ub-harmonic
>>>> and the carrier. You rarely know what the phase shift is, but you can
>>>> read
>>>> the sub-harmonic. The simple db to jitter ratio gets you close enough to
>>>> make rational decisions on how much filtering you need. You could
>>&
on of precise time and frequency measurement
Subject: Re: [time-nuts] Z3805 two frequency maxima
I followed your argument and tried to synthesize such a signal. I built
a simple power combiner (3 times 18 ohms resistors) and combined the 10
MHz reference output of my signal generator with a 5
I agree. Please, Paul, start a new thread, and we'll be there.
Volker
Am 28.11.2012 08:10, schrieb Hal Murray:
You might get better answers by starting a new thread rather than hiding your
question in an existing thread. (Use your New message button rather than
Reply, and cut-paste the To ad
You might get better answers by starting a new thread rather than hiding your
question in an existing thread. (Use your New message button rather than
Reply, and cut-paste the To address from an old message, then type in the new
Subject.)
Using a useful Subject also helps people find things i
Greetings!
I just joined the list a few hours ago and you have already peeked
my interest in this aside:
On Tuesday, 27 November 2012, Volker Esper wrote:
Though the SR620 TIC is a great instrument when hunting the pico seconds
we have to realize, that it's a thermal design desaster (I have
th
filter phase but I've never seen that done in practice.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Volker Esper
Sent: Tuesday, November 27, 2012 2:34 PM
To: Discussion of precise time and frequency measurement
Subject: Re
r Esper
> Sent: Tuesday, November 27, 2012 2:34 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Z3805 two frequency maxima
>
>
> I followed your argument and tried to synthesize such a signal. I built
> a simple power combiner (3 times
2:34 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Z3805 two frequency maxima
I followed your argument and tried to synthesize such a signal. I built
a simple power combiner (3 times 18 ohms resistors) and combined the 10
MHz reference output of my s
I followed your argument and tried to synthesize such a signal. I built
a simple power combiner (3 times 18 ohms resistors) and combined the 10
MHz reference output of my signal generator with a 5 MHz signal from the
same generators regular output at the same amplitude. My oscilloscope
showed
Hi
I've always wondered if the magic A1U1 1820-2312 in the 5380A has a frequency
multiplier of some sort in it. I've never dug into it far enough to answer the
question though.
Bob
On Nov 18, 2012, at 8:12 PM, Volker Esper wrote:
>
> As far as I can see the PLL loop filter (SR620) has a co
As far as I can see the PLL loop filter (SR620) has a corner frequency
of about 33Hz. My HP counter 5385A has simply a switch to toggle between
the external source and the internal osc.
Am 18.11.2012 22:45, schrieb Bob Camp:
Hi
Most modern counters have an internal oscillator that they l
Hi
Most modern counters have an internal oscillator that they lock up to the
external reference. The PLL bandwidth is (hopefully) chosen to optimize the
noise contribution of the internal oscillator (quiet broad band) and the
external reference (quiet close in). It will reject anything MHz away
> ...A PLL multiplier will (likely) also ignore the sub-harmonic, the
> jitter will not show up if you use the 10 MHz as a counter timebase
> in a HP counter...
Yes, I wondered what the histogram would show when using the
2-maxima-Z3805 signal as a reference for the SR620 counter. Would the
P
Hi
This is one of those interesting areas where a broadband measurement (like a
counter) and a narrowband measurement (like a DMTD) will give very different
results. The counter will see the sub-harmonic, and call it jitter. It can show
up in an ADEV calculation. A DMTD will ignore the sub-harm
@Azelio: Yes, (like Bob told) it's the phase lock, that locks the two
maxima. Actually the counter is able to look between the 60ps spaced
towers, have a look at the pictures in the first mail of this thread.
However, there is a smallest time value the counter can determine, but
it is much sm
Hi
The 5 MHz and 10 MHz are "locked together" by the multiplier. Their relative
phase is fixed. The 5 MHz component is not free to wander independently
relative to the 10 MHz. Since it's a doubler, you get a two peak plot. If it
was a X3 you would get three peaks. It really only makes sense i
Interesting this, but why exactly 60pS? I would expect also something
in-between. That is, to have the 5MHz energy 64dB below, in my opinion
nothing prevents to have the edge to wander not only at 60pS but
continuously between 0 and 60pS. Maybe the SR620, being a 25pS resolution
counter, simply doe
Hi
A little more detail:
What's going on is more clear if you trigger a scope on the positive edge of
the 5 MHz and look at the 10 MHz. With an ideal multiplier, both the positive
and negative edges of the 5 MHz should line up exactly with a positive edge of
the 10 MHz. In reality, negative ed
Hi
Just good old Fourier series.
Bob
On Nov 17, 2012, at 9:12 PM, Volker Esper wrote:
>
> I'm impressed - but what law is behind this?
>
>
> Am 17.11.2012 21:26, schrieb Bob Camp:
>> Hi
>>
>> 60 db isn't to bad a number. More or less:
>>
>> 100 ns -> 100 ps is 1000:1. 20 log of that is
I'm impressed - but what law is behind this?
Am 17.11.2012 21:26, schrieb Bob Camp:
Hi
60 db isn't to bad a number. More or less:
100 ns -> 100 ps is 1000:1. 20 log of that is 60 db. 100 ps to 60 ps is about
4.4 db. That would sum up to -64.4 dbc. The main gotcha is that you *might* also
Hi
60 db isn't to bad a number. More or less:
100 ns -> 100 ps is 1000:1. 20 log of that is 60 db. 100 ps to 60 ps is about
4.4 db. That would sum up to -64.4 dbc. The main gotcha is that you *might*
also have some 15 MHz (and higher) energy in the signal as well. Also phase
gets into the calc
So let's have a look into the machine... and what do we see? There's a
nice little Symmetrcom oven, with the sign reading "5.000 MHz" - bingo!
May be there's a time saving way to determine the energie of the sub
harmonic: using my spectrum analyzer. It tells me, that there's a 5 MHz
subharmo
Hi
That's what you get if you have "sub harmonic" energy in the output of your
OCXO. I'd bet you a warm glass of beer that you have a 5 MHz / doubled to 10
MHz MTI OCXO in your Z3805. If you have a lot of time on your hands, you can
calculate the likely level of the energy from the amount of j
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