In message , "John Miles" writes:
>> That is actually a very debatable proposition, a lot of them are
>> tracking types that conveniently cover up any lack of linearity
>> on the analog side of the fence.
>
>Can you elaborate on that? Linearity is linearity - wouldn't it ultimately
>show up in th
On 27 June 2010 10:05, Chris Stake wrote:
> Here we go again
OK, firstly I must apologise to the list for generating a large amount
of, useful, traffic on this topic as it seems to have upset some.
Maybe it's because of the sensitivity to run away threads caused by
the TPLL debarcle or maybe it's
Moin-Moin Atilla,
The 4002 expects a tight phase lock on the two inputs to properly stay locked,
and your adc/dac will likely introduce too much phase lag and cause
oscillation. In fact when using the Analog Devices PLL simulator one has to
closely follow the component values of the loop filter
Was 'surfing' and stumbled across this.
http://www.precisionsundials.com/index.htm
Had to share it.
Joe
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I have been thinking about a faster counter also but the Shera board was
depending on the jitter in the 24 Mhz clock to average out the +- count. The
faster clock would reduce the need for this but without the right amount of
jitter we lose the benefit of this average.
Stanley
- Original
Stanley
the faster counter also has the jitter, no change, as long as it is not
tied to the input frequency. The 24 MHz is not unique, the 100 MHz is same
technology just four times faster and thus gives me smaller steps on the D/A
and since I use it on Rub. the full range of the 18 bit cove
Yes I see your need for a reduced range with smaller steps. But I was looking
for smaller steps to improve the tracking accuracy without a loss of the
benefit of averaging. From the QST article:
"Interestingly, it is desirable to have the frequency of U7 drift slightly
rather than being synchr
Going from 24 to 100 MHz only gives you smaller steps (resolution) every
thing else stays the same.
If the he saw 2 to 3 nsec should be more like 8, going to 100 MHz will
improve it by a factor of 4. In a redesign of the total system I would have two
sample sizes maybe stay with 30 or go to 5
> "Interestingly, it is desirable to have the frequency of U7 drift slightly
> rather than being synchronized with the VCXO. A slight random drift averages
> out the count ambiguity that is inherent in any pulse-counting device. My
> measurements indicate that the simple phase-measuring circuit I
I have a design which locks a high performance 10MHz OCXO to a 10MHz
source which should work equally well with the LEA5, or any source of 5
or 10MHz.
I designed it for use with a distributed factory GPS reference which has
picked up noise, hum and phase modulation, in order to deliver a high
qual
Without knowing your 100Mhz clock would it not need less jitter to average out
+- one count at 100Mhz vs one count at 24Mhz?
The GPS error has improved with better hardware/software in the receivers as
well as turning off SA. So I'm not so sure the GPS error will wash out the
counter's error. E
Stanley
I am not an expert but it is not only the jitter it is the fact that since
the two sources are not linked the independent drift of the 100 MHz causes
a distribution of the count. Again even with the same resolution the count
error will be four X and the subsequent correction will be t
On 06/26/2010 09:11 AM, Richard H McCorkle wrote:
Fellow Time-Nuts,
When I first uploaded the Simple PICTIC interpolating time interval
counter to the K04BB site in 12/08 and presented it to the group as
a Christmas present my goal was to get amateurs building their own
interpolating time interva
Jitter may not be the correct word. I also don't know how accurate or
repeatable the averaging effect is as described in the article. But I do
believe the amount of drift is important for this to work as stated before.
Independent is required, if locked then this is the extreme case of no drift
As asked by another, please post a PDF of the schematic. I don't have
any software installed that can read the files you posted.
Joe Gray
W5JG
On Sun, Jun 27, 2010 at 3:54 PM, Magnus Danielson
wrote:
> On 06/26/2010 09:11 AM, Richard H McCorkle wrote:
>>
>> Fellow Time-Nuts,
>> When I first uplo
My last statement is not quite correct.
"If the drift is too big we will over shoot to the next higher integer number
and this will bias the average up too high."
In the case where the 100Mhz clock drifts both up and down the number could
average to the correct fraction. But now the rate of dr
Stanley
Let me try one more time after that I give up maybe some one else can try.
If the time between the GPS signal and the reference drifts by 100 nsec.
the counter in the Shera 24 MHz board will detect it and based on that make
the decision to change the D/A to compensate for it at a rate
done
www.n4iqt.com/picticii/circuit.jpg
www.n4iqt.com/picticii/PICTICII.bmp
both above as pdf
www.n4iqt.com/picticii/circuit-pcb.pdf
Stanley
- Original Message
From: Joseph Gray
To: Discussion of precise time and frequency measurement
Sent: Sun, June 27, 2010 6:01:28 PM
Subject:
Instead of a real "Geochron" (www.geochron.com) I saved a big bundle of cash
by purchasing the "World Watch" software from www.exptech.com . But now I'm
wondering if there's anything like that for the iPad (and/or if anyone on
this list would be interested in creating such an App).
Short of that,
I'm just a hobbyist and have a lesser understanding of this stuff than
yourself. I'm interested to hear more about your project and also the
PICTIC+ II that is mentioned on the web page. Some specs would be nice
and if you have any type of user manual, that would even be better. If
a kit is in the
All this talk about interpolation reminds me of a little neat chip by Analog
Devices, AD9500. It's programmable digital delay, bit, with lops resolution
with a loons full-scale range. I believe (from app notes) you can push it
to 100us FS, giving 390ns resolution. I think the minimum jitter a
Thanks for the PDF files.
Joe Gray
W5JG
On Sun, Jun 27, 2010 at 5:46 PM, Stanley Reynolds
wrote:
> done
>
> www.n4iqt.com/picticii/circuit.jpg
>
> www.n4iqt.com/picticii/PICTICII.bmp
>
> both above as pdf
>
> www.n4iqt.com/picticii/circuit-pcb.pdf
>
> Stanley
>
>
>
> - Original Message
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