Re: [time-nuts] How did they distribute time in the old days?

[Luke Mester]

>>> edge of the pulse was synchronized and would release the clock to operate
>>>> normally.
>>>>
>>>> That they had something as accurate and widespread as it was so early
>>>> is astonishing.
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Re: [time-nuts] Electronically Disciplined Mechanical Pendulum

[Luke Mester]

Bert,

Thank you for posting your project info!

One of my hobbies is collecting and repairing clocks. For several years
I've been thinking of making an add-on device to discipline pendulum
clocks. I've been using PIC based circuits to provide pendulum impulse.
I've not tried to discipline the rate as you've done.

You said that your circuit had problems locking the pendulum rate when you
used an aluminum pendulum rod. Now that you have an oak rod I was wondering
if your pendulum would remain locked when you turned off the temperature
control. With an oak rod and no temperature control your pendulum would
have temperature stability similar to common pendulum clocks. If your
circuit can maintain lock without temperature control that tells me that it
should be possible to discipline a common pendulum clock using this method.

I'm sorry, I'm asking you to perform another test on your pendulum. Can it
maintain lock with normal temperature changes? Let it run for a few days
with the heater off and see what happens.

Also, You may want to try something other than a hard drive bearing to
suspend your pendulum. Since your circuit is line powered this is not a big
problem. I've performed tests with several pendulum suspension methods
including the head support arm bearing from a hard drive. The hard drive
bearing performed poorly. You'll need less power to keep it swinging with
other suspension methods.

Using the hard drive bearing, my pendulum had a Q factor of about 2,000.
Using various traditional clock pendulum suspension springs the Q ranged
from 5,000 to 13,000. With a crossed wire suspension the Q was 28,000.

Finally, below is a link to some pictures of my clock project. I want this
to be a traditional style master clock. Something that my wife won't
complain about if I put it in the living room! I don't have the skills or
machine tools needed to build a completely mechanical master clock.
Electromagnetic impulse is my current choice.

http://mesterhome.com/clock/picpend/index.html




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Re: [time-nuts] RFTG-m-XO KS-24019 RS-422 Query

[Luke Mester]

Bill,

I have the KS-24361 units. This may also work with yours.

When I connect a terminal to the J6 1PPS connector I see data similar to
yours. This is sending the time.

Here is an example from my unit:

:000185426EE918A301DB
:000185426EE919A301DC
:000185426EE91AA301DD
:000185426EE91BA301DE
:000185426EE91CA301DF
:000185426EE91DA301E0


Connect your terminal and try typing this:

Please note that there is no character echo. You won't see what you type.

ptim:tcod:cont 0

to turn off the time.

then try:

*IDN?

See if the unit responds.

if it responds try:

diag:log:read:all?

to display the log.

You can turn the time display back on with:

ptim:tcod:cont 1

If this works you may be able to use the Z38XX softrware to monitor your
unit.

I don't remember the URL where I downloaded this program. Search for Z38XX
by Ulrich Bangert and you should be able to find it.


You may need to patch the Z38XX software for use with your RTFG.

Here is the patch info to make it work with the Z3811 unit. This is from
the time nuts list:

and here comes another trick:
Ulrich's Z38XX can be persuaded to accept the Z3811 instead of an Z3805.
For this to happen search with an Hex-editor in Z38XX twice for the
string z3805 and replace this z3805 with z3811, save the changes and
enjoy the various "View"s Ulrich provided.
Götz

Instead of replacing with "z3811" You'll need to use the model that your
unit returns with the *IDN? command.



On Tue, Apr 28, 2015 at 2:04 AM, Bill Hawkins  wrote:

> Have the subject RFTG unit. Bought an RS-422 to USB converter, found a
> simple terminal emulator (PuTTY), and scoured KO4BB's site.
> Discovered that the pins for the otherwise unlabeled "RFTG-m RS-422
> INTERFACE" drawing were reversed, and that you don't connect R to R and
> T to T. The diagnostic software on KO4BB's site will not run on modern
> Windows systems (sorry, I used Unix in the eighties but it's all windows
> now).
>
> Every second, PuTTY shows the string :11E109FB with the
> initial Failed status and :10E109FA when the green light
> comes on after about 20 minutes. Does anyone know how to decode that
> string (presumably hex)? The strings were copied from the PuTTY screen
> with ^C, not manually transcribed.
>
> The RFTG unit does not acquire GPS lock after 32 hours. I had hoped that
> the status message would tell me why it isn't locked.
>
> Note that this is the 1998 version, not the newer ones.
>
> Any clues to documentation appreciated.
>
> Bill Hawkins
>
>
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[time-nuts] Lucent KS-24361 mystery LED resolved.

[Luke Mester]

There are two LED's on the circuit board next to the power supply module.
One is green blinking. I'd never seen the other one on.

I needed to get them off of my bench power supply and onto a permanent
supply. I tried a 24V  3A supply. They must have been cheating a little on
the ratings. The voltage dropped down to about 16V when the oven heaters
fired up. I noticed that the mystery LED was lit. It's red. A good guess is
that it's a power fault indicator. The LED's are next to the black power
supply module. A picture is attached.

Also, Below is a link to some plots from Ulrich Bangert's Z38XX software of
the initial day of operation. The units had about 30 minutes of run time
before I got a permanent power supply, GPS Antenna  and RS-422 connection
set up. I thought it was interesting to see the graph of the EFC Value
slowly flattening out. I guess if I was asleep for 15 years It'd probably
take me a while to get going too :-)

http://mesterhome.com/timenuts/gpsdo/

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Re: [time-nuts] HP5335A GPIB questions.

[Luke Mester]

>Luke, the HP5335A was introduced in around 1980 and has an early
>(pre-IEEE-488.2) HP implementation of IEEE-488 which requires a
>terminator character at the end of each string. According to the manual,
>this terminator can be a comma, semicolon, space, carriage return, or
>line feed character.



>The delays are extremely important.  The 5335A can and will hang if you
>don't wait long enough.  In keeping with that, *do not* set your adapter to
>do an automatic read after sending data over the GPIB.

Bill, Orin, Thank you!  You solved my problem!

It's working normally now! I was not sending a terminator at the end of the
command and I had automatic read after send turned on. Setting to manual
read, sending  and then reading manually stopped the strange behavior.

With a few lines of BASIC I'm now saving frequency readings to a file.


 I've already found that my home-built adapter won't work with Timelab. It
has served it's purpose. With less than $10 worth of parts I was able to
verify that the GPIB on my HP5335A is working. Now it's time to get a
better GPIB adapter.

I like the Prologix because It's easy for me to write code to access a com
port.  Do you know if the 82357 type adapters can be accessed as a com
port?  Any suggestions on what adapter to use?
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[time-nuts] HP5335A GPIB questions.

[Luke Mester]

I recently bought a HP5335A counter and have some questions about operating
the instrument with GPIB.

 I expect that a lot of time nuts are using this instrument and may be able
to help. Please excuse me if this is a stupid question. This is my first
GPIB instrument.

After each GPIB command that I send I've found that I then need to send an
RE (reset) command. If I Don't send RE the instrument takes no readings and
has a blank display. For example I send FN9 to select period and  get no
readings until RE is sent. Is this normal?

I'm currently talking to it with a USB to GPIB adapter and a terminal
program.

Since I had no idea if the GPIB interface was functional I didn't want to
buy an expensive GPIB adapter. I build the cheapest GPIB adapter that I
could find on the internet. It's possible that this is causing problems.

It emulates a Prologix adapter. Here is a link if you're interested.
HTTP://http://www.dalton.ax/gpib/
I've found that this adapter does not properly report the serial control
line status. Because of this, Timelab won't detect the GPIB adapter.

You can get Timelab to work if you choose the "Acquire from counter in talk
only mode" option.







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Re: [time-nuts] Using a UBlox NEO-6 GPS module for calibrating a PIC microprocessor based timer.

[Luke Mester]

I want to thank everyone for the info! I'm still reading and trying to
learn from it. I think I have another hobby starting.


Monitoring the GPS performance looked like a good start. I have the serial
port connected to a PC and have been monitoring it with the U-Center
software available on the U-Blox site. So far, the minimum number of
connected satellites is 5 and the maximum is 12. I also see a maximum
position error of about 50 meters. Is this good enough or do I need a
better signal? I don't have the receiver located in a very good spot. My
workshop is in the basement. I have it next to a basement window. I have a
view of less than half of the sky. I did check the configuration of the 1
PPS output. It's set to only output pulses when the data is valid. After
monitoring it for a couple of days the 1 PPS signal has not dropped out.


Also, I should say that I'm not planning on having my PIC timer permanently
connected to a GPS. I just want to use it for testing and an occasional
calibration check.


Quartz55,

Yes, you can use a PC with a sound card. There's even a program called
"Windows timing machine" available that does this.  I've tested it and had
poor results. One computer worked better than the other. Neither worked
very well. I think it's probably dependent on the quality of the sound
card. I also wanted the convenience of a small portable timer instead of a
PC.


Tom Van Baak,

I've looked at Brian Mumford's Microset timer. I think it's the best one
available. If I hadn't decided to make my own I'd have bought his. I really
don't need all of the features of his timer.  It just came down to the fact
that my spare time to write code is free and PIC chips only cost about a
buck :-)


I'm using a PIC 18F13K22. My code is in assembly language. The external
clock is 10MHz. Internally it's running at 40MHz using the 4x PLL. The PIC
18 takes four clock cycles to execute one instruction cycle. The hardware
timers advance at the instruction cycle rate, Fosc/4. I chose 10MHz to try
to make the math a little easier. So far I'm only using fixed point math.
I'm trying to avoid using any floating point. Floating point in assembler
would quickly turn a fun project into a nightmare.

 I think that the PIC 18 interrupt latency is 3 instruction cycles. I'll
have to double check the PIC 18 data sheet and verify this. There will also
be some more latency because I have two interrupts occurring
asynchronously. When the pic input pin is triggered an interrupt is
generated. This interrupt routine captures the current value of a free
running timer. Unfortunately, the pic only has 16 bit timers. I needed 32
bits. Because of this, I generate another interrupt whenever the timer
overflows. I use this to manually increment another 16 bits. If an input
pin interrupt occurs during a timer rollover there will be a little more
delay while the timer rollover is handled. I'm sure there are better ways
to code this.

Also, internally I think I'm doing something similar what your picpet does.
My timer displays the clock rate and other info. Internally I'm just taking
a snapshot of a free running timer. I then subtract the last two samples to
get the beat time. I do an average of two beats to get the clock rate and
finally the difference between two beats to show the beat error. From what
you're saying there's an advantage to output the raw timer values. I'd then
see a series of steadily increasing values until the timer rolled over. A
plot would look like a sawtooth waveform. I'll add another log option to
output the raw timer value.

 I'd definitely be interested in talking more about your picpet and it's
isochronous coding. I think this may be getting off-topic for this list. It
looks like this list is more about the hardware used for precision time
measurement than the software. We could continue this topic off list if you
think other members won't be interested.


Finally, Here are some pictures of the timer.

Back 

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[time-nuts] Using a UBlox NEO-6 GPS module for calibrating a PIC microprocessor based timer.

[Luke Mester]

One of my hobbies is collecting and repairing mechanical clocks. I was
looking at buying one of the specialized electronic timers used to measure
the performance of mechanical clocks. I really couldn't justify the cost
just for hobby use.

Since I have electronics and programming skills I decided to build my own
timer using a PIC chip. This became a much bigger project than I expected!

I have my clock timer running and have most of the software features that I
need working. I then realized that I need some way to calibrate it and
verify it's accuracy.

I didn't have any source of accurate time available.  After searching the
internet and finding this mailing list I decided to try a GPS module. I
bought a $20 module from DX.com. It has a built in antenna, voltage
regulator, serial interface and most important, a 1 PPS output.The GPS is a
UBlox NEO-6M. After reading the specs on this module I see that they claim
a 99% accuracy of <60ns for the time pulse signal. What does this mean?
What about the other 1%? How much variation can the time pulse have? If
it's really 60ns it's much better than I need.

I'm hoping that some of the time experts on this mailing list can give me
some idea what to expect from this GPS module. Also, if there are any
settings that I should change to get better timing performance. There are a
huge number of settings available when I run it's configuration program. I
have no idea what most of them do.

I'm using one of the hardware timers on the PIC chip to measure the time
interval. The PIC is running with a 100ns (10MHz) instruction cycle. The
timer will provide 100ns resolution. I'm getting occasional variations of
about a microsecond. Because I'm using interrupt driven code to capture the
timer value there will be some unavoidable jitter in the timing. I was
expecting about 4 or 5 cycles (400ns - 500ns) but I'm getting more than
twice that. Is it safe to assume that these are due to problems in my
hardware or software? Is this from variations in the GPS PPS output? Maybe
I'm just not interpreting the data correctly.

Below are links to some data plots:

Four plots are shown. The first two are the Rate and Beat error that my
timer reports while monitoring the GPS PPS signal. Rate is normally the
average of two beats ( two time interval samples). If a clock is not in
beat (the tick and tock take different amounts of time) the displayed rate
would jump back and forth. Averaging two beats eliminates this jump. I have
disabled this average in my code so that the rate is now showing each beat
and not the average of two. I turned it off because I expect that this
averaging could hide possible problems with my timer.  Beat error is the
difference between the two beats. This shows the rate change for each pair
of beats. This is needed so that you can get the clock pendulum or balance
wheel adjusted properly.

Raw Data 


Average Data 

Average data has been filtered with a 100 sample running average. The plot
looks really good. The average is just hiding the instability.


I also noticed variations that appeared to be due to temperature changes. I
borrowed a temperature data logger from work and did some testing. The
temperature and rate graphs track perfectly. I can see my furnace cycling
and my programmable thermostat moving the temperature setting up and down!
That got me interested in trying a TCXO instead of the standard crystal
that I was using. A $3.00 TCXO from EBay made a huge difference! Both of
these plots have the running average applied. You can't see the temperature
changes with the raw data.

Crystal 


TCXO 

In case anyone is interested, here is a link to a data file captured from
the clock timer. It's in CSV format. The first column labeled "Rate" is the
time for each beat of the clock. "Rate Avg" is a running average rate and
"Beat E" the beat error.

Data file 

Finally, I think I might be turning into a time nut! For the clocks that I
work with this timer is already far better than I need. Millisecond
accuracy Is good enough to test most mechanical clocks. Microsecond is
great! I know that a microprocessor based timer is capable of better
performance. I then had the problem of what I could use to measure the
performance of my timer. I Needed a better clock than my timer. Now I'm
wondering if this cheap Chinese GPS is good enough. I'm having fun tweaking
the hardware and software to see just how good I can get it to perform!
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