10 MHz -> 16 MHz
Same question 10 to 12:-)
On Sat, Sep 29, 2018, 8:58 PM Tom Van Baak tvb@leapsecond.com wrote:
What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out of
10 MHz? Low phase noise isn't a big requirement and jitter doesn't need to
be sub-nanosecond. The main requirement is perfect cycle count accuracy.
This is for driving a 16 MHz microcontroller from a 10 MHz Rb/Cs/GPSDO. 10
MHz input is likely sine; 16 MHz output is 3v3 or 5v CMOS.
Thanks,
/tvb
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Am 30.09.2018 um 15:44 schrieb Pete Lancashire:
Same question 10 to 12:-)
Same Answer.
Select pins = (1, 1, 0) for 12 instead of (1, 1, 1) for 16.
\Gerhard
Almost same answer as I gave Tom. Double to 20, divide by 10, and then mix
the 2 with the original 10, You could also just divide by 5 and then mix
that 2 with the original 10. Again, filtering required. 73 - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
848-245-9115
-----Original Message-----
From: time-nuts time-nuts-bounces@lists.febo.com On Behalf Of Pete
Lancashire
Sent: Sunday, September 30, 2018 9:45 AM
To: Tom Van Baak tvb@leapsecond.com; Discussion of precise time and
frequency measurement time-nuts@lists.febo.com
Subject: Re: [time-nuts] 10 MHz -> 16 MHz
Same question 10 to 12:-)
On Sat, Sep 29, 2018, 8:58 PM Tom Van Baak < mailto:tvb@leapsecond.com
tvb@leapsecond.com> wrote:
What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out
of
1Almost 0 MHz? Low phase noise isn't a big requirement and jitter doesn't
need to be sub-nanosecond. The main requirement is perfect cycle count
accuracy.
This is for driving a 16 MHz microcontroller from a 10 MHz
Rb/Cs/GPSDO. 10 MHz input is likely sine; 16 MHz output is 3v3 or 5v CMOS.
Thanks,
/tvb
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It surprises me how the SDR designers in 90% of the cases don't even allow
for an external clock. It's like accuracy never came into thought.
On Sat, Sep 29, 2018, 8:58 PM Tom Van Baak tvb@leapsecond.com wrote:
What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out of
10 MHz? Low phase noise isn't a big requirement and jitter doesn't need to
be sub-nanosecond. The main requirement is perfect cycle count accuracy.
This is for driving a 16 MHz microcontroller from a 10 MHz Rb/Cs/GPSDO. 10
MHz input is likely sine; 16 MHz output is 3v3 or 5v CMOS.
Thanks,
/tvb
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On Sat, 29 Sep 2018 20:57:14 -0700
"Tom Van Baak" tvb@LeapSecond.com wrote:
What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out of
10 MHz? Low phase noise isn't a big requirement and jitter doesn't need
to be sub-nanosecond. The main requirement is perfect cycle count accuracy.
This is for driving a 16 MHz microcontroller from a 10 MHz Rb/Cs/GPSDO.
10 MHz input is likely sine; 16 MHz output is 3v3 or 5v CMOS.
The simplest way I can think of is the following:
Use a 74LV8154 to divide the 10MHz down to 152.587890625Hz.
Use the capture timer unit of the uC to measure the phase of the
pulse. Use any kind of DAC (internal, external, PWM,...) to steer
the 16MHz VCO. Depending on how fast the timer unit runs, this
will give you something in the order of 10-200ns dead-band.
By choosing the right frequency for the timer unit, one can
get it to "dither" a bit and then use averaging.
For lower jitter, use one half of a Nutt interpolator
to get the timing difference between the 152Hz signal
and the 16MHz (ie similar to what the SRS FS740 does).
Use something akin Nick Sayer's time-to-amplitude converter
for the fine measurement.
Same works equally well for 12MHz.
Attila Kinali
--
<JaberWorky> The bad part of Zurich is where the degenerates
throw DARK chocolate at you.
On 9/29/18 8:57 PM, Tom Van Baak wrote:
What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out of 10 MHz? Low phase noise isn't a big requirement and jitter doesn't need to be sub-nanosecond. The main requirement is perfect cycle count accuracy. This is for driving a 16 MHz microcontroller from a 10 MHz Rb/Cs/GPSDO. 10 MHz input is likely sine; 16 MHz output is 3v3 or 5v CMOS.
Thanks,
/tvb
cycle counts over what interval? 5 and 8 cycles respectively? or over,
say, 1 second?
Multiply by 8 divide by 5 seems a bit tricky (although any number of off
the shelf DDS will do it at fairly high power dissipation)
You might be able to injection lock an 80MHz oscillator by coupling the
10 MHz in on the Vcc or output.
Then a divide by 5 down to 16.
If the requirement is over 1 second, then you can play a game with
counting the first half of the second, and adjusting in the second by
dropping/adding cycles to make it come out right. THat sounds pretty icky.
Am 30.09.2018 um 16:49 schrieb Attila Kinali:
The simplest way I can think of is the following:
Use a 74LV8154 to divide the 10MHz down to 152.587890625Hz.
Use the capture timer unit of the uC to measure the phase of the
pulse. Use any kind of DAC (internal, external, PWM,...) to steer
the 16MHz VCO. Depending on how fast the timer unit runs, this
will give you something in the order of 10-200ns dead-band.
By choosing the right frequency for the timer unit, one can
get it to "dither" a bit and then use averaging.
For lower jitter, use one half of a Nutt interpolator
to get the timing difference between the 152Hz signal
and the 16MHz (ie similar to what the SRS FS740 does).
Use something akin Nick Sayer's time-to-amplitude converter
for the fine measurement.
Same works equally well for 12MHz.
Wow. That's truly a Rube Goldberg design.
There is a simpler way. IDT ICS570. Digikey 800-1073-5-ND
Solder time less than 10 minutes.
I had the 3V3-Version in the parts drawers, officially it takes the 5V
version to generate the 160 MHz, but the 3V3 version happened to work, too.
The difference between 120 and 160 MHz is just a GND wire on pin 6 (vs.
open)
Divide by 10 is left as an exercise.
regards,
Gerhard
(But then, some like to build and tune multiplier chains and mixers.)
My 2 cents. Attached image is a little board with OCXO that
outputs 16MHz locked automatically to either 5 or 10MHz. I have
several that will be part of the oscillator giveaway.
I bet someone can figure out how it works from the picture!
Best,
Bob Martin
On 9/29/2018 9:57 PM, Tom Van Baak wrote:
What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out of 10 MHz? Low phase noise isn't a big requirement and jitter doesn't need to be sub-nanosecond. The main requirement is perfect cycle count accuracy. This is for driving a 16 MHz microcontroller from a 10 MHz Rb/Cs/GPSDO. 10 MHz input is likely sine; 16 MHz output is 3v3 or 5v CMOS.
Thanks,
/tvb
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I'd recommend keeping the involved frequencies and power as low as
possible. The VCO/PLL route is probably the most straightforward, but
using arithmetic operations instead can be simpler at this frequency,
because the filtering can be readily done with common crystals.
If you divide the 10 MHz by 5, then mix the resulting 2 MHz back with
the 10, you'll get mostly 12 and 8 MHz. Double that result to get mostly
24 and 16 MHz, then filter the 16 MHz out with as fancy a filter as
necessary. 16 MHz is a very common crystal frequency, so you could do
that for filtering, or even make a ladder filter with a bunch of them.
With the VCO/PLL approach, the desired 16 MHz will be the highest
frequency, while the arithmetic one uses 24 MHz maximum working
frequency, neglecting harmonics. The logic can all be done with 74HC, at
reasonable quietness and power.
Ed
and what wold happen if you divide the 10MHz by 10 -- with any simple
counter chip -- and injection lock a 16MHz crystal oscillator with that
1MHz, since the jitter is not critical .... of course it does not hurt
if you make the 1MHz pulses narrow, you could use the micro-controller's
own oscillator circuit, plus that counter [freq divider chip ] it is
simple and cheap enough?
73
KJ6UHN
Alex
On 9/30/2018 7:54 AM, jimlux wrote:
On 9/29/18 8:57 PM, Tom Van Baak wrote:
What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out
of 10 MHz? Low phase noise isn't a big requirement and jitter doesn't
need to be sub-nanosecond. The main requirement is perfect cycle
count accuracy. This is for driving a 16 MHz microcontroller from a
10 MHz Rb/Cs/GPSDO. 10 MHz input is likely sine; 16 MHz output is 3v3
or 5v CMOS.
Thanks,
/tvb
cycle counts over what interval? 5 and 8 cycles respectively? or
over, say, 1 second?
Multiply by 8 divide by 5 seems a bit tricky (although any number of
off the shelf DDS will do it at fairly high power dissipation)
You might be able to injection lock an 80MHz oscillator by coupling
the 10 MHz in on the Vcc or output.
Then a divide by 5 down to 16.
If the requirement is over 1 second, then you can play a game with
counting the first half of the second, and adjusting in the second by
dropping/adding cycles to make it come out right. THat sounds pretty
icky.
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