Re: [time-nuts] Frequency counter questions

[Bruce Griffiths]

Reciprocal counter where one measures the period of the output of a divide by N 
and then takes the reciprocal of this period multiplied by N as the frequency 
of the divider input. With a 100MHz clock one can achieve ~ 0.01ppm resolution  
for a 1 second averaging time. if one uses interpolators with 100ps resolution 
(equivalent to a 10GHz clock)  the resolution improves to ~0.1ppb for a 1s 
averaging time.

Bruce

> 
> On 24 April 2017 at 13:25 Jerry Hancock  wrote:
> 
> For some reason I am not getting the individual emails so I apologize for 
> not replying more promptly. I’ll have to check my profile.
> 
> As far as I can tell from the notes, and by the way, the number of notes 
> was why I was trying to move this off list, to get to .001hz I need to 
> measure over 1000 seconds. This is ok. Since I am looking for an average over 
> time anyway, this is not a problem. By the way I am using a GPSDO and planned 
> to use it divided down for the gate.
> 
> The only reason I mentioned a prescaler was that there was a 12 digit 
> counter schematic on the web that looked pretty complete. This person used a 
> prescaler and I was trying to wrap my head around how this helped with 
> resolution and I guess from the replies, that is not a practical solution 
> (using a prescaler) when you want high resolution unless I use the inverse 
> operation which I can’t remember what it is called off the top of my head.
> 
> I’ve seen some HP 12 digit counters but since I have a GPSDO and who 
> knows how many micro development boards around here, I thought I would take a 
> run at it.
> 
> So to summarize, if I limit my high resolution to 99,999,999.999hz and 
> use a gate of 1000 seconds, would that get me to .01hz? If not, then what 
> would the possible resolution be?
> 
> Thanks for all the input, very helpful.
> 
> Jerry
> 
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Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader

[Dave Wood]

Glenn, your calculator comes up with the value I first calculated, around
13k.  However, I'm pretty sure the original value may have been 4 times
higher based on the partially visible bands on one of the resistors that
indicates it might have been a 56k.  If I use the zener test current in the
data sheet and the max current of the load, I end up with about the same
value the calculator estimates.  But if I use a lower value of zener
current and a lower drain from load I end up with a value pretty close to
what may have been in there originally.  I was hoping someone on the list
had an 8181 and could look to see or have a diagram.  If I use the lower
values then the dissipation of the resistor is within limits but at the
high end.  Using 13k ups the power to a one watt device, which I realize
should have been the value in the first place.  Worse case I start with 56k
and work down until the circuit is happy again.  73  and thanks!

On Sun, Apr 23, 2017 at 5:50 PM, Artek Manuals 
wrote:

> Dave
>
> If you know the Zener voltage and the supply voltage then calculating a
> reasonable value for the series resistor is pretty straight forward
>
> Dave
>
>
> On 4/23/2017 2:31 PM, Dave Wood wrote:
>
>> Bill, actually what happened is the zener diode that the resistor fed
>> shorted and that's the reason it burned up.  I have two units with this
>> issue and I cannot read the resistor value since it burned up.  What I
>> would love to know is what the original value of the dropping resistor
>> was?  73  Dave
>>
>> On Sat, Apr 22, 2017 at 11:39 PM, Bill Hawkins 
>> wrote:
>>
>> There is usually a power dissipation reason why a resistor becomes
>>> toast, and the reason is frequently a shorted bypass cap or a shorted
>>> device.
>>>
>>> Have you measured the resistance to ground of the end of the resistor
>>> opposite the power supply?
>>>
>>> Sometimes inputs get high voltages and short the amplifying device.
>>>
>>> Sometimes that is reason the units were for sale.
>>>
>>> Hope I'm wrong.
>>>
>>> Bill Hawkins
>>>
>>>
>>> -Original Message-
>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave
>>> Wood
>>> Sent: Saturday, April 22, 2017 8:43 PM
>>>
>>> Anyone on the list own the above Time Code Readesr.  I have one of each,
>>> they are identical with the same issue.  I need to identify the correct
>>> value of a resistor in the power supply that provides 27 volts to the
>>> input amp.  They are both toast in my units and I do not have a manual.
>>> Thanks in advance!  Dave ___
>>>
>>> ___
>>> 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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>> ailman/listinfo/time-nuts
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>>
> --
> Dave
> manu...@artekmanuals.com
> www.ArtekManuals.com
>
>
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Re: [time-nuts] Frequency counter questions

[Chris Albertson]

Confusion comes about because there is a ton of on-chip hardware an
addition to the CPU.  An edge detector, prescaller and a few hardware
counters on the STM32.   So I said he'd likely not be actually counting in
software but just setting up the desired tiger condition, loading the
prescaler then letting it run for a gate interval and finally reading out
the count. The hardware is good for some tens of MHz.  But you really
have to be careful in your programming to get this exactly right.  Easy to
by off by one.

The chip has all kinds of other devices that greatly off load the CPU for
example making PWM outputs.

But you are right, we don't know what the OP wants to do.  Is he a ham what
needs to monitor the output of a transmitter and is this HF or microwave.
We's need to know the real world use case in order to suggest a solution.



On Sun, Apr 23, 2017 at 12:48 PM, Bob kb8tq  wrote:

>
> >
> > Yes, But I assume he is not going to do the actual counting in software.
>
> Except that’s not what he *said* he was trying to do. Thus the confusion
> and attempt
> to clarify what he’s trying to do. We now have a half dozen people who are
> equally
> confused about the task and no further input from the only person who
> actually
> *knows* what he’s trying to do. If indeed you have registers and the like,
> then they
> are probably in an FPGA. If you already have an FPGA doing the high speed
> stuff,
> the need for the F7 is even more questionable. Yes it’s a $12 or so chip,
> what needs
> to be done can be done with a $2 chip. Not only is would it be cheaper. It
> likely
> would be faster and easier to get working.
>
> Bob
>
>
> > He will likely be using the CPU to set and read some registers and
> control
> > the user interface.
> >
> > The time stamping idea is not bad.  But today you do NOT need to "post
> > process".  Your little processor could do this in nearly real-time and
> > you'd have results on the screen in seconds.
> >
> >
> >
> > --
> >
> > Chris Albertson
> > Redondo Beach, California
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
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> mailman/listinfo/time-nuts
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>
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-- 

Chris Albertson
Redondo Beach, California
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[time-nuts] Frequency counter questions

[Jerry Hancock]

For some reason I am not getting the individual emails so I apologize for not 
replying more promptly.  I’ll have to check my profile.

As far as I can tell from the notes, and by the way, the number of notes was 
why I was trying to move this off list, to get to .001hz I need to measure over 
1000 seconds.  This is ok.  Since I am looking for an average over time anyway, 
this is not a problem.  By the way I am using a GPSDO and planned to use it 
divided down for the gate.

The only reason I mentioned a prescaler was that there was a 12 digit counter 
schematic on the web that looked pretty complete.  This person used a prescaler 
and I was trying to wrap my head around how this helped with resolution and I 
guess from the replies, that is not a practical solution (using a prescaler) 
when you want high resolution unless I use the inverse operation which I can’t 
remember what it is called off the top of my head.

I’ve seen some HP 12 digit counters but since I have a GPSDO and who knows how 
many micro development boards around here, I thought I would take a run at it.

So to summarize, if I limit my high resolution to 99,999,999.999hz and use a 
gate of 1000 seconds, would that get me to .01hz?  If not, then what would the 
possible resolution be?

Thanks for all the input, very helpful.

Jerry


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Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader

[Tom Miller]

If you know what the zener is and what the unregulated supply voltage is, 
you should be able to calculate the resistance and power.


Regards

- Original Message - 
From: "Dave Wood" 
To: "Discussion of precise time and frequency measurement" 


Sent: Sunday, April 23, 2017 2:31 PM
Subject: Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader



Bill, actually what happened is the zener diode that the resistor fed
shorted and that's the reason it burned up.  I have two units with this
issue and I cannot read the resistor value since it burned up.  What I
would love to know is what the original value of the dropping resistor
was?  73  Dave

On Sat, Apr 22, 2017 at 11:39 PM, Bill Hawkins  
wrote:



There is usually a power dissipation reason why a resistor becomes
toast, and the reason is frequently a shorted bypass cap or a shorted
device.

Have you measured the resistance to ground of the end of the resistor
opposite the power supply?

Sometimes inputs get high voltages and short the amplifying device.

Sometimes that is reason the units were for sale.

Hope I'm wrong.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave
Wood
Sent: Saturday, April 22, 2017 8:43 PM

Anyone on the list own the above Time Code Readesr.  I have one of each,
they are identical with the same issue.  I need to identify the correct
value of a resistor in the power supply that provides 27 volts to the
input amp.  They are both toast in my units and I do not have a manual.
Thanks in advance!  Dave ___

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Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader

[Artek Manuals]

Dave

If you know the Zener voltage and the supply voltage then calculating a 
reasonable value for the series resistor is pretty straight forward


Dave


On 4/23/2017 2:31 PM, Dave Wood wrote:

Bill, actually what happened is the zener diode that the resistor fed
shorted and that's the reason it burned up.  I have two units with this
issue and I cannot read the resistor value since it burned up.  What I
would love to know is what the original value of the dropping resistor
was?  73  Dave

On Sat, Apr 22, 2017 at 11:39 PM, Bill Hawkins  wrote:


There is usually a power dissipation reason why a resistor becomes
toast, and the reason is frequently a shorted bypass cap or a shorted
device.

Have you measured the resistance to ground of the end of the resistor
opposite the power supply?

Sometimes inputs get high voltages and short the amplifying device.

Sometimes that is reason the units were for sale.

Hope I'm wrong.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave
Wood
Sent: Saturday, April 22, 2017 8:43 PM

Anyone on the list own the above Time Code Readesr.  I have one of each,
they are identical with the same issue.  I need to identify the correct
value of a resistor in the power supply that provides 27 volts to the
input amp.  They are both toast in my units and I do not have a manual.
Thanks in advance!  Dave ___

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--
Dave
manu...@artekmanuals.com
www.ArtekManuals.com


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Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader

[Glenn Little WB4UIV]

Here is a calculator to determine the resistor value.



You will probably have to provide an external supply, at the zener 
voltage, to know what the current draw is for the calculator.


You might find that the original resistor value was too low or the zener 
wattage was too low for the circuit draw.


You might also find a leaky filter capacitor down stream causing the 
current to be too high.
There may be a leaky filter capacitor up stream causing the zener to 
draw too much current as the peak voltage may have exceeded the original 
calculations.


73
Glenn


On 4/23/2017 2:31 PM, Dave Wood wrote:

Bill, actually what happened is the zener diode that the resistor fed
shorted and that's the reason it burned up.  I have two units with this
issue and I cannot read the resistor value since it burned up.  What I
would love to know is what the original value of the dropping resistor
was?  73  Dave

On Sat, Apr 22, 2017 at 11:39 PM, Bill Hawkins  wrote:


There is usually a power dissipation reason why a resistor becomes
toast, and the reason is frequently a shorted bypass cap or a shorted
device.

Have you measured the resistance to ground of the end of the resistor
opposite the power supply?

Sometimes inputs get high voltages and short the amplifying device.

Sometimes that is reason the units were for sale.

Hope I'm wrong.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave
Wood
Sent: Saturday, April 22, 2017 8:43 PM

Anyone on the list own the above Time Code Readesr.  I have one of each,
they are identical with the same issue.  I need to identify the correct
value of a resistor in the power supply that provides 27 volts to the
input amp.  They are both toast in my units and I do not have a manual.
Thanks in advance!  Dave ___

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---
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QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
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of the Amateur that holds the license"
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Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader

[Dave Wood]

Bill, actually what happened is the zener diode that the resistor fed
shorted and that's the reason it burned up.  I have two units with this
issue and I cannot read the resistor value since it burned up.  What I
would love to know is what the original value of the dropping resistor
was?  73  Dave

On Sat, Apr 22, 2017 at 11:39 PM, Bill Hawkins  wrote:

> There is usually a power dissipation reason why a resistor becomes
> toast, and the reason is frequently a shorted bypass cap or a shorted
> device.
>
> Have you measured the resistance to ground of the end of the resistor
> opposite the power supply?
>
> Sometimes inputs get high voltages and short the amplifying device.
>
> Sometimes that is reason the units were for sale.
>
> Hope I'm wrong.
>
> Bill Hawkins
>
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave
> Wood
> Sent: Saturday, April 22, 2017 8:43 PM
>
> Anyone on the list own the above Time Code Readesr.  I have one of each,
> they are identical with the same issue.  I need to identify the correct
> value of a resistor in the power supply that provides 27 volts to the
> input amp.  They are both toast in my units and I do not have a manual.
> Thanks in advance!  Dave ___
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
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> mailman/listinfo/time-nuts
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Re: [time-nuts] Frequency counter questions

[Bob kb8tq]

Hi


> On Apr 23, 2017, at 2:43 PM, Chris Albertson  
> wrote:
> 
> On Sun, Apr 23, 2017 at 7:38 AM, Bob kb8tq  wrote:
> 
>> 
>> 
>> If you want to do something like the 53131 or even the 5335, you will need
>> something a bit different
>> than the F7 to do it. They are wonderful MCU’s but not really fast enough
>> to do the fancy stuff.
>> 
> 
> 
> Yes, But I assume he is not going to do the actual counting in software.

Except that’s not what he *said* he was trying to do. Thus the confusion and 
attempt
to clarify what he’s trying to do. We now have a half dozen people who are 
equally 
confused about the task and no further input from the only person who actually 
*knows* what he’s trying to do. If indeed you have registers and the like, then 
they
are probably in an FPGA. If you already have an FPGA doing the high speed stuff,
the need for the F7 is even more questionable. Yes it’s a $12 or so chip, what 
needs
to be done can be done with a $2 chip. Not only is would it be cheaper. It 
likely 
would be faster and easier to get working. 

Bob


> He will likely be using the CPU to set and read some registers and control
> the user interface.
> 
> The time stamping idea is not bad.  But today you do NOT need to "post
> process".  Your little processor could do this in nearly real-time and
> you'd have results on the screen in seconds.
> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
> ___
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Re: [time-nuts] Frequency counter questions

[Bob kb8tq]

Hi


> On Apr 23, 2017, at 12:43 PM, Richard Solomon  wrote:
> 
> At that resolution, you need a very accurate and stable Time Base.
> 
> A GPSDO may not be good enough for 10 e12 measurements.
> 

If buy some truly strange chance, this *is* a 100,000 second gate time exercise
(which I very much doubt) …. a GPSDO may well be just fine for that level of 
performance. 
It would need to have a good antenna location and to be in a reasonable 
environment.
Other than that an OCXO based device should not have a lot of trouble after a 
couple days warmup. 

If somehow this morphs into a three sigma at 1x10^-12 accuracy at 1 second 
project 
then indeed, a GPSDO is not in any way going to be adequate to the task. You 
can pretty well
extend that to 10 and 100 seconds without much chance of being contradicted.  
You also
aren’t going to get that sort of accuracy at 1 second without doing a lot of 
heavy lifting 
counter hardware wise. The MCU choice becomes a very minor point on a fairly
long list. 

Bob


> 
> 73, Dick, W1KSZ
> 
> 
> Sent from Outlook
> 
> From: time-nuts  on behalf of Jerry Hancock 
> 
> Sent: Sunday, April 23, 2017 12:14:49 AM
> To: Discussion of precise time and frequency measurement
> Cc: met...@hanler.com
> Subject: [time-nuts] Frequency counter questions
> 
> Hello,  I would like to find a person that would be able to answer some 
> frequency counter questions I have.
> 
> Basically, I am thinking of building my own using one of the high end STM32F7 
> boards as the counter.  I would like it to count reliably to 12 digits (e.g. 
> 30,000,000.001x hz).  I am not worried about input conditioning as I have a 
> circuit that is suitable for my needs.  Most of my questions have to do with 
> using a prescaler on the front (divide by N where what is N) to get to the 
> desired resolution when using multiples of the PPS coming from my GPSDO.  
> Gate times could be as long as needed to get the resolution.  So what 
> prescaler do I need and what gate time is required are the first two 
> questions.  I suggest if someone is willing to help that they either reply 
> here with an email address or send a note to meters at hanler dot com.  This 
> is for my own non-commercial use.
> 
> Thanks!
> 
> Jerry
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Re: [time-nuts] Frequency counter questions

[Richard Solomon]

At that resolution, you need a very accurate and stable Time Base.

A GPSDO may not be good enough for 10 e12 measurements.


73, Dick, W1KSZ


Sent from Outlook

From: time-nuts  on behalf of Jerry Hancock 

Sent: Sunday, April 23, 2017 12:14:49 AM
To: Discussion of precise time and frequency measurement
Cc: met...@hanler.com
Subject: [time-nuts] Frequency counter questions

Hello,  I would like to find a person that would be able to answer some 
frequency counter questions I have.

Basically, I am thinking of building my own using one of the high end STM32F7 
boards as the counter.  I would like it to count reliably to 12 digits (e.g. 
30,000,000.001x hz).  I am not worried about input conditioning as I have a 
circuit that is suitable for my needs.  Most of my questions have to do with 
using a prescaler on the front (divide by N where what is N) to get to the 
desired resolution when using multiples of the PPS coming from my GPSDO.  Gate 
times could be as long as needed to get the resolution.  So what prescaler do I 
need and what gate time is required are the first two questions.  I suggest if 
someone is willing to help that they either reply here with an email address or 
send a note to meters at hanler dot com.  This is for my own non-commercial use.

Thanks!

Jerry
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Re: [time-nuts] Frequency counter questions

[Chris Albertson]

On Sun, Apr 23, 2017 at 7:38 AM, Bob kb8tq  wrote:

>
>
> If you want to do something like the 53131 or even the 5335, you will need
> something a bit different
> than the F7 to do it. They are wonderful MCU’s but not really fast enough
> to do the fancy stuff.
>


Yes, But I assume he is not going to do the actual counting in software.
He will likely be using the CPU to set and read some registers and control
the user interface.

The time stamping idea is not bad.  But today you do NOT need to "post
process".  Your little processor could do this in nearly real-time and
you'd have results on the screen in seconds.



-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Frequency counter questions

[Chris Albertson]

 Assuming you are counting every cycle with no pre-scaler and can't measure
the period, the answer is easy.

If you want to measure Hz then the gate needs to be 1 second.  If you want
to measure too 0.1 Hz then you need a 10 second gate.  In your case 0.001
Hz you need to count for 1,000 seconds.

If you use a prescaler let's say it is a "divide by N" then you multiply
the gate time by N.

If the frequency is high and you want to measure to .001 Hz then you need a
really large maximum count and will overflow a 32 bit integer  You want 12
digits so you need to use a 64 bit integer counter.

The STM32 has some pre-scalers built in and a built in counter too, I
think.  I don't know what their maximum speed is.   You don't need the
compute power is an STM32 but "why not" as they cost only $12, I use the
Nucleo boards and mbed.

The problem with counting to 12 digits is that you are only measuring the
average frequency over a very long interval.  The signal is likely not that
stable.   Lets say during that 10 second gate the signal was DC or zero Hz
for 5 seconds then went to 2 MHz.  You meter would read 1.000 MHz but the
signal was NEVER 1 MHz.


The OTHER way to measure frequency is harder but faster.  You measure the
period.   A perfect meter could mere the unknown frequency in one cycle.
It would not be an average.   But there are no perfect meters.

On Sun, Apr 23, 2017 at 12:14 AM, Jerry Hancock  wrote:

> Hello,  I would like to find a person that would be able to answer some
> frequency counter questions I have.
>
> Basically, I am thinking of building my own using one of the high end
> STM32F7 boards as the counter.  I would like it to count reliably to 12
> digits (e.g. 30,000,000.001x hz).  I am not worried about input
> conditioning as I have a circuit that is suitable for my needs.  Most of my
> questions have to do with using a prescaler on the front (divide by N where
> what is N) to get to the desired resolution when using multiples of the PPS
> coming from my GPSDO.  Gate times could be as long as needed to get the
> resolution.  So what prescaler do I need and what gate time is required are
> the first two questions.  I suggest if someone is willing to help that they
> either reply here with an email address or send a note to meters at hanler
> dot com.  This is for my own non-commercial use.
>
> Thanks!
>
> Jerry
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>



-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Frequency counter questions

[Bob kb8tq]

Hi

Counting 12 digits is relatively easy, if that is the only constraint. Bring 
your “signal” into one of the 
timer clock inputs on the MCU. If your “signal” is 10 MHz that will be simple. 
If it’s 30 GHz it will be
more difficult. 

10 MHz gives you 7 digits a second. To get to 12 digits, you need 100,000 
seconds. Roughly speaking,
your counter “gate time” would be one day.  If your input is 1 MHz, your “gate 
time” would be 10 days.

My *guess* is that there is a disconnect between what you want to do and what 
I’m hearing you want to do.



If you want to do something like the 53131 or even the 5335, you will need 
something a bit different 
than the F7 to do it. They are wonderful MCU’s but not really fast enough to do 
the fancy stuff.

Bob


> On Apr 23, 2017, at 3:14 AM, Jerry Hancock  wrote:
> 
> Hello,  I would like to find a person that would be able to answer some 
> frequency counter questions I have.  
> 
> Basically, I am thinking of building my own using one of the high end STM32F7 
> boards as the counter.  I would like it to count reliably to 12 digits (e.g. 
> 30,000,000.001x hz).  I am not worried about input conditioning as I have a 
> circuit that is suitable for my needs.  Most of my questions have to do with 
> using a prescaler on the front (divide by N where what is N) to get to the 
> desired resolution when using multiples of the PPS coming from my GPSDO.  
> Gate times could be as long as needed to get the resolution.  So what 
> prescaler do I need and what gate time is required are the first two 
> questions.  I suggest if someone is willing to help that they either reply 
> here with an email address or send a note to meters at hanler dot com.  This 
> is for my own non-commercial use.
> 
> Thanks!
> 
> Jerry 
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Re: [time-nuts] Frequency counter questions

[Azelio Boriani]

Up to the point that, to get 1milliHz resolution, you have to wait
1000 seconds (without the prescaler)? If you have a prescaler then it
will be N*1000 seconds...

On Sun, Apr 23, 2017 at 9:14 AM, Jerry Hancock  wrote:
> Hello,  I would like to find a person that would be able to answer some 
> frequency counter questions I have.
>
> Basically, I am thinking of building my own using one of the high end STM32F7 
> boards as the counter.  I would like it to count reliably to 12 digits (e.g. 
> 30,000,000.001x hz).  I am not worried about input conditioning as I have a 
> circuit that is suitable for my needs.  Most of my questions have to do with 
> using a prescaler on the front (divide by N where what is N) to get to the 
> desired resolution when using multiples of the PPS coming from my GPSDO.  
> Gate times could be as long as needed to get the resolution.  So what 
> prescaler do I need and what gate time is required are the first two 
> questions.  I suggest if someone is willing to help that they either reply 
> here with an email address or send a note to meters at hanler dot com.  This 
> is for my own non-commercial use.
>
> Thanks!
>
> Jerry
> ___
> 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] Frequency counter questions

[Magnus Danielson]

Hi Jerry,

Consider building a fractional frequency counter. In it, you will 
measure both the time and number of input events.


Consider building a time-stamping counter, in which post-processing can 
combine multiple timestamps (each holding time and event counters), as 
post-processing can help to improve resolution.


Consider how you can achieve highest time resolution of your start time 
and stop time, i.e. time-stamping.


Cheers,
Magnus

On 04/23/2017 09:14 AM, Jerry Hancock wrote:

Hello,  I would like to find a person that would be able to answer some 
frequency counter questions I have.

Basically, I am thinking of building my own using one of the high end STM32F7 
boards as the counter.  I would like it to count reliably to 12 digits (e.g. 
30,000,000.001x hz).  I am not worried about input conditioning as I have a 
circuit that is suitable for my needs.  Most of my questions have to do with 
using a prescaler on the front (divide by N where what is N) to get to the 
desired resolution when using multiples of the PPS coming from my GPSDO.  Gate 
times could be as long as needed to get the resolution.  So what prescaler do I 
need and what gate time is required are the first two questions.  I suggest if 
someone is willing to help that they either reply here with an email address or 
send a note to meters at hanler dot com.  This is for my own non-commercial use.

Thanks!

Jerry
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[time-nuts] Frequency counter questions

[Jerry Hancock]

Hello,  I would like to find a person that would be able to answer some 
frequency counter questions I have.  

Basically, I am thinking of building my own using one of the high end STM32F7 
boards as the counter.  I would like it to count reliably to 12 digits (e.g. 
30,000,000.001x hz).  I am not worried about input conditioning as I have a 
circuit that is suitable for my needs.  Most of my questions have to do with 
using a prescaler on the front (divide by N where what is N) to get to the 
desired resolution when using multiples of the PPS coming from my GPSDO.  Gate 
times could be as long as needed to get the resolution.  So what prescaler do I 
need and what gate time is required are the first two questions.  I suggest if 
someone is willing to help that they either reply here with an email address or 
send a note to meters at hanler dot com.  This is for my own non-commercial use.

Thanks!

Jerry 
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