Update on GPSDO video


chuck adams
 

https://youtu.be/CzJgEqJY3mg

I managed to beat the 11pm MST deadline by 3 hours.  Enjoy.

Frequency comparison is within 1mH (milli-Hertz) between the two standards.
We know that the GPS system is going to be around a long time.  It's in use in
too many critical applications now to give it up.

Re GPS:  I was impressed with the Chinese railroad people getting high speed rail tracks
laid to a tolerance of 5mm.  Their record speed now stands at 600 kph (km per hour).

When do we want to start the winter building season?  It's not even fall type wx here
in the valley of the sun.  :-)

Any one have the serial output data for the GPSDO?  Might be interesting to build a
1mW transmitter to emulate WWVB and feed my atomic clocks during the daylight
hours from time to time.  Of course, keeping it in a Faraday cage.

FYI

chuck, k7qo,


Alan Biocca
 

The GPS chips with PPS output are sufficient for that, don't even need a
GPSDO. I bought one the other day for under $20. The GPS's for drones are
quite inexpensive. Just make sure the PPS output is available as well as
the serial.

-- Alan, w6akb


On Sat, Sep 22, 2018 at 7:47 PM chuck adams <chuck.adams.k7qo@gmail.com>
wrote:

https://youtu.be/CzJgEqJY3mg

I managed to beat the 11pm MST deadline by 3 hours. Enjoy.

Frequency comparison is within 1mH (milli-Hertz) between the two standards.
We know that the GPS system is going to be around a long time. It's in
use in
too many critical applications now to give it up.

Re GPS: I was impressed with the Chinese railroad people getting high
speed rail tracks
laid to a tolerance of 5mm. Their record speed now stands at 600 kph
(km per hour).

When do we want to start the winter building season? It's not even fall
type wx here
in the valley of the sun. :-)

Any one have the serial output data for the GPSDO? Might be interesting
to build a
1mW transmitter to emulate WWVB and feed my atomic clocks during the
daylight
hours from time to time. Of course, keeping it in a Faraday cage.

FYI

chuck, k7qo,






chuck adams
 

Alan,

I assume that you are talking about the WWVB emulator.

The GPSDO, IMHO, is a requirement to get a good 10.00MHz
frequency standard for calibrating a lot of stuff.

chuck, k7qo

On 09/22/2018 08:20 PM, Alan Biocca wrote:
The GPS chips with PPS output are sufficient for that, don't even need a
GPSDO. I bought one the other day for under $20. The GPS's for drones are
quite inexpensive. Just make sure the PPS output is available as well as
the serial.

-- Alan, w6akb


On Sat, Sep 22, 2018 at 7:47 PM chuck adams <chuck.adams.k7qo@gmail.com>
wrote:

https://youtu.be/CzJgEqJY3mg

I managed to beat the 11pm MST deadline by 3 hours. Enjoy.

Frequency comparison is within 1mH (milli-Hertz) between the two standards.
We know that the GPS system is going to be around a long time. It's in
use in
too many critical applications now to give it up.

Re GPS: I was impressed with the Chinese railroad people getting high
speed rail tracks
laid to a tolerance of 5mm. Their record speed now stands at 600 kph
(km per hour).

When do we want to start the winter building season? It's not even fall
type wx here
in the valley of the sun. :-)

Any one have the serial output data for the GPSDO? Might be interesting
to build a
1mW transmitter to emulate WWVB and feed my atomic clocks during the
daylight
hours from time to time. Of course, keeping it in a Faraday cage.

FYI

chuck, k7qo,






Doug Hendricks <ki6ds13@...>
 

Chuck, do you have one of the qrpguys tcxo's? I built mine, and was curious as to the accuracy. I took it to a friend of mine, Pete Rowe, and had him measure it. His counter was locked to God, and he measured it accurate to within 0.001 Hz. He was astonished. I made no adjustment. He let it run for an hour, and it didn't change. If you have one, can you do the same measurements? Doug


Doug Hendricks <ki6ds13@...>
 

Locked to GPS. God is busy.


Doug Hendricks <ki6ds13@...>
 

I just ordered mine. I have secretly listed after a rubidium standard for a long time. Chuck has discovered something as good and actually better in my opinion because it has a longer lifetime. As he said, it will do everything I need to do as far as Ham radio is concerned.


Graham, VE3GTC
 

For those who like to build (most on this list) and experiment, an alternate to a GPSDO like Chuck has been working on is the simple QRP-Labs PROGROCK disciplined to a GPS receiver with a PPS output.

http://shop.qrp-labs.com/index.php?route=product/product&path=59&product_id=92

Simple kit to build and interface to a GPS, three programmable outputs i.e. 5, 10, 15 MHz or whatever you would like. The disciplining works by using the PPS a reference and "counting" the reference frequency of the si5351a and applying a periodic adjustment to the PROGROCK.  While not in the category as a GPSDO like Chuck has been playing around with it it still quite good.

The qrp-labs si5351a synthesizer can be improved by replacing the crystal with a SMD oscillator/TCXO but requires soldering in a fiddly SMD part.

Additionally, if you have a GPSDO, with a PPS output, you can use that to discipline the PROGROCK and use the PROGROCK to generate whatever frequency(s) you might need in order to GPSDO lock your LO in your latest TX or RX project.

cheers, Graham ve3gtc

On 2018-09-23 03:26, chuck adams wrote:
Alan,

I assume that you are talking about the WWVB emulator.

The GPSDO, IMHO, is a requirement to get a good 10.00MHz
frequency standard for calibrating a lot of stuff.

chuck, k7qo


On 09/22/2018 08:20 PM, Alan Biocca wrote:
The GPS chips with PPS output are sufficient for that, don't even need a
GPSDO. I bought one the other day for under $20. The GPS's for drones are
quite inexpensive. Just make sure the PPS output is available as well as
the serial.

-- Alan, w6akb


On Sat, Sep 22, 2018 at 7:47 PM chuck adams <chuck.adams.k7qo@gmail.com>
wrote:

https://youtu.be/CzJgEqJY3mg

I managed to beat the 11pm MST deadline by 3 hours.  Enjoy.

Frequency comparison is within 1mH (milli-Hertz) between the two standards.
We know that the GPS system is going to be around a long time.  It's in
use in
too many critical applications now to give it up.

Re GPS:  I was impressed with the Chinese railroad people getting high
speed rail tracks
laid to a tolerance of 5mm.  Their record speed now stands at 600 kph
(km per hour).

When do we want to start the winter building season?  It's not even fall
type wx here
in the valley of the sun.  :-)

Any one have the serial output data for the GPSDO?  Might be interesting
to build a
1mW transmitter to emulate WWVB and feed my atomic clocks during the
daylight
hours from time to time.  Of course, keeping it in a Faraday cage.

FYI

chuck, k7qo,







chuck adams
 

Doug,

No, don't have one to compare.  Sorry.

chuck, k7qo

On 09/23/2018 12:02 AM, Doug Hendricks via Groups.Io wrote:
Chuck, do you have one of the qrpguys tcxo's? I built mine, and was curious as to the accuracy. I took it to a friend of mine, Pete Rowe, and had him measure it. His counter was locked to God, and he measured it accurate to within 0.001 Hz. He was astonished. I made no adjustment. He let it run for an hour, and it didn't change. If you have one, can you do the same measurements? Doug


chuck adams
 

OK.  Since this went to the group at large let me make one more comment.
The TCXO that you guys sell has an adjustment trimmer.  What this does,
IMHO, is bring in the 'golden screwdriver' effect.

If a radio amateur has any available adjustments to be made, then all
bets are off.  The TCXO will have to be calibrated using a GPSDO or
rubidium source or one of the high end HP digital frequency counters
that measure down to 1mHz (milli or 0.001) and is in NIST spec.

I did take one of the 8-digit red LED displays from China.  The one that
this group has beat to death with a stick on discussions.  Out of the
package it reads 10.000000MHz without a fluctuation in the last digit.
So, I am pretty sure they calibrate them at the factory using some
frequency standard that is dead on.  This is the LED freq counter that
runs about $15 or less on ebay.

For radio amateur work, the level of precision and accuracy for frequency
measurement is really overkill.   In physics, the most accurate measurement
we can make is for time.  For the human race, time is the most wasted resource
given to us.  You can write that down if you want.  :-)  ;-)

I brought up the topic of the GPSDO 'cuz it was something that I got yesterday
and thought there might be some interest.

One of the projects for my winter list is the FCC-1 'clone' that is just a lab
counter that displays only the input frequency on a 1601 display (16x1).
With only two settings.  One second for resolution down to 1 Hz and a ten
second time interval sampling for 0.1 Hz resolution.  I've put the project
off for a decade now and need to get a 'round-to-it or drop it completely.
I want to learn the ins and outs of the PIC uP.  Diz had a counter for the group
years ago that used the AVR uP, but had a random jump by 2Hz aperiodically
and it he did an article in QQ at one time and there was a note on possible
'jitter' I believe.  I'd have to dig it out.

In searching ebay, I note that the model GPSDO being tested is in short supply.
You snooze you lose applies here.  Other GPSDO's are going for over $100 USD.

FYI

chuck, k7qo

... snip snip ...



On 09/23/2018 12:02 AM, Doug Hendricks via Groups.Io wrote:
Chuck, do you have one of the qrpguys tcxo's?  I built mine, and was curious as to the accuracy.  I took it to a friend of mine, Pete Rowe, and had him measure it. His counter was locked to God, and he measured it accurate to within 0.001 Hz.  He was astonished.  I made no adjustment.  He let it run for an hour, and it didn't change.  If you have one, can you do the same measurements?  Doug


Doug Hendricks <ki6ds13@...>
 

Chuck, I never touched the adjustment. I am curious to see if they were set at the factory like you suspect the 8 digit counter might be. I will be home Oct. 15 from my vacation in Europe and hopefully my frequency standard will have arrived. I will be able to make some measurements at that time.


The exciting thing to me is our ability to buy such accurate test equipment so cheaply. There has never been a better time to be a builder and a ham in my not so humble opinion.

Doug


Richard Seguin
 

Does it matter that the cheaper modules don't produce a clean sine wave?
The modifications are easy enough to make on the cheaper modules, if you
have steady hands.

On Sun, Sep 23, 2018, 12:20 AM Alan Biocca <alan.biocca@gmail.com> wrote:

The GPS chips with PPS output are sufficient for that, don't even need a
GPSDO. I bought one the other day for under $20. The GPS's for drones are
quite inexpensive. Just make sure the PPS output is available as well as
the serial.

-- Alan, w6akb


On Sat, Sep 22, 2018 at 7:47 PM chuck adams <chuck.adams.k7qo@gmail.com>
wrote:

https://youtu.be/CzJgEqJY3mg

I managed to beat the 11pm MST deadline by 3 hours. Enjoy.

Frequency comparison is within 1mH (milli-Hertz) between the two
standards.
We know that the GPS system is going to be around a long time. It's in
use in
too many critical applications now to give it up.

Re GPS: I was impressed with the Chinese railroad people getting high
speed rail tracks
laid to a tolerance of 5mm. Their record speed now stands at 600 kph
(km per hour).

When do we want to start the winter building season? It's not even fall
type wx here
in the valley of the sun. :-)

Any one have the serial output data for the GPSDO? Might be interesting
to build a
1mW transmitter to emulate WWVB and feed my atomic clocks during the
daylight
hours from time to time. Of course, keeping it in a Faraday cage.

FYI

chuck, k7qo,








chuck adams
 

Richard,

Not sure which modules you are talking about.  There are the square wave
generators and there are the sine wave generators.  The majority of the
OCXO's that are sine wave generators are some of the cleanest signals
that I have seen from a crystal oscillator.

Attached is the output from the GPSDO showing the spectrum of the output.
I am using a Hantek DSO-2150 which samples at 150MHz and 8-bits, so
it is not the best of spectrum analyzers, but it does show how clean the
signal is.  Ignore the table of values as the software engineer blew the
programming.  Again.

I prefer the Hantek over the Rigol 1024Z scope SA.  Hands down, even
though the Rigol as a faster sample rate.  Their software display is lacking
in detail.  IMHO.

FYI

chuck, k7qo

On 09/23/2018 05:27 PM, Richard Seguin wrote:
Does it matter that the cheaper modules don't produce a clean sine wave?
The modifications are easy enough to make on the cheaper modules, if you
have steady hands.

On Sun, Sep 23, 2018, 12:20 AM Alan Biocca <alan.biocca@gmail.com> wrote:

The GPS chips with PPS output are sufficient for that, don't even need a
GPSDO. I bought one the other day for under $20. The GPS's for drones are
quite inexpensive. Just make sure the PPS output is available as well as
the serial.

-- Alan, w6akb


On Sat, Sep 22, 2018 at 7:47 PM chuck adams <chuck.adams.k7qo@gmail.com>
wrote:

https://youtu.be/CzJgEqJY3mg

I managed to beat the 11pm MST deadline by 3 hours. Enjoy.

Frequency comparison is within 1mH (milli-Hertz) between the two
standards.
We know that the GPS system is going to be around a long time. It's in
use in
too many critical applications now to give it up.

Re GPS: I was impressed with the Chinese railroad people getting high
speed rail tracks
laid to a tolerance of 5mm. Their record speed now stands at 600 kph
(km per hour).

When do we want to start the winter building season? It's not even fall
type wx here
in the valley of the sun. :-)

Any one have the serial output data for the GPSDO? Might be interesting
to build a
1mW transmitter to emulate WWVB and feed my atomic clocks during the
daylight
hours from time to time. Of course, keeping it in a Faraday cage.

FYI

chuck, k7qo,







Richard Seguin
 

The waveform in your video looked amazing. What I was referring to was
some of the cheaper neo-7m and neo8-m modules where you remove the LED and
program the module to output 10Mhz. I don't believe that they use an OCXO
on the neo modules which may be part of the problem.

For more info about what I'm talking about:
https://www.youtube.com/watch?v=01IBdhcEmOw&list=PLUMG8JNssPPySuxZWuKyEOVvrz2ZyH5eB

Richard, VE9IT


On Sun, Sep 23, 2018 at 9:49 PM chuck adams <chuck.adams.k7qo@gmail.com>
wrote:

Richard,

Not sure which modules you are talking about. There are the square wave
generators and there are the sine wave generators. The majority of the
OCXO's that are sine wave generators are some of the cleanest signals
that I have seen from a crystal oscillator.

Attached is the output from the GPSDO showing the spectrum of the output.
I am using a Hantek DSO-2150 which samples at 150MHz and 8-bits, so
it is not the best of spectrum analyzers, but it does show how clean the
signal is. Ignore the table of values as the software engineer blew the
programming. Again.

I prefer the Hantek over the Rigol 1024Z scope SA. Hands down, even
though the Rigol as a faster sample rate. Their software display is
lacking
in detail. IMHO.

FYI

chuck, k7qo


On 09/23/2018 05:27 PM, Richard Seguin wrote:
Does it matter that the cheaper modules don't produce a clean sine wave?
The modifications are easy enough to make on the cheaper modules, if you
have steady hands.

On Sun, Sep 23, 2018, 12:20 AM Alan Biocca <alan.biocca@gmail.com>
wrote:

The GPS chips with PPS output are sufficient for that, don't even need a
GPSDO. I bought one the other day for under $20. The GPS's for drones
are
quite inexpensive. Just make sure the PPS output is available as well as
the serial.

-- Alan, w6akb


On Sat, Sep 22, 2018 at 7:47 PM chuck adams <chuck.adams.k7qo@gmail.com
wrote:

https://youtu.be/CzJgEqJY3mg

I managed to beat the 11pm MST deadline by 3 hours. Enjoy.

Frequency comparison is within 1mH (milli-Hertz) between the two
standards.
We know that the GPS system is going to be around a long time. It's in
use in
too many critical applications now to give it up.

Re GPS: I was impressed with the Chinese railroad people getting high
speed rail tracks
laid to a tolerance of 5mm. Their record speed now stands at 600 kph
(km per hour).

When do we want to start the winter building season? It's not even
fall
type wx here
in the valley of the sun. :-)

Any one have the serial output data for the GPSDO? Might be
interesting
to build a
1mW transmitter to emulate WWVB and feed my atomic clocks during the
daylight
hours from time to time. Of course, keeping it in a Faraday cage.

FYI

chuck, k7qo,









--
Richard