Re: [time-nuts] FE-5680A Mechanical Question
What we know is that you can set the Rb in 7 E-13. Dithering would allow
even closer setting, the question is what rate will the Rb accept with out
loosing lock or deterioration of the performance. Some one should explore
that. I am still waiting to se some aging. Taking the 10 MHz output and than
use an analog loop and something like a Morion OCXO and you have the best of
all.
Digitally controlling the Rb will cut the cost of the control loop in half.
For $10 in parts and a PC board for less than $10 using Shera like
controller can be realized. What is needed is some one able to do the PIC.
If some one is interested and able, please contact me off list. A low cost
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
In a message dated 1/12/2012 12:20:15 P.M. Eastern Standard Time,
lists@rtty.us writes:
Hi
I think it would be worth the effort to try dithering the DDS commands into
the Rb while measuring ADEV. You might find that you can do it with
little
or no impact on the unit's stability. If so it takes out some modification
effort and should make the controller cheaper.
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, January 12, 2012 10:43 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] FE-5680A Mechanical Question
Bringing out the C field in my estimation does not effect long or short
term. External magnetic field I think is a joke. An other option is a loop
that generates a tuning word for the DDS but that means your steps are 7
E-13.
Bert Kehren
In a message dated 1/12/2012 10:34:10 A.M. Eastern Standard Time,
davidwhess@gmail.com writes:
I was more interested in the technical details of how to adjust the
output of a RbO without sacrificing the short and long term stability.
I have seen a few designs that used a DDS to generate the 10 MHz
output which lends itself to this but they all suffer from DDS and
tuning noise. I see now that the RbO can be adjusted with an external
magnetic field.
On Thu, 12 Jan 2012 07:34:44 -0600, "J. L. Trantham" jltran@att.net
wrote:
David,
I have been following discussions on the list about a GPSDRbO for a year
or
so. Some interesting challenges and probably best implemented in a
'stable'
environment rather than portable operation but as best I can tell, it
would
require a very stable and good antenna location, stable and clean power,
and
I was thinking of using something like an LPRO-101 with an Ext C Field
input, a Shera type controller, and a GPS timing receiver, though, I
suspect
there are likely to be some 'multi-tasking' receivers out there that will
look at several sources including GPS, GLOSNASS, etc.
While the project might be fun, for portable work, it is likely far
easier
and probably just as good (almost), to use a Tbolt.
In any event, something to think about for the future.
Joe
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of David
Sent: Wednesday, January 11, 2012 11:12 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FE-5680A Mechanical Question
How would a GPSDRbO work? Phase lock the DDS output to the GPS? Phase
lock
a VCXO to the GPS and then phase lock to the RbO on loss of GPS lock?
On Wed, 11 Jan 2012 22:55:58 -0600, "J. L. Trantham" jltran@att.net
wrote:
Bill, Brian, Bill, and Peter,
Thanks for the info. All I need now is a 'project' to incorporate the
unit into.
In the back of my mind, I have the thought of a 'box' that will be
battery powered or 110 VAC powered (perhaps with an internal SLA
battery) and include a GPSDO and Rb unit (possibly a GPSDRbO) for the
purpose of a 'reference' for portable operation in the microwave
regions.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
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To unsubscribe, go to
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On Fri, Jan 13, 2012 at 3:19 AM, EWKehren@aol.com wrote:
What we know is that you can set the Rb in 7 E-13. Dithering would allow
even closer setting, the question is what rate will the Rb accept with out
loosing lock or deterioration of the performance. Some one should explore
that. I am still waiting to se some aging. Taking the 10 MHz output and than
use an analog loop and something like a Morion OCXO and you have the best of
all.
Digitally controlling the Rb will cut the cost of the control loop in half.
For $10 in parts and a PC board for less than $10 using Shera like
controller can be realized. What is needed is some one able to do the PIC.
If some one is interested and able, please contact me off list. A low cost
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
Don't use a PIC for the prototype. A desktop PC could work as well
and everyone here already has one. Connect the FE5680 to the PC's
serial port and send commands to adjust it. The PC also needs to be
able to read a voltage. Many already have audio input with 24-bit
ADC chips.
Later you can move the C code from the PC pretty much directly to an
AVR. PICs typically use assembly language, that is harder and limits
the number of people who can contribute changes to the code. But you
can start with a PC, maybe running Linux or BSD.
Chris Albertson
Redondo Beach, California
On 1/13/12 8:15 AM, Chris Albertson wrote:
On Fri, Jan 13, 2012 at 3:19 AM,EWKehren@aol.com wrote:
What we know is that you can set the Rb in 7 E-13. Dithering would allow
even closer setting, the question is what rate will the Rb accept with out
loosing lock or deterioration of the performance. Some one should explore
that. I am still waiting to se some aging. Taking the 10 MHz output and than
use an analog loop and something like a Morion OCXO and you have the best of
all.
Digitally controlling the Rb will cut the cost of the control loop in half.
For $10 in parts and a PC board for less than $10 using Shera like
controller can be realized. What is needed is some one able to do the PIC.
If some one is interested and able, please contact me off list. A low cost
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
Don't use a PIC for the prototype. A desktop PC could work as well
and everyone here already has one. Connect the FE5680 to the PC's
serial port and send commands to adjust it. The PC also needs to be
able to read a voltage. Many already have audio input with 24-bit
ADC chips.
But those audio inputs are almost always AC coupled.
Bringing up a question: Does anyone know of a cheap (<$20ish) USB
voltage sensor (16 bits or better, ideally).. I can see one of those
Atmel USB capable micros (like the one on the Arduino Uno) hooked to a
dual slope or successive approximation ADC.
There seem to be an amazing number of times that I want something like
that. The DATAQ $29 widget is only 10 bits, unfortunately. A USB
interface DMM would work nicely, but I haven't found one that's in the
under $50 price range.
Hi
Another thing that would need to be investigated - How fast (and how
uniformly) does it respond to a frequency set command. If you dither, you
care about how long it's at this or that frequency. Measuring 7x10^-13
frequency shifts on the unit probably isn't the best way to check that out
....
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Friday, January 13, 2012 6:20 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] FE-5680A Mechanical Question
What we know is that you can set the Rb in 7 E-13. Dithering would allow
even closer setting, the question is what rate will the Rb accept with out
loosing lock or deterioration of the performance. Some one should explore
that. I am still waiting to se some aging. Taking the 10 MHz output and
than
use an analog loop and something like a Morion OCXO and you have the best
of
all.
Digitally controlling the Rb will cut the cost of the control loop in half.
For $10 in parts and a PC board for less than $10 using Shera like
controller can be realized. What is needed is some one able to do the PIC.
If some one is interested and able, please contact me off list. A low cost
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
In a message dated 1/12/2012 12:20:15 P.M. Eastern Standard Time,
lists@rtty.us writes:
Hi
I think it would be worth the effort to try dithering the DDS commands into
the Rb while measuring ADEV. You might find that you can do it with
little
or no impact on the unit's stability. If so it takes out some modification
effort and should make the controller cheaper.
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EWKehren@aol.com
Sent: Thursday, January 12, 2012 10:43 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] FE-5680A Mechanical Question
Bringing out the C field in my estimation does not effect long or short
term. External magnetic field I think is a joke. An other option is a loop
that generates a tuning word for the DDS but that means your steps are 7
E-13.
Bert Kehren
In a message dated 1/12/2012 10:34:10 A.M. Eastern Standard Time,
davidwhess@gmail.com writes:
I was more interested in the technical details of how to adjust the
output of a RbO without sacrificing the short and long term stability.
I have seen a few designs that used a DDS to generate the 10 MHz
output which lends itself to this but they all suffer from DDS and
tuning noise. I see now that the RbO can be adjusted with an external
magnetic field.
On Thu, 12 Jan 2012 07:34:44 -0600, "J. L. Trantham" jltran@att.net
wrote:
David,
I have been following discussions on the list about a GPSDRbO for a year
or
so. Some interesting challenges and probably best implemented in a
'stable'
environment rather than portable operation but as best I can tell, it
would
require a very stable and good antenna location, stable and clean power,
and
I was thinking of using something like an LPRO-101 with an Ext C Field
input, a Shera type controller, and a GPS timing receiver, though, I
suspect
there are likely to be some 'multi-tasking' receivers out there that will
look at several sources including GPS, GLOSNASS, etc.
While the project might be fun, for portable work, it is likely far
easier
and probably just as good (almost), to use a Tbolt.
In any event, something to think about for the future.
Joe
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of David
Sent: Wednesday, January 11, 2012 11:12 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FE-5680A Mechanical Question
How would a GPSDRbO work? Phase lock the DDS output to the GPS? Phase
lock
a VCXO to the GPS and then phase lock to the RbO on loss of GPS lock?
On Wed, 11 Jan 2012 22:55:58 -0600, "J. L. Trantham" jltran@att.net
wrote:
Bill, Brian, Bill, and Peter,
Thanks for the info. All I need now is a 'project' to incorporate the
unit into.
In the back of my mind, I have the thought of a 'box' that will be
battery powered or 110 VAC powered (perhaps with an internal SLA
battery) and include a GPSDO and Rb unit (possibly a GPSDRbO) for the
purpose of a 'reference' for portable operation in the microwave
regions.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
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To unsubscribe, go to
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and follow the instructions there.
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To unsubscribe, go to
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and follow the instructions there.
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To unsubscribe, go to
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On Fri, Jan 13, 2012 at 8:37 AM, Jim Lux jimlux@earthlink.net wrote:
On 1/13/12 8:15 AM, Chris Albertson wrote:
On Fri, Jan 13, 2012 at 3:19 AM,EWKehren@aol.com wrote:
What we know is that you can set the Rb in 7 E-13. Dithering would allow
even closer setting, the question is what rate will the Rb accept with
out
loosing lock or deterioration of the performance. Some one should explore
that. I am still waiting to se some aging. Taking the 10 MHz output and
than
use an analog loop and something like a Morion OCXO and you have the
best of
all.
Digitally controlling the Rb will cut the cost of the control loop in
half.
For $10 in parts and a PC board for less than $10 using Shera like
controller can be realized. What is needed is some one able to do the
PIC.
If some one is interested and able, please contact me off list. A low
cost
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
Don't use a PIC for the prototype. A desktop PC could work as well
and everyone here already has one. Connect the FE5680 to the PC's
serial port and send commands to adjust it. The PC also needs to be
able to read a voltage. Many already have audio input with 24-bit
ADC chips.
But those audio inputs are almost always AC coupled.
Bringing up a question: Does anyone know of a cheap (<$20ish) USB voltage
sensor (16 bits or better, ideally).. I can see one of those Atmel USB
capable micros (like the one on the Arduino Uno) hooked to a dual slope or
successive approximation ADC.
There seem to be an amazing number of times that I want something like that.
The DATAQ $29 widget is only 10 bits, unfortunately. A USB interface DMM
would work nicely, but I haven't found one that's in the under $50 price
Many computer audio interfaces are AC coupled but not all of them.
But even with AC coupling what you can do is use the VCO portion of a
CD4046. This will convert voltage to frequency in the audio range.
It's a cheap work around. But really not because frequency in nearly
imune to noise and can be sent over long cables.
What I really want is a lower price GBIP interface. I just bought an
HP5328A on eBay that has the option 21 DVM. This meter can measure
volts to about 5 digits and send the data out the GPIB but getting
that into a computer is the hard part.
OK so I check on eBay. Most are $300 but If you can find a computer
with an old ISA slot then there are working GBIB cards for about $20.
The trick is finding an old PC. These are AT class or early Pentium
type computers. Most of these are now in landfills some place.
But now I will be looking.
I do software all day, every day. From experience, I can say it is
MUCH more productive to develop code on a larger desktop computer.
Better tools are available. Then move it down to the target computer
after you have it debugged. The process is helped if the target
computer is like the desktop computer.
There is a lot we don't know about the FE5680, like how fast can you
move the phase of the PPS? Does the FE5680 maintain lock when you
step the DDS? how fast can you step the DDS. All this will take
experiments. best to do those on the big desktop machine where we
have tools to log data to disk, make plots and so on.
Again, if anyone makes PCBs PLEASE include a way to program the uP on
the card without need of extra hardware. The firmware will get
upgraded and not everyone has a programmer. There must be a way for
end users upgrade the firmware.
Chris Albertson
Redondo Beach, California
Bringing up a question: Does anyone know of a cheap (<$20ish) USB voltage
sensor (16 bits or better, ideally).. I can see one of those Atmel USB
capable micros (like the one on the Arduino Uno) hooked to a dual slope or
successive approximation ADC.
Doesn't quite meet your price, but there's a 3.3V version of an Arduino called a "JeeNode" designed for sensor work, and there are a number of I2C based sensor plugins for it. For example the "analog plug" based on Microchip MCP3424 with 4 channels of differential inputs at 18 bits. Jeenode (kit) is $23 and Analog plug (assembled) is $12. It's the standard Arduino architecture, so it is simple to use and (re-)program from your PC via USB, no extra programmer needed.
http://shop.moderndevice.com/products/jeenode-kit
http://shop.moderndevice.com/products/jeelabs-analog-plug
I have some and they work well. Here's a plot of voltage vs time on an AA battery, showing the 18 bit performance (1 LSB = 15 uV). Noise is generally +/-1 LSB. https://picasaweb.google.com/lh/photo/q7Lq4oAX_0347S8BO0eHSA
You can plug up to four "analog plugs" directly into the JeeNode (software I2C) and these can actually be daisy-chained as well, with 6 different I2C addresses per I2C chain, for up to 24 total plugs per JeeNode which would be 96 ADC channels. If you are in Europe you can buy hardware direct from the designer at http://jeelabs.com/
In message 20120113200200.14805.qmail@s421.sureserver.com, "=?iso-8859-1?Q?be
ale?=" writes:
I have some and they work well. Here's a plot of voltage vs time
on an AA battery, showing the 18 bit performance (1 LSB = 15 uV).
Noise is generally +/-1 LSB.
https://picasaweb.google.com/lh/photo/q7Lq4oAX_0347S8BO0eHSA
Did you try to hold the battery in your hand while you did that ? :-)
Be aware that once you get to approx microvolt, you have to take
into account things like the temperature difference between plug and
socket because the thermoelectric effect kicks in.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
If you have a PC and an AC coupled audio interface then send a low
frequency audio saw tooth wave to the audio out. Connect that and the
device to be measured to an LM311 comparator. The comparator will
flip when your output voltage passes the DUT's voltage. One could
get fancy and use multiple comparators Then connect the comparator(s)
to a parallel port. You get 8 channels of low bandwidth analog input
for about 25 cents per channel, if you already have the parallel port.
I think that is the cheapest possible way to get voltages into a computer.
Also this kind of ADC can be very accurate. You can tie one or more
of the LM311s to a voltage reference and then your instrument is
continuoly calibrated.
This works because in our case the signal, has low bandwidth so we can
take out time and collect 1000 samples
On Fri, Jan 13, 2012 at 12:02 PM, beale beale@bealecorner.com wrote:
Bringing up a question: Does anyone know of a cheap (<$20ish) USB voltage
sensor (16 bits or better, ideally).. I can see one of those Atmel USB
capable micros (like the one on the Arduino Uno) hooked to a dual slope or
successive approximation ADC.
Doesn't quite meet your price, but there's a 3.3V version of an Arduino called a "JeeNode" designed for sensor work, and there are a number of I2C based sensor plugins for it. For example the "analog plug" based on Microchip MCP3424 with 4 channels of differential inputs at 18 bits. Jeenode (kit) is $23 and Analog plug (assembled) is $12. It's the standard Arduino architecture, so it is simple to use and (re-)program from your PC via USB, no extra programmer needed.
http://shop.moderndevice.com/products/jeenode-kit
http://shop.moderndevice.com/products/jeelabs-analog-plug
I have some and they work well. Here's a plot of voltage vs time on an AA battery, showing the 18 bit performance (1 LSB = 15 uV). Noise is generally +/-1 LSB. https://picasaweb.google.com/lh/photo/q7Lq4oAX_0347S8BO0eHSA
You can plug up to four "analog plugs" directly into the JeeNode (software I2C) and these can actually be daisy-chained as well, with 6 different I2C addresses per I2C chain, for up to 24 total plugs per JeeNode which would be 96 ADC channels. If you are in Europe you can buy hardware direct from the designer at http://jeelabs.com/
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
I would just use a picaxe, has a simple to use IDE and several different
sizes. No need for assembly, cheap enough for quasi-production.
Don
Chris Albertson
On Fri, Jan 13, 2012 at 3:19 AM, EWKehren@aol.com wrote:
What we know is that you can set the Rb in 7 E-13. Dithering would
allow
even closer setting, the question is what rate will the Rb accept with
out
loosing lock or deterioration of the performance. Some one should
explore
that. I am still waiting to se some aging. Taking the 10 MHz output
and than
use an analog loop and something like a Morion OCXO and you have the
best of
all.
Digitally controlling the Rb will cut the cost of the control loop in
half.
For $10 in parts and a PC board for less than $10 using Shera like
controller can be realized. What is needed is some one able to do the
PIC.
If some one is interested and able, please contact me off list. A low
cost
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
Don't use a PIC for the prototype. A desktop PC could work as well
and everyone here already has one. Connect the FE5680 to the PC's
serial port and send commands to adjust it. The PC also needs to be
able to read a voltage. Many already have audio input with 24-bit
ADC chips.
Later you can move the C code from the PC pretty much directly to an
AVR. PICs typically use assembly language, that is harder and limits
the number of people who can contribute changes to the code. But you
can start with a PC, maybe running Linux or BSD.
Chris Albertson
Redondo Beach, California
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
R. Bacon
"If you don't know what it is, don't poke it."
Ghost in the Shell
Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com
Right, Poul! And I've found, by lots of headbanging on walls,
GROUNDLOOPS!!!!! even at 12 bits...
Don
Poul-Henning Kamp
In message 20120113200200.14805.qmail@s421.sureserver.com,
"=?iso-8859-1?Q?be
ale?=" writes:
I have some and they work well. Here's a plot of voltage vs time
on an AA battery, showing the 18 bit performance (1 LSB = 15 uV).
Noise is generally +/-1 LSB.
https://picasaweb.google.com/lh/photo/q7Lq4oAX_0347S8BO0eHSA
Did you try to hold the battery in your hand while you did that ? :-)
Be aware that once you get to approx microvolt, you have to take
into account things like the temperature difference between plug and
socket because the thermoelectric effect kicks in.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
R. Bacon
"If you don't know what it is, don't poke it."
Ghost in the Shell
Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com