Re: [time-nuts] FE-5680A software calibration units ?

2015-09-21 Thread Nick Sayer via time-nuts 

> On Sep 19, 2015, at 4:20 PM, Nick Sayer via time-nuts  
> wrote:
> […]
> I’ve tested it against GPS and as it came, it had about a 0.5 ppm error.

Oops. That was supposed to be 0.5 ppb - 500 ppt.


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[time-nuts] SRS FS710 10MHz distribution amp

2015-09-21 Thread Orin Eman 
I see a couple on eBay, already bid up to $150.  Seems rather a lot, but
what do I know.

The manual, including schematic is here:

http://www.thinksrs.com/downloads/PDFs/Manuals/FS710m.pdf

Comments?

Orin.
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Re: [time-nuts] algorithms and hardware for comparing clock pulses

2015-09-21 Thread Jim Lux 

On 9/21/15 12:13 PM, Robert LaJeunesse wrote:

The Teensy 3.1 (http://www.pjrc.com/store/teensy31.html ~$20) has a Flex Timer 
Module that appears to allow a single counter to be captured into independent 
registers from independent inputs. Not sure, but PJRC tends to run the clock 
fast (96MHz) so relative timing resolution should be much better than 0.1 
microseconds.



I was looking at the discussion of the Flex Timer on the teensy forum..
One might want to be careful about the quality of the clock fed to those 
timers.  It's the regular old CPU clock, but it runs through a DPLL.
(e.g. the crystal is a 48 MHz crystal, and converted to either 72 or 96 
MHz as you select..)


I run my teensys at 48MHz, so I could hook up a 1pps to a pin and log 
some data pretty easily.  I suspect that the ADEV will be dominated by 
the CPU crystal, so I can use any convenient 1pps.





Bob LaJeunesse


Sent: Monday, September 21, 2015 at 1:45 PM
From: "Can Altineller" 
To: "Discussion of precise time and frequency measurement" 
Subject: [time-nuts] algorithms and hardware for comparing clock pulses

Dear Time-nuts,

  ...
I probably need a hardware to measure the time pulses more precisely.
  ...
Are there any solutions to this problem?
  ...
Best Regards,
Can Altineller
___

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Re: [time-nuts] algorithms and hardware for comparing clock pulses

2015-09-21 Thread Hal Murray 

altinel...@gmail.com said:
>I finally found a way to measure 1pps output from my DS3231's, with a mcu
> unit, and modify the aging register on the RTC, I have been able to sync
> between 2-3 microseconds between clocks by substracting and adding 0.1ppm to
> 12.8ppm, with 7 bit resolution. 

I'd expect you can do much better than that.

What are you using for a MCU?  Many of them have timer/counter units that 
latch a counter on the rising edge of a pin.  That avoids any problems with 
the interrupt response time.

Another way you can do it is to take an interrupt on the rising edge of one 
pulse and the falling edge of the other pulse.  Then you have to correct for 
the pulse width in software.  That introduces errors when the pulse width 
changes with temperature, but they are probably small.  I might trigger a 
scope on the rising edge and zoom in on the trailing edge and see how much it 
moved around when I hit the unit under test with heat or cold.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] algorithms and hardware for comparing clock pulses

2015-09-21 Thread Jim Lux 

On 9/21/15 12:13 PM, Robert LaJeunesse wrote:

The Teensy 3.1 (http://www.pjrc.com/store/teensy31.html ~$20) has a Flex Timer 
Module that appears to allow a single counter to be captured into independent 
registers from independent inputs. Not sure, but PJRC tends to run the clock 
fast (96MHz) so relative timing resolution should be much better than 0.1 
microseconds.



A bit of googling:  FreqMeasure library for the Teensy can time stamp 
zero crossings on pin 3
Apparently, the code is there to use up to 4 pins, but it's not really 
set up for multiple pins.
It uses the hardware to capture, and then an ISR to unload the register 
and buffer them up.


It also works on Arduinos.


https://www.pjrc.com/teensy/td_libs_FreqMeasure.html

the diagram in the K20 manual shows a two stage D flip-flop synchronizer 
driven off the system clock, and then a simple rising/falling edge (or, 
really, a 0->1 or 1->0 transition detector, which then latches the counter.

(Figure 37-175 in the manual)

Is this "time-nuts" precision capable. I've not tried to drive an 
Arduino or teensy with an external clock, which I think might be a 
starting point.




Bob LaJeunesse


Sent: Monday, September 21, 2015 at 1:45 PM
From: "Can Altineller" 
To: "Discussion of precise time and frequency measurement" 
Subject: [time-nuts] algorithms and hardware for comparing clock pulses

Dear Time-nuts,

  ...
I probably need a hardware to measure the time pulses more precisely.
  ...
Are there any solutions to this problem?
  ...
Best Regards,
Can Altineller
___

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Re: [time-nuts] FE-5680A software calibration units ?

2015-09-21 Thread Bob Camp 
Hi

Assuming it shows locked, that would suggest that (for what ever reason) 
it’s been re-tuned at some point after it left the factory.

Bob

> On Sep 20, 2015, at 9:06 PM, Nick Sayer via time-nuts  
> wrote:
> 
> 
>> On Sep 19, 2015, at 4:20 PM, Nick Sayer via time-nuts  
>> wrote:
>> […]
>> I’ve tested it against GPS and as it came, it had about a 0.5 ppm error.
> 
> Oops. That was supposed to be 0.5 ppb - 500 ppt.
> 
> 
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[time-nuts] algorithms and hardware for comparing clock pulses

2015-09-21 Thread Can Altineller 
   Dear Time-nuts,

   I finally found a way to measure 1pps output from my DS3231's, with a
mcu unit, and modify the aging register on the RTC, I have been able to
sync between 2-3 microseconds between clocks by substracting and adding
0.1ppm to 12.8ppm, with 7 bit resolution.

   Since the current setup involves a mcu and interrupts to measure the
time between time pulses, *(RTC being calibrated and RTC being used as sync
signal) and when the pulses are within 1 micro seconds away, the interrupt
service routines execute consecutively, loosing microseconds of precision.

   I probably need a hardware to measure the time pulses more precisely. I
thought of XOR'ing the clocks, and measuring both rising and falling edges
trough interrupts, but when the pulse is close enough, it will lead to same
condition.

   Are there any solutions to this problem? Maybe an analog hack? And what
are the mostly used algorithms to tune an oscillator to another? Currently
my algorithm sign corrects the result difference, and adjusts aging
register simply by adding to it, then runs a conversion command each second
to add or substract the ppms.

   This looks a lot of fun,

   Best Regards,
   Can Altineller
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Re: [time-nuts] FE-5680A software calibration units ?

2015-09-21 Thread Nick Sayer via time-nuts 
When I got it, the setting was zero. That suggests to me that the factory 
tuning was erased, assuming that the factory tunes it the same way - by 
changing the value adjusted by that software.

> On Sep 21, 2015, at 4:34 AM, Bob Camp  wrote:
> 
> Hi
> 
> Assuming it shows locked, that would suggest that (for what ever reason) 
> it’s been re-tuned at some point after it left the factory.
> 
> Bob
> 
>> On Sep 20, 2015, at 9:06 PM, Nick Sayer via time-nuts  
>> wrote:
>> 
>> 
>>> On Sep 19, 2015, at 4:20 PM, Nick Sayer via time-nuts  
>>> wrote:
>>> […]
>>> I’ve tested it against GPS and as it came, it had about a 0.5 ppm error.
>> 
>> Oops. That was supposed to be 0.5 ppb - 500 ppt.
>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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> 

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Re: [time-nuts] FE-5680A software calibration units ?

2015-09-21 Thread ewkehren via time-nuts 
Depends on who you got it from




Sent from Samsung tabletNick Sayer via time-nuts  
wrote:When I got it, the setting was zero. That suggests to me that the factory 
tuning was erased, assuming that the factory tunes it the same way - by 
changing the value adjusted by that software.

> On Sep 21, 2015, at 4:34 AM, Bob Camp  wrote:
> 
> Hi
> 
> Assuming it shows locked, that would suggest that (for what ever reason) 
> it’s been re-tuned at some point after it left the factory.
> 
> Bob
> 
>> On Sep 20, 2015, at 9:06 PM, Nick Sayer via time-nuts  
>> wrote:
>> 
>> 
>>> On Sep 19, 2015, at 4:20 PM, Nick Sayer via time-nuts  
>>> wrote:
>>> […]
>>> I’ve tested it against GPS and as it came, it had about a 0.5 ppm error.
>> 
>> Oops. That was supposed to be 0.5 ppb - 500 ppt.
>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 

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Re: [time-nuts] algorithms and hardware for comparing clock pulses

2015-09-21 Thread Robert LaJeunesse 
The Teensy 3.1 (http://www.pjrc.com/store/teensy31.html ~$20) has a Flex Timer 
Module that appears to allow a single counter to be captured into independent 
registers from independent inputs. Not sure, but PJRC tends to run the clock 
fast (96MHz) so relative timing resolution should be much better than 0.1 
microseconds.

Bob LaJeunesse

> Sent: Monday, September 21, 2015 at 1:45 PM
> From: "Can Altineller" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Subject: [time-nuts] algorithms and hardware for comparing clock pulses
>
>Dear Time-nuts,
> 
>  ...  
>I probably need a hardware to measure the time pulses more precisely. 
>  ...
>Are there any solutions to this problem? 
>  ...
>Best Regards,
>Can Altineller
> ___
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Re: [time-nuts] algorithms and hardware for comparing clock pulses

2015-09-21 Thread Jim Lux 

On 9/21/15 12:13 PM, Robert LaJeunesse wrote:

The Teensy 3.1 (http://www.pjrc.com/store/teensy31.html ~$20) has a Flex Timer 
Module that appears to allow a single counter to be captured into independent 
registers from independent inputs. Not sure, but PJRC tends to run the clock 
fast (96MHz) so relative timing resolution should be much better than 0.1 
microseconds.


I have, literally, a box full of teensy 3.1s at work.
If there's a quick test that would help answer any questions, I'm 
willing to set them up.
I have, in the lab with the Teensys, a SRS Rb and a Wenzel OCXO (not a 
superduper, just the streamline).


Is there a Flex Timer Module in the teensyduino library?



Bob LaJeunesse


Sent: Monday, September 21, 2015 at 1:45 PM
From: "Can Altineller" 
To: "Discussion of precise time and frequency measurement" 
Subject: [time-nuts] algorithms and hardware for comparing clock pulses

Dear Time-nuts,

  ...
I probably need a hardware to measure the time pulses more precisely.
  ...
Are there any solutions to this problem?
  ...
Best Regards,
Can Altineller
___

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Re: [time-nuts] algorithms and hardware for comparing clock pulses

2015-09-21 Thread Jim Harman 
Hi Can,

For a simple analog solution, you might try a 74HC4046 phase detector
followed by a diode and RC network as used in Lars Walenius' GPSDO,
described here in the archives:

https://www.febo.com/pipermail/time-nuts/2014-February/082820.html

The phase detector produces a pulse whose width equals the time difference
between the two pulses. The RC network converts this to a voltage
proportional to the time difference, which you then measure with the MCU's
A/D converter. Using the rising edge of the signal at pin 14 as the
interrupt source triggers the A/D converter at the end of the pulse, which
corresponds to the peak of the analog signal.. The 1 meg resistor
discharges the capacitor between pulses.

Lars' code also includes a filtering algorithm which does a nice job of
controlling one of the oscillators to match the 1-PPS generated by the GPS.
I have enhanced this if you are interested.

On Mon, Sep 21, 2015 at 1:45 PM, Can Altineller 
wrote:

>
>
>I probably need a hardware to measure the time pulses more precisely. I
> thought of XOR'ing the clocks, and measuring both rising and falling edges
> trough interrupts, but when the pulse is close enough, it will lead to same
> condition.
>
>Are there any solutions to this problem? Maybe an analog hack? And what
> are the mostly used algorithms to tune an oscillator to another? Currently
> my algorithm sign corrects the result difference, and adjusts aging
> register simply by adding to it, then runs a conversion command each second
> to add or substract the ppms.
>
>This looks a lot of fun,
>
>Best Regards,
>Can Altineller
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

--Jim Harman
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