Re: [time-nuts] Trimble Thunderbolt GPSDO Troubleshooting

[Ryan Stasel]

All,

Yay progress (one step forward into the next wall). I got the MAX232 chip 
replaced with a MAX202 (pin compatible, better ESD and Latchup protection). 
That got the serial working, and I was able to watch the unit do a survey, and 
then confirm it saw that the Osc was off by ~ -2700ppb, and the PPS. I did a 
factory reset as well.

After it did a full survey, it came back and confirmed that the oscillator 
adjustment was at a rail. It read the DAC 4.90. But the output of the 
reference was still -0.6V. So I’m guessing that chip is toast. I’ve got one on 
order. Also confusing is the quad op-amp seems to be saturated at the negative 
rail. I can see this Opamp feeds the adjust pin on the OCXO, but I’m not sure 
what feeds it. Guessing the FPGA? I still can’t find the DAC… all I see are 
these pictures http://www.leapsecond.com/pages/tbolt/photos.htm but the 
pictures aren’t of the DAC, unless the DAC is a resistor ladder (hadn’t thought 
of that until now). Now I’m starting to realize this is probably the case. =P

So, any input on where I might want to look? Does it seem likely the 5V 
reference is dead, or just being down below ground? Tracing the board out is 
proving rather beyond my ability. I don’t really want to just lift the output 
of the 5V reference and leave whatever it feeds floating.

Any help would be greatly appreciated.

Thanks!

-Ryan Stasel

On Mar 27, 2016, at 4:59 PM, Ryan Stasel 
> wrote:

All,

So, ended up pulling the 232 chip, and it seems to test okay as far as 
resistance between pins, and the board still only shows 65ohms or so between 
+5v and ground around that chips pads (support caps, pads, etc). I’m not sure 
if that’s “normal”, but it doesn’t seem like it is to me. Nothing seems to be 
getting abnormally warm. =/ I’m half curious if my meter (Keithley 196, and a 
Fluke 189) is turning on a transistor partially. =/

I do see what appears to be TTL level serial communication on the inputs to 
that chip. The replacement should be here on Monday, but at this point I'm 
wondering if my meter might be turning on some transistor (it shouldn't), 
or...? I would think a shorted cap would itself heat up.

There's a thread online relating to MAX232 type chips suffering from latchup 
under certain conditions 
(https://e2e.ti.com/support/interface/etc_interface/f/392/t/233847). But the 
low resistance between power and ground rails has me a bit concerned. :/

I did leave the unit running for about an hour, and the 10Mhz never came down 
from its 26hz high. Seeing that, I looked at the adjust pin on the OCXO, and 
it’s pegged at -10.25V. That also appears on all the outputs from the LT1014. 
=/ Also in that area is the 5V reference, and checking the output of that shows 
-0.6V (should be 5V). I’m… really starting to worry this whole thing is toast. 
All the rails appear fine, so I can’t help but think the previous owner hooked 
up the power wrong, and either -12V or +12V got applied to the 5V parts. =/ I’m 
fine replacing these two other LT parts, I’m just starting to worry that 
something not as easy to replace could be damaged (the FPGA, the Trimble chip, 
etc). Where is the actual DAC (is that in the FPGA)? Though I suppose if the 5V 
reference is dead, that would probably prevent the DAC from functioning. I 
guess the question would be if something is pulling the ref down (below 
ground), or is it just borked?

Anyway, hopefully I’ll at least be able to hook up serial to it tomorrow 
evening and see what Tboltmon says.

Thanks again for the help. Let me know if you have any other thoughts for 
things I can check.

Ryan Stasel
IT Operations Manager, SOJC
University of Oregon

Sent from my iPhone

On Mar 27, 2016, at 8:53 AM, Robert LaJeunesse 
> 
wrote:

Ryan,

The cap across 1-3 is the one that boosts +5V to +10V, with pin 2 being the 
+10V result. Thus the pins on this "flying" cap swing 5V p-p (pin 3 is 0 to 5, 
pin 1 is 5 to 10). The cap across 4-5 is the one that inverts +10V to -10V, 
with pin 6 being the -10V result. Pin 6 should NOT be at ground. The pins on 
this second flying cap swing 10V p-p (pin 4 is 10 to 0, pin 5 is 0 to -10).

Inputs to the transmitter stages (10 & 11) should be at valid logic levels, for 
the ICL232 these are standard TTL levels. Be aware that other part types that 
do this same function may not have the same logic levels (Vih and Vil) so be 
careful when substituting.

I did not mean to suggest lifting pins 10 or 11, although you might consider 
that last, but pins 7 and 14 should idle near -10V since the transmitter inputs 
have pullups and the drivers invert. What I was suggesting is to make sure pins 
8 & 13 were disconnected [just pull off any RS-232 cable] and look for pins 9 
and 12 to be at a good high level, say above 4V or so.

FWIW it's just as difficult to get -12V from +12V via an inverter chip as it is 

[time-nuts] Databooks now on KO4BB site

[paul swed]

Thanks to Walter for the databooks and Didiers work to grab and then
organize them on the KO4BB site they now have another great home.


The Sphere documents are on line.

"
http://www.ko4bb.com/getsimple/index.php?id=manuals=09_Components_Specs_Datasheets/Databooks_from_Sphere
"


Regards
Paul
WB8TSL
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Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

[Bruce Griffiths]

Inversion of gain isn't required, the system will just lock on the opposite 
slope of the phase detector output. Level shifting to accommodate different EFC 
ranges nay be useful however.
Bruce
 

On Tuesday, 29 March 2016 1:12 PM, Magnus Danielson 
 wrote:
 

 Hi Oleg,

I like the simplicity here.

Would not GNUradio be a good platform to encode the calibration stuff a 
little more gift-wrapped?

What spectrum-analyzer software do you use? (Just curious)

This simple setup would be useful for many purposes.

Depending on the oscillator, the EFC can need inversion, so I sketched 
for a similar design such that I could jumper it for either polarity. In 
that design I put the inverter after the integrating op-amp.

Cheers,
Magnus

On 03/28/2016 10:04 PM, Oleg Skydan wrote:
> Hi, everybody!
>
> OK. Let's start. Here is the schematics of the "test set"
> http://skydan.in.ua/PNTestSet/PN%20Test%20set.pdf . It consists of three
> small
> boards:
> 1. Mixer board - a simple mixer (500MHz ADE-1+) with 200kHz pi-LPF at
> the mixer output.
> 2. LNA board - a non-inverting low noise AF amplifier based on AD797
> with switchable 20/40dB gain.
> 3. PLL board - contains two TL071 OP amps. One is inverting amplifier,
> the other is PLL integrator. The R4,R8,R2,R7,C8 sets the PLL parameters
> - gain, passband and damping factor. Loop parameters are also dependent
> of signal levels and VCO tuning sensitivity. So you may need to correct
> them if your setup differs from mine - VCXO's I use have tuning
> sensitivity approx 100Hz/V and I set RF level at mixer near 0dBm with LO
> level near +7dBm. If you want to build universal test set you will need
> to use some switchs to allow setting different loop parameters (I just
> use my soldering iron and change parts if needed :) ).
>
> The power supply is a simple design based on 7812/7912 regulators.
>
> I use the E-MU 0202 USB external sound card and laptop PC as the AF
> spectrum analyzer.
>
> You will also need some cables. Different fixed attenuators or
> switchable one will be also helpful.
>
> I also have several homemade low noise VCXOs for some frequencies (7MHz,
> 10MHz, 14.318MHz, 60MHz) which I use as the reference signal sources to
> make measurements at these frequencies.
>
> Another option is to test two identical oscillators (or other signal
> sources). Assuming that both signals will have identical phase noise
> characteristics we can correct the results by 3dB (or just add 3dB
> correction during calibration).
>
> The calibration and use is simple.
> 1. Set LNA gain to 20dB.
> 2. Set the FFT parameters - flattop window, small (2048..4096) points
> number and short averaging in SA software.
> 3. Connect reference signal to LO mixer port and signal you are going to
> test to RF mixer port through the attenuator. Do not close the PLL yet.
> 4. Set the beat level a bit less then the sound card full scale using
> the attenuator. Check the beat harmonics levels - they should be at
> least 30dB lower then the beat level (add more attenuation if harmonics
> are higher).
> 5. Now set the spectrum analyzer calibration so that beat level is at
> -27dB if you measure against low noise reference VXCO, or -30dB if you
> use two identical oscillators.
> 6. Switch the LNA to 40dB gain.
> 7. Set SA software to Blackman window, 131072points/96kHz SR/necessary
> averaging, close PLL, wait for the lock, measure the phase noise.
>
> Why I am calibrating to -27/-30dB:
> 20dB because the LNA gain is 20dB less during the calibration (compared
> to measurement time)
> 1dB because of FFT parameters 96k/131072 = 0.73Hz * 1.73 (Blackman
> window) = 1.267Hz, 10 log10(1.267) = 1.03dB
> 6dB is the correction inherent to used calibration method
> additional 3dB needed in case of testing identical oscillators.
>
> Now some words about results. The noise floor of this test set depends
> of the signals levels, and with the optimal levels it is in
> -160..-170dBc/Hz range (depending of the offset from the carrier). It
> completely satisfies my needs, better results can be achieved with the
> higher level mixer and/or better LNA. I just used parts that I had :).
>
> Here http://skydan.in.ua/PNTestSet/Screen%20(420)-e.png is an example of
> the phase noise measurements results of my homemade low noise 60MHz VCXO
> (two identical units were measured). The results at the offsets greater
> then 1kHz should be corrected cause the oscillators noise is too close
> to test set noise (the real oscillator noise is a bit lower then the
> displayed one). The test set noise floor and calibration spectrum is
> also there.
>
> The boards also have other use.
>
> For example I was able to measure my home made 60MHz VCXO harmonic
> content http://skydan.in.ua/PNTestSet/Screen%20(414)-e.png using the
> mixer, LNA boards and signal generator. I have no spectrum analyzer so
> it is a big help to me :).
>
> Power supply noise can be investigated with the LNA board and sound
> card. Look 

Re: [time-nuts] Prescaler

[Bob Albert via time-nuts]

Dave, my counter is a 5328A with channel C to 500 MHz.  It actually counts well 
to about 700 MHz.
Yes I would like a copy of that article; my email is bob91343 at yahoo dot com. 
 I will also check out the ebay references to boards; I hadn't seen those.
Thanks for the help!
Bob
 

On Monday, March 28, 2016 7:20 AM, Bob Albert via time-nuts 
 wrote:
 

 Dennis, that looks interesting but it seems to be a complete counter.  I 
wonder if I could cannibalize it to get the important input circuitry adapted 
to my counter.
Maybe some info on it is available; I'll take a look.
Bob
 

    On Sunday, March 27, 2016 6:04 PM, Alexander Pummer  
wrote:
 

 there is a very inexpensive one ADF4118 works up to 3GHz
which has a  programmable prescaler
http://www.analog.com/media/en/technical-documentation/data-sheets/ADF4116_4117_4118.pdf

more here: 
http://www.qsl.net/bg1ceo/Tech_topic/rf/7G_prescaler/prescaler.html
or here:  http://www.qsl.net/n9zia/pre/prescaler.pdf

73
KJ6UHN
Alex

On 3/27/2016 1:41 PM, Bob Camp wrote:
> Hi
>
> There are a *lot* of chips that will divide down from a couple of GHz. Once 
> you have a chip, what do you do with it? There is more to a practical counter 
> front end than just the divider. Getting it all to work requires a bit of 
> time and a pretty good pc board.
>
> This guy:
>
> http://www.analog.com/en/products/rf-microwave/frequency-dividers-multipliers-detectors/frequency-dividers-prescalers-counters/hmc705.html
>
> Will do a divide by 10 and go higher than your counter will. It’s a bit 
> expensive … The eval board is cheaper than a single piece and it will give 
> you a pretty good start.
>
> This guy:
>
> http://www.analog.com/en/products/rf-microwave/frequency-dividers-multipliers-detectors/frequency-dividers-prescalers-counters/hmc434.html
>
> Will only divide by 8, it still goes higher than your counter. The eval board 
> is a bit over $200. One piece of the Ic is < $12.
>
> Bob
>
>
>> On Mar 27, 2016, at 3:45 PM, Bob Albert via time-nuts  
>> wrote:
>>
>> Does anyone know of an inexpensive prescaler for a counter that goes beyond 
>> 2 GHz?  I would actually like to find a kit but everything seems a bit 
>> pricy.  I currently have capability of 500 MHz and that will stretch to 
>> about 700 with care.  So a divide by 10 would be ideal.
>>
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>
> -
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> Checked by AVG - www.avg.com
> Version: 2016.0.7497 / Virus Database: 4545/11897 - Release Date: 03/27/16

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Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

[Magnus Danielson]

Hi Oleg,

I like the simplicity here.

Would not GNUradio be a good platform to encode the calibration stuff a 
little more gift-wrapped?


What spectrum-analyzer software do you use? (Just curious)

This simple setup would be useful for many purposes.

Depending on the oscillator, the EFC can need inversion, so I sketched 
for a similar design such that I could jumper it for either polarity. In 
that design I put the inverter after the integrating op-amp.


Cheers,
Magnus

On 03/28/2016 10:04 PM, Oleg Skydan wrote:

Hi, everybody!

OK. Let's start. Here is the schematics of the "test set"
http://skydan.in.ua/PNTestSet/PN%20Test%20set.pdf . It consists of three
small
boards:
1. Mixer board - a simple mixer (500MHz ADE-1+) with 200kHz pi-LPF at
the mixer output.
2. LNA board - a non-inverting low noise AF amplifier based on AD797
with switchable 20/40dB gain.
3. PLL board - contains two TL071 OP amps. One is inverting amplifier,
the other is PLL integrator. The R4,R8,R2,R7,C8 sets the PLL parameters
- gain, passband and damping factor. Loop parameters are also dependent
of signal levels and VCO tuning sensitivity. So you may need to correct
them if your setup differs from mine - VCXO's I use have tuning
sensitivity approx 100Hz/V and I set RF level at mixer near 0dBm with LO
level near +7dBm. If you want to build universal test set you will need
to use some switchs to allow setting different loop parameters (I just
use my soldering iron and change parts if needed :) ).

The power supply is a simple design based on 7812/7912 regulators.

I use the E-MU 0202 USB external sound card and laptop PC as the AF
spectrum analyzer.

You will also need some cables. Different fixed attenuators or
switchable one will be also helpful.

I also have several homemade low noise VCXOs for some frequencies (7MHz,
10MHz, 14.318MHz, 60MHz) which I use as the reference signal sources to
make measurements at these frequencies.

Another option is to test two identical oscillators (or other signal
sources). Assuming that both signals will have identical phase noise
characteristics we can correct the results by 3dB (or just add 3dB
correction during calibration).

The calibration and use is simple.
1. Set LNA gain to 20dB.
2. Set the FFT parameters - flattop window, small (2048..4096) points
number and short averaging in SA software.
3. Connect reference signal to LO mixer port and signal you are going to
test to RF mixer port through the attenuator. Do not close the PLL yet.
4. Set the beat level a bit less then the sound card full scale using
the attenuator. Check the beat harmonics levels - they should be at
least 30dB lower then the beat level (add more attenuation if harmonics
are higher).
5. Now set the spectrum analyzer calibration so that beat level is at
-27dB if you measure against low noise reference VXCO, or -30dB if you
use two identical oscillators.
6. Switch the LNA to 40dB gain.
7. Set SA software to Blackman window, 131072points/96kHz SR/necessary
averaging, close PLL, wait for the lock, measure the phase noise.

Why I am calibrating to -27/-30dB:
20dB because the LNA gain is 20dB less during the calibration (compared
to measurement time)
1dB because of FFT parameters 96k/131072 = 0.73Hz * 1.73 (Blackman
window) = 1.267Hz, 10 log10(1.267) = 1.03dB
6dB is the correction inherent to used calibration method
additional 3dB needed in case of testing identical oscillators.

Now some words about results. The noise floor of this test set depends
of the signals levels, and with the optimal levels it is in
-160..-170dBc/Hz range (depending of the offset from the carrier). It
completely satisfies my needs, better results can be achieved with the
higher level mixer and/or better LNA. I just used parts that I had :).

Here http://skydan.in.ua/PNTestSet/Screen%20(420)-e.png is an example of
the phase noise measurements results of my homemade low noise 60MHz VCXO
(two identical units were measured). The results at the offsets greater
then 1kHz should be corrected cause the oscillators noise is too close
to test set noise (the real oscillator noise is a bit lower then the
displayed one). The test set noise floor and calibration spectrum is
also there.

The boards also have other use.

For example I was able to measure my home made 60MHz VCXO harmonic
content http://skydan.in.ua/PNTestSet/Screen%20(414)-e.png using the
mixer, LNA boards and signal generator. I have no spectrum analyzer so
it is a big help to me :).

Power supply noise can be investigated with the LNA board and sound
card. Look at this screen
http://skydan.in.ua/PNTestSet/Screen%20(431)-e.png to see how bad the
LDO regulator noise can be and a great difference in noise with the
simple transistor filter (sorry there are a lot of power line noise
pickup - I needed just to quickly check the power supply noise, so did
not pay a lot attention to minimize them).

The low noise VCXOs with the combiner and attenuator can be used to
measure IMD3 of the receiver. If you add 

Re: [time-nuts] Lucent GPS UTC confusion

[Magnus Danielson]

Hi,

Actually, most systems these days wants UTC rather than GPS time.

Cheers,
Magnus

On 03/17/2016 02:42 AM, Bob Camp wrote:

Hi

The CDMA world (and most systems) want GPS lock rather than UTC. The only real 
change is likely in the status messages. I strongly suspect that a “UTC locked” 
version will not send a double pps pulse (or drop one) at a leap second 
boundary …

Bob


On Mar 16, 2016, at 8:29 PM, Joseph Gray  wrote:

I noticed on the Status screen that the Lucent unit said the PPS was
locked to GPS, not UTC, as the Z3801A is. So, I issued ":DIAG:GPS:UTC
1" and "TST?" to correct this.

But things are not as I expected. Displaying the clock for both
GPSDO's in Z38xx now shows them to be 17 seconds different, which is
of course the leap seconds.

This seems backwards. With both units set to UTC, why are they showing
different times?

Joe Gray
W5JG
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Re: [time-nuts] Time Lord, video of

[Magnus Danielson]

He is indeed a nice guy.
I'm scheduled to speak directly after him at IFCS in may... oups.

He has a nice topic thought, 50 years of Allan Deviation.
Pitty I was unable to complete my article relating to that topic, will 
have to resurrect that one eventually.


Cheers,
Magnus

On 03/04/2016 08:05 PM, William H. Fite wrote:

I had the privilege of meeting Dr. Levine once at NIST. He is a completely
disarming, modest, unassuming.genius.

On Thu, Mar 3, 2016 at 8:41 PM, Tom Van Baak  wrote:


There was just a CNN link to this timely video of Judah Levine:

Just Call Him the 'Time Lord'
https://www.youtube.com/watch?v=VkMR5q-R-sM

I first met Judah in the late 1990's when he installed a DEC Alpha time
server at microsoft.com. An OCXO (from an HP 5245L), and a GPS receiver
(Oncore VP from Synergy), and a rubidium (Efratom M100 from Lehman), and a
cesium (FTS 4050 from Corby) later -- I was hooked, and started time nuts.
Judah has always been supportive of us amateurs that play with precise time
& frequency for fun.

Additional links:

The Nation's Time Lord
http://cuindependent.com/2011/08/23/the-nations-time-lord/

Judah Levine Featured on Youtube: Just Call Him 'The Timelord'

http://phys.colorado.edu/events/judah-levine-featured-youtube-just-call-him-timelord

Dr. Judah Levine - The Nation's Time Lord

http://www.soposted.com/reality-bites/tech/dr-judah-levine-the-nations-time-lord/

JUST CALL HIM THE 'TIME LORD'
http://www.greatbigstory.com/stories/just-call-him-america-s-time-lord

Judah Levine
https://jila.colorado.edu/faculty/judah-levine

An Interview With Dr. Judah Levine, America's Real Life 'Time Lord'

https://laughingsquid.com/an-interview-with-dr-judah-levine-americas-real-life-time-lord/

/tvb
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Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

[Bruce Griffiths]

That's probably a good example of how not to do it well.

1) The chosen mixer isnt as low noise as the various Minicircuits phase 
detectors.

2) The 50 ohm load after the filter merely serves to halve the phase detector 
gain. The IF port is terminated by a 15nF capacitor at RF and LO frequencies 
and their harmonics. This produces a frequency dependent gain, however it will 
likely be relatively flat over the sound card bandwidth.

3) Saturating both mixer ports increases the phase detector gain substantially 
and has the lowest noise 

4) Cascading the PLL circuitry with the preamp causes interaction between the 
Preamp gain settings and the PLL bandwidth. Driving the PLL circuit in 
parallel with the preamp input directly from the low pass filtered mixer output 
avoids this issue as well as your 0.1x amplifier in the PLL section.

5) Another method of calibration is desirable in order to account for 
potentially  non flat frequency response.

There are a large number of NIST papers on PN measurement including a few on 
the effect of mixer IF port terminations. A recent one 
(http://tf.boulder.nist.gov/general/pdf/2556.pdf) compares the PN performance 
of various mixers used as phase detectors.

An OCXO like the 10811A has an EFC gain of around 0.1Hz/volt.
The PLL bandwidth should ideally be less than 1/10 of the lowest offset 
frequency for which the PN is to be measured.
If the system frequency response is measured then the PLL bandwidth can be a 
little higher albeit with a reduction is sensitivity and an increase in system 
PN at the low offset frequency end of the range.

AS is the PN noise of this test set is far too high to measure the PN of state 
of the art OCXOs or indeed most modern OXCOs.

Bruce

On Monday, March 28, 2016 11:04:45 PM Oleg Skydan wrote:
> Hi, everybody!
> 
> OK. Let's start. Here is the schematics of the "test set"
> http://skydan.in.ua/PNTestSet/PN%20Test%20set.pdf . It consists of three
> small
> boards:
> 1. Mixer board - a simple mixer (500MHz ADE-1+) with 200kHz pi-LPF at the
> mixer output.
> 2. LNA board - a non-inverting low noise AF amplifier based on AD797 with
> switchable 20/40dB gain.
> 3. PLL board - contains two TL071 OP amps. One is inverting amplifier, the
> other is PLL integrator. The R4,R8,R2,R7,C8 sets the PLL parameters - gain,
> passband and damping factor. Loop parameters are also dependent of signal
> levels and VCO tuning sensitivity. So you may need to correct them if your
> setup differs from mine - VCXO's I use have tuning sensitivity approx
> 100Hz/V and I set RF level at mixer near 0dBm with LO level near +7dBm. If
> you want to build universal test set you will need to use some switchs to
> allow setting different loop parameters (I just use my soldering iron and
> change parts if needed :) ).
> 
> The power supply is a simple design based on 7812/7912 regulators.
> 
> I use the E-MU 0202 USB external sound card and laptop PC as the AF spectrum
> analyzer.
> 
> You will also need some cables. Different fixed attenuators or switchable
> one will be also helpful.
> 
> I also have several homemade low noise VCXOs for some frequencies (7MHz,
> 10MHz, 14.318MHz, 60MHz) which I use as the reference signal sources to make
> measurements at these frequencies.
> 
> Another option is to test two identical oscillators (or other signal
> sources). Assuming that both signals will have identical phase noise
> characteristics we can correct the results by 3dB (or just add 3dB
> correction during calibration).
> 
> The calibration and use is simple.
> 1. Set LNA gain to 20dB.
> 2. Set the FFT parameters - flattop window, small (2048..4096) points number
> and short averaging in SA software.
> 3. Connect reference signal to LO mixer port and signal you are going to
> test to RF mixer port through the attenuator. Do not close the PLL yet.
> 4. Set the beat level a bit less then the sound card full scale using the
> attenuator. Check the beat harmonics levels - they should be at least 30dB
> lower then the beat level (add more attenuation if harmonics are higher).
> 5. Now set the spectrum analyzer calibration so that beat level is at -27dB
> if you measure against low noise reference VXCO, or -30dB if you use two
> identical oscillators.
> 6. Switch the LNA to 40dB gain.
> 7. Set SA software to Blackman window, 131072points/96kHz SR/necessary
> averaging, close PLL, wait for the lock, measure the phase noise.
> 
> Why I am calibrating to -27/-30dB:
> 20dB because the LNA gain is 20dB less during the calibration (compared to
> measurement time)
> 1dB because of FFT parameters 96k/131072 = 0.73Hz * 1.73 (Blackman window) =
> 1.267Hz, 10 log10(1.267) = 1.03dB
> 6dB is the correction inherent to used calibration method
> additional 3dB needed in case of testing identical oscillators.
> 
> Now some words about results. The noise floor of this test set depends of
> the signals levels, and with the optimal levels it is in -160..-170dBc/Hz
> range (depending of the 

Re: [time-nuts] Prescaler

[Dave M]

Good catch on that board, Ignacio.  I didn't read the complete description 
before posting.  Given that it seems to be a 1-board solution, I might buy 
one and see how it turns out.  My frequency counting capabilities are 
limited to 1.3 GHz right now, as is my signal generation capabilities, so I 
really haven't had a need to go higher.
I need to investigate the input and output conditions and limitations of 
these Hittite chips.  Might have to add an amp and/or attenuator pad to make 
it work with my instruments.


Cheers,
Dave M

EB4APL wrote:

The first reference is a board for a two stage divider.  They mention
that a /2 and a /5 chips can be combined, so you can make a /10
prescaler.
Regards,
Ignacio, EB4APL


El 27/03/2016 a las 23:24, Dave M escribió:

Bob Albert via time-nuts wrote:

Does anyone know of an inexpensive prescaler for a counter that goes
beyond 2 GHz? I would actually like to find a kit but everything
seems a bit pricy. I currently have capability of 500 MHz and that
will stretch to about 700 with care. So a divide by 10 would be
ideal.




If you're good at kit-building, you might take a look at the Ebay
items 160703629055, 181982380658, 400265187641, and 60703624281.
These are PCBs made to specifically fit a number of frequency divider
chips.  Each board holds a single divider chip and associated
components, such as the decoupling caps, bias resistors, and pads for
interconnections.
A series of these boards that add up to a divide-by-100 can get you
to 2 - 5GHz easily. I've never used any of these boards or dividers,
but I have used a few of the seller's amplifier boards, with great
success. There's also a construction article from Silicon Chip magazine 
(Oct,

2006) dedicated to constructing a 2.8 GHz 1000:1 prescaler for
counters.  The PCB layout and all the active parts are available.
Send me an email for a copy of the article.

I don't know of any prescaler chips that get you a divide-by-10
prescaler at your target frequency range.  There might be (probably
is) one available... I just haven't run across it.

BTW, which frequency counter do you have?  There might be a better
solution for you than an external prescaler.

Cheers,
Dave M


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government fears the people, there is liberty -- Thomas Jefferson


Dave M 



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Re: [time-nuts] Oleg' s PN test Re: A new member & PN test set

[Oleg Skydan]

Hi, everybody!

OK. Let's start. Here is the schematics of the "test set" 
http://skydan.in.ua/PNTestSet/PN%20Test%20set.pdf . It consists of three 
small

boards:
1. Mixer board - a simple mixer (500MHz ADE-1+) with 200kHz pi-LPF at the 
mixer output.
2. LNA board - a non-inverting low noise AF amplifier based on AD797 with 
switchable 20/40dB gain.
3. PLL board - contains two TL071 OP amps. One is inverting amplifier, the 
other is PLL integrator. The R4,R8,R2,R7,C8 sets the PLL parameters - gain, 
passband and damping factor. Loop parameters are also dependent of signal 
levels and VCO tuning sensitivity. So you may need to correct them if your 
setup differs from mine - VCXO's I use have tuning sensitivity approx 
100Hz/V and I set RF level at mixer near 0dBm with LO level near +7dBm. If 
you want to build universal test set you will need to use some switchs to 
allow setting different loop parameters (I just use my soldering iron and 
change parts if needed :) ).


The power supply is a simple design based on 7812/7912 regulators.

I use the E-MU 0202 USB external sound card and laptop PC as the AF spectrum 
analyzer.


You will also need some cables. Different fixed attenuators or switchable 
one will be also helpful.


I also have several homemade low noise VCXOs for some frequencies (7MHz, 
10MHz, 14.318MHz, 60MHz) which I use as the reference signal sources to make 
measurements at these frequencies.


Another option is to test two identical oscillators (or other signal 
sources). Assuming that both signals will have identical phase noise 
characteristics we can correct the results by 3dB (or just add 3dB 
correction during calibration).


The calibration and use is simple.
1. Set LNA gain to 20dB.
2. Set the FFT parameters - flattop window, small (2048..4096) points number 
and short averaging in SA software.
3. Connect reference signal to LO mixer port and signal you are going to 
test to RF mixer port through the attenuator. Do not close the PLL yet.
4. Set the beat level a bit less then the sound card full scale using the 
attenuator. Check the beat harmonics levels - they should be at least 30dB 
lower then the beat level (add more attenuation if harmonics are higher).
5. Now set the spectrum analyzer calibration so that beat level is at -27dB 
if you measure against low noise reference VXCO, or -30dB if you use two 
identical oscillators.

6. Switch the LNA to 40dB gain.
7. Set SA software to Blackman window, 131072points/96kHz SR/necessary 
averaging, close PLL, wait for the lock, measure the phase noise.


Why I am calibrating to -27/-30dB:
20dB because the LNA gain is 20dB less during the calibration (compared to 
measurement time)
1dB because of FFT parameters 96k/131072 = 0.73Hz * 1.73 (Blackman window) = 
1.267Hz, 10 log10(1.267) = 1.03dB

6dB is the correction inherent to used calibration method
additional 3dB needed in case of testing identical oscillators.

Now some words about results. The noise floor of this test set depends of 
the signals levels, and with the optimal levels it is in -160..-170dBc/Hz 
range (depending of the offset from the carrier). It completely satisfies my 
needs, better results can be achieved with the higher level mixer and/or 
better LNA. I just used parts that I had :).


Here http://skydan.in.ua/PNTestSet/Screen%20(420)-e.png is an example of the 
phase noise measurements results of my homemade low noise 60MHz VCXO (two 
identical units were measured). The results at the offsets greater then 1kHz 
should be corrected cause the oscillators noise is too close to test set 
noise (the real oscillator noise is a bit lower then the displayed one). The 
test set noise floor and calibration spectrum is also there.


The boards also have other use.

For example I was able to measure my home made 60MHz VCXO harmonic content 
http://skydan.in.ua/PNTestSet/Screen%20(414)-e.png using the mixer, LNA 
boards and signal generator. I have no spectrum analyzer so it is a big help 
to me :).


Power supply noise can be investigated with the LNA board and sound card. 
Look at this screen http://skydan.in.ua/PNTestSet/Screen%20(431)-e.png to 
see how bad the LDO regulator noise can be and a great difference in noise 
with the simple transistor filter (sorry there are a lot of power line noise 
pickup - I needed just to quickly check the power supply noise, so did not 
pay a lot attention to minimize them).


The low noise VCXOs with the combiner and attenuator can be used to measure 
IMD3 of the receiver. If you add the mixer, LNA and signal generator you can 
measure the IMD3 of the separate units (mixers, filters, amplifiers and 
etc.).


The low noise VCXO can also be used to test reciprocal mixing DR of the 
receiver.


Other useful combinations are possible.

If you like I can post the photos of the boards. They a bit ugly :). Every 
time I use them I think about mounting them in personal metal boxes, but I 
always find something more important to do...


Best wishes,

Re: [time-nuts] A new member & PN test set

[Bob Stewart]

Hi Oleg,

I'm interested in your PN test set.  I'm sure a number of us are.  If you have 
webpages or documents up, could you share them with the list?  Otherwise, could 
you email me direct?bob at evoria dot net

Bob

On Sun, 3/27/16, Oleg Skydan  wrote:

 Subject: [time-nuts] A new member & PN test set
 To: time-nuts@febo.com
 Date: Sunday, March 27, 2016, 3:25 PM
 
 Hi list,
 
 I am in a process of making a low noise frequency
 synthesizer for the 1st LO
 for my new DSP HF transceiver (http://neon.skydan.in.ua). This list is not
 directly related to my project, but I found a lot of useful
 information in
 this list - thanks for all contributors!
 
 I see a discussion regarding "$40 phase noise test set". I
 have built one 
 and
 already use it for several months. It is a great help in
 design process (I
 am not "blind" anymore :) ). If somebody is interested I can
 share all the
 information about it.
 
 Best wishes!
 Oleg 
 
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[time-nuts] Oleg' s PN test Re: A new member & PN test set

[Alex Pummer]

Hi Oleg,
" If somebody is interested I can share all the information about it. "
Yes I would be very interested to see your phase noise test at least the 
principle

73
KJ6UHN
Alex


On 3/28/2016 6:49 AM, Magnus Danielson wrote:

Hi Oleg,

Welcome. As always, it's a combination of tools, experiments and 
theory which over a number of iterations develops into skills. You 
will notice that there is quite a bit of hams here too, some just 
forget to give their signals.


73 de SA0MAD Magnus

On 03/27/2016 10:25 PM, Oleg Skydan wrote:

Hi list,

I am in a process of making a low noise frequency synthesizer for the
1st LO
for my new DSP HF transceiver (http://neon.skydan.in.ua). This list 
is not
directly related to my project, but I found a lot of useful 
information in

this list - thanks for all contributors!

I see a discussion regarding "$40 phase noise test set". I have built
one and
already use it for several months. It is a great help in design 
process (I
am not "blind" anymore :) ). If somebody is interested I can share 
all the

information about it.

Best wishes!
Oleg
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-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.7497 / Virus Database: 4545/11905 - Release Date: 
03/28/16


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Re: [time-nuts] Spectrum Analyzer Specifications [Phase noise tester Bare Boards and Layout]

[Oz-in-DFW]

On 3/24/2016 1:08 PM, Bob Bownes wrote:
> Don't really need anyone who can order up bare boards in bulk anymore. 
Oshpark; www.oshpark.org does 2 layer for $5/sq in and 4 layer for
$10/sq.  That price gets you three boards. Designs can be made public so
anyone can buy them. I buy from them all the time. About 2 weeks turn.

There are several Chinese suppliers that will do 2 X 2 inch boards for
about $20 for 10 copies, about $30 by the time you have them in your
hands. Also about 2 Weeks turn, though may end up as much as 4 weeks.
> Many
> of the board houses will make them on demand for single customers. They fit
> them into empty spaces in larger board orders.
>
> I'd love one if someone is willing to draw it up. I'll even put together a
> Mouser BOM that can be shared if N8UR will layout the board. :)
If we can hash out a schematic, I can do a layout as a spare time
project - but I don't have a huge amount of spare time in the plan
before June or July.  I'd use KiCAD

We can do a public BoM on Digikey or Mouser so folks in the EU most of
the rest of the world have easy access.

There are few questions I have - surface mount or through-hole.  Through
hole parts are getting harder to get.  If you are afraid of SM we have
have a low cost service like Macrofab build small batches (they'll do as
few as one) and if we use parts from their standard parts list we only
pay the part cost, not the insertion cost. They'll also buy boards from
Oshpark. If you are not afraid of SM, buy a stencil from Oshstencils
https://oshstencils.com and get your hotplate out.

Connectors: SMA are cheap and reliable. More delicate than TNC, but not
by much, and a whole lot cheaper and more available as surplus.

> Bob
> KI2L
Oz, N1OZ

-- 
mailto:o...@ozindfw.net
Oz
POB 93167 
Southlake, TX 76092 (Near DFW Airport) 



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Re: [time-nuts] A new member & PN test set

[Mark Spencer]

Hi Oleg, I'd be interested in seeing more information about your phase noise 
measurement setup.

All the best
Mark Spencer
VE7AFZ

Sent from my iPhone

> On Mar 27, 2016, at 1:25 PM, Oleg Skydan  wrote:
> 
> Hi list,
> 
> I am in a process of making a low noise frequency synthesizer for the 1st LO
> for my new DSP HF transceiver (http://neon.skydan.in.ua). This list is not
> directly related to my project, but I found a lot of useful information in
> this list - thanks for all contributors!
> 
> I see a discussion regarding "$40 phase noise test set". I have built one and
> already use it for several months. It is a great help in design process (I
> am not "blind" anymore :) ). If somebody is interested I can share all the
> information about it.
> 
> Best wishes!
> Oleg 
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Re: [time-nuts] A new member & PN test set

[Magnus Danielson]

Hi Oleg,

Welcome. As always, it's a combination of tools, experiments and theory 
which over a number of iterations develops into skills. You will notice 
that there is quite a bit of hams here too, some just forget to give 
their signals.


73 de SA0MAD Magnus

On 03/27/2016 10:25 PM, Oleg Skydan wrote:

Hi list,

I am in a process of making a low noise frequency synthesizer for the
1st LO
for my new DSP HF transceiver (http://neon.skydan.in.ua). This list is not
directly related to my project, but I found a lot of useful information in
this list - thanks for all contributors!

I see a discussion regarding "$40 phase noise test set". I have built
one and
already use it for several months. It is a great help in design process (I
am not "blind" anymore :) ). If somebody is interested I can share all the
information about it.

Best wishes!
Oleg
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Re: [time-nuts] A new member & PN test set

[Rob Sherwood .]

Yes interested in what you are doing as to measuring phase noise. Rob, NC0B

Sent from my iPad

> On Mar 28, 2016, at 3:01 AM, "Oleg Skydan"  wrote:
> 
> 
> 
> Hi list,
> 
> I am in a process of making a low noise frequency synthesizer for the 1st LO
> for my new DSP HF transceiver (http://neon.skydan.in.ua). This list is not
> directly related to my project, but I found a lot of useful information in
> this list - thanks for all contributors!
> 
> I see a discussion regarding "$40 phase noise test set". I have built one and
> already use it for several months. It is a great help in design process (I
> am not "blind" anymore :) ). If somebody is interested I can share all the
> information about it.
> 
> Best wishes!
> Oleg 
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> 
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Re: [time-nuts] A new member & PN test set

[Herbert Poetzl]

On Sun, Mar 27, 2016 at 11:25:36PM +0300, Oleg Skydan wrote:
> Hi list,

> I am in a process of making a low noise frequency
> synthesizer for the 1st LO for my new DSP HF transceiver
> (http://neon.skydan.in.ua). This list is not directly 
> related to my project, but I found a lot of useful 
> information in this list - thanks for all contributors!

> I see a discussion regarding "$40 phase noise test set". 
> I have built one and already use it for several months. 

> It is a great help in design process (I am not "blind" 
> anymore :) ). 

> If somebody is interested I can share all the infor-
> mation about it.

Yes, please do! I'm interested!

Thanks,
Herbert

> Best wishes!
> Oleg 

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Re: [time-nuts] high rev isolation amps

[Magnus Danielson]

Hi John,

This would indeed be interesting.

I would assume that one would like to have shielded boxes for these.

Cheers,
Magnus

On 03/27/2016 04:33 AM, John Ackermann N8UR wrote:

In light of this discussion, I'm taking a deep gulp to mention a project
that's finished but has been on my back burner for a while.

A few years ago I laid out a high isolation, low noise buffer amp based
on one of Bruce's cascaded-transistor designs.  Isolation was measured
in excess of 100dB with PN floor around -170dBc/Hz.  The frequency range
is 1 MHz to 30 MHz and gain can be set from -10 to +7 dB.  It's designed
for 18VDC input but will work at 13.8, with less headroom.  At 18V it
can put out close to +20dBm.  It's a 1.75 x 3.75 inch board using SMT
parts (nothing tiny, but *lots* of passives -- about 80 parts total).

The board is ready to go, but I wasn't sure if there would be enough
interest to justify production.  Given the tedious surface mount
assembly, I assumed that there wouldn't be much interest in a kit, and
an assembly run requires at least 50, and preferably 100, units to get a
reasonable price.  At 100 units, I hope the price for an assembled board
could be below $100, but no guarantees.

If there is enough interest, TAPR could consider doing a production run.
  If not, I'll release the design package including Gerbers.

I'll try to get some better documentation put together in the next week
or two, and figure out a way to create a sign-up list for people who are
interested.  We'd have to have a minimum number of committed orders
before kicking things off.

John


On 03/26/2016 08:24 PM, jimlux wrote:

On 3/26/16 4:14 PM, Richard (Rick) Karlquist wrote:

Nothing has come to my attention in the last
35 years that is superior for buffer amplifiers
to the simple cascade of grounded base transistors
as described by numerous NBS/NIST papers.
The chain usually starts with a common emitter
(with emitter degeneration resistor), which
is an even older NBS classic.

I realize you asked for an OTS connectorized
version.  Unfortunately, I have never seen
one of these offered in said 35 years.


Yeah, i've spent a while looking through various catalogs..

Odd that nobody sells one: sure, it's probably a limited market, but
there's plenty of companies that sell limited market widgets (e.g. I'm
surprised Wenzel doesn't sell one.. in the online catalog info, they
don't even give S12 data of any kind)




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Re: [time-nuts] Reliability of atomic clocks

[jimlux]

On 3/27/16 8:20 PM, Mark Sims wrote:

Mil-spec parts would be somewhat more reliable than commercial
parts.

Actually,  that is seldom true.  The main difference between mil-spec
parts and commercial parts tends to be in the post-packaging device
testing (e.g.. extended temperature / voltage range).  They usually
have the same guts inside the package.I friend of mine was a test
engineer at a major semiconductor manufacturer and he said their
commercial parts were actually more reliable than the mil-spec ones.
The commercial parts were built in vastly greater quantities and
their production flow / experience enabled them to continually fine
tune the process and testing.  The production / test regimen of
mil-spec parts tended to be locked-down by inflexible specs and
procedures.  Changing anything required re-qualification of the
entire process.




Back in the day (e.g. 70s) there was a lot more process variability, so 
the whole screening process involved in selling 883B parts (54LS vs 
74LS, for instance) made for lower infant mortality, and smaller 
performance variations (e.g. if it had to meet performance specs from 
-40 to +85, the performance at 25 would likely have smaller variance 
than for a part that wasn't necessarily tested at any temperature)


There was also the thing of the perceived "higher reliability" of the 
packaging: ceramic packages with leak tests vs plastic encapsulation. 
(for space applications, I'm always intrigued by folks being concerned 
about leak test performance.. the parts going to operate in a vacuum, 
after all; what the leak test performance is really about is as a 
manufacturing process quality assurance, not because you actually care 
about leakage).


This concern with consistency is where Source Control Drawings and the 
rigorous process management comes from for high rel parts.  I'm not sure 
that this is such an issue today.


These days, processes are MUCH more consistent: if you're making deep 
submicron geometries, you've got to have your process under control to 
get acceptable yield.


As noted above, it's probably the same die in the package whether it's 
flipchip/chip-on-board/plastic/ceramic flatpack.


However there is a whole new issue of "fabless mfrs" - your design's 
performance might depend on some non-datasheet aspect of the part 
(radiation tolerance in particular) and if the new parts come from a 
different fab, or if the fab changes their process, that non-datasheet 
performance might change.


In my business of space electronics, we build tiny volumes, and tend to 
make the same design for years: this is not a big money maker for any 
chip supplier.  And when it comes to parts selection, it's easier, come 
design review time, to just use whatever venerable part you used before 
than to justify selecting a new part. This gets us into trouble all the 
time, when that trusty part was end-of-lifed 10 years ago, and we've 
been building units from new old stock we bought 20 years ago, and now 
we're out of parts.  The software defined radios we fly to Mars use 
Xilinx Virtex 2 FPGAs, which end-of-lifed a few years ago, yet that's 
what's likely to fly in 2020 and later.  Not only do you have to 
scrounge parts, but getting and running development tools is non-trivial.



Given the huge market these days, and the tiny, tiny market for 
MIL/Class-S high rel, most mfrs aren't interested in providing detailed 
information on the fab and processes (if for no other reason than it's 
the proprietary secret sauce). Nor are they particularly interested in 
following some process approved 30 years ago for a part on which they 
won't make any money.


There are firms like Rochester Electronics (leader in the trailing edge) 
who fill this niche, they stockpile obsolete parts, get manufacturing 
artifacts (masks, etc.).  but they aren't cheap.


These days, the automotive industry really drives high rel extreme 
environments: under-hood engine control units have to be very reliable: 
a failure rate of 0.01% would be crippling for most auto manufacturers. 
 Some consumer electronics also has to be fairly reliable, at least for 
infant mortality (warranty returns cost money)



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Re: [time-nuts] Meaning of MTBF (was: Reliability of atomic clocks)

[dlewis6767]

It's been a while since I designed aerospace hardware, but seems I remember we 
had both a calculated AND  a demonstrated MTBF.

Back then we called it Mil-Std 781. (I am sure it morphed into more modern 
tests).

We had both a pre-production qual-test and a production acceptance-test, both 
required to meet MTBF's, that were run for reliability.

I took stock in them; as did others.  They did have merit in predicting weak 
engineering designs catching weak designs during 'life' production. 

It wasn't 'simplistic' at all.  

Maybe the military and aerospace world is different from the 'commercial' world.

-Don














==
On Mon, 28 Mar 2016 13:04:23 +0200
Florian Teply  wrote:

> Am Mon, 28 Mar 2016 01:32:03 +0200
> schrieb Attila Kinali :
> 
> > Yes, the MTBF is a very simplicistic measure and there are a couple
> > of assumptions in its calculation which do not hold generally (or
> > rather, it's rather seldom that they hold). Yet it gives a number to
> > something that is otherwise relatively hard to measure and the number,
> > even though flawed, makes it possible to compare different devices
> > on their reliability. As this is more a rule of thumb comparison,
> > you shouldn't read too much into a 10% difference. Yet a 100%
> > difference is significant, no matter which of the assumptions do not
> > hold.
> > 
> Umm, well, even a 100% difference still might mean nothing if the
> derivation of MTBF between different devices is based on different
> assumptions. That both these derivations might be seriously flawed does
> not help at all.
> Yet, even MIL-Spec parts documentation does rarely contain sufficient
> detail to assess the validity of the numbers in a certain application.
> 
> At the very least, one would need to know acceleration factors for the
> different failure mechanisms, and shape parameters of the
> failure-vs-time plot. This kind of data I wouldn't expect to find
> outside the manufacturers premises, and even there it's not likely to
> be accessible if it exists at all.
> 
> Best regards,
> Florian
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-- 
dlewis6767 
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Re: [time-nuts] Meaning of MTBF (was: Reliability of atomic clocks)

[John Green]

We make some thick film, plastic molded , plug in attenuators for the cable
TV industry. We have been asked on several occasions to provide MTBF data.
Being a small company with limited resources, we have never been able to
provide that data. The parts we make will easily outlast the equipment they
are used in, because such equipment is frequently upgraded. We tell our
customers that very few, if any, parts have ever been returned for being
defective. While true, it is somewhat misleading. The plug in attenuator is
an inexpensive part that is carried in a tech's belt bag by the handful. If
he encounters a bad one, he simply removes it, tosses it on the ground, and
installs a new one. In recent years the Chinese have taken most of the
market away from us with lower cost products. A lot of them use FR4 and
chip resistors. I have heard that some OEMs are going away from those
because of reduced reliability. I have been seeing some Chinese products
that are actually thick film. Most are either copies of ours, or they
didn't spend any time to optimize the RF performance. Sometimes, I do see
parts that out perform our own. The Chinese also make plug in, molded
equalizers, but I have yet to see one that works well. I must say to their
credit though, that they have gone from cheap imitations to parts that are
actually well designed and built. AT least some of them are.

On Mon, Mar 28, 2016 at 6:04 AM, Florian Teply  wrote:

> Am Mon, 28 Mar 2016 01:32:03 +0200
> schrieb Attila Kinali :
>
> > Yes, the MTBF is a very simplicistic measure and there are a couple
> > of assumptions in its calculation which do not hold generally (or
> > rather, it's rather seldom that they hold). Yet it gives a number to
> > something that is otherwise relatively hard to measure and the number,
> > even though flawed, makes it possible to compare different devices
> > on their reliability. As this is more a rule of thumb comparison,
> > you shouldn't read too much into a 10% difference. Yet a 100%
> > difference is significant, no matter which of the assumptions do not
> > hold.
> >
> Umm, well, even a 100% difference still might mean nothing if the
> derivation of MTBF between different devices is based on different
> assumptions. That both these derivations might be seriously flawed does
> not help at all.
> Yet, even MIL-Spec parts documentation does rarely contain sufficient
> detail to assess the validity of the numbers in a certain application.
>
> At the very least, one would need to know acceleration factors for the
> different failure mechanisms, and shape parameters of the
> failure-vs-time plot. This kind of data I wouldn't expect to find
> outside the manufacturers premises, and even there it's not likely to
> be accessible if it exists at all.
>
> Best regards,
> Florian
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Re: [time-nuts] Framework for simulation of oscillators

[Magnus Danielson]

Hi Tom,

On 03/28/2016 04:25 AM, Tom Van Baak wrote:

BTW: I discovered that Timelab stops processing after 10'000'000 datapoints,
which is kind inconvenient when doing a long term measurment...

Attila Kinali


I've collected a day of TimeLab/TimePod data at tau 0.001 which is 86'400'000 
datapoints. Should be no problem.

Note Stable32 has a user-configurable limit (Conf -> Data -> 
Max_Data_File_Size). Or you can decimate during reading.

My command line tools have no sample limit (well, just malloc() limited) and 
can be orders of magnitude faster than Stable32 or Timelab since they are batch 
and not GUI.

But this begs the question -- what are you doing with 10M datapoints? Once you 
get beyond a couple of decades of data it's often better to compute statistics 
in segments and display all the segments of the whole as a time series.

So, for example, don't compute a single stddev or ADEV number from the entire 10M data 
set. While this gives an apparently "more precise" measurement due to sampling, 
it will also hide key factors like trends, periodicity, spectral components, outliers, 
and glitches.


Agree. You need to use a better tool for those systematics than ADEV is. 
MDEV and PDEV is even better at filtering out noise and give power 
estimates, which smoothes out it more, which thus just makes it harder 
to discover. The dynamic ADEV can help a litte.


It is the diversity of plots, ADEV, FFT and phase-/frequency-plots 
(residue plots of some suitable matching model) which can help to unveil 
behaviors of interest.


Swapping between MDEV and TDEV can at some times be illustrative.

Cheers,
Magnus
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Re: [time-nuts] Framework for simulation of oscillators

[John Miles]

> > BTW: I discovered that Timelab stops processing after 10'000'000 datapoints,
> > which is kind inconvenient when doing a long term measurment...
> 
> I didn't know that. Good to know.

Attila, wasn't this related to an invalid ':' character in the filename coming 
through from VirtualBox?  Or is this issue different from the one we discussed 
in email last month?

-- john, KE5FX
Miles Design LLC

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Re: [time-nuts] Framework for simulation of oscillators

[Bob Camp]

Hi


> On Mar 27, 2016, at 9:23 PM, John Miles  wrote:
> 
>> BTW: I discovered that Timelab stops processing after 10'000'000 datapoints,
>> which is kind inconvenient when doing a long term measurment...
> 
> It had better not! :)  Any steps to reproduce?
> 


It’s never stopped here …. I routinely run over 10M points.

Bob

> -- john, KE5FX
> Miles Design LLC
> 
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Re: [time-nuts] Prescaler

[Herbert Poetzl]

On Sun, Mar 27, 2016 at 07:45:23PM +, Bob Albert via time-nuts wrote:
> Does anyone know of an inexpensive prescaler for a counter 
> that goes beyond 2 GHz?  

A few years ago, I was looking for something cheap to build
a PIC based GHz counter and I stumbled over the LMX23xx
chips from TI (PLL frequency synthesizers), which have
a prescaler built in.

Specifically the LMX2322 and LMX2364, which are quite cheap
and easy to use (older ones available on eBay, the newer 
ones at your favorite distributor).

http://www.ti.com/lit/ds/symlink/lmx2364.pdf

> I would actually like to find a kit but everything seems 
> a bit pricy.  

I have designed breakout boards for both, so if that looks
like something which could be useful to you, just drop me
a note and I'll make them available.

Best,
Herbert

> I currently have capability of 500 MHz and that will 
> stretch to about 700 with care.  

> So a divide by 10 would be ideal.

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Re: [time-nuts] Prescaler

[EB4APL]

The first reference is a board for a two stage divider.  They mention 
that a /2 and a /5 chips can be combined, so you can make a /10 prescaler.


Regards,
Ignacio, EB4APL


El 27/03/2016 a las 23:24, Dave M escribió:

Bob Albert via time-nuts wrote:

Does anyone know of an inexpensive prescaler for a counter that goes
beyond 2 GHz? I would actually like to find a kit but everything
seems a bit pricy. I currently have capability of 500 MHz and that
will stretch to about 700 with care. So a divide by 10 would be
ideal.




If you're good at kit-building, you might take a look at the Ebay 
items 160703629055, 181982380658, 400265187641, and 60703624281. These 
are PCBs made to specifically fit a number of frequency divider 
chips.  Each board holds a single divider chip and associated 
components, such as the decoupling caps, bias resistors, and pads for 
interconnections.
A series of these boards that add up to a divide-by-100 can get you to 
2 - 5GHz easily. I've never used any of these boards or dividers, but 
I have used a few of the seller's amplifier boards, with great success.


There's also a construction article from Silicon Chip magazine (Oct, 
2006) dedicated to constructing a 2.8 GHz 1000:1 prescaler for 
counters.  The PCB layout and all the active parts are available.  
Send me an email for a copy of the article.


I don't know of any prescaler chips that get you a divide-by-10 
prescaler at your target frequency range.  There might be (probably 
is) one available... I just haven't run across it.


BTW, which frequency counter do you have?  There might be a better 
solution for you than an external prescaler.


Cheers,
Dave M


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Re: [time-nuts] Framework for simulation of oscillators

[Magnus Danielson]

Goddag Attila,

On 03/28/2016 01:48 AM, Attila Kinali wrote:

N'abend Magnus,

On Tue, 22 Mar 2016 01:11:41 +0100
Magnus Danielson  wrote:


Yes, of course. Noise is generally not i.i.d. and thus one cannot use
the same generator for more than one model in the same simulation.

Oh.. and just to make things more complicated: Gaussian noise is not
necessarily white (only if it's Gaussian distributed and i.i.d.).
And noise with white spectrum is not necessarily Gaussian or i.i.d.
(only if phase and amplitude noise are both white).


Indeed.

BTW. You are increasingly PhD damaged in your use of abbreviations
without explaining them on first use, as you should.


Oops.. sorry about that.
i.i.d = independent, identically distributed.
I.e. the samples have all the same probability density function,
which does not change over time and does not depend on any previous samples.


Indeed.

You can have noise which at first look seems Gaussian, but isn't, as 
there is systematics hidden within it. For proper estimations the 
systematics needs to be separated from the random noise and both 
estimated without the effect of the other, as they then can scale 
significantly different depending on what question you ask about the 
system. For communications I use a scale factor of 14 for the Bit Error 
Rate (BER) of 1E-12 (the value of 14 is an approximation, but since you 
need margin on it, it's fine to get the right proportions).


Another aspect is that noise which looks Gaussian at first look can hide 
other noises such as flicker etc. which only reveal itself for longer 
observations times.


As we deal with oscillators, we have three or four noise-forms to deal with.


Consider that you have an integrator for the oscillator, and a null due
to the Q. Look at the Leeson model (Feb 1966), see also Enrico's book on
phase noise.


I don't see how the Q, beside acting as an integrator, will affect my system
(keep in mind, the "loop" is non-linear). But I havent gone through the
math here...


Without going through Leeson in details, only the part of the spectrum
being inside of the f/Q bandwidth will behave as integration for the
noise inside the loop. Signals from the outside will integrate, after
being low-pass filtered by the f/Q bandwidth. The oscillator is just
like a loop.


I think I get what are are hinting at, but I do not fully understand it.
I guess we should discuss this next week in York.


It's a loop with an integrator in it. Signals inside the loop and 
signals outside (being introduced into the loop) the loop will have 
different filtering effects on them. No big magic, but it is easier to 
show with paper and pen.


Seems that my link to the Leeson paper got lost.


Something according to those lines might be where your systems behavior
can be explained.


Well, we do not really have a deadband (save the TDC resolution and
my guess is that the inherent noise in the system does a good job
in decreasing this "deadband" as well). The long cycle time results
rather in a small loop bandwidth. As we only measure one pulse per
cycle, everything that happens between pulses averages out. Ie if we
have any deadband like jitter behavior, we don't see it.


Well, maybe not really, but what you have is kinda similar as the
outermost will have a higher gain being pushed back and the more central
will have weaker pull-in. The time between pulses is indeed a measure to
loop time-constant/bandwidth.

I just say the dead-band give similar pulses.


We currently have a long term measurement running. And there are
intermittent rises in "noise" of the node pair we are measuring.
My assumption is that the order of the center frequencies of the
oscillators changed, thus swapping two of the nodes in their pulse
time order. When two nodes get close to eachother the algorithm
switches between using nodes A & B and using nodes A & C. This can
indeed be seen as a deadband behaviour.


Yes. I meant it as somewhat of an analogy. Notice how each of your nodes 
makes independent choices and how a shift in such a choice will 
indirectly affect the other nodes through how the node will steer it's 
own oscillator.



I'll look further into that behavior as soon as we have some simulation
system running and I see more than one node pair.


Can you record the TICs and the "selected TICs" (essentially 1 bit of if 
the TIC was selected or not in each min/max elimination round)?
That would suffice to analyze the systems internal dynamics. External 
TIC measurements is only to evaluate the variances for an external 
viewer (which the system itself isn't really able to fully value, as the 
common mode variations isn't observeable).



BTW: I discovered that Timelab stops processing after 10'000'000 datapoints,
which is kind inconvenient when doing a long term measurment...


I didn't know that. Good to know.

Cheers,
Magnus
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Re: [time-nuts] Reliability of atomic clocks

[Florian Teply]

Am Mon, 28 Mar 2016 03:20:14 +
schrieb Mark Sims :

> > Mil-spec parts would be somewhat more reliable than commercial
> > parts.
> Actually,  that is seldom true.  The main difference between mil-spec
> parts and commercial parts tends to be in the post-packaging device
> testing (e.g.. extended temperature / voltage range).  They usually
> have the same guts inside the package.I friend of mine was a test
> engineer at a major semiconductor manufacturer and he said their
> commercial parts were actually more reliable than the mil-spec ones.
> The commercial parts were built in vastly greater quantities and
> their production flow / experience enabled them to continually fine
> tune the process and testing.  The production / test regimen of
> mil-spec parts tended to be locked-down by inflexible specs and
> procedures.  Changing anything required re-qualification of the
> entire process.
> 
In general, there are two kinds of MIL-Spec parts:
a) Genuine MIL parts that use specialized processes. And
b) Up-screened commercial parts.

The genuine MIL parts (which often nowadays don't have a commercial
counterpart as these have long been obsoleted) in terms of
reliability usually suffer from low volume. Low volume implies poor
statistical process monitoring and/or long factory storage. This can
not always be seen on the datecode as in many cases the stored entity
is the wafer, not packaged parts.

b) Up-screened commercial parts usually benefit from sufficient volume
in production to keep the process under good statistical control.

But in both cases the major effort for MIL-Spec parts is
qualification, documentation and screening. This actually makes up a
huge chunk of the parts cost in MIL-Spec parts. Due to frequent
testing, for MIL-Spec parts you'd know how they'll behave to a good
degree of precision. But this doesn't mean they would be more reliable
in the sense that they last longer. You just COULD POSSIBLY get more
detailed knowledge on when they'll likely fail under certain conditions.

COULD and POSSIBLY, because for one thing one would need to have
sufficient importance to the manufacturer to actually get the required
data, and second the derivations of lifetime often are based on
MIL-Standard assumptions, which have been established 30+ years ago and
do not necessarily cover modern technologies appropriately.

I could go into more detail, but I'm not sure this is of interest in
this context.

Best regards,
Florian
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Re: [time-nuts] Meaning of MTBF (was: Reliability of atomic clocks)

[Florian Teply]

Am Mon, 28 Mar 2016 01:32:03 +0200
schrieb Attila Kinali :

> Yes, the MTBF is a very simplicistic measure and there are a couple
> of assumptions in its calculation which do not hold generally (or
> rather, it's rather seldom that they hold). Yet it gives a number to
> something that is otherwise relatively hard to measure and the number,
> even though flawed, makes it possible to compare different devices
> on their reliability. As this is more a rule of thumb comparison,
> you shouldn't read too much into a 10% difference. Yet a 100%
> difference is significant, no matter which of the assumptions do not
> hold.
> 
Umm, well, even a 100% difference still might mean nothing if the
derivation of MTBF between different devices is based on different
assumptions. That both these derivations might be seriously flawed does
not help at all.
Yet, even MIL-Spec parts documentation does rarely contain sufficient
detail to assess the validity of the numbers in a certain application.

At the very least, one would need to know acceleration factors for the
different failure mechanisms, and shape parameters of the
failure-vs-time plot. This kind of data I wouldn't expect to find
outside the manufacturers premises, and even there it's not likely to
be accessible if it exists at all.

Best regards,
Florian
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[time-nuts] Long measurements and Timelab (was: Framework for simulation of oscillators)

[Attila Kinali]

Moin,

On Sun, 27 Mar 2016 19:25:30 -0700
"Tom Van Baak"  wrote:

> > BTW: I discovered that Timelab stops processing after 10'000'000 datapoints,
> > which is kind inconvenient when doing a long term measurment...

> I've collected a day of TimeLab/TimePod data at tau 0.001 which is 
> 86'400'000 datapoints. Should be no problem.

I guess it's a bug in the ASCII file import subsystem then..

> My command line tools have no sample limit (well, just malloc() limited)
> and can be orders of magnitude faster than Stable32 or Timelab since they
> are batch and not GUI.

Yes. I didn't had the time to look closely at your tools and those
that John Ackermann wrote. This will probably happen after EFTF.


(Side note: the measurements discussed below are of a fault tolerant clock 
synchronization system prototype, built using of the shelf FPGA boards.
Measuring the phase difference of two nodes of a system consisting of
four nodes)


> But this begs the question -- what are you doing with 10M datapoints? 
> Once you get beyond a couple of decades of data it's often better to compute
> statistics in segments and display all the segments of the whole as a time
> series.

Currently, it's just data collection. Until now we have mostly run the
system for a couple of hours at a time. The longest measurements we have
done were just two days. So, we are now running a measurment that should
go for at least two weeks, to see if something funny happens.
The data collection is done using some small, hacked together c program
that interfaces with the E5810. I use Timelab to have a look at the
data once in a while to see if the data collection is still ok and whether
anything noteworthy is going on. This is especially important as the
measurements are done in Vienna (ie ~800km away) by a friend who,
unfortunately, is not an electrical engineer.



> So, for example, don't compute a single stddev or ADEV number from the
> entire 10M data set. While this gives an apparently "more precise"
> measurement due to sampling, it will also hide key factors like trends,
> periodicity, spectral components, outliers, and glitches.

I've not really done any in depth analysis of the data yet. But so far
it seems like that the data set is very regular, safe for two things:

1) We get a couple of outliers of ~700ps (in average 2 a day) that result
from some issue within the DTS-2075. We have not seen these earlier, so
couldn't investigate them yet. What we see is, that the DTS-2075 reports
measurments of exactly 0 for a couple of 10ms (at one time even up to 100ms),
then the next measurement is in the range of 600-700ps.

2) There are short periods (1-2h) of time when the "noise" increases by
a factor of 1.2-1.5. As I wrote in a previous mail, my guess is that we
get some interaction of the nodes when their oscillatof frequenies get
close to each other. Sofar this happend only three times.

Other than that, we have an almost textbook like behavior. The TDEV
decreases with tau^-0.5 up to 100s, from where it flattens out at 5e-13s
and then rises with bumps where one would expect them from temperature
variations. When using a stretch of measurment where 2) does not happen,
the TDEV goes even further down to ~2e-13s.

Just for fun, I also did a plot of sample/bin density of the phase differences
and got a very nice Gaussian bell. A fit of a real Gaus function, revealed
though, that the density distribution is ever so slightly slanted into the
positive direction.

> I'm not sure if you got your answer on synthetic data, but Stable32 has a
> data noise generator, where you get to specify alpha from -2 to +2.
> I created 1M samples of each of the 5 noise types and use those cached
> files as a noise reference.

Thanks. We might use that as a reference.

I got a student who will implement a simulation framework (including the
noise generation) for me over spring/summer, with the goal of making
it public under GPL as license.


> http://www.leapsecond.com/pages/allan/Exploring_Allan_Deviation_v2.pdf
> http://www.leapsecond.com/pages/allan/

Oh.. nice! That's a good reference to have!

Attila Kinali

-- 
Reading can seriously damage your ignorance.
-- unknown
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Re: [time-nuts] Prescaler

[Bob Albert via time-nuts]

Dennis, that looks interesting but it seems to be a complete counter.  I wonder 
if I could cannibalize it to get the important input circuitry adapted to my 
counter.
Maybe some info on it is available; I'll take a look.
Bob
 

On Sunday, March 27, 2016 6:04 PM, Alexander Pummer  
wrote:
 

 there is a very inexpensive one ADF4118 works up to 3GHz
which has a  programmable prescaler
http://www.analog.com/media/en/technical-documentation/data-sheets/ADF4116_4117_4118.pdf

more here: 
http://www.qsl.net/bg1ceo/Tech_topic/rf/7G_prescaler/prescaler.html
or here:  http://www.qsl.net/n9zia/pre/prescaler.pdf

73
KJ6UHN
Alex

On 3/27/2016 1:41 PM, Bob Camp wrote:
> Hi
>
> There are a *lot* of chips that will divide down from a couple of GHz. Once 
> you have a chip, what do you do with it? There is more to a practical counter 
> front end than just the divider. Getting it all to work requires a bit of 
> time and a pretty good pc board.
>
> This guy:
>
> http://www.analog.com/en/products/rf-microwave/frequency-dividers-multipliers-detectors/frequency-dividers-prescalers-counters/hmc705.html
>
> Will do a divide by 10 and go higher than your counter will. It’s a bit 
> expensive … The eval board is cheaper than a single piece and it will give 
> you a pretty good start.
>
> This guy:
>
> http://www.analog.com/en/products/rf-microwave/frequency-dividers-multipliers-detectors/frequency-dividers-prescalers-counters/hmc434.html
>
> Will only divide by 8, it still goes higher than your counter. The eval board 
> is a bit over $200. One piece of the Ic is < $12.
>
> Bob
>
>
>> On Mar 27, 2016, at 3:45 PM, Bob Albert via time-nuts  
>> wrote:
>>
>> Does anyone know of an inexpensive prescaler for a counter that goes beyond 
>> 2 GHz?  I would actually like to find a kit but everything seems a bit 
>> pricy.  I currently have capability of 500 MHz and that will stretch to 
>> about 700 with care.  So a divide by 10 would be ideal.
>>
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>
> -
> No virus found in this message.
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[time-nuts] A new member & PN test set

[Oleg Skydan]

Hi list,

I am in a process of making a low noise frequency synthesizer for the 1st LO
for my new DSP HF transceiver (http://neon.skydan.in.ua). This list is not
directly related to my project, but I found a lot of useful information in
this list - thanks for all contributors!

I see a discussion regarding "$40 phase noise test set". I have built one 
and

already use it for several months. It is a great help in design process (I
am not "blind" anymore :) ). If somebody is interested I can share all the
information about it.

Best wishes!
Oleg 


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