Re: [time-nuts] WWVB Simulator

[Will Kimber]

I came across this: " rpitx "  it is python software that enables a 
RaspberryPi to transmit using a GPIO pin.


The links refer to using the Rpi to produce 2m Tx signal.   Rpitx seems 
able to produce most modulation schemes. I have not tried it so have no 
idea if it would produce your need directly.


http://zr6aic.blogspot.co.nz/2016/11/creating-2m-fm-repeater-with-raspberry.html

http://zr6aic.blogspot.co.nz/2016/10/vhf-2m-low-pass-filter-design-for.html

Cheers,

Will


On 01/05/2017 09:53 PM, M. Simon via time-nuts wrote:

Paul,
The design of the  - wwvb cheatn d-psk-r - is an excellent start. It is why I 
wanted a WWVB simulator. There are some points that need improvement though. To 
cover the full range of a VCXO the current design might require (in theory) as 
much as a +90 to  -90 deg phase difference between the local oscillator and 
WWVB. I thought that should be reduced to +22.5 to -22.5 degrees ( in theory - 
actual will be less because the VCXO I'm using is active from about .5V to 2.5V 
instead of the full 0 to 3.3V). So that adds a voltage reference (for the 
offset),  op amp and offset resistors to the frequency control loop.

I'm also doing full surface mount (designed for hand soldering) and 
rationalizing the parts values. A fast CMOS comparator (instead of the clunky 
LM311) etc. Power required will be +/-12V and +5. Local regulator(s) will 
supply parts that need 3.3V. I'm designing with low cost in mind.

I still have a lot more work to do but the general outline is more or less 
complete. I will publish when I get some testing done.
The AM detector is also not like any other I have seen. It may be overkill. But 
it is not very expensive.

Simon
  Engineering is the art of making what you want from what you can get at a 
profit.
I like Polywell Fusion.
  


 On Wednesday, January 4, 2017 7:29 PM, paul swed  
wrote:
  
  


  SimonLike you I tend to like hardware. But today complete micros are so cheap and 
powerful they make life easy. Heck a bit to complex use 2 or 3. I like to follow the  
"Get-er-done" philosophy.
That said search the time-nuts archive for the wwvb cheatn d-psk-r. It knows 
how to create the bpsk time stream aligned to wwvb then flips a BPSK switch to 
remove the BPSK. This allows all of the old phase tracking receivers work 
without modifications.I used an Arduino $8 maybe and shared all of the details 
and software with the group. It preserves the old AM for radios that need that 
modulation.So a corrected wwvb signal can be had for cheap and it works very 
well here on the east coast. As well as wwvb ever did.
Have fun and use whatever technology you like as you are the do-er, you get to 
choose.
RegardsPaulWB8TSL
On Wed, Jan 4, 2017 at 2:48 AM, Chris Albertson  
wrote:

You don't need to tie up a PC.It could likely output the WWVB
signal while it was also surfing the web and reading emails.   60KHz
is NOTHING compared to displaying a you-tube video

In fact I bet your 48MHz uP could directly synthesize the signal.
Look at the ratio of 48 MHz / 60 KHz.  The uP can execute about 800
instructions during one cycle of a 60 KHz courier. Your PC can do
a million operations during that same one cycle.



Sure. I considered software. But I'm a hardware guy. I like designing boards. 
The rig was designed to do amplitude and phase simply. The final design will 
have a $5 48 MHz microprocessor included. I'm using that one because of speed 
and memory. When that proves out I might redesign for a $2 24 MHz processor. 
Onesies prices at Mouser

Besides the hardware better illustrates the concepts than software. And I don't 
have to tie up a PC if I don't want to.

I haven't priced everything out yet because the design is not done. I'd be 
surprised if the cost was over $20 in parts for everything - power supply not 
included. PCB extra.

Feel free to send this along to the list if you are inclined.




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Re: [time-nuts] TICC Timestamping / Time Interval Counter -- Available to Order

[Mark Spencer]

Thanks John.   I just placed an order.

All the best
Mark S
VE7AFZ

Sent from my iPhone

> On Dec 7, 2016, at 11:45 AM, John Ackermann N8UR  wrote:
> 
> I'm happy to report that TAPR is now accepting orders for the TICC 
> timestamping / time interval counter.  We've placed an order with the 
> contract manufacturer and expect to have finished product ready to ship 
> sometime in February.  The TICC system will include the TICC shield mounted 
> on an Arduino Mega 2560 compatible processor, with TICC software loaded.  
> Each system will be tested for function before shipping.
> 
> As I mentioned in my original email, TAPR is going a bit out on a limb to 
> produce the TICC, and we have to make a significant up-front payment to our 
> contract manufacturer. So, early orders are very much appreciated to help 
> recover our cash flow.
> 
> The regular price will be $190 each for the TICC shield with Arduino 
> compatible processor,* but to encourage early orders, we're offering a $10 
> discount for orders placed on or before December 21 -- that makes the price 
> $180 plus shipping.
> 
> You can order from: http://tapr.org/kits_ticc.html
> 
> Thanks!
> John
> 
> * We will provide a Sainsmart version of the Arduino Mega 2560 R3.  They seem 
> to be a reliable supplier and we used these boards for TICC development.
> 
> 
>  Forwarded Message 
> Subject: [time-nuts] New Timestamping / Time Interval Counter: the TICC
> Date: Wed, 23 Nov 2016 10:48:57 -0500
> From: John Ackermann N8UR 
> 
> Counters with resolution below 1 nanosecond are difficult.
> They require either outrageous clock speeds, or interpolators
> that are typically a bunch of analog components mixed with black
> magic and stirred by frequent calibration.  The very best single-shot
> resolution that's been commercially available is 20 picoseconds in
> the Keysight 53230A and HP 5370A/B.  My 5370B has an one-second
> noise ADEV of about 4x10e-11.
> 
> With the help of some very talented friends, I've been working on a new
> counter called the "TICC" with <60ps resolution and similar jitter,
> based on the Texas Instruments TDC7200 time-to-data-converter chip. The
> one-second noise ADEV is about 7x10e-11, not much worse than the 5370,
> but here's the trick:  the TICC is an Arduino shield (mounting on a
> Mega 2560 controller) that weighs only a couple of ounces, requires
> *no* calibration, and is powered from a USB cable!
> 
> The TICC is implemented as a two-channel timestamping counter.  That
> means it can measure one or two low-frequency (e.g., pulse-per-second)
> inputs against an external 10 MHz reference, or it can do a traditional
> time interval measurement of one input against the other.  It can also
> measure period, ratio, or any other function of two-channel  timestamp
> data.  (And by the way -- multiple TICCs can be connected to yield 4,
> 6, 8, or more synchronized channels, though we haven't tested this
> capability yet.)
> 
> I've attached a picture of the TICC prototype as well as an ADEV plot
> of a 17+ day run of multiple measurements taken by two TICCs, and also
> showing the TICC noise floor.  The good news behind that plot is that
> there are more than 6 million data points behind these results, and
> there was not a single glitch or significant outlier among them.
> 
> There's more information available at http://febo.com/pages/TICC
> 
> The software is open source (BSD license) and is available at
> https://github.com/TAPR/TICC -- the current version seems be reliable
> but there are still features to add and a *lot* of cleanup to do; it's
> currently ugly and very much a work in process.
> 
> As always, I'll be making the TICC available through TAPR.  We're still
> finalizing details, but we expect the price to be less than $200 for a
> turn-key system:  TICC mounted on an Arduino with software loaded and
> tested for basic functionality.  We hope to ship the TICC by February.
> 
> I'll post a note in a week or two with final price and ordering
> information.  As a heads up, we will probably offer a small discoun
> for pre-orders.  TAPR is a shoestring non-profit group and the up-front
> cost to manufacture this unit will frankly be a challenge for us.
> Getting pre-orders will help our cash flow significantly, so we ask you
> to keep that in mind.
> 
> John
> 
> 
> 
> 
> 
> 
> 
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Re: [time-nuts] Temperature (environmental) sensors

[Hal Murray]

jim...@earthlink.net said:
> I'm kind of curious about their "UI".. hold CapsLock? how does this  device
> manifest itself to the host computer? I saw a mention of HID, so  it is
> emulating a keyboard? 

I have a couple of the non-Gold versions.  Plastic with a push button.  They 
have one sensor in the USB blob and a second sensor on a 3ft cable.  There is 
Linux code that lets you grab a reading when you want.
2017/01/05 12:40:03
Temperature (internal) 76.21F 24.56C
Temperature (external) 72.39F 22.44C

Yes, it's HID.  I don't know anything about that area.  The Linux code is 
big/ugly (my opinion) enough that I didn't just extract the few lines of code 
to stuff into my code but called their run-from-the-shell package.  It's open 
source so it shouldn't be too hard to figure out how it works.


Dec 27 04:02:54 deb kernel: [3857654.032036] usb 3-3: new low-speed USB 
device number 6 using ohci_hcd
Dec 27 04:02:55 deb kernel: [3857654.246845] usb 3-3: New USB device found, 
idVendor=0c45, idProduct=7401
Dec 27 04:02:55 deb kernel: [3857654.246854] usb 3-3: New USB device strings: 
Mfr=1, Product=2, SerialNumber=0
Dec 27 04:02:55 deb kernel: [3857654.246861] usb 3-3: Product: 
TEMPer2_M12_V1.3
Dec 27 04:02:55 deb kernel: [3857654.246867] usb 3-3: Manufacturer: RDing
Dec 27 04:02:55 deb kernel: [3857654.258488] input: RDing TEMPer2_M12_V1.3 as 
/devices/pci:00/:00:03.1/usb3/3-3/3-3:1.0/input/input7
Dec 27 04:02:55 deb kernel: [3857654.259140] generic-usb 0003:0C45:7401.0007: 
input,hidraw0: USB HID v1.10 Keyboard [RDing TEMPer2_M12_V1.3] on 
usb-:00:03.1-3/input0
Dec 27 04:02:55 deb kernel: [3857654.266134] generic-usb 0003:0C45:7401.0008: 
hiddev0,hidraw1: USB HID v1.10 Device [RDing TEMPer2_M12_V1.3] on 
usb-:00:03.1-3/input1

The blurb for the Gold version said LM75.  I haven't taken the cover off a 
non Gold version.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Temperature (environmental) sensors

[Gary E. Miller]

Yo jimlux!
 
 On Thu, 5 Jan 2017 12:21:44 -0800
 jimlux  wrote:
 
> I'm kind of curious about their "UI".. hold CapsLock? how does this 
> device manifest itself to the host computer? I saw a mention of HID,
> so it is emulating a keyboard?  

I received serveral off list requests, so I looked into this a bit more.

As I said before, I use temper-python on Linux to read my TEMPer's:
 
https://github.com/padelt/temper-python

All you need to run that program is Python and the pyusb library:

https://pypi.python.org/pypi/pyusb/1.0.0

Python runs on pretty much anything half-way sane.  pyusb runs on
Linux, Windblows, OS X, and most POSIX systems.

The paranoids will want to run Wireshark in USB capture mode to be
sure nothing devious is going on.

RGDS Veritas liberabit vos
GARY Quid est veritas?
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Temperature (environmental) sensors

[Gary E. Miller]

Yo jimlux!

On Thu, 5 Jan 2017 12:21:44 -0800
jimlux  wrote:

> > http://www.pcsensor.com/usb-hygrometer/temperhum.html  
> 
> I'm kind of curious about their "UI".. hold CapsLock? how does this 
> device manifest itself to the host computer? I saw a mention of HID,
> so it is emulating a keyboard?

It presents to the host OS as an HID/Keyboard,, but sends no data by
default.  I run it on Linux and use the following FOSS Python program to
read it:

https://github.com/padelt/temper-python

Looking at the Python code, a simple binary packet is sent to the
device and it returns a binary packet with the data.

I can't speak to how it works on anything but Linux.  I've never seen
the TEMPer interfere with anything.

RGDS Veritas liberabit vos
GARY Quid est veritas?
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Temperature (environmental) sensors

[jimlux]

On 1/5/17 11:15 AM, Gary E. Miller wrote:

Yo All!

I am surprised that the TEMPer and TEMPerHUM have not been mentioned
yet.  They are cheap reliable USB temperature sensors.  The TEMPerHUM
adds a humidity sensor.

I have several TEMPer's running to log room temp around NTP servers.

The basic TEMPer reads to 0.1°F is only $9:

http://www.pcsensor.com/usb-thermometers/gold-temper.html

I can't speak to its accuracy, but it tracks well with my OXO's frequency
shifts.

There is the double sensor TEMPER for about $19:

http://www.pcsensor.com/usb-thermometer/temper2.html

I do NOT recommend this one.  The external temp will not match the internal
temp.  When I put an IR camera on it I found the external temp sensor
self heats in free ait by several degrees F.

I have not tried the TEMPerHum.  It adds a humidity sensor and is $20:

http://www.pcsensor.com/usb-hygrometer/temperhum.html


I'm kind of curious about their "UI".. hold CapsLock? how does this 
device manifest itself to the host computer? I saw a mention of HID, so 
it is emulating a keyboard?


(which, by the way, is the current strategy for infecting computers with 
USB thumb drives you leave in the parking lot of your victim.. it works 
as a thumb drive, except it also looks for other interesting traffic and 
injects a payload at that time, as if you were on a keyboard..)


https://www.schneier.com/blog/archives/2014/07/the_fundamental.html




From what I can tell, many different Chinese companies make TEMPer's so
YMMV.  But hard to go wrong for $9.

RGDS Veritas liberabit vos
GARY Quid est veritas?
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588



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Re: [time-nuts] No sat positions in LH with Trimble NTBW50AA?

[EB4APL]

I'm using /rxt for my NTBW50AA and after reading your message I changed 
it to /rxy.
I got the same problems as Pete described, so I returned to Thunderbolt 
mode.


Regards,
Ignacio, EB4APL

El 05/01/2017 a las 18:41, Mark Sims escribió:

The Nortel devices can talk either as a Thunderbolt or as a SCPI device.  Use 
it as a Thunderbolt (/rxt).   In SCPI mode the satellite positions are polled 
for once a minute (at xx:xx:33).  Thunderbolt mode provides much more and 
better control of the receiver.

---


  I just got my Trimble NTBW50AA GPSDO up and running with Lady Heather 5.0.

However I don't see any satellite data as I do with my Resolution T.   I
am using
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Re: [time-nuts] Temperature (environmental) sensors

[Gary E. Miller]

Yo All!

I am surprised that the TEMPer and TEMPerHUM have not been mentioned
yet.  They are cheap reliable USB temperature sensors.  The TEMPerHUM
adds a humidity sensor.

I have several TEMPer's running to log room temp around NTP servers.

The basic TEMPer reads to 0.1°F is only $9:

http://www.pcsensor.com/usb-thermometers/gold-temper.html

I can't speak to its accuracy, but it tracks well with my OXO's frequency
shifts.

There is the double sensor TEMPER for about $19:

http://www.pcsensor.com/usb-thermometer/temper2.html

I do NOT recommend this one.  The external temp will not match the internal
temp.  When I put an IR camera on it I found the external temp sensor
self heats in free ait by several degrees F.

I have not tried the TEMPerHum.  It adds a humidity sensor and is $20:

http://www.pcsensor.com/usb-hygrometer/temperhum.html

From what I can tell, many different Chinese companies make TEMPer's so
YMMV.  But hard to go wrong for $9.

RGDS Veritas liberabit vos
GARY Quid est veritas?
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] No sat positions in LH with Trimble NTBW50AA?

[Jeff AC0C]

I have a '50AA here.  But I don't use any command line options relating to 
box ID.  Just start up LH - LH talks to the box, determines it's a Trimble 
variant, and off to the races it goes.


73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-Original Message- 
From: Peter Reilley

Sent: Thursday, January 05, 2017 12:11 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] No sat positions in LH with Trimble NTBW50AA?

I tried /rxt but that won't communicate.   Must I put the unit in
Thunderbolt mode?Is there
a jumper or a command that will do it?   The manual that I have does not
mention different
modes.   It only talks about SCPI.

Thanks,
Pete.



On 1/5/2017 12:41 PM, Mark Sims wrote:
The Nortel devices can talk either as a Thunderbolt or as a SCPI device. 
Use it as a Thunderbolt (/rxt).   In SCPI mode the satellite positions are 
polled for once a minute (at xx:xx:33).  Thunderbolt mode provides much 
more and better control of the receiver.


---

  I just got my Trimble NTBW50AA GPSDO up and running with Lady Heather 
5.0.

However I don't see any satellite data as I do with my Resolution T.   I
am using
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Re: [time-nuts] No sat positions in LH with Trimble NTBW50AA?

[Peter Reilley]

I tried /rxt but that won't communicate.   Must I put the unit in 
Thunderbolt mode?Is there
a jumper or a command that will do it?   The manual that I have does not 
mention different

modes.   It only talks about SCPI.

Thanks,
Pete.



On 1/5/2017 12:41 PM, Mark Sims wrote:

The Nortel devices can talk either as a Thunderbolt or as a SCPI device.  Use 
it as a Thunderbolt (/rxt).   In SCPI mode the satellite positions are polled 
for once a minute (at xx:xx:33).  Thunderbolt mode provides much more and 
better control of the receiver.

---


  I just got my Trimble NTBW50AA GPSDO up and running with Lady Heather 5.0.

However I don't see any satellite data as I do with my Resolution T.   I
am using
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[time-nuts] EFOS Maser turns 34!

[cdelect]

"Copper has a quite high temperature expansion, so could you servo
that via the cavity temperature ?"

To answer, both Copper and Aluminum cavities use the temperature setting
to coarse tune the cavity.

Fine tuning is via Varactor diode and modern Masers do servo "Auto-tune"
the cavity to reduce drift.

Corby

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[time-nuts] No sat positions in LH with Trimble NTBW50AA?

[Mark Sims]

The Nortel devices can talk either as a Thunderbolt or as a SCPI device.  Use 
it as a Thunderbolt (/rxt).   In SCPI mode the satellite positions are polled 
for once a minute (at xx:xx:33).  Thunderbolt mode provides much more and 
better control of the receiver.

---

>  I just got my Trimble NTBW50AA GPSDO up and running with Lady Heather 5.0.
However I don't see any satellite data as I do with my Resolution T.   I 
am using
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Re: [time-nuts] σ vs s in ADEV

[William H. Fite]

Professional statistician here.

Your explanation is clear and lucid, in contrast to some earlier attempts
here. I agree that with oscillators the distinction between N and N-1 is
not particularly relevant. I must caution you, however, not to be too
dismissive of the difference between the two. There are excellent reasons
for the "pedantic" distinction between samples and populations, especially
in small-sample work and when extrapolations are involved. A mistake by
NASA between N and n might mean putting the lander on Mars or missing it by
100,000km. You may count that distinction "beyond ridiculous" but it isn't
going away because, for mamy applications, it is absolutely critical.

Many thanks for your invaluable contributions in your field over the year.

Bill (PhD, as if that mattered)



On Wednesday, January 4, 2017, Tom Van Baak  wrote:

> Hi Attila,
>
> The plain ADEV calculation is essentially a measure of unexpected or
> unwanted drift in frequency; which is the 1st difference of frequency
> error; the 2nd difference of phase error; the 3rd difference in clock time
> itself.
>
> When measuring the quality of a clock, the key idea is that initial phase
> doesn't matter (you can always manually set the time), and even initial
> frequency doesn't matter (you can often adjust the rate: whether pendulum,
> quartz or atomic clock), and so a more honest measure of intrinsic
> timekeeper stability is its ability to maintain frequency; that is,
> statistically speaking, the lower the change in frequency, tau to tau, the
> better. Change in frequency is frequency drift.
>
> If you have N phase samples, you get N-1 frequency samples and N-2 drift
> samples. The standard ADEV calculation is simply based on the mean of those
> drift samples. (and you know Hadamard takes this one step deeper).
>
> If you look a the code at http://leapsecond.com/tools/adev_lib.c you'll
> see I avoid the confusing issue of N-1, N, N+1 and simply count the number
> of terms in the rms sum. Not only does that give the correct result but
> IMHO it make it clear what is being averaged. The code passes the official
> NBS ADEV sample suite, agrees with Bill's Stable32, is used in John's
> TimeLab, and also Mark's Lady Heather.
>
> I've never quite understood the pedantic separation of "sample" and
> "population" mean that statistic textbooks and academics love to discuss.
> They clearly have never measured oscillators. In my experience if you think
> there's an important difference between N and N-1, then that's nature's way
> of telling you to go back to sleep and wait until tomorrow when you have
> more data. If your N is too small your ADEV wanders all over the place
> (TimeLab is good at displaying this in real-time) -- meaning that the
> distinction between sample (n-1) and population (n) mean is beyond
> ridiculous; even if there's a "correct" textbook answer.
>
> /tvb
>
> - Original Message -
> From: "Attila Kinali" >
> To: "Discussion of precise time and frequency measurement" <
> time-nuts@febo.com >
> Sent: Wednesday, January 04, 2017 12:12 PM
> Subject: [time-nuts] σ vs s in ADEV
>
>
> Hi,
>
> A small detail caught my eye, when reading a paper that informally
> introduced ADEV. In statistics, when calculating a variance over
> a sample of a population the square-sum is divided by (n-1)(denoted by s in
> statistics) instead of (n) (denoted by σ) in order to account for a small
> bias
> the "standard" variance introduces
> (c.f. https://en.wikipedia.org/wiki/Unbiased_estimation_of_
> standard_deviation )
> In almost all literature I have seen, ADEV is defined using an average,
> i.e. dividing by (n) and very few use (n-1).
>
> My question is two-fold: Why is (n) being used even though it's known
> to be an biased estimator? And why do people not use s when using (n-1)?
>
> Attila Kinali
>
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] No sat positions in LH with Trimble NTBW50AA?

[EB4APL]

Hi Pete,

I have a NTBW50AA running with Lady Heather 5.0 (and also with previous 
version) and I don't see any anomaly, it sees all satellites in view and 
the clock updates every second. BTW, I have done a mod for outputting 1 
PPS instead of 1/2 PPS, but it does not go to LH.


I can only suggest you to test it using Trimble Visual Timing Studio to 
have a "second opinion".


Regards,

Ignacio, EB4APL


El 05/01/2017 a las 15:25, Peter Reilley escribió:
I just got my Trimble NTBW50AA GPSDO up and running with Lady Heather 
5.0.
However I don't see any satellite data as I do with my Resolution T.   
I am using

/rxy which specifies SCPI-(NORTEL) as the device.

What am I doing wrong?

Also, the clock updates every 2 seconds.   I assume that this is an 
artifact of the

2PPS output.

Thanks,
Pete.

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[time-nuts] No sat positions in LH with Trimble NTBW50AA?

[Peter Reilley]

I just got my Trimble NTBW50AA GPSDO up and running with Lady Heather 5.0.
However I don't see any satellite data as I do with my Resolution T.   I 
am using

/rxy which specifies SCPI-(NORTEL) as the device.

What am I doing wrong?

Also, the clock updates every 2 seconds.   I assume that this is an 
artifact of the

2PPS output.

Thanks,
Pete.

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Re: [time-nuts] Tom's PICDiv?

[John Ackermann N8UR]

Sorry, I missed the "complete unit" part... the TAPR products do require 
some soldering.  The TADD-2 does have a case available if that helps.


John

On 1/5/2017 8:21 AM, John Ackermann N8UR wrote:

Hi Bob --

TAPR has two boards that provide life support for Tom's PICDiv chips:

The "TADD-2" is a six-channel divider allowing each channel to have its
rate independently set from a common source:
https://www.tapr.org/kits_tadd-2.html

The "T2-Mini" is a tiny board that provides a single channel of PPS (or
whatever you want) from an RF input:
https://www.tapr.org/kits_t2-mini.html

John



On 1/5/2017 12:34 AM, Bob Stewart wrote:

Hi all,
I was wondering if anyone makes a nice, complete unit from one of
Tom's PICDivs; preferably with an external 10MHz input, a 10MHz output
and a 1PPS output?  It would be nice if it also accepted a 1PPS in to
sync the PIC's output to an external 1PPS source, but that's not a
necessity.  I've got something kludged together here that I can drive
from my Cs standard for testing, but I was hoping for something a bit
more purpose made if anyone makes one?  Not looking for a kit or just
a board, nor do I have any interest in making/marketing such a unit.

Bob -
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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Re: [time-nuts] Tom's PICDiv?

[John Ackermann N8UR]

Hi Bob --

TAPR has two boards that provide life support for Tom's PICDiv chips:

The "TADD-2" is a six-channel divider allowing each channel to have its 
rate independently set from a common source:

https://www.tapr.org/kits_tadd-2.html

The "T2-Mini" is a tiny board that provides a single channel of PPS (or 
whatever you want) from an RF input:

https://www.tapr.org/kits_t2-mini.html

John



On 1/5/2017 12:34 AM, Bob Stewart wrote:

Hi all,
I was wondering if anyone makes a nice, complete unit from one of Tom's 
PICDivs; preferably with an external 10MHz input, a 10MHz output and a 1PPS 
output?  It would be nice if it also accepted a 1PPS in to sync the PIC's 
output to an external 1PPS source, but that's not a necessity.  I've got 
something kludged together here that I can drive from my Cs standard for 
testing, but I was hoping for something a bit more purpose made if anyone makes 
one?  Not looking for a kit or just a board, nor do I have any interest in 
making/marketing such a unit.

Bob -
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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Re: [time-nuts] σ vs s in ADEV

[Bob Camp]

HI

> On Jan 5, 2017, at 6:33 AM, Magnus Danielson  
> wrote:
> 
> Hi,
> 
> On 01/05/2017 01:26 AM, Tom Van Baak wrote:
>> Hi Attila,
>> 
>> The plain ADEV calculation is essentially a measure of unexpected or
>> unwanted drift in frequency; which is the 1st difference of frequency
>> error; the 2nd difference of phase error; the 3rd difference in clock
>> time itself.
> 
> ADEV is thus sensitive to linear drift, which becomes a limiting factor for 
> higher tau.
> 

Which is *why* the standard verbal description of ADEV always includes the 
qualifier 
“drift corrected”. If drift is not removed from the data, ADEV is not doing 
what it should.
This gets overlooked when we take ADEV straight off of a cool piece of gear 
that is unable
to properly / automatically remove the drift.

Bob


> I can't see how clock time itself would integrate from phase. The time of a 
> clock is just an enumeration of phase. Phase is often presented in a wrapped 
> phase, but if you enumerate it is still just phase with larger numbers, ADEV 
> is still just 2nd difference away, not 3rd. It's actually the time of x being 
> used, not phase.
> 
>> When measuring the quality of a clock, the key idea is that initial
>> phase doesn't matter (you can always manually set the time), and even
>> initial frequency doesn't matter (you can often adjust the rate:
>> whether pendulum, quartz or atomic clock), and so a more honest
>> measure of intrinsic timekeeper stability is its ability to maintain
>> frequency; that is, statistically speaking, the lower the change in
>> frequency, tau to tau, the better. Change in frequency is frequency
>> drift.
> 
> Due to the second difference, phase offset and frequency offset does not 
> affect the ADEV. Similarly for frequency measurement which is the first 
> difference, phase offset does not affect the frequency estimation.
> 
>> If you have N phase samples, you get N-1 frequency samples and N-2
>> drift samples. The standard ADEV calculation is simply based on the
>> mean of those drift samples. (and you know Hadamard takes this one
>> step deeper).
>> 
>> If you look a the code at http://leapsecond.com/tools/adev_lib.c
>> you'll see I avoid the confusing issue of N-1, N, N+1 and simply
>> count the number of terms in the rms sum. Not only does that give the
>> correct result but IMHO it make it clear what is being averaged. The
>> code passes the official NBS ADEV sample suite, agrees with Bill's
>> Stable32, is used in John's TimeLab, and also Mark's Lady Heather.
> 
> The NIST 1000-point test-suite in NIST SP 1065 is recommended these days
> as a test sequence. That's what I used to test all my implementations.
> 
>> I've never quite understood the pedantic separation of "sample" and
>> "population" mean that statistic textbooks and academics love to
>> discuss. They clearly have never measured oscillators. In my
>> experience if you think there's an important difference between N and

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Re: [time-nuts] σ vs s in ADEV

[Magnus Danielson]

Hi,

On 01/05/2017 01:26 AM, Tom Van Baak wrote:

Hi Attila,

The plain ADEV calculation is essentially a measure of unexpected or
unwanted drift in frequency; which is the 1st difference of frequency
error; the 2nd difference of phase error; the 3rd difference in clock
time itself.


ADEV is thus sensitive to linear drift, which becomes a limiting factor 
for higher tau.


I can't see how clock time itself would integrate from phase. The time 
of a clock is just an enumeration of phase. Phase is often presented in 
a wrapped phase, but if you enumerate it is still just phase with larger 
numbers, ADEV is still just 2nd difference away, not 3rd. It's actually 
the time of x being used, not phase.



When measuring the quality of a clock, the key idea is that initial
phase doesn't matter (you can always manually set the time), and even
initial frequency doesn't matter (you can often adjust the rate:
whether pendulum, quartz or atomic clock), and so a more honest
measure of intrinsic timekeeper stability is its ability to maintain
frequency; that is, statistically speaking, the lower the change in
frequency, tau to tau, the better. Change in frequency is frequency
drift.


Due to the second difference, phase offset and frequency offset does not 
affect the ADEV. Similarly for frequency measurement which is the first 
difference, phase offset does not affect the frequency estimation.



If you have N phase samples, you get N-1 frequency samples and N-2
drift samples. The standard ADEV calculation is simply based on the
mean of those drift samples. (and you know Hadamard takes this one
step deeper).

If you look a the code at http://leapsecond.com/tools/adev_lib.c
you'll see I avoid the confusing issue of N-1, N, N+1 and simply
count the number of terms in the rms sum. Not only does that give the
correct result but IMHO it make it clear what is being averaged. The
code passes the official NBS ADEV sample suite, agrees with Bill's
Stable32, is used in John's TimeLab, and also Mark's Lady Heather.


The NIST 1000-point test-suite in NIST SP 1065 is recommended these days
as a test sequence. That's what I used to test all my implementations.


I've never quite understood the pedantic separation of "sample" and
"population" mean that statistic textbooks and academics love to
discuss. They clearly have never measured oscillators. In my
experience if you think there's an important difference between N and
N-1, then that's nature's way of telling you to go back to sleep and
wait until tomorrow when you have more data. If your N is too small
your ADEV wanders all over the place (TimeLab is good at displaying
this in real-time) -- meaning that the distinction between sample
(n-1) and population (n) mean is beyond ridiculous; even if there's a
"correct" textbook answer.


Traditional statistical textbooks only measure with white noise 
disturbance for starters. What we do in ADEV and friends space is much 
more complex. Traditional textbooks can get us up to speed with some of 
the basics, but as we get flicker involved we are doomed. The 
integration of the oscillator loop then give support for four noise 
forms which is quite different.


So, the (n-1) and (n) issue is relevant when n is small and you have 
white noise measurements. Compared to ADEV and friends you already get 
the full degree of freedom and estimating it is trivial, it's (n-1) 
which is why this is the average to use for standard deviation/variance.
That you can loose degrees of freedom due to how the noise interact with 
the estimator is well beyond the textbooks. As you study these tools 
more deeply, you essentially study advanced statistical methods.


After studying that I've become more particular about saying things like 
estimator, bias functions, degrees of freedom and confidence intervals.


As the noiseforms work against us, we have to work hard to get high 
degree of freedom for part of a measure, so that the confidence 
intervals goes down. As we do that we either measure longer or use 
another estimator with better performance. Some of these measures 
introduce biases, but those can be worked out and compensated for, often 
without too much effort.


Terms like deviation, variance, degrees of freedom, confidence interval 
and estimator can be best learned in traditional statistics first. Then 
you need to do the follow-up coarse for non-white noise statistics.


Cheers,
Magnus
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Re: [time-nuts] WWVB Simulator

[M. Simon via time-nuts]

Paul,
The design of the  - wwvb cheatn d-psk-r - is an excellent start. It is why I 
wanted a WWVB simulator. There are some points that need improvement though. To 
cover the full range of a VCXO the current design might require (in theory) as 
much as a +90 to  -90 deg phase difference between the local oscillator and 
WWVB. I thought that should be reduced to +22.5 to -22.5 degrees ( in theory - 
actual will be less because the VCXO I'm using is active from about .5V to 2.5V 
instead of the full 0 to 3.3V). So that adds a voltage reference (for the 
offset),  op amp and offset resistors to the frequency control loop.

I'm also doing full surface mount (designed for hand soldering) and 
rationalizing the parts values. A fast CMOS comparator (instead of the clunky 
LM311) etc. Power required will be +/-12V and +5. Local regulator(s) will 
supply parts that need 3.3V. I'm designing with low cost in mind. 

I still have a lot more work to do but the general outline is more or less 
complete. I will publish when I get some testing done.
The AM detector is also not like any other I have seen. It may be overkill. But 
it is not very expensive. 

Simon
 Engineering is the art of making what you want from what you can get at a 
profit. 
I like Polywell Fusion.
 

On Wednesday, January 4, 2017 7:29 PM, paul swed  
wrote:
 
 

 SimonLike you I tend to like hardware. But today complete micros are so cheap 
and powerful they make life easy. Heck a bit to complex use 2 or 3. I like to 
follow the  "Get-er-done" philosophy.
That said search the time-nuts archive for the wwvb cheatn d-psk-r. It knows 
how to create the bpsk time stream aligned to wwvb then flips a BPSK switch to 
remove the BPSK. This allows all of the old phase tracking receivers work 
without modifications.I used an Arduino $8 maybe and shared all of the details 
and software with the group. It preserves the old AM for radios that need that 
modulation.So a corrected wwvb signal can be had for cheap and it works very 
well here on the east coast. As well as wwvb ever did.
Have fun and use whatever technology you like as you are the do-er, you get to 
choose.
RegardsPaulWB8TSL
On Wed, Jan 4, 2017 at 2:48 AM, Chris Albertson  
wrote:

You don't need to tie up a PC.    It could likely output the WWVB
signal while it was also surfing the web and reading emails.   60KHz
is NOTHING compared to displaying a you-tube video

In fact I bet your 48MHz uP could directly synthesize the signal.
Look at the ratio of 48 MHz / 60 KHz.  The uP can execute about 800
instructions during one cycle of a 60 KHz courier.     Your PC can do
a million operations during that same one cycle.

But go ahead.  I'm subscribed to another list dedicated to building
stuff with vacuum tubes.  I kind of enjoy building with that
technology.    I used to like building with 70'd vintage 74xxx TTL.
city is like lego blocks for big kids.   But as a practical matter if
you just want something to work, 21st century technology gets the job
done.




On Tue, Jan 3, 2017 at 6:49 PM, M. Simon via time-nuts
 wrote:
> Sure. I considered software. But I'm a hardware guy. I like designing boards. 
> The rig was designed to do amplitude and phase simply. The final design will 
> have a $5 48 MHz microprocessor included. I'm using that one because of speed 
> and memory. When that proves out I might redesign for a $2 24 MHz processor. 
> Onesies prices at Mouser
>
> Besides the hardware better illustrates the concepts than software. And I 
> don't have to tie up a PC if I don't want to.
>
> I haven't priced everything out yet because the design is not done. I'd be 
> surprised if the cost was over $20 in parts for everything - power supply not 
> included. PCB extra.
>
> Feel free to send this along to the list if you are inclined.
>
> Simon
>  Engineering is the art of making what you want from what you can get at a 
>profit.
> I like Polywell Fusion.
>
>
>     On Tuesday, January 3, 2017 5:53 AM, Hal Murray  
>wrote:
>
>
>
>
> time-nuts@febo.com said:
>> I have come up with a ridiculously simple WWVB simulator that simulates both
>> the AM modulation and the BPSK modulation.
>
> Did you consider software?
>
> Is the audio on a Raspberry Pi fast enough?
>
> I haven't looked at any details, but you can get ARM CPUs for ballpark of $5
> on eBay.  There is a good chance that one of their IO devices will let you
> send raw bits via a DMA channel.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
>
>
>
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--

Chris Albertson
Redondo Beach, California
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