5V pulse every 1.00 seconds from the PPS port, as 
> per specifications.  I cannot give you greater precision than that on the 
> pulse interval.
> 
> 
> Nigel,
> 
> I agree that something appears odd with this unit that had been running with 
> no problems for at least a year at my location.  There have been no known 
> system / config changes by me, although there is always the chance that I 
> fat-fingered something when playing with the Lady Heather display at some 
> point.
> 
> The receiver self identifies as a TSIP (Trimble TSIP Binary) receiver when 
> Lady Heather starts up.  The receiver type is not specified in my cfg file, 
> which instead has the default line /rx which as you know means auto-detect 
> receiver type.
> 
> I had assumed that the "Nortel NTGS/NTBW" designation that you mention and 
> that appears on the Lady Heather parameter display had something to do with 
> Trimble having supplied the unit I now have to Nortel and this "Nortel 
> NTGS/NTBW" designation being a custom ID placed in the firmware so that the 
> unit would be "branded" as Nortel.  This supposition is consistent with line 
> 2170 of the heather.txt file which says "Trimble telecom GPSDOs 
> (NTBW,NTPX,NTGS,etc)".  There is also a line in the heather.pdf file that 
> says, "Note that non-Thunderbolt GPSDOs (such as the NTBW and NTPx telecom 
> devices) do not all support saving disciplining parameters to EEPROM and some 
> do not allow users to change the disciplining parameters. You can use "/d" 
> command line options for setting the PLL parameters from the command line. If 
> you run the auto-tune command on non-Thunderbolt devices then only the 
> satellite elevation mask (and perhaps the signal level mask) values will be 
> set".
> 
> The physical unit is labeled "Trimble THUNDERBOLT", so I guess, looking at 
> all of the data, that I have a Trimble / Nortel device.
> 
> But the issue of whether it is a Nortel/Trimble Thunderbolt or just a 
> Thunderbolt wouldn't cause the current problem that I am having now in a unit 
> that previously worked perfectly for me.
> 
> Just so you know that my heather.cfg file is "OK" and not responsible for any 
> problems, here it is:
> 
> /9
> /rx
> /br=9600:8:n:1
> /ro=1*
> /tz=-5EST/EDT
> /b=1
> /tb=W3SZ
> /gm
> /gw=0
> /gqw
> /gcs-
> /gcg
> 
> To further document that this issue is not a "setup" problem, I did another 
> factory reset of the unit and then did not use Lady Heather but only 
> monitored function with TBoltMon.exe and I did not do any setup with that 
> utility until the self survey was done and more than two hours had passed, 
> and then I only set and saved the position. Function and  results were 
> unchanged, and the unit was still stuck in Power-Up mode and DAC voltage was 
> still stuck at zero, but everything else was normal according to the TBoltMon 
> readouts.
> 
> Thanks again and 73,
> 
> Roger
> W3SZ
> 
> 
> ___
> time-nuts mailing list -- 

Re: [time-nuts] chrony vs other NTP

[Dustin Marquess]

On Thu, Sep 26, 2019 at 6:08 PM djl  wrote:
>
>
> Any quick opinions re use of chrony vs other NTP implementations?
> THANKS
> Don

It really depends on the use case.  chrony seems to pick a "best"
source and try really really hard to track that one true source.  ntpd
tries to intelligently track multiple sources at a time.

For a stratum 2/3 box that just tracks internet sources only, I've had
pretty good luck using chrony instead of ntpd.  For a stratum 1 box
that tracks a single GPS/PPS source, it probably would work great for
that too.  For a local stratum 2 that tracks just local stratum 1s,
that would probably be an excellent use case for ntpd.  For a local
stratum 3 that just tracks multiple local stratum 2s?  That would
probably be a good chrony use, as has temperature compensation.

It's hard to really be generic, this is one of those cases where
"test!" kind of applies.

-Dustin

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Re: [time-nuts] Am I doing something wrong?

[Bill Beam]

It looks like since last Oct the osc jumped frequency and has become less 
stable.
This is not unheard of for an ocxo.  It may be time to replace with a true
Trimble Thunderbolt.  A couple are now on ebay for 2-300$.  It is possible to
replace the ocxo, assuming nothing else is wrong with the circuit.

On Thu, 26 Sep 2019 13:21:25 -0400, Roger Rehr W3SZ wrote:

>Hi All,

>Sorry I forgot to attach the freq vs DAC voltage table to the email that 
>I just sent:
>DAC V-  Freq
>+5.0- - - -  9.999.961
>+0.0- - - -  9.999.985
>-3.0- - - -  9.999.998
>-3.5- - - -  10.000.000
>-3.8- - - -  10.000.001
>-4.0- - - -  10.000.002
>-4.5- - - -  10.000.004
>-5.0- - - -  10.000.006

>So the oscillator is not "centered" on 10.000.000 anymore.

>73,
>Roger
>W3SZ

>On 9/26/2019 1:06 PM, Roger Rehr W3SZ wrote:
>> Hi Nigel, and Bob, and Bill!
>>
>> Thanks for the notes!-  I very much appreciate your helpful comments.-  
>> I will give my responses to all of your helpful posts here.-  Sorry for 
>> the delay in responses.-  The reason for the delay is that my 
>> Thunderbolt is at a remote site and I can communicate with it via Lady 
>> Heather remotely, but I had to drive out to the site to do the tests 
>> with an HP 5342A frequency counter and pulse analysis of the pps 
>> port.-  I drove out to the site today.
>>
>> First, Bob and Bill,
>>
>> 1.
>> DAC set to +0.5 V gives significant frequency errors:-  HP counter 
>> reads 9.999.984 MHz and osc error as reported by LH is 1,68x,xxx.xx 
>> ppt.-  Interestingly, at this voltage pps error is flipping between +50 
>> and -50.
>>
>> The DAC voltage that minimizes both counter error and pps/osc error as 
>> reported by LH is around -3.553 V.-  This is dramatically different 
>> than the setting last October when all was working well, as you know.
>>
>> With DAC voltage -3.553 V the osc error and pps error are reduced, but 
>> they jump around quite a bit:
>> pps short-term variation is for example between about +50 and -50 and 
>> osc short term variation is between about +5000 and -5000.-  HP counter 
>> reads 10.000.000 MHz.
>>
>> Even when I have the DAC close enough to optimum that my counter reads 
>> 10.000.000 MHz and the osc error is flipping around both sides of 
>> zero, the unit stays in "Power-up" mode and the DAC voltage stays at 
>> wherever I set it (either using d>>s or &>>i and then power cycle) and 
>> does not vary.
>>
>>
>> 2.
>> I get a 10 usec duration +5V pulse every 1.00 seconds from the PPS 
>> port, as per specifications.-  I cannot give you greater precision than 
>> that on the pulse interval.
>>
>>
>> Nigel,
>>
>> I agree that something appears odd with this unit that had been 
>> running with no problems for at least a year at my location.-  There 
>> have been no known system / config changes by me, although there is 
>> always the chance that I fat-fingered something when playing with the 
>> Lady Heather display at some point.
>>
>> The receiver self identifies as a TSIP (Trimble TSIP Binary) receiver 
>> when Lady Heather starts up.-  The receiver type is not specified in my 
>> cfg file, which instead has the default line /rx which as you know 
>> means auto-detect receiver type.
>>
>> I had assumed that the "Nortel NTGS/NTBW" designation that you mention 
>> and that appears on the Lady Heather parameter display had something 
>> to do with Trimble having supplied the unit I now have to Nortel and 
>> this "Nortel NTGS/NTBW" designation being a custom ID placed in the 
>> firmware so that the unit would be "branded" as Nortel.-  This 
>> supposition is consistent with line 2170 of the heather.txt file which 
>> says "Trimble telecom GPSDOs (NTBW,NTPX,NTGS,etc)".-  There is also a 
>> line in the heather.pdf file that says, "Note that non-Thunderbolt 
>> GPSDOs (such as the NTBW and NTPx telecom devices) do not all support 
>> saving disciplining parameters to EEPROM and some do not allow users 
>> to change the disciplining parameters. You can use "/d" command line 
>> options for setting the PLL parameters from the command line. If you 
>> run the auto-tune command on non-Thunderbolt devices then only the 
>> satellite elevation mask (and perhaps the signal level mask) values 
>> will be set".
>>
>> The physical unit is labeled "Trimble THUNDERBOLT", so I guess, 
>> looking at all of the data, that I have a Trimble / Nortel device.
>>
>> But the issue of whether it is a Nortel/Trimble Thunderbolt or just a 
>> Thunderbolt wouldn't cause the current problem that I am having now in 
>> a unit that previously worked perfectly for me.
>>
>> Just so you know that my heather.cfg file is "OK" and not responsible 
>> for any problems, here it is:
>>
>> /9
>> /rx
>> /br=9600:8:n:1
>> /ro=1*
>> /tz=-5EST/EDT
>> /b=1
>> /tb=W3SZ
>> /gm
>> /gw=0
>> /gqw
>> /gcs-
>> /gcg
>>
>> To further document that this issue is not a "setup" problem, I did 
>> another factory reset of the unit and then did not use Lady Heather 
>> but only monitored function with 

[time-nuts] chrony vs other NTP

[djl]

Any quick opinions re use of chrony vs other NTP implementations?
THANKS
Don
--
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304


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Re: [time-nuts] FA2 counter

[djl]

Got mine today as well, Bert. Haven't gotten a chance to use it yet, 
good to know you had positive results.


Don

On 2019-09-26 11:05, ew via time-nuts wrote:

Did receive FA2 counter today. Everything as promised, like the 10
second mode best.Use a Datum 2000 as source 10 MHz in the back 5 MHz
in the front reliable +- 1 on the last 12th digit.


Bert Kehren
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--
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304


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Re: [time-nuts] Two types of GPDSO / Rubidium

[Taka Kamiya via time-nuts]

Bob, et al.
First, current line up of timing source:OCXODOCXOEfratom Rb of various 
kindPRS-10GPSDO of various kindDatum FTS4040/AHP5071A high-performance (DEAD 
tube)
Time measurement gear:HP85132AHP5335AHP5370ATIC

My first and at most problem is, I don't know which one to trust and in what 
circumstances.  They all settle around 10E-10 to 10E-12 but since nothing 
stands out, (like Hydrogen Maser) I have no ways of knowing if the 
drift/error/noise I see is coming from DUT or the clock source.  I need to 
establish "the" lab standard which everything can be compared against.
So what's my ultimate goal?  Just that.  There is no way for me to tell if I 
will get into microwave or something else.  Either way, having one reliable 
standard is a must.  I am aware, there is no such thing as "the" standard.  
Various DUT and purpose calls for different standard.  It could be OCXO or 
Maser.  But still, I need to characterize them to know how bad/good DUT is.
NUT case is already taken care of.  I'm a certified NUT.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, September 26, 2019, 11:56:56 AM EDT, Bob kb8tq  
wrote:  
 
 Hi

There are some “simple” answers to this:

1) You can (and many of us do) set up to measure things yourself. For most 
setups this means
comparing devices, but indeed Time Nuts seem to have piles and piles of 
devices. You can do this
with shiny new gear (possibly for a lot of money), eBay versions of the same 
stuff (hopefully for 
less money) or with home brew / DIY gear. Phase noise and the various xDEV’s 
(like ADEV) can 
be measured this way. 

2) You *do* need to figure out what the objective is. If it’s microwaves then 
the test gear needs to 
run to those frequencies. If it’s just 10 MHz then not so much. If you do 
indeed anticipate having
gear at the 1x10^-15 @1 sec level then your setup needs to be a bit fancier 
than if “only” 1x10^-11 
is what you are after. 

3) If this is cost constrained, be realistic about the costs. It is *very* easy 
to say “max $100” and then
start talking about many thousands of dollars of gear. It is also easy to start 
with a budget and have it 
creep on and on and on. Even projects funded by national governments (with far 
larger charge cards 
than any of us have) hit limits in terms of costs. It is part of this at any 
level. 

It’s easy to say that you are setting up a full lab. If so, a hydrogen maser 
(possibly two or three of them)
*could* be part of the mix. There *are* Time Nuts who have set up that way, but 
very few of them. Short
of setting up that way, you will be in a compromise situation. (Indeed even a 
maser is a bit of a compromise
compared to other more exotic gear). Some degree of focus will be needed. Few 
of us have a really good
handle on that “focus” thing …..:)

Another wrinkle to this is that there are indeed measurements and terminology 
that are a bit unique to
the field. Indeed the measurements and gear that were common in the 1950’s have 
evolved into something
a bit different today. The same is true if you go back into the 1930’s. 
Different disciplines focus on different 
measures, even today. Tying papers, spec sheets, or measurements from one era 
or discipline to another 
can be challenging. There is no one universal single number that measures 
“best”. 

So yes, it’s complicated and it *can* be confusing. Welcome to why it’s called 
Time Nuts :)

Bob

> On Sep 26, 2019, at 1:29 AM, Taka Kamiya via time-nuts 
>  wrote:
> 
> Tom,
> I know you are absolutely right.  When I buy from eBay, I have no idea where 
> they came from.  Reject pile, junk yard, or pristine clean room.  
> Unfortunately, I can afford up to certain amount.  I have lots of PRS10 but 
> their origin is unknown.  Even if I buy 5065A, origin will be unknown and so 
> as condition.  Recently, I called around local cal-lab to see who can help me 
> validate these devices.  No one could.  I'm very tempted to buy T-bolt or 
> PRS10 new but at $1500, it's quite hefty.  I may just have to.
> I'm at learn as much as I can stage.  I have a Cesium but it's old.  4040/A  
> I have no idea how it was used or stored.  It would be nice to have one known 
> good standard.  The best I can do for now is my array of GPSDOs.  (from 
> unknown sources)
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> 
> 
>    On Thursday, September 26, 2019, 3:05:19 AM EDT, Tom Van Baak 
> wrote:  
> 
> It might be a bit of an over-simplification to split oscillators in 
> those two camps, "fixed" and "agile". There are often many trade-offs in 
> performance that you have to deal with. Moreover if you are getting your 
> oscillators from eBay, or especially parts from China, you may also have 
> to assume that original factory specs are no longer valid.
> 
> This is one reason why the time nuts list is so preoccupied with making 
> accurate measurements of frequency standards. You only know what 

Re: [time-nuts] NTP apps on Windows question

[Paul Theodoropoulos via time-nuts]

On 9/25/19 01:19, Martin Burnicki wrote:

Paul Theodoropoulos via time-nuts wrote:

Only tangentially related, but for keeping a Windows PC synced, I'm
rather partial to NetTime. It's a tiny tray app, quite flexible, and
otherwise unobtrusive.  It's a freeware app, though donations are
accepted

http://www.timesynctool.com/

It would be interesting to know how this tools works. Over the years
there have been quite a number of tools that just *set* or quickly
adjust the system time in periodic intervals.

ntpd compares the system time to its configured reference time source(s)
periodically, adjusts the system time smoothly so that the time offset
becomes as small as possible, and even tries to determine and compensate
the system time drift, so that the time offset *stays* small over time.

Martin
Further down the page on that site, the author describes the 
functionality - it's a typical SNTP client, only syncing periodically, 
rather than  disciplining the clock, and rightly discourages setting the 
interval too small if you're using public NTP servers. But with a local 
NTP server, that should be immaterial.


I use it not because I require super-accurate time on my PC, but because 
it offers a lot more options than Window's built-in and dumbed-down SNTP 
client.


--
Paul Theodoropoulos
www.anastrophe.com

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Re: [time-nuts] Am I doing something wrong?

[Roger Rehr W3SZ]

Hi All,

Sorry I forgot to attach the freq vs DAC voltage table to the email that 
I just sent:

DAC V  Freq
+5.0 9.999.961
+0.0 9.999.985
-3.0 9.999.998
-3.5 10.000.000
-3.8 10.000.001
-4.0 10.000.002
-4.5 10.000.004
-5.0 10.000.006

So the oscillator is not "centered" on 10.000.000 anymore.

73,
Roger
W3SZ

On 9/26/2019 1:06 PM, Roger Rehr W3SZ wrote:

Hi Nigel, and Bob, and Bill!

Thanks for the notes!  I very much appreciate your helpful comments.  
I will give my responses to all of your helpful posts here.  Sorry for 
the delay in responses.  The reason for the delay is that my 
Thunderbolt is at a remote site and I can communicate with it via Lady 
Heather remotely, but I had to drive out to the site to do the tests 
with an HP 5342A frequency counter and pulse analysis of the pps 
port.  I drove out to the site today.


First, Bob and Bill,

1.
DAC set to +0.5 V gives significant frequency errors:  HP counter 
reads 9.999.984 MHz and osc error as reported by LH is 1,68x,xxx.xx 
ppt.  Interestingly, at this voltage pps error is flipping between +50 
and -50.


The DAC voltage that minimizes both counter error and pps/osc error as 
reported by LH is around -3.553 V.  This is dramatically different 
than the setting last October when all was working well, as you know.


With DAC voltage -3.553 V the osc error and pps error are reduced, but 
they jump around quite a bit:
pps short-term variation is for example between about +50 and -50 and 
osc short term variation is between about +5000 and -5000.  HP counter 
reads 10.000.000 MHz.


Even when I have the DAC close enough to optimum that my counter reads 
10.000.000 MHz and the osc error is flipping around both sides of 
zero, the unit stays in "Power-up" mode and the DAC voltage stays at 
wherever I set it (either using d>>s or &>>i and then power cycle) and 
does not vary.



2.
I get a 10 usec duration +5V pulse every 1.00 seconds from the PPS 
port, as per specifications.  I cannot give you greater precision than 
that on the pulse interval.



Nigel,

I agree that something appears odd with this unit that had been 
running with no problems for at least a year at my location.  There 
have been no known system / config changes by me, although there is 
always the chance that I fat-fingered something when playing with the 
Lady Heather display at some point.


The receiver self identifies as a TSIP (Trimble TSIP Binary) receiver 
when Lady Heather starts up.  The receiver type is not specified in my 
cfg file, which instead has the default line /rx which as you know 
means auto-detect receiver type.


I had assumed that the "Nortel NTGS/NTBW" designation that you mention 
and that appears on the Lady Heather parameter display had something 
to do with Trimble having supplied the unit I now have to Nortel and 
this "Nortel NTGS/NTBW" designation being a custom ID placed in the 
firmware so that the unit would be "branded" as Nortel.  This 
supposition is consistent with line 2170 of the heather.txt file which 
says "Trimble telecom GPSDOs (NTBW,NTPX,NTGS,etc)".  There is also a 
line in the heather.pdf file that says, "Note that non-Thunderbolt 
GPSDOs (such as the NTBW and NTPx telecom devices) do not all support 
saving disciplining parameters to EEPROM and some do not allow users 
to change the disciplining parameters. You can use "/d" command line 
options for setting the PLL parameters from the command line. If you 
run the auto-tune command on non-Thunderbolt devices then only the 
satellite elevation mask (and perhaps the signal level mask) values 
will be set".


The physical unit is labeled "Trimble THUNDERBOLT", so I guess, 
looking at all of the data, that I have a Trimble / Nortel device.


But the issue of whether it is a Nortel/Trimble Thunderbolt or just a 
Thunderbolt wouldn't cause the current problem that I am having now in 
a unit that previously worked perfectly for me.


Just so you know that my heather.cfg file is "OK" and not responsible 
for any problems, here it is:


/9
/rx
/br=9600:8:n:1
/ro=1*
/tz=-5EST/EDT
/b=1
/tb=W3SZ
/gm
/gw=0
/gqw
/gcs-
/gcg

To further document that this issue is not a "setup" problem, I did 
another factory reset of the unit and then did not use Lady Heather 
but only monitored function with TBoltMon.exe and I did not do any 
setup with that utility until the self survey was done and more than 
two hours had passed, and then I only set and saved the position. 
Function and  results were unchanged, and the unit was still stuck in 
Power-Up mode and DAC voltage was still stuck at zero, but everything 
else was normal according to the TBoltMon readouts.


Thanks again and 73,

Roger
W3SZ




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Re: [time-nuts] Am I doing something wrong?

[Roger Rehr W3SZ]

Hi Nigel, and Bob, and Bill!

Thanks for the notes!  I very much appreciate your helpful comments.  I 
will give my responses to all of your helpful posts here.  Sorry for the 
delay in responses.  The reason for the delay is that my Thunderbolt is 
at a remote site and I can communicate with it via Lady Heather 
remotely, but I had to drive out to the site to do the tests with an HP 
5342A frequency counter and pulse analysis of the pps port.  I drove out 
to the site today.


First, Bob and Bill,

1.
DAC set to +0.5 V gives significant frequency errors:  HP counter reads 
9.999.984 MHz and osc error as reported by LH is 1,68x,xxx.xx ppt.  
Interestingly, at this voltage pps error is flipping between +50 and -50.


The DAC voltage that minimizes both counter error and pps/osc error as 
reported by LH is around -3.553 V.  This is dramatically different than 
the setting last October when all was working well, as you know.


With DAC voltage -3.553 V the osc error and pps error are reduced, but 
they jump around quite a bit:
pps short-term variation is for example between about +50 and -50 and 
osc short term variation is between about +5000 and -5000.  HP counter 
reads 10.000.000 MHz.


Even when I have the DAC close enough to optimum that my counter reads 
10.000.000 MHz and the osc error is flipping around both sides of zero, 
the unit stays in "Power-up" mode and the DAC voltage stays at wherever 
I set it (either using d>>s or &>>i and then power cycle) and does not vary.



2.
I get a 10 usec duration +5V pulse every 1.00 seconds from the PPS port, 
as per specifications.  I cannot give you greater precision than that on 
the pulse interval.



Nigel,

I agree that something appears odd with this unit that had been running 
with no problems for at least a year at my location.  There have been no 
known system / config changes by me, although there is always the chance 
that I fat-fingered something when playing with the Lady Heather display 
at some point.


The receiver self identifies as a TSIP (Trimble TSIP Binary) receiver 
when Lady Heather starts up.  The receiver type is not specified in my 
cfg file, which instead has the default line /rx which as you know means 
auto-detect receiver type.


I had assumed that the "Nortel NTGS/NTBW" designation that you mention 
and that appears on the Lady Heather parameter display had something to 
do with Trimble having supplied the unit I now have to Nortel and this 
"Nortel NTGS/NTBW" designation being a custom ID placed in the firmware 
so that the unit would be "branded" as Nortel.  This supposition is 
consistent with line 2170 of the heather.txt file which says "Trimble 
telecom GPSDOs (NTBW,NTPX,NTGS,etc)".  There is also a line in the 
heather.pdf file that says, "Note that non-Thunderbolt GPSDOs (such as 
the NTBW and NTPx telecom devices) do not all support saving 
disciplining parameters to EEPROM and some do not allow users to change 
the disciplining parameters. You can use "/d" command line options for 
setting the PLL parameters from the command line. If you run the 
auto-tune command on non-Thunderbolt devices then only the satellite 
elevation mask (and perhaps the signal level mask) values will be set".


The physical unit is labeled "Trimble THUNDERBOLT", so I guess, looking 
at all of the data, that I have a Trimble / Nortel device.


But the issue of whether it is a Nortel/Trimble Thunderbolt or just a 
Thunderbolt wouldn't cause the current problem that I am having now in a 
unit that previously worked perfectly for me.


Just so you know that my heather.cfg file is "OK" and not responsible 
for any problems, here it is:


/9
/rx
/br=9600:8:n:1
/ro=1*
/tz=-5EST/EDT
/b=1
/tb=W3SZ
/gm
/gw=0
/gqw
/gcs-
/gcg

To further document that this issue is not a "setup" problem, I did 
another factory reset of the unit and then did not use Lady Heather but 
only monitored function with TBoltMon.exe and I did not do any setup 
with that utility until the self survey was done and more than two hours 
had passed, and then I only set and saved the position. Function and  
results were unchanged, and the unit was still stuck in Power-Up mode 
and DAC voltage was still stuck at zero, but everything else was normal 
according to the TBoltMon readouts.


Thanks again and 73,

Roger
W3SZ


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[time-nuts] FA2 counter

[ew via time-nuts]

Did receive FA2 counter today. Everything as promised, like the 10 second mode 
best.Use a Datum 2000 as source 10 MHz in the back 5 MHz in the front reliable 
+- 1 on the last 12th digit.


Bert Kehren
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Re: [time-nuts] Two types of GPDSO / Rubidium

[Didier Juges]

I have a number of revisions of the John Vig tutorial in my Manual pages.
The most recent was sent to me directly by John but I am not sure if it has
the notes.
www.ko4bb.com
Go to Manuals and search for Vig

Didier KO4BB

On Thu, Sep 26, 2019 at 7:03 AM Chris Caudle  wrote:

> On Wed, September 25, 2019 5:45 pm, Taka Kamiya via time-nuts wrote:
> > discussions take place both for GPSDO with Crystal Oscillators and
> > Rubidium modules.  It appears there are two types of each.
> > 1)  fixed frequency type (less jitter)
> > 2)  frequency agile type (more jitter)
>
> That is a bit oversimplified.  GPSDO is "GPS disciplined oscillator,"
> meaning that the output frequency of the oscillator is forced to follow
> the inverse of the time measurements derived from the Global Positioning
> System.
> Obviously if the oscillator has to follow another reference it cannot
> truly be fixed frequency on the output, but there are various different
> ways that the frequency can be varied.  Depending on the important
> parameters for your needs the differences in mechanism may or may not be
> important.
>
> > I've read frequency agile Rb modules (ones you can change output
> > frequency) is one kind of Rb (sa.22c and fe5650, etc), and there is
> > another one that you cannot change frequency. (ie. T-bolt, PRS10, etc).
>
> You are mixing different types of equipment together, so it is a little
> difficult to know what you are asking.
> FE5650, PRS10 and SA.22C are rubidium frequency standards.  A rubidium
> frequency standard is fundamentally an OCXO which is slaved in a frequency
> lock loop to a way to measure atomic transitions in rubidium vapor.  There
> are various systematic errors which pull the frequency of that atomic
> transition measurement, so a rubidium standard will commonly have an
> adjustment mechanism that can adjust the output frequency far enough to
> compensate for those systematic errors, but you need a more accurate
> device for comparison for that adjustment to be worthwhile.
>
> A Thunderbolt is a complete GPS disciplined oscillator system which
> accepts GPS signals from an antenna, and outputs 10MHz which is slaved so
> that on average there are always 10 million output transitions per
> GPS-derived second estimation, and outputs a pulse once per second which
> occurs on  the transition of the GPS-derived second estimation.
>
> When the GPS signal is not available for some reason (antenna failure, GPS
> system problems, etc.) the GPS disciplined oscillator has to run in
> undisciplined mode.  Over that time the corrections to the oscillator
> frequency are not available, so only the intrinsic stability of the
> oscillator used sets the long term stability of the output frequency.  In
> that particular case (no GPS available) a GPSDO using a rubidium
> controlled oscillator as part of the design will have more  stable long
> term frequency than an oven quartz oscillator.
> While GPS signal is available to measure and control the output frequency
> there is little difference between an ovenized quartz and a rubidium
> controlled (which recall also has an ovenized quartz oscillator driving
> the output, but has a control loop using rubidium vapor transitions to
> correct any frequency drift of the quartz oscillator).
>
> > Words like phase noise and PLL are thrown out often in discussions.
>
> A very good place to start is searching for John Vig oscillator tutorial.
> John Vig has a lengthy presentation about all things relating to
> oscillators, if you can find the version which includes the notes along
> with the presentation slides you can spend a couple of days studying that
>
> > Is this because frequency agile type has the ultimate output from PLL
> > (subject to jitter) and fixed frequency type is from OCXO?
>
> Mixing different types of things into a single question again.
> The term PLL is phase locked loop, it is a particular type of control loop
> design which measures the edge transitions of a reference frequency input,
> the edge transitions of an output signal, and controls the output so that
> the edges match the reference.
> You can phase lock quartz, rubidium, pendulum.   Maybe an hour glass, but
> the only transition I can think of is when you turn the hour glass over,
> so that  would be an impractical PLL.
>
> > Even in main well known brands, I understand PRS10
> > and sa.22C and fe5650 are fundamentally different.
> > I guess they are all "GPS disciplined" in some way
>
> No, SA.22C and FE5650 have no connection to GPS,  they are not GPS
> disciplined in any way as stand alone devices, but can be used as part of
> a full GPS disciplined oscillator design. The SA.22C has a
> pulse-per-second (PPS) input, so it can be connected to GPS, but that gets
> into a lot of secondary questions relating to how that PPS is derived and
> whether it helps or hurts overall stability.
>
> --
> Chris Caudle
>
>
>
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[time-nuts] Vig tutorial link at NIST Re: Two types of GPDSO / Rubidium

[jimlux]

On 9/26/19 6:15 AM, Chris Caudle wrote:


A very good place to start is searching for John Vig oscillator tutorial.
John Vig has a lengthy presentation about all things relating to
oscillators, if you can find the version which includes the notes along
with the presentation slides you can spend a couple of days studying that




https://tf.nist.gov/sim/2010_Seminar/vig3.ppt

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Re: [time-nuts] Precision Time Protocol – Windows 10 implementation

[David J Taylor via time-nuts]

From: Adam Kumiszcza

It will be connected via a short cable (1,5 m or less) to one computer. The
second will join much later, I will worry about splitting the signal then.
Other computers would be in different rooms, so I would need another time
source.
My question was rather if stacking another board with serial port on it
would be a good idea. I'm thinking of using PPS signal there directly via
GPIO. And maybe NMEA, too.

Cheers,
Adam
=

Adam,

You may be unable to stack another board on top, but that depends on the 
boards, of course.  I would suggest using the network connection between the 
computers (with the Internet as a backup) for getting the coarse seconds. 
You then need to know what voltage level is required on the second computer 
for its serial connections - +/- 12 V or TTL levels.  If it's a standard 
serial port on the computer, use a RS232-TTL converter just to connect the 
PPS line to the DCD pin (1 on a DB9 connector).  No need to the TX/RX lines, 
just ground and PPS.


I had hoped that someone else on the group who had real-world experience of 
distributing PPS might chip in


Cheers,
David
--
SatSignal Software - Quality software for you
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 



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Re: [time-nuts] Two types of GPDSO / Rubidium

[Chris Caudle]

On Wed, September 25, 2019 5:45 pm, Taka Kamiya via time-nuts wrote:
> discussions take place both for GPSDO with Crystal Oscillators and
> Rubidium modules.  It appears there are two types of each.
> 1)  fixed frequency type (less jitter)
> 2)  frequency agile type (more jitter)

That is a bit oversimplified.  GPSDO is "GPS disciplined oscillator,"
meaning that the output frequency of the oscillator is forced to follow
the inverse of the time measurements derived from the Global Positioning
System.
Obviously if the oscillator has to follow another reference it cannot
truly be fixed frequency on the output, but there are various different
ways that the frequency can be varied.  Depending on the important
parameters for your needs the differences in mechanism may or may not be
important.

> I've read frequency agile Rb modules (ones you can change output
> frequency) is one kind of Rb (sa.22c and fe5650, etc), and there is
> another one that you cannot change frequency. (ie. T-bolt, PRS10, etc).

You are mixing different types of equipment together, so it is a little
difficult to know what you are asking.
FE5650, PRS10 and SA.22C are rubidium frequency standards.  A rubidium
frequency standard is fundamentally an OCXO which is slaved in a frequency
lock loop to a way to measure atomic transitions in rubidium vapor.  There
are various systematic errors which pull the frequency of that atomic
transition measurement, so a rubidium standard will commonly have an
adjustment mechanism that can adjust the output frequency far enough to
compensate for those systematic errors, but you need a more accurate
device for comparison for that adjustment to be worthwhile.

A Thunderbolt is a complete GPS disciplined oscillator system which
accepts GPS signals from an antenna, and outputs 10MHz which is slaved so
that on average there are always 10 million output transitions per
GPS-derived second estimation, and outputs a pulse once per second which
occurs on  the transition of the GPS-derived second estimation.

When the GPS signal is not available for some reason (antenna failure, GPS
system problems, etc.) the GPS disciplined oscillator has to run in
undisciplined mode.  Over that time the corrections to the oscillator
frequency are not available, so only the intrinsic stability of the
oscillator used sets the long term stability of the output frequency.  In
that particular case (no GPS available) a GPSDO using a rubidium
controlled oscillator as part of the design will have more  stable long
term frequency than an oven quartz oscillator.
While GPS signal is available to measure and control the output frequency
there is little difference between an ovenized quartz and a rubidium
controlled (which recall also has an ovenized quartz oscillator driving
the output, but has a control loop using rubidium vapor transitions to
correct any frequency drift of the quartz oscillator).

> Words like phase noise and PLL are thrown out often in discussions.

A very good place to start is searching for John Vig oscillator tutorial.
John Vig has a lengthy presentation about all things relating to
oscillators, if you can find the version which includes the notes along
with the presentation slides you can spend a couple of days studying that

> Is this because frequency agile type has the ultimate output from PLL
> (subject to jitter) and fixed frequency type is from OCXO?

Mixing different types of things into a single question again.
The term PLL is phase locked loop, it is a particular type of control loop
design which measures the edge transitions of a reference frequency input,
the edge transitions of an output signal, and controls the output so that
the edges match the reference.
You can phase lock quartz, rubidium, pendulum.   Maybe an hour glass, but
the only transition I can think of is when you turn the hour glass over,
so that  would be an impractical PLL.

> Even in main well known brands, I understand PRS10
> and sa.22C and fe5650 are fundamentally different.
> I guess they are all "GPS disciplined" in some way

No, SA.22C and FE5650 have no connection to GPS,  they are not GPS
disciplined in any way as stand alone devices, but can be used as part of
a full GPS disciplined oscillator design. The SA.22C has a
pulse-per-second (PPS) input, so it can be connected to GPS, but that gets
into a lot of secondary questions relating to how that PPS is derived and
whether it helps or hurts overall stability.

-- 
Chris Caudle



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Re: [time-nuts] NTP apps on Windows question

[David J Taylor via time-nuts]

From: Peter Laws

I've noticed the same issue (running Meinberg's build of NTP) with the
same amateur radio program where the PC is a certain number of seconds
off (4 or 6 or so or whatever but on the order of what the OP
reported).  A restart of NTP "fixes" it.  This happens after a cold
boot and even if I let the system run for an hour, NTP never fixes
things.

You've reminded me that I need to check if I did, in fact, disable the
Windows Time service (whatever it is on W10).  That's much more likely
to be the issue rather than NTP.

Peter Laws | N5UWY | plaws plaws net | Travel by Train!
==

Peter,

You might also check that NTP is working correctly.  Have you used the 
"ntpq -pn" command?  If your PC is out by more than 500 ppm (43 seconds a 
day) special steps are required for NTP so that it corrects such an 
inaccurate clock!


73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 



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Re: [time-nuts] Two types of GPDSO / Rubidium

[Taka Kamiya via time-nuts]

Tom,
I know you are absolutely right.  When I buy from eBay, I have no idea where 
they came from.  Reject pile, junk yard, or pristine clean room.  
Unfortunately, I can afford up to certain amount.  I have lots of PRS10 but 
their origin is unknown.  Even if I buy 5065A, origin will be unknown and so as 
condition.  Recently, I called around local cal-lab to see who can help me 
validate these devices.  No one could.  I'm very tempted to buy T-bolt or PRS10 
new but at $1500, it's quite hefty.  I may just have to.
I'm at learn as much as I can stage.  I have a Cesium but it's old.  4040/A  I 
have no idea how it was used or stored.  It would be nice to have one known 
good standard.  The best I can do for now is my array of GPSDOs.  (from unknown 
sources)

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, September 26, 2019, 3:05:19 AM EDT, Tom Van Baak 
 wrote:  
 
 It might be a bit of an over-simplification to split oscillators in 
those two camps, "fixed" and "agile". There are often many trade-offs in 
performance that you have to deal with. Moreover if you are getting your 
oscillators from eBay, or especially parts from China, you may also have 
to assume that original factory specs are no longer valid.

This is one reason why the time nuts list is so preoccupied with making 
accurate measurements of frequency standards. You only know what you 
have if 1) you buy it new from a reputable company, or 2) when you buy 
it cheap and measure it yourself with reputable test equipment, or 3) 
you get it from a friend who has measured it for you.

If you're asking specifically about Rb, I think the data shows that hp 
5065A has best performance, followed by PRS10, followed by all the cheap 
telecom Rb. Sorry, I don't have plots or URL's handy at the moment to 
support this with real data. My main take-away is to start with your 
requirements, see which products / specs meet that, and if you're buying 
dirt cheap surplus, make your own measurements to validate your 
requirements.

/tvb


On 9/25/2019 3:45 PM, Taka Kamiya via time-nuts wrote:
> This is a cross post from EEVBLOG.  I'm hoping there is someone who's 
> familiar with this subject would help me out here.
> I am hoping someone can help me understand this.  I've seen similar 
> discussions take place both for GPSDO with Crystal Oscillators and Rubidium 
> modules.  It appears there are two types of each.
> 1)  fixed frequency type (less jitter)
> 2)  frequency agile type (more jitter)
>
> I've read frequency agile Rb modules (ones you can change output frequency) 
> is one kind of Rb (sa.22c and fe5650, etc), and there is another one that you 
> cannot change frequency. (ie. T-bolt, PRS10, etc).  Words like phase noise 
> and PLL are thrown out often in discussions.  I vaguely remember frequency 
> agile types are less suitable if ultimate in stability is needed such as 
> multiplying the output into GHz range.  This discussion was about 10GHz 
> transverter.
> Is this because frequency agile type has the ultimate output from PLL 
> (subject to jitter) and fixed frequency type is from OCXO?  If this is the 
> case, why frequency agile type even exist?  It's not like it can be used as a 
> VFO (on radio).
>
> I'm sorry this is SO vague but that's the reason for this post.  I need to 
> understand this.  There was a wiki page on this, but it doesn't go into this 
> discussion deep enough.
>
> Would someone help me gain knowledge in this?
>
> ---
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> ___
> time-nuts mailing list --time-nuts@lists.febo.com
> To unsubscribe, go 
> tohttp://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.


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Re: [time-nuts] Two types of GPDSO / Rubidium

[Azelio Boriani]

Maybe that "GPS tamed" is literally translated from chinese for "GPS
disciplined". It is indeed the disciplining that gives personality to
the GPSDO. You can PLLize the OCXO's 10MHz or the PPS derived from the
OCXO's 10MHz and see different results on the 10MHz's stability and
accuracy. It seems that Chinese built GPSDOs are derived from the
BG7TBL's design, you can find performance data here:


On Thu, Sep 26, 2019 at 8:00 AM Taka Kamiya via time-nuts
 wrote:
>
> I also see terms like GPS tamed or PLL-GPS.
> https://www.ebay.com/itm/1pcs-PLL-GPSDO-10M-GPS-tamed-clocks/263392170249?hash=item3d53659109:g:1p0AAOSwH3haNo7c
> https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313.TR12.TRC2.A0.H0.Xgps-pll.TRS0&_nkw=gps-pll&_sacat=0
> It is not at all clear which one is what type and how it is designed.
>
> Even in main well known brands, I understand PRS10 and sa.22C and fe5650 are 
> fundamentally different.
> I guess they are all "GPS disciplined" in some way but for a newbie, telling 
> one apart from the other and picking a suitable architecture for the purpose 
> is very difficult.
> ---
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
>
>
> On Wednesday, September 25, 2019, 9:28:29 PM EDT, Bob kb8tq 
>  wrote:
>
>  Hi
>
> The first gotcah is that the distinction is not very clear. A TBolt varies 
> the frequency of
> the OCXO in the GPSDO. GPSDO’s that use Rb’s can and often do vary the 
> frequency.
>
> Indeed some devices use a DDS to generate an output rather than varying 
> something else.
> I suspect that is what you are bumping into. In some cases a DDS feeds a 
> cleanup loop or filter
>  that restricts the output range.
>
> If you are after low noise at 10 GHz, the multiplier chain needs to be 
> carefully designed. There
> is a lot more to it than you might think. The first and most basic question 
> would be “is it a fixed
> frequency output or tuned?”. From there you can head off in a number of 
> directions.
>
> If you need to be able to change frequency from 1 MHz to 10 GHz in a few 
> nanoseconds, then
> there is no alternative to using a DDS. If hat is part of the requirement 
> then you go from there. If
> you want only 10 GHz +/- 0.001Hz then there are other, more quiet / lower 
> spur ways to do the job.
>
> Indeed it goes on and on …..
>
> Bob
>
>
>
> > On Sep 25, 2019, at 4:45 PM, Taka Kamiya via time-nuts 
> >  wrote:
> >
> > This is a cross post from EEVBLOG.  I'm hoping there is someone who's 
> > familiar with this subject would help me out here.
> > I am hoping someone can help me understand this.  I've seen similar 
> > discussions take place both for GPSDO with Crystal Oscillators and Rubidium 
> > modules.  It appears there are two types of each.
> > 1)  fixed frequency type (less jitter)
> > 2)  frequency agile type (more jitter)
> >
> > I've read frequency agile Rb modules (ones you can change output frequency) 
> > is one kind of Rb (sa.22c and fe5650, etc), and there is another one that 
> > you cannot change frequency. (ie. T-bolt, PRS10, etc).  Words like phase 
> > noise and PLL are thrown out often in discussions.  I vaguely remember 
> > frequency agile types are less suitable if ultimate in stability is needed 
> > such as multiplying the output into GHz range.  This discussion was about 
> > 10GHz transverter.
> > Is this because frequency agile type has the ultimate output from PLL 
> > (subject to jitter) and fixed frequency type is from OCXO?  If this is the 
> > case, why frequency agile type even exist?  It's not like it can be used as 
> > a VFO (on radio).
> >
> > I'm sorry this is SO vague but that's the reason for this post.  I need to 
> > understand this.  There was a wiki page on this, but it doesn't go into 
> > this discussion deep enough.
> >
> > Would someone help me gain knowledge in this?
> >
> > ---
> > (Mr.) Taka Kamiya
> > KB4EMF / ex JF2DKG
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to 
> > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to 
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.

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Re: [time-nuts] Two types of GPDSO / Rubidium

[Tom Van Baak]

It might be a bit of an over-simplification to split oscillators in 
those two camps, "fixed" and "agile". There are often many trade-offs in 
performance that you have to deal with. Moreover if you are getting your 
oscillators from eBay, or especially parts from China, you may also have 
to assume that original factory specs are no longer valid.


This is one reason why the time nuts list is so preoccupied with making 
accurate measurements of frequency standards. You only know what you 
have if 1) you buy it new from a reputable company, or 2) when you buy 
it cheap and measure it yourself with reputable test equipment, or 3) 
you get it from a friend who has measured it for you.


If you're asking specifically about Rb, I think the data shows that hp 
5065A has best performance, followed by PRS10, followed by all the cheap 
telecom Rb. Sorry, I don't have plots or URL's handy at the moment to 
support this with real data. My main take-away is to start with your 
requirements, see which products / specs meet that, and if you're buying 
dirt cheap surplus, make your own measurements to validate your 
requirements.


/tvb


On 9/25/2019 3:45 PM, Taka Kamiya via time-nuts wrote:

This is a cross post from EEVBLOG.  I'm hoping there is someone who's familiar 
with this subject would help me out here.
I am hoping someone can help me understand this.  I've seen similar discussions 
take place both for GPSDO with Crystal Oscillators and Rubidium modules.  It 
appears there are two types of each.
1)  fixed frequency type (less jitter)
2)  frequency agile type (more jitter)

I've read frequency agile Rb modules (ones you can change output frequency) is 
one kind of Rb (sa.22c and fe5650, etc), and there is another one that you 
cannot change frequency. (ie. T-bolt, PRS10, etc).  Words like phase noise and 
PLL are thrown out often in discussions.  I vaguely remember frequency agile 
types are less suitable if ultimate in stability is needed such as multiplying 
the output into GHz range.  This discussion was about 10GHz transverter.
Is this because frequency agile type has the ultimate output from PLL (subject 
to jitter) and fixed frequency type is from OCXO?  If this is the case, why 
frequency agile type even exist?  It's not like it can be used as a VFO (on 
radio).

I'm sorry this is SO vague but that's the reason for this post.  I need to 
understand this.  There was a wiki page on this, but it doesn't go into this 
discussion deep enough.

Would someone help me gain knowledge in this?

---
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Two types of GPDSO / Rubidium

[Taka Kamiya via time-nuts]

I also see terms like GPS tamed or PLL-GPS.  
https://www.ebay.com/itm/1pcs-PLL-GPSDO-10M-GPS-tamed-clocks/263392170249?hash=item3d53659109:g:1p0AAOSwH3haNo7c
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313.TR12.TRC2.A0.H0.Xgps-pll.TRS0&_nkw=gps-pll&_sacat=0
It is not at all clear which one is what type and how it is designed.  

Even in main well known brands, I understand PRS10 and sa.22C and fe5650 are 
fundamentally different.
I guess they are all "GPS disciplined" in some way but for a newbie, telling 
one apart from the other and picking a suitable architecture for the purpose is 
very difficult.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, September 25, 2019, 9:28:29 PM EDT, Bob kb8tq  
wrote:  
 
 Hi

The first gotcah is that the distinction is not very clear. A TBolt varies the 
frequency of
the OCXO in the GPSDO. GPSDO’s that use Rb’s can and often do vary the 
frequency. 

Indeed some devices use a DDS to generate an output rather than varying 
something else. 
I suspect that is what you are bumping into. In some cases a DDS feeds a 
cleanup loop or filter
 that restricts the output range. 

If you are after low noise at 10 GHz, the multiplier chain needs to be 
carefully designed. There
is a lot more to it than you might think. The first and most basic question 
would be “is it a fixed
frequency output or tuned?”. From there you can head off in a number of 
directions. 

If you need to be able to change frequency from 1 MHz to 10 GHz in a few 
nanoseconds, then 
there is no alternative to using a DDS. If hat is part of the requirement then 
you go from there. If
you want only 10 GHz +/- 0.001Hz then there are other, more quiet / lower spur 
ways to do the job.

Indeed it goes on and on …..

Bob



> On Sep 25, 2019, at 4:45 PM, Taka Kamiya via time-nuts 
>  wrote:
> 
> This is a cross post from EEVBLOG.  I'm hoping there is someone who's 
> familiar with this subject would help me out here.
> I am hoping someone can help me understand this.  I've seen similar 
> discussions take place both for GPSDO with Crystal Oscillators and Rubidium 
> modules.  It appears there are two types of each.  
> 1)  fixed frequency type (less jitter)
> 2)  frequency agile type (more jitter)
> 
> I've read frequency agile Rb modules (ones you can change output frequency) 
> is one kind of Rb (sa.22c and fe5650, etc), and there is another one that you 
> cannot change frequency. (ie. T-bolt, PRS10, etc).  Words like phase noise 
> and PLL are thrown out often in discussions.  I vaguely remember frequency 
> agile types are less suitable if ultimate in stability is needed such as 
> multiplying the output into GHz range.  This discussion was about 10GHz 
> transverter.
> Is this because frequency agile type has the ultimate output from PLL 
> (subject to jitter) and fixed frequency type is from OCXO?  If this is the 
> case, why frequency agile type even exist?  It's not like it can be used as a 
> VFO (on radio).
> 
> I'm sorry this is SO vague but that's the reason for this post.  I need to 
> understand this.  There was a wiki page on this, but it doesn't go into this 
> discussion deep enough.
> 
> Would someone help me gain knowledge in this?
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to 
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
  
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