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Hi Bob,
On 12/14/2014 06:00 PM, Bob Camp wrote:
Hi
On Dec 14, 2014, at 11:36 AM, Magnus Danielson
wrote:
On 12/12/2014 06:15 PM, Bob Camp wrote:
Hi
On Dec 12, 2014, at 11:44 AM, Li Ang wrote:
Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and
ref=5650 case.
Tom,
On 12/12/2014 08:01 PM, Tom Van Baak wrote:
Hi Li,
What you're doing is the same "trick" the Pendulum CNT-91 uses, as well as
modern Agilent frequency counters, and even my own picPET.
The good news is that for frequency measurement all those many samples and the sqrt(N)
advantage allow
Hi
> On Dec 14, 2014, at 11:36 AM, Magnus Danielson
> wrote:
>
>
>
> On 12/12/2014 06:15 PM, Bob Camp wrote:
>> Hi
>>
>>> On Dec 12, 2014, at 11:44 AM, Li Ang wrote:
>>>
>>> Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and
>>> ref=5650 case.
>>
>> In the “both sa
On 12/12/2014 06:15 PM, Bob Camp wrote:
Hi
On Dec 12, 2014, at 11:44 AM, Li Ang wrote:
Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and
ref=5650 case.
In the “both same (5650 / 5650) case” your linear regression filtering is
faking you out a bit. The SR620 count
quot;, 12, t);
msecond = 0;
i = 0;
}
}
2014-12-12 21:18 GMT+08:00 Bob Camp :
HI
On Dec 12, 2014, at 4:04 AM, Tom Van Baak wrote:
This large posting is from Li Ang.
/tvb
- Original Message -
From: Li Ang
To: Discussion of precise time and fr
Li,
> Since I really want to reduce the noise, what is the best test set you
> suggest?
...
> How to analyze the ADEV plot to get information about noise?
Note these two statements are at odds. On the one hand we all want to reduce
noise. But ADEV is all about measuring noise, not making it go
-
From: "Li Ang"
To: "Discussion of precise time and frequency measurement"
Sent: Friday, December 12, 2014 7:40 AM
Subject: Re: [time-nuts] Homebrew frequency counter, need help
Hi Bob,
The job done by linear regression is to reduce the uncertainty. This
counte
gt;> printf("\r\nFreq=%.*f", 14, t);
>>> ref_curr = refcnt - t3;
>>> sig_curr = sigcnt;
>>>
>>> t = CalcFreq(ref_curr - ref_start, sig_curr -
>>> sig_start); // without linear regression
>&
p;rv) ; // with linear regression
>>> printf("\r\nFreq=%.*f", 14, t);
>>> ref_curr = refcnt - t3;
>>> sig_curr = sigcnt;
>>>
>>> t = CalcFreq(ref_curr - ref_start, sig_curr -
>>>
ig_curr -
> > sig_start); // without linear regression
> >printf(" Interpolated=%.*f", 12, t);
> >
> > msecond = 0;
> > i = 0;
> >}
> > }
> >
> > 2014-12-12 21:18 GMT+08:00 Bob Camp :
> &
);
>
>msecond = 0;
> i = 0;
>}
> }
>
> 2014-12-12 21:18 GMT+08:00 Bob Camp :
>>
>> HI
>>
>>> On Dec 12, 2014, at 4:04 AM, Tom Van Baak wrote:
>>>
>>> This large posting is from Li Ang.
>>&
gt;msecond = 0;
> i = 0;
>}
> }
>
> 2014-12-12 21:18 GMT+08:00 Bob Camp :
>>
>> HI
>>
>>> On Dec 12, 2014, at 4:04 AM, Tom Van Baak wrote:
>>>
>>> This large posting is from Li Ang.
>>> /tvb
>>
> /tvb
> >
> > - Original Message -
> > From: Li Ang
> > To: Discussion of precise time and frequency measurement
> > Sent: Thursday, December 11, 2014 7:37 AM
> > Subject: Re: [time-nuts] Homebrew frequency counter, need help
> >
> >
> > Hi Bob
ject: Re: [time-nuts] Homebrew frequency counter, need help
>
>
> Hi Bob,
> I've sent the PCB to the factory and I am waiting for the new board. This
> time, it's a 4-layer borad and changed from CPLD to FPGA. This is the first
> time of FPGA & 4-layer proj
On Thu, 27 Nov 2014 08:20:59 -0800, you wrote:
>Your project sounds wonderful. The TDC-GP22 has been mentioned only a few
>times over the years and I keep waiting for someone to post actual results
>from this chip, or better yet -- schematics, photos, and source code.
Just happened to notice th
Hi
> On Dec 2, 2014, at 1:05 AM, LiAng wrote:
>
>
> Bob Camp writes:
>
>>
>> Hi
>>
>> Looks like something came loose when you swapped around the parts. That
> or the regulator is very noisy.
>>
>> Bob
>>
>
>
> I know why the stop1-start is not stable. There is a noise generator
> ena
Bob Camp writes:
>
> Hi
>
> Looks like something came loose when you swapped around the parts. That
or the regulator is very noisy.
>
> Bob
>
I know why the stop1-start is not stable. There is a noise generator
enabled. If start & stop1 is OK, I can change configuration to get 45ps or
Hi
Looks like something came loose when you swapped around the parts. That or the
regulator is very noisy.
Bob
> On Dec 1, 2014, at 11:39 AM, Li Ang wrote:
>
> New tests today. It's strange that the data is not so stable as before.
>
> I've already add a 22uF Ceramic Cap and a 100nF. 10ohm
New tests today. It's strange that the data is not so stable as before.
I've already add a 22uF Ceramic Cap and a 100nF. 10ohm resistor is removed.
First:
reg [15:0] shift;
always @(posedge refclk10M) begin
shift <= {shift[14:0], sw_gate};
end
assign tdc_start = shift[3];
assign tdc_stop1 = sh
Hi
Your data would be called “10 digits +/- 1.5 least significant digits”. Shave a
the spread down to 2 instead of 3 and you are at a very tight 10 digit spec.
Based on your equipment inventory, you have seen 10 digit +/- 2 counters. You
have them beat. The same is true of 9 digit +/- any count
Hi
Thanks for the great article.
I did a little test just now. To measure the refclk of itself. And this
is the result(I kept 10 digits of the fraction part):
### Frequency Counter startup ###
gate=1s #=8985 freq=10.02
gate=1s #=9038 freq=10.01
gate=1s #=9039 freq=10.0
> On Nov 28, 2014, at 9:18 PM, Angus wrote:
>
>
>
>
> On Fri, 28 Nov 2014 08:57:37 -0600, you wrote:
>
>> Hi
>>
>>> On Nov 28, 2014, at 7:04 AM, Li Ang wrote:
>>>
>>> The TDC-GP22 is the best choise for me at the moment. Since I am not a
>>> hardware guy, simplicity is important. It's ver
On Fri, 28 Nov 2014 08:57:37 -0600, you wrote:
>Hi
>
>> On Nov 28, 2014, at 7:04 AM, Li Ang wrote:
>>
>> The TDC-GP22 is the best choise for me at the moment. Since I am not a
>> hardware guy, simplicity is important. It's very cheap in China(About 3$
>> for each piece ).
>
>Which is a very g
On Fri, 28 Nov 2014 21:04:27 +0800, you wrote:
>The TDC-GP22 is the best choise for me at the moment. Since I am not a
>hardware guy, simplicity is important. It's very cheap in China(About 3$
>for each piece ).
>
>
>TDC-GP22 has 2 modes and 3 trigger inputs (start, stop1, stop2). The min
>time b
On 11/27/2014 03:08 PM, lllaaa wrote:
> Hi guys,
> I've just get my homebrew counter working. And the resolution seems 10x
> better than my RACAL DANA 1992.
> This counter is heavily inspired by the idea from Kasper Pedersen.
> http://n1.taur.dk/permanent/frequencymeasurement.pdf
> STM3
Hi
> On Nov 28, 2014, at 10:14 AM, Li Ang wrote:
>
>>
>> 1) What frequency is the crystal at? (can you drive the chip from an OCXO?)
>
> I'm clking this chip with the refclk/2=5Mhz, which is done by cpld.
> something like always @(posedge refclk) tdc_clk <= ~tdc_clk; Not sure if
> it's noisy.
>
> 1) What frequency is the crystal at? (can you drive the chip from an OCXO?)
I'm clking this chip with the refclk/2=5Mhz, which is done by cpld.
something like always @(posedge refclk) tdc_clk <= ~tdc_clk; Not sure if
it's noisy.
2) Is there more bypassing on the circuit than shown? (If not, a
Hi
> On Nov 28, 2014, at 7:04 AM, Li Ang wrote:
>
> The TDC-GP22 is the best choise for me at the moment. Since I am not a
> hardware guy, simplicity is important. It's very cheap in China(About 3$
> for each piece ).
Which is a very good reason to play with it …
>
>
> TDC-GP22 has 2 modes a
Hi
> On Nov 28, 2014, at 6:26 AM, Li Ang wrote:
>
> I did a little calculation and it's a 10 digits counter.
> log(10,000,000,005) = 10.
> There is still a big gap between this one and 53132A :(
Not if you can hit the advertised time resolution of your chip. Keep on working
on this.
>
> For
I did a little calculation and it's a 10 digits counter.
log(10,000,000,005) = 10.
There is still a big gap between this one and 53132A :(
For 53132A, the time resolution is 150ps, which I think is 10digits/s with
interpolator. According to the schematics the only difference between
53132A & 53131
Hi
One way of looking at resolution is at the one standard deviation point.
Another way of looking at it is as a +/- 1 digit accuracy point. Each approach
has it’s advantages. It’s more common to see single shot timing specified as
one sigma and frequency specified as +/- 1 count. Often you nee
Thanks for the info.
What's the standard to be 11 digits/s? For real 11 digits/s, the ADEV
needs to reach the 1e-11 level? I'm not sure if my GPSDO & Rb is stable
enough. Maybe 2 MV89A as the refclk and signal?
TDC-GP22 has it problem, I will post some data/schematic/source code
about it late
way the host
software (for example PC running John's TimeLab program) can manage the data
stream, simultaneously delivering phase, frequency, and ADEV plots.
/tvb
- Original Message -
From: "lllaaa"
To:
Sent: Thursday, November 27, 2014 6:08 AM
Subject: [time-nuts] Hom
Hi guys,
I've just get my homebrew counter working. And the resolution seems 10x
better than my RACAL DANA 1992.
This counter is heavily inspired by the idea from Kasper Pedersen.
http://n1.taur.dk/permanent/frequencymeasurement.pdf
STM32F051RB & EMP240T100C5 do the control and counting
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