Re: [time-nuts] WWVB SDR discussion

[Chris Burford]

I have one of these wall clocks and it too has a minor misalignment of the
second hand. The second hand will overshoot the face marker by about
one-fourth of the distance between successive markings.

If the fix is not too terribly involved I might would give it a try,
otherwise, It will just have to remain a sub time-nuts piece of hardware.

Chris

-Original Message-
From: time-nuts  On Behalf Of Tom Van Baak
Sent: Thursday, August 20, 2020 22:59
To: time-nuts@lists.febo.com
Subject: Re: [time-nuts] WWVB SDR discussion

Mike,

I've used that seller a lot; no worries. They have 800+ items for sale,
mostly clock and weather products by La Crosse Technology [1]. It looks like
this eBay seller is their online retail store, as well as an outlet for
their overstock and refurbished items:

https://www.ebay.com/itm/274056463528
Seller: greatbigoutlet
Item location: La Crosse, Wisconsin, United States
Condition: Manufacturer refurbished

One of the complaints that I had about the La Crosse 404-1235UA-SS
UltrAtomic clock was that several of the ones I bought had misaligned hands
[2]. If you're into Lavet stepper motor watch movements using optical
feedback it's something you can fix yourself. The other solution is to
return it to the factory. It wouldn't surprise me that La Crosse has a pile
of these refurbished clocks for sale. Or maybe 1235UA just never sold well;
or maybe there's a new model coming; who knows.

And, yes, this is a deal for $35. They are so much better than older WWVB
clocks. AFAIK it is still the only LF radio clock that uses the new eWWVB PM
format. The smaller clocks and watches all use the legacy WWVB AM format.

/tvb

[1] https://www.lacrossetechnology.com/

[2] http://leapsecond.com/pages/ultratomic/


On 8/20/2020 8:00 PM, Mike Feher wrote:
> Hi Don -
>
> I got two of them on eBay. I got these 274056463528 . They were only 
> $35 each with free shipping, a bargain in my opinion. Of course you 
> can find smaller diameter ones as well. 73 - Mike
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell NJ 07731
> 848-245-9115
>
> -Original Message-
> From: time-nuts  On Behalf Of DON 
> MURRAY via time-nuts
> Sent: Thursday, August 20, 2020 8:41 PM
> To: time-nuts@lists.febo.com
> Cc: DON MURRAY 
> Subject: Re: [time-nuts] WWVB SDR discussion
>
>
> Mike...
>
> Which model did you order?
>
>
> 73
> Don
> W4WJ
>
> On Thursday, August 20, 2020 Mike Feher  wrote:
> I just purchased 2 of those La Crosse 14" clocks and was totally 
> amazed. I live on the Jersey shore on one acre surrounded by trees and 
> about 8 miles from the ocean. After I placed batteries in the clock, 
> it went through its initially routine which was neat in itself, and 
> about an hour or less later the motors purred again and it went to the 
> exact time and continues to do so. This was on the first floor of my 
> Colonial in my office next to the computer and all sorts of other 
> digital and switching PS noise and only about a foot off the floor. My 
> old Junghans Mega 1000 could never do that. I have to take it upstairs 
> with me and place it by the front (South facing) window of the master 
> bedroom and sometime during the night it acquires and corrects if need 
> be. Regardless, I still like my Junghans, but this new waveform is 
> amazing. Thanks for mentioning it. Regards - Mike
>
>   
>
> Mike B. Feher, N4FS
>
> 89 Arnold Blvd.
>
> Howell NJ 07731
>
> 848-245-9115
>
>   
>
>
> ___
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Re: [time-nuts] UBlox F9T and Lady Heather

[Chris Burford]

I too posted a similar issue with my F9P on the EEVBlog with the exact same
results as you are having. I still don't have an answer for the satellites
not showing up in LH.

-Original Message-
From: time-nuts  On Behalf Of Ben Hall
Sent: Thursday, May 28, 2020 16:01
To: time-nuts@lists.febo.com
Subject: [time-nuts] UBlox F9T and Lady Heather

Afternoon all,

I finally got ahold of a UBlox F9T in the form of the RCB-F9T evaluation
module.

Got it talking to Lady Heather on an old Raspberry Pi, and everything is
working, but the satellite table is blank.  Just shows ".." in the PRN
column, with AZ, EL, SIG, and DOPPLER blank.

Clearly, she's tracking satellites, as the "Tracking sats" message is on and
the 1PPS LED is in phase with all the others here.

I've been searching thru old posts, the manual, EEVBlog webpage, pretty much
any place that has Lady Heather information...and can't figure out what I'm
doing wrong.

Anyone know what I might be doing wrong?  I am using the /rxu switch, have
tried toggling different GNSS systems on and off, all with no effect...

When I connect the unit to my PC with uCenter, I can see satellite
information just fine...

thanks much and 73,
ben, kd5byb


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Re: [time-nuts] GPS antenna splitter recommendation?

[Chris Burford]

I use a 4 port splitter from InStock Wireless, all with SMA jacks. You can
view the specs here as well as browse for other configurations. To help with
the attenuation factor use the lowest loss coax between the splitter and the
GPS antenna. I'm using Times Microwave LMR-400 for just that reason.

https://www.instockwireless.com/gps-splitter-4way-SMA-gps410.htm

Chris Burford

-Original Message-
From: time-nuts  On Behalf Of Frank
O'Donnell
Sent: Wednesday, April 29, 2020 19:18
To: time-nuts@lists.febo.com
Subject: [time-nuts] GPS antenna splitter recommendation?

I'm looking for a splitter to allow three or four GPSDO's to share my
roof-mounted Lucent PCTEL KS24019L112C 26db GPS twist antenna.

I understand from scanning past threads that inexpensive splitters by
companies like Mini-Circuits often turn up on eBay, but I'm having trouble
narrowing down to one that will work for my situation. Can anyone recommend
a specific splitter that wouldn't be too expensive?

Thanks much,

Frank




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[time-nuts] TimeLab / TICC

[Chris Burford]

Hello All.

 

I'm looking for some offline assistance with the TAPR TICC and TimeLab for
making some measurements. My repository of notes on prior attempts vanished
in a hard drive failure.

 

I can provide clearly labeled wiring diagrams for the TICC and DUT if
needed.

 

Thanks,

Chris

 

 

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Re: [time-nuts] Vaperware Parts and pulse stretching circuits

[Chris Burford]

Here's a good follow along for close pitch soldering:

https://www.youtube.com/watch?v=5uiroWBkdFY

Haven't had to solder anything this close pitch but the video is just one in
a series of good soldering techniques.

Chris

-Original Message-
From: time-nuts  On Behalf Of Hal Murray
Sent: Saturday, April 25, 2020 05:27
To: Discussion of precise time and frequency measurement

Cc: hmur...@megapathdsl.net
Subject: Re: [time-nuts] Vaperware Parts and pulse stretching circuits


j...@scawbydesign.co.uk said:
> Just to put the record straight, I am a 72-year-old retired 
> electronics specialist who uses a 50-year-old Weller soldering iron 
> and a magnified
> (x3.5) bench light to solder 64pin 0.5mm pitch MSP430 microprocessors 
> by hand. As I said - "... not impossible to solder."

How long does it take?

I've seen a writeup that says roughly, lots of flux, get a blob of solder on
the tip of the iron and sweep it across a row of pins.  If all goes well, it
just works.  I haven't tried it.

-

It was many years ago when I noticed that my eyes getting older had crossed
over the pins getting smaller.

--
These are my opinions.  I hate spam.




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Re: [time-nuts] Using speaker / earphone for PPS testing (not a question)

[Chris Burford]

I reached out to SRS several months ago to inquire if the pulse width could be 
configured from the default of 10 micro second. Their responses was no.

Chris

-Original Message-
From: time-nuts  On Behalf Of Taka Kamiya via 
time-nuts
Sent: Monday, April 20, 2020 22:35
To: Discussion of precise time and frequency measurement 

Cc: Taka Kamiya 
Subject: Re: [time-nuts] Using speaker / earphone for PPS testing (not a 
question)

Out of all signal source, the shortest 1 pps is PRS-10 at 10 micro second.  
T-bolt is quite short as well but I don't have a definite data.
For those, speaker method worked just fine.  I'm just sharing what I learned on 
happenstance.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, April 20, 2020, 11:05:02 PM EDT, Bill Byrom 
 wrote:  
 
 It's easy to trigger on short pulses on most oscilloscopes if you follow these 
steps:
(1) Do NOT use Auto Trigger mode. Instead use Normal trigger mode.
(2) Set the vertical coupling mode to DC.
(3) Set the vertical gain (volts/div) and offset so that the baseline (OFF 
voltage between pulses) and pulse ON voltage should both be visible on the 
vertical scale. 
(4) Set the trigger coupling mode to DC and the trigger source to the proper 
channel.
(5) Set the trigger voltage to the midpoint between the pulse OFF and ON 
voltage. 
(6) Set the trigger slope appropriately, depending on the polarity of the 1 PPS 
pulse.
(7) Many oscilloscopes have a trigger indicator LED. It should flash visibly on 
each 1 PPS signal.
(8) If you are using an analog scope which does NOT have a microchannel plate 
(which was used on the Tektronix 2467 family and a few other models), the pulse 
ON signal may be difficult to see at a fast time/div setting, even with a high 
scope intensity setting. But you can slow down the time/div of an analog scope 
to something easy to see, such as 10 ms/div. This will allow you to see a 
bright sweep each time the scope triggers, even if a short pulse can't be seen.
(9) When using a digital oscilloscope, turn on the peak detect display mode. 
This allows the oscilloscope to keep a high sampling rate even if the time/div 
is set for a moderately slow sweep.

If the 1 PPS signal is very short, you won't be able to hear it on a speaker 
with a direct connection as you describe. But you can use a pulse stretcher 
circuit (such as a 555 timer IC) to drive a LED or speaker with a long output 
pulse (such as 10 ms). If you use two 555 IC's (or a 556 dual timer IC), you 
can even configure one section as a one-shot and the other as a tone generator 
so that a beep is produced for each pulse. The 555 and 556 may be sold as  
LM555/LM556 or NE555/NE556.
--
Bill Byrom N5BB
Retired Tektronix Application Engineer

On Mon, Apr 20, 2020, at 9:25 PM, Taka Kamiya via time-nuts wrote:
> Maybe everyone but I knew, but I just did this and found it useful.
> 1 pps signal from some GPS are notoriously narrow and difficult to sync 
> on and see on scopes.  LED will barely light if some kind of stretcher 
> is not used.  If your purpose is ONLY to see if it's there or not, hook 
> up a small speaker, earphone, amplified or not, and you can hear the 
> tick-tick sound.  
> 
> I like DIYing and many times, I wonder if pps distribution circuit is 
> working.  I can tell a very short pulse that will barely register on 
> LED is clearly audible.
> I thought I'd share.
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
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Re: [time-nuts] GPS module recommendation for Pi timing

[Chris Burford]

A nice post processing application such as RTKLIB will show any cycle 
slips that your receiver might have encountered.


A good write up about cycle slips is available here:

https://rtklibexplorer.wordpress.com/2016/05/08/raw-data-collection-cycle-slips/ 



Regards,

Chris

On 03/13/20 15:14:13, Hal Murray wrote:

Thanks.

kb...@n1k.org said:

One of the ways a GPS module “freaks out� is to slip by one code cycle
(which is just slightly over 1 ms). If you have a surveyed location, some
firmware will reject the solution and at least you will be in holdover.

If it slips, how long does it stay slipped?

I have plenty of old GPS units.  I'm a bit surprised I haven't noticed
something like that.  Maybe I'm not looking hard enough and/or in the right
place.


In a case where the *only* thing you can trust is the GPS, filtering isn’t
going to do much good.

You also have the CPU crystal.  It's not good for long term stability, but
shouldn't have any troubles holding to a ms over several seconds.




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Re: [time-nuts] PRS10

[Chris Burford]

Hi Christoph,

You might would want to try and calibrate the (T)ime (O)ffset as per 
page 32 of the Operation and Service Manual and then write that value 
with the TO! command.


This may or may not clear out any residual issues.

Regards,

Chris

On 02/10/20 03:10:37, Christoph Guenther via time-nuts wrote:

PRS10 - Help Wanted !!!


My PRS10 v.3.21 sends "SYNTAX ERROR" in the TT string for TT values above
approx. 99640 (ext. 1PPS input active). LadyHeather therefore shows no
negative TTs. Only when the TT gets smaller does LH also show more negative
values than approx. -360ns, otherwise 0 or positive. If you read the other
parameters, you will find that TO = 0 and TS = 12000, PS = 200 (unlikely
that these round values are correct ). If 1PPS output and input are
connected, TT = 1855 is output. This value should be saved with TO as
-1855. A full recall (RC1) also brought no change. Attached is an LH screen
printout.



Do you have any ideas on how I can fix the problem? The part has the
customer PN: 123-44101-06. Could these strange parameters possibly be
related to this PN? Does anyone have such a PRS10 v. 3.21 with this PN and
could he send me his values (TO, TS, PS)?

Support from SRS is unfortunately not really available because I did not
buy the device directly from them - thanks SRS !!! -

Does anyone *know the factory access code* (will of course be treated
confidentially) to write the correct values in the device?

I would be very grateful if there was a “PRS10 professional” who could help
me. For direct answers, I can also be reached at veroch...@web.de.



Thank you very much
Christoph

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Re: [time-nuts] NTP apps on Windows question

[Chris Burford]

Yes,

You want to disable Windows Time service (w32time) if running the client 
from Meinberg. If you scroll down about 1/3 from the top of this 
document  you will see where it 
makes mention to disable win32time.


Chris

On 09/24/19 14:08:12, Chris Wilson wrote:


   24/09/2019 19:58

I have used Meinberg NTP and also Thinking Man's Dimension 4 as NTP
applications on Windows 7 64 bit OS's on 3 PC's. I use them to sync
the PC time for WSJT-X WSPR (a low power digital amateur radio mode)
which requires an accurate time on the PC's for successful decoding
and transmitting of digital signals.

Both Dimension 4 and Meinberg have occasionally not allowed proper
syncing with the WSPR application attempting to decode up to 4 seconds
late, despite my Trimble Thunderbolt and Lady Heather showing the PC
is synced to GPS time within less than a second, by eye.


I am now trying another NTP app by DL4YHF Wolfgang Buscher. My
questions are, is such an anomaly known and should I disable Windows
Internet Time synchronization when using another NTP app? I see no
mention of disabling this in any of the NTP application's notes... The
WSPR application, WSJT-X has very recently been released in a 64 bit
version, which is what I am using, and I have to wonder if the new
version has some minor bug as I find it hard to believe two well known
and used NTP apps are buggy.


Thanks.


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Re: [time-nuts] Most popular NMEA sentence with date and time?

[Chris Burford]

You can get date (UTC) and time (UTC) from a ZDA string.

https://www.trimble.com/oem_receiverhelp/v4.44/en/NMEA-0183messages_ZDA.html

On 07/22/19 12:33:48, David Van Horn via time-nuts wrote:

I'm helping a friend with a hobby project, a "Countdown To Christmas"  clock.
I haven't looked at the NMEA docs in a while or three..  What's the most widely 
supported sentence(s) that will give me date and time?

We're doing one Arduino to grab the data from GPS and talk to the others, which 
each drive one digit of the display selectable by straps so that all the digits 
will be identical except for their strap settings.

--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: 
david.vanh...@backcountryaccess.com

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[time-nuts] PRS10 calibration

[Chris Burford]

I have been digging through the TN archives and came across a post dated 
May 2, 2012 having to do with the calibration of the PRS10 RFS.


In reading this it appears to be a process of stepping through the 
various time constant (PT) values during the discipline process and 
monitoring the time tag values being as close to 0ns for ideal results.


My questions are these:

 * Is there a quicker way to individually step through the PT values
   and is it possible to use every other PT value when calibrating?
   When all is said and done a total of 61+ cumulative hours is
   required given the expiration of each natural time constant setting.
 * Should the time offset value (TO) also be adjusted in conjunction
   with each successive increment of the time constant?
 * Are there any other adjustments to be made during the calibration
   process?

Thanks,

Chris


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[time-nuts] Galileo Service Outage Update

[Chris Burford]

Here is an update from EGSA on the continued outage of navigation and 
timing services for the Galileo constellation:


https://www.gsc-europa.eu/news/update-on-the-availability-of-some-galileo-initial-services

As of now the service outage is at T+ 105.5 hours.


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Re: [time-nuts] Thunderbolt E

[Chris Burford]

Hi John,

That repair cost is enough to steer me away from buying one. I have a 
mediocre view of the sky with my current antenna setup.


I'll continue on and research some additional possibilities for a GPSDO 
unit. Thanks for sharing your experience with the Thunderbolt E unit.


Chris

On 07/12/19 04:00:39, Jon “KF5TFJ” Noxon wrote:

Chris,

i have one which I bought new several years ago. It had a failure under 
warranty where in the serial chip stopped doing its thing. The unit continued 
to lock to SVs and delivered 10MHz and the PPS. Took almost two months to be 
returned, where it worked fine until very recently. Same issue with the serial 
chip. Trimble quoted a price of $650 for repairs. Ouch.

As they say "Other than that Mrs Lincoln, how did you enjoy the play...”,  it 
played fine as long as you could talk to it. Antenna location is very important as 
is true for all timing GPS units.

The fit is supplied with a good length of 75 Ohn coax, power supply, antenna, 
and some coas adapters.

So the question is how much do you intend to spend?

Lady Heather works great when the serial chip was still good.

Jon KF5TFJ

Re:
Date: Thu, 11 Jul 2019 14:22:51 -0500
From: Chris Burford 
To: Time Nuts Listings 
Subject: [time-nuts] Thunderbolt E
Message-ID: <9165f782-88f7-d015-6a82-6102a4258...@austin.rr.com>
Content-Type: text/plain; charset=utf-8; format=flowed

I'm on the fence on purchasing a new Thunderbolt E from Trimble and
wanted to hear from current or past owners.

I have a couple of the eBay x-telecom patchwork quilt GPSDO units which
seem to do an OK job. Is there anything else besides a warranty and
better performance specs that the Thunderbolt offers? My intention is to
use the Thunderbolt as a backup reference to my PRS10.

Thanks.

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[time-nuts] Thunderbolt E

[Chris Burford]

I'm on the fence on purchasing a new Thunderbolt E from Trimble and 
wanted to hear from current or past owners.


I have a couple of the eBay x-telecom patchwork quilt GPSDO units which 
seem to do an OK job. Is there anything else besides a warranty and 
better performance specs that the Thunderbolt offers? My intention is to 
use the Thunderbolt as a backup reference to my PRS10.


Thanks.


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[time-nuts] Data collection sample interval and duration

[Chris Burford]

I have been collecting data previously at a one second interval for a 
duration of 24 hours for my RFS. What are the potential "gotchas", if 
any, for a .1 second interval for say 6 hours?


Will going to a shorter sample interval skew the results I have been 
seeing previously with the one second intervals?


Thanks.


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Re: [time-nuts] TimeLab phase difference (slope sec/sec)

[Chris Burford]

Hello David,

It could quite possibly be tempco induced. I have this on my schedule of 
future events for additional analysis.


Thanks,

Chris



Chris,

Just looking at the graph reminds me of a daily variation - perhaps 
due to temperature.  Is that likely?  Would a two-day graph be worth 
doing in this particular case?


Cheers,
David


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Re: [time-nuts] TimeLab phase difference (slope sec/sec)

[Chris Burford]

Hi Dana,

My PRS10 is the DUT that has its 1PPS(Out) wired into the TICC on ChA. 
The reference is my GPSDO which has a 8663-XS DOCXO and has its 
1PPS(Out) wired into the TICC on ChB. The 10 MHz clock signal for the 
TICC comes from my GPSDO also, which as I understand, need not be quite 
so precise when measuring in time interval mode.


Chris


On 07/03/19 04:01:38, Dana Whitlow wrote:

Chris,

Ok, one source is a PRS-10.  Is it the DUT or the reference?  And if it's
the DUT, what
is the reference source?

Dana


On Tue, Jul 2, 2019 at 8:00 PM Chris Burford
wrote:


Hi Bob,

I'm seeing 4.22E-12 as the slope value in the upper right of the TimeLab
phase difference plot. Is that telling me that my DUT is within +4.22ps
/ sec from my reference 1PPS for the 24 hour measurement duration?

I have attached a screen capture that will hopefully make its way
through for viewing.

Thanks,

Chris

On 07/02/19 11:50:10, Bob kb8tq wrote:

Hi

The difference in seconds between the start phase and the end phase

divided by the number

of seconds duration gives you the parts in whatever of the error.

If you see 1us ( = 1x10^-6 seconds)  of change in a second, you are off

by 1 ppm (or 1x10^-6).

If you see 1 us of change in 1,000 seconds you are off by 1 ppb (or

1x10^-9). At a bit over 10

days (1,000,000 seconds) your 1 us change is 1 ppt (or 1x10^-12).

Bob


On Jul 2, 2019, at 10:17 AM, Chris Burford

wrote:

Is the slope value for the phase difference shown in TimeLab an average

of the overall data sample duration? The reason I ask is that my service
manual for my RFS says:

/"//A faster way to make the comparison between the reference frequency

and the DUT is to use the time interval measurement mode of the counters.
In this case, the time intervals between the 10MHz zero crossings of the
reference frequency and the DUT are measured and averaged. If this time
interval changes by less than 10ps per second, then the DUT is within 1
part in //10^11 of the frequency reference."/

I'm just curious if the phase difference slope value can be plugged in

to this equation.

Regards,

Chris


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Re: [time-nuts] TimeLab phase difference (slope sec/sec)

[Chris Burford]

Hi Bob,

I'm seeing 4.22E-12 as the slope value in the upper right of the TimeLab 
phase difference plot. Is that telling me that my DUT is within +4.22ps 
/ sec from my reference 1PPS for the 24 hour measurement duration?


I have attached a screen capture that will hopefully make its way 
through for viewing.


Thanks,

Chris

On 07/02/19 11:50:10, Bob kb8tq wrote:

Hi

The difference in seconds between the start phase and the end phase divided by 
the number
of seconds duration gives you the parts in whatever of the error.

If you see 1us ( = 1x10^-6 seconds)  of change in a second, you are off by 1 
ppm (or 1x10^-6).
If you see 1 us of change in 1,000 seconds you are off by 1 ppb (or 1x10^-9). 
At a bit over 10
days (1,000,000 seconds) your 1 us change is 1 ppt (or 1x10^-12).

Bob


On Jul 2, 2019, at 10:17 AM, Chris Burford  wrote:

Is the slope value for the phase difference shown in TimeLab an average of the 
overall data sample duration? The reason I ask is that my service manual for my 
RFS says:

/"//A faster way to make the comparison between the reference frequency and the DUT 
is to use the time interval measurement mode of the counters. In this case, the time 
intervals between the 10MHz zero crossings of the reference frequency and the DUT are 
measured and averaged. If this time interval changes by less than 10ps per second, then 
the DUT is within 1 part in //10^11 of the frequency reference."/

I'm just curious if the phase difference slope value can be plugged in to this 
equation.

Regards,

Chris


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[time-nuts] TimeLab phase difference (slope sec/sec)

[Chris Burford]

Is the slope value for the phase difference shown in TimeLab an average 
of the overall data sample duration? The reason I ask is that my service 
manual for my RFS says:


/"//A faster way to make the comparison between the reference frequency 
and the DUT is to use the time interval measurement mode of the 
counters. In this case, the time intervals between the 10MHz zero 
crossings of the reference frequency and the DUT are measured and 
averaged. If this time interval changes by less than 10ps per second, 
then the DUT is within 1 part in //10^11 of the frequency reference."/


I'm just curious if the phase difference slope value can be plugged in 
to this equation.


Regards,

Chris


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[time-nuts] 8663 Oscillator Tuning

[Chris Burford]

I have an Oscilloquartz 8663-XS DOCXO in a generic eBay GPSDO. I would 
like to fine tune the output to get it a little closer to MHz.


At current it appears to be running at 9.93x10^-13 at t1000. I'm 
clocking it against a PRS10C RFS using a TICC and TimeLab. Specifically 
I'm looking for the procedure or what is involved in tuning the output 
frequency of my GPSDO.


I have at my disposal an oscilloscope, DMM, frequency counter and 
various other bench hardware. I'd be curious to hear how this is done 
whether it is specific to this oscillator type or not.


Any assistance is certainly appreciated.

Chris


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[time-nuts] PRS10 tuning

[Chris Burford]

I came across an older Time Nuts post that talked to setting the time
constant (PT) values on the PRS10 RFS. It read as follows ...
"Calibrate the Time offset (TO) according to the example on page 32 in
themanual, by looping the 1pps_out to 1pps_in on the PRS10, keep in
mind thatyou should use the cable, buffers, etc that later will take
your GPS 1PPSto the 1PPS_in on the PRS, so that you really take care
of all delay fromthe GPS 1pps to the PRS10, including internal PRS10
delays, that mighthave changed from previous calibration."
I have followed this procedure and wanted to know if I'm correct in my
methodology for steering my RFS with my GPSDO. Is it ok to adjust the
TO value at each time constant (PT) increment on the PRS10?
In other words I have been adjusting the TO value at the expiration of
the Natural Time Constant value and getting as close as I can to 0ns
time tag (TT) values at each increment.
Please advise if my thinking is correct or otherwise.
Thanks.
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[time-nuts] Stable32 tau

[Chris Burford]

I'm not sure if this post would be of sufficient SNR value to approve for 
comment. Perhaps you may have a quick and easy answer.

I'm using Stable32 to print ADEV, MDEV plots and I would like to have the tau 
values listed as 1, 10, 100, 1000 ...
Stable32 currently denotes these values in scientific notation (1.00e+00, 
2.00e+00, 4.00e+00, 1.00e+01 ...)

The data is originally from TimeLab 1.35b exported as ASCII phase data, no time 
stamps. The data looks as follows:

-9.724507003434E-001
-9.7245070123599986E-001
-9.724507005128E-001
-9.7245070079599982E-001
.
.
.


I'm looking for the same formatted output for ADEV as the TimeLab plot for the 
tau scale. I think the scientific notation for the tau values adjacent to the 
sigma values just crowds the plot. Is there a way to just get logarithmic (base 
10) values for the tau plot in Stable32? Any help is appreciated.

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[time-nuts] ublox M8T receiver

[Chris Burford]

I have a ublox NEO-M8T receiver and would like to know if it could be utilized 
to steer an RFS for corrections / calibration. It is a standalone receiver unit 
and not a GPSDO component.

The receiver is featured here: 
https://www.csgshop.com/product.php?id_product=249

Thank you for any assistance.

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Re: [time-nuts] multimeter

[Chris Burford]

I use both the Fluke 87V and Keysight 34465A at my bench. Both will handle 
anything I need them to.

 Jim Palfreyman  wrote: 
> Hi all,
> 
> I think I'm in the market for a new digital multimeter.
> 
> Could I have some recommendations?
> 
> Jim
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[time-nuts] ZED F9T first look

[Chris Burford]

For those that are interested in the soon to be released ZED-F9T receiver here 
is a quick write up on the RTLExplorer blog:

https://rtklibexplorer.wordpress.com/

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Re: [time-nuts] Rooftop antenna and splitter

[Chris Burford]

For a 30-35 outdoor cable run go with as big a coax as you can afford. At these 
frequencies attenuation becomes even more critical than say an HF application. 
There are several online attenuation calculators for various cable 
configurations that you might want to play around with:

https://www.timesmicrowave.com/

https://www.pasternack.com/t-rf-microwave-calculators-and-conversions.aspx

Chris

 Denny Page via time-nuts  wrote: 
> Hi all,

I’m looking for recommendations on an antenna / splitter configuration. I 
currently have six GPS/GLONASS/Galileo timing devices, each with it’s own puck 
antenna in a window. I have an opportunity to move to a (single) roof top 
antenna, with a splitter to feed the individual devices, and I am looking for 
recommendations on which antenna and splitter people would recommend.

So far, I am looking at the following antennas:

 PCTEL GNSS1-TMG-26N 
(https://www.pctel.com/antenna-product/global-gnss-timing-reference-antenna-gnss1-tmg-26n/)

 PCTEL GNSS1-TMG-40N 
(https://www.pctel.com/antenna-product/global-gnss-timing-antenna-gnss1-tmg-40n/)

And the following splitters:

 GPS Networking ALDCBS1x8 (https://www.gpsnetworking.com/products/aldcbs1x8)

 GPS Source S18 
(https://www.gpssource.com/collections/gps-splitter/products/s18-1x8-standard-gps-splitter)

The run from the antenna to the splitter will be 30-35 feet, and from the 
splitter to the units will be 3-5 feet. I’m wondering about the need for the 
40dB vs the 26dB. I haven’t looked at any passive splitters, but even with the 
40dB I’m thinking won’t offer enough to support even a 1x6 splitter.

I would appreciate any thoughts folk have to offer.

Thanks,
Denny


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Re: [time-nuts] Ublox F9P multi-band GPS receiver

[Chris Burford]

Another aspect of this is what do you consider "good enough"? I've used my 
Neo-M8T-0 receiver for a positional fix down to about 4cm with the use of a 
CORS facility at 5.6km distance.

The F9x series would probably narrow this range considerably, but again, what 
is good enough? It will be interesting to hear the results of these two new 
units from ublox once they get in to the hands of more consumers.

Chris

 Mike Cook  wrote: 
> So the ultimate question is: Do you need a F9P  in order to find the precise 
> position of your F9T Antenna so that you can set up the F9T or is the F9T’s 
> survey mode as accurate ( I doubt it as the doc gives position accuracy 2m ). 
> Come to think of it, do you need three positioning receivers to be sure of 
> your position? and three P9Ts so that you can use differential mode for best 
> timing accuracy. I see no on board quantization error correction mentioned, 
> nor quantization error reporting though I expect that is there, so for best 
> accurracy that has to be added.  This looks as though it could get expensive.


> Le 24 janv. 2019 à 07:30, Dustin Marquess  a écrit :
> 
> This looks ideal to me:
> 
> https://www.u-blox.com/sites/default/files/RCB-F9T_ProductSummary_%28UBX-18069985%29.pdf
> 
> -Dustin
> 
> On Wed, Jan 23, 2019 at 8:01 PM Angus via time-nuts
>  wrote:
>> 
>> Hi,
>> 
>> It doesn't look like the F9P does anything special for timing - the
>> timing specs given in the F9T spec sheet are 5 ns (1-sigma, clear sky,
>> absolute mode) and +/- 4ns jitter, but for the F9P are 30ns RMS and
>> 60ns for 99%.
>> 
>> I think I want an F9T :)
>> 

In the year 1000 CE, the Persian Muslim scholar al-Biruni first used the term 
second in Arabic and defined it as 1⁄86,400 (that is, 1/(24 × 60 × 60)) of a 
mean solar day.


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Re: [time-nuts] Calculating time of lunar eclipse

[Chris Burford]

Mr. Eclipse, hosted by Fred Espenak,  is your go-to page for this. The data for 
both solar and lunar eclipse events seems to be accurate based on my experience 
of past events.

http://www.eclipsewise.com/lunar/LEprime/2001-2100/LE2019Jan21Tprime.html


 Mark Sims  wrote: 
> While on the subject of the accuracy/reliability of various algorithms and 
> web pages showing various astronomical data, we had a full moon / total lunar 
> eclipse in the northern hemisphere.  And not just any full moon, but a Super 
> Blood Werewolf Zombie Apocalypse full moon (or some such drivel spouted by 
> all the TV stations).

Anyway, I wanted to know when the eclipse was at it's maximum.  Most web sites 
gave a time here as 23:12,  some differed by several minutes.  None gave the 
time to the second.  That just won't do for a moon worshiping time-nut, will 
it?  So, I tricked up a version of Lady Heather to do a screen dump when the 
difference of the  sun and moon azimuth and elevation were at a (180 degree) 
minimum.  Looks like it happened at 23:12:04

Heather's sun position code (based on Grena's algorithm 5) is VERY accurate 
(and quite simple).  The moon position code is pretty good... a better version 
would require several thousand lines of code evaluating a zillion polynomials 
with hundreds of terms.

Anyway,, attached is a copy of the screen dump.  Note the difference in the 
sun/moon az/el values and also the calculated moon phase.

Does anybody know of a reliable source of the true time of the lunar eclipse 
down to the second (or better)?

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[time-nuts] TAPR TICC (Mode - Time Interval) Help

[Chris Burford]

Hello All,

I'm looking for some assistance, off list, in getting the TICC in Time Interval 
mode to output data in TimeLab 1.31 (Beta). I've been successful in the 
Timestamp and Period modes in collecting data and generating ADEV, MDEV plots 
etc.

Please feel free to contact me for additional setup info with and screen 
captures.

regards,

Chris

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Re: [time-nuts] Short term 10MHz source

[Chris Burford]

I'll give the window placement a try and see if I can maintain a usable lock.

Thanks for the assistance.

Chris
 Hal Murray  wrote: 
> 
> > I do realise that the long term stability of the GPSDO is somewhat superior
> > to a Rubidium source. I'm planning on using my TICC to validate both my 
> > GPSDO
> > and RFS. I'm aware that such a short "power on" period is somewhat
> > counterproductive but I have no other options. I'd like to know if a 6-8 
> > hour
> > window for the GPSDO is sufficient for use as a 10MHz source for the TICC. 
> 
> Try using the Rubidium as the clock source for the TICC and watch the PPS 
> from 
> the GPSDO.
> 
> 
> > I have a situation in which I have access to a GPSDO 10MHz source but for
> > only about 10-12 hours at a time. My current residence does not allow a
> > permanent GPS antenna therefore I am limited in its use. 
> 
> Step two would be to see how well your GPSDO works with an internal antenna.  
> Sometimes it works with the antenna in a window.  ...
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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[time-nuts] Short term 10MHz source

[Chris Burford]

I have a situation in which I have access to a GPSDO 10MHz source but for only 
about 10-12 hours at a time. My current residence does not allow a permanent 
GPS antenna therefore I am limited in its use.

I do realise that the long term stability of the GPSDO is somewhat superior to 
a Rubidium source. I'm planning on using my TICC to validate both my GPSDO and 
RFS. I'm aware that such a short "power on" period is somewhat 
counterproductive but I have no other options. I'd like to know if a 6-8 hour 
window for the GPSDO is sufficient for use as a 10MHz source for the TICC.

I appreciate any and all comments.

Regards,

Chris

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Re: [time-nuts] PRS10 MDEV

[Chris Burford]

I suspect now after your review that the effect is thermally drive,
specifically my HVAC. My PRS10 is in a free air environment suspect to
the wall thermostat.
I'm sure I could parallel the RFS measurements with Lady Heather and
find a correlation between RFS case temp and the MDEV.
Thanks Tom for the analysis. 
Chris

-From: "Tom Van Baak" 
To: "Discussion of precise time and frequency measurement"
Cc: 
Sent: Monday October 15 2018 12:31:07AM
Subject: Re: [time-nuts] PRS10 MDEV

 When I see an ADEV or MDEV plot that looks unusual I like to check
the phase or frequency plots for clues. Thanks for your .TIM file.

 Attached are:

 Burford-6h-adev.png -- TimeLab 'a' command. This is a straight line
with slope -1; what you expect for a self-test. Note the ADEV at tau 1
second is right about 7e-11, 70 p/s, which is typical noise for the
TICC counter.

 Burford-6h-mdev.png -- TimeLab 'm' command. As you observed this has,
a plateau. Sort of unexpected given you weren't using a GPSDO.

 Burford-6h-phase.png -- TimeLab 'p' command. Phase difference plot.
Notice all those bumps.

 Burford-6h-phase-100s.png -- TimeLab 'g100' command. Phase difference
plot with 100 second averaging makes the variations stand out much
clearer. Can you guess what that is?

 So the smoking gun is that you have quasi-periodic perturbations in
phase on the order of about 100 ps. The shape looks thermal to me. Do
you have a thermostatically controlled heater in the room or house? I
suspect this is causing your MDEV plateau.

 If so, you've accidentally done a nice experiment -- which is to
establish your measurement noise floor and to examine the
environmental conditions of your work bench. Ah, the annoying joys of
working with precise time!

 Again, assuming it is due to thermal effects, you can now find out if
it's your TICC or your cables or your PRS10. Since TimeLab will
display plots in real-time a heat gun or cold spray may help you
isolate the culprit quickly.

 /tvb


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[time-nuts] TAPR TICC (Cable run time delay)

[Chris Burford]

Hello All,
I've just received my new TAPR TICC and have been performing some
initial dry runs against my PRS10.
I have to ask about cable(s) delay and and what is essentially best
practice for the TICC configuration. Is it commonplace to add both
cables (10MHz source and 1PPS) or just the length of the 1PPS cable
alone? I already have the cable delay specs from Times Microwave for
the medium that I'm using.
I would assume that the delay(s) in pico seconds are input to the TICC
as the "Fudge" values? I'm just trying to get most of the bases
covered here for a fair assessment of my RFS.
Any and all comments are appreciated.
Thanks,Chris
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Re: [time-nuts] Oscilloscope-based measurements of frequency stability

[Chris Burford]

This sounds interesting enough and I would appreciate any notes or insight on 
doing this. I have a PRS10 and several GPSDOs that I would like to evaluate for 
performance on my scope.

Many thanks.


 Dana Whitlow  wrote: 
> I cheered when I saw Dave B's "silly question", for
> then I realized that I'm not the only one who likes
> to measure things with an o'scope.
> 
> I had purchased a GPSDO a few weeks before and
> had  been observing its behavior relative to a free-
> running Rb by watching 10 MHz sinewaves drift with
> respect to each other as an aid in setting the Rb's
> frequency.  However, I was seeing enough fairly
> rapid random drift to limit the usefulness of this kind
> of observation.   It dawned on me that I was sometimes
> seeing drifts of several ns over the course of just
> several seconds, thus implying that sometimes the
> relative frequency error between the two sources was
> reaching as high as roughly 1E-9.  I wanted to be able
> to capture and plot a somewhat extended run of data
> so I could try to understand this behavior better.
> 
> Being TIC-less, I decided to see what I could do with
> my o'scope, which is a Chinese-made 2-channel DSO
> with synchronous sampling by the two channels and
> with a respectable trace memory depth (28 MSA per
> channel).
> 
> I began this effort  in earnest a couple of days before I
> saw Dave's question, and have only now brought it to
> a sufficient state of completion to feel justified in reporting
> some results.
> 
> I am presently able to record about 45 minute's worth of
> data as limited by the 'scope's trace memory, but my XP
> computer's RAM space limits me to processing only about
> 35 minutes of that in a seamless run.   Over that time
> span I've seen a peak relative frequency discrepancy of
> about 1.4E-9, with a handful reaching or exceeding 1E-9.
> I've also measured average frequency differences between
> the source's a a few parts in 10E11.
> 
> Most of the effort went into developing a C program to do
> the processing and then correctly scaling and displaying
> the results in a form which I considered useful to me.  This
> processing of course had to deal with an off-frequency and
> drifting 'scope timebase, which is *horrible* compared to the
> quantities under measurement (as expected from the outset).
> 
> Present indications are that at this level of GPSDO mis-
> behavior, the results I'm viewing are about 20 dB higher
> than the basic floor, which I am still characterizing.  I
> believe that the floor is limited primarily by uncorrelated
> sampling jitter between the two 'scope channels.
> 
> If there is an expression of interest in this technique, I'll
> publish a detailed description of the technique and some
> plots showing results, probably in the form of an attachment
> in pdf format.
> 
> Dana
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[time-nuts] 1PPS for the beginner

[Chris Burford]

Hello members,

At the risk of personal embarrassment and perhaps a chuckle, or two, I'm going 
to ask the following questions about 1PPS.

I have a (generic?) GPSDO which contains an Oscilloquartz STAR 4+ OCXO that I 
am using to steer a PRS10 RFS. I'm a little confused on where the 1PPS is 
coming from with respect to the GPSDO. Is the 1PPS in the RF signal from the 
satellite data stream or does it originate from the OCXO oscillation?

This I'm sure is quite trivial for most of the members here but I am trying to 
understand certain concepts, processes and terminology along the way. I look 
forward to anyone who cares to share their comments.

Thanks for assistance.

Chris Burford 

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