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Today's Topics:
1. TBolt signal levels (Tom Van Baak)
2. Re: FE5680 GPS Disciplined Controller (Chris Albertson)
3. Re: FE5680 GPS Disciplined Controller (Tom Van Baak)
4. Re: FE5680 GPS Disciplined Controller (Tom Van Baak)
5. Re: TBolt signal levels (Charles Steinmetz)
----------------------------------------------------------------------
Message: 1
Date: Thu, 19 Jun 2014 10:34:03 -0700
From: "Tom Van Baak" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Subject: [time-nuts] TBolt signal levels
Message-ID: <D5D4AC13B145410AAFCF1C6A2DD939D3@pc52>
Content-Type: text/plain; charset="iso-8859-1"
I'm testing several Trimble Thunderbolt's here with several different
antenna setups: indoor/outdoor, low-gain/high-gain, patch/helix,
plain/choke-ring.
Has anyone done a comparative analysis of antenna make/model/type against
signal levels for this receiver?
Or is there a rule of thumb for what is consider "good" vs. "bad"
reception?
Thanks,
/tvb
------------------------------
Message: 2
Date: Thu, 19 Jun 2014 08:31:19 -0700
From: Chris Albertson <[email protected]>
To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] FE5680 GPS Disciplined Controller
Message-ID:
<cabbxvhujcr54evig4ur8v2ncv3otx71rsw85qvmeb0mo31w...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
I've been working in the same thing BUT I don't want anyone who builds it
to need a PCB. And I want the firmware to load over USB so there is no
need to ship programmed chips or deal with external programmers. I think
I can get the cost below $20. That said I doubt I'll get 1E-13
performance out of my Rb.
My little Arduino based controller has been running now for a couple
months
and keeping a crystal in lock. The board has a pins left over for a
serial
port that I'll hook up to the Rb.
The trick to getting the cost down is NOT to do a custom PCB. Take
advantage of one of the uP development boards and then for under $5 you
get
the USB interface, D/A and A/D, serial ports, timers and quite a bit of
logic all 1/3rd the size of a credit card.
On Thu, Jun 19, 2014 at 12:57 AM, Jan Boutsen <[email protected]>
wrote:
Count me in for an assembled and tested board. Great project.
Jan
----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Wednesday, June 18, 2014 8:49 PM
Subject: [time-nuts] FE5680 GPS Disciplined Controller
FE5680 GPS Disciplined Controller
With all the FE 5680 rubidium oscillators being used as door stops out
there some of us decided to develop a GPSDO for it. The main question we
have:
Is there sufficient interest among time nuts for a discipline controller
for the FE5680 to make it available? Looking at the postings over the
last
two years I am not so sure.
The construction and preliminary testing of a Brooks Shera style GPS
discipline controller for the later version (6.81e-13 resolution) of the
FE5680
has been completed. We are trying to determine the number of people that
would be interested in obtaining an FE5680 discipline controller (if
there
is
sufficient interest about $45 a kit shipping included, $75 for an
assembled and tested board, international orders for an additional $5)
when
it is
released.
We are also looking for three Beta testers that would be willing to
purchase, assemble, and test our Beta release controller kit with their
own
FE5680A and GPS receiver or Tbolt and provide feedback. Please send an
email to
[email protected]_ (mailto:[email protected]) Subject Time-Nuts FE
5680A,
if you would be interested in being one of the three Beta testers. A key
requirement is the willingness to get to it right away, the board
assembly
takes about 30 minutes. Instrumentation to measure results is also a
requirement. We obtained impressive results using a cheap ublox 6M
receiver.
The FE5680 GPS discipline controller is a small (2? x 2?) board using 8
DIP?s and 1 SOT23-5 package powered by +5v with 0.1? headers for all
inputs
and outputs. Our plan is to have the kit supplier solder in the only SMD
device on the board. A GPS receiver 1PPS and 10 MHz sine from the FE5680
feed the board with two 9600 baud serial ports sending TTL level tuning
commands to the FE5680 and receiving commands from and sending status
data
to a
PC for data logging and system control via a simple terminal program.
In the chip count are two opto couplers that allow the use of isolated
TTL
to USB conversion. These USB adapters are readily available and furnish
the 5 V necessary for the secondary of the opto circuit. An option is to
not
use the opto couplers and send the PIC TTL level RX and TX into a TTL to
RS232 adapter. Another option is to use a TTL to RS232 converter after
the
opto couplers but then an external 5 V source would have to be supplied
for
the opto couplers.
As I mentioned before to get best performance from the FE5680
temperature
control is a must and after much fan and metal work I realized that a
Lap
Top heat pipe is the easiest lowest cost solution. Comments appreciated.
As
an alternative the temperature correction needs to be disabled.
Otherwise
two control loops fight each other. If you look close on page 7 of the
brochure temperature stability from ?10 to +60 C looks good but a closer
look
and you see 4 E-11 changes over small temperature changes in the -10 to
60
C range. Extensive analysis has been done on the FE 5680 A and maybe some
one can tackle that problem. Please look at what N5TNL did. It is
attached
and click on his link. The FE 5680A does have a 4 channel MAX 1246 ADC
and
most likely it is used to monitor temperature.
Also mentioned before the FE 5680 output is not the cleanest, I did
observe it and some one posted the attached. I apologize but my records
do
not
show who did, so if you posted the data please come forward. For serious
applications where you are using it as your main reference a clean up
like
the
Morion MV89 or HP 10811 should be considered.
This addition is not required for beta tests but temperature control
will
help.
I am also enclosing the express PCB layout, be free to use it but it
would
be more economical to do a group buy if there is enough interest and
some
one steps up to kit.
Bert Kehren
To not exceed the attachment limit the plot will be a separate posting
----------------------------------------------------------------------------
----
> _______________________________________________
> time-nuts mailing list -- [email protected]
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
------------------------------
Message: 3
Date: Thu, 19 Jun 2014 11:47:43 -0700
From: "Tom Van Baak" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Subject: Re: [time-nuts] FE5680 GPS Disciplined Controller
Message-ID: <9077B7C22C5C490284E8F66329117C75@pc52>
Content-Type: text/plain; charset="utf-8"
Chris,
I'm glad you're making progress on your Arduino GPSDO. You've mentioned it
in a dozen postings the past half year. Perhaps you will post the source
code sketch, full design, and actual phase / frequency / adev results some
day. Many of us are willing to help as independent testers and see actual
results.
Meanwhile... Now would be the time for you to let Bert have the stage; he
has an actual working design, with PCB, and several tests in progress.
High-performance results. This represents a year of work on his part, and
others who have freely collaborated and contributed to all aspects of his
project. It's really nice.
Please do not hijack the thread of another time nut's superb effort. Some
week it will be your turn to post final results of your project. This is
not the week.
Thanks,
/tvb
----- Original Message -----
From: "Chris Albertson" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Thursday, June 19, 2014 8:31 AM
Subject: Re: [time-nuts] FE5680 GPS Disciplined Controller
I've been working in the same thing BUT I don't want anyone who builds it
to need a PCB. And I want the firmware to load over USB so there is no
need to ship programmed chips or deal with external programmers. I
think
I can get the cost below $20. That said I doubt I'll get 1E-13
performance out of my Rb.
My little Arduino based controller has been running now for a couple
months
and keeping a crystal in lock. The board has a pins left over for a
serial
port that I'll hook up to the Rb.
The trick to getting the cost down is NOT to do a custom PCB. Take
advantage of one of the uP development boards and then for under $5 you
get
the USB interface, D/A and A/D, serial ports, timers and quite a bit of
logic all 1/3rd the size of a credit card.
------------------------------
Message: 4
Date: Thu, 19 Jun 2014 11:49:48 -0700
From: "Tom Van Baak" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Subject: Re: [time-nuts] FE5680 GPS Disciplined Controller
Message-ID: <B8A8B7594D9E4B499FFEE26D2A90B619@pc52>
Content-Type: text/plain; charset="utf-8"
----- Original Message -----
From: "Chris Albertson" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Thursday, June 19, 2014 8:31 AM
Subject: Re: [time-nuts] FE5680 GPS Disciplined Controller
I've been working in the same thing BUT I don't want anyone who builds it
to need a PCB. And I want the firmware to load over USB so there is no
need to ship programmed chips or deal with external programmers. I
think
I can get the cost below $20. That said I doubt I'll get 1E-13
performance out of my Rb.
My little Arduino based controller has been running now for a couple
months
and keeping a crystal in lock. The board has a pins left over for a
serial
port that I'll hook up to the Rb.
The trick to getting the cost down is NOT to do a custom PCB. Take
advantage of one of the uP development boards and then for under $5 you
get
the USB interface, D/A and A/D, serial ports, timers and quite a bit of
logic all 1/3rd the size of a credit card.
On Thu, Jun 19, 2014 at 12:57 AM, Jan Boutsen <[email protected]>
wrote:
Count me in for an assembled and tested board. Great project.
Jan
----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Wednesday, June 18, 2014 8:49 PM
Subject: [time-nuts] FE5680 GPS Disciplined Controller
FE5680 GPS Disciplined Controller
With all the FE 5680 rubidium oscillators being used as door stops out
there some of us decided to develop a GPSDO for it. The main question
we
have:
Is there sufficient interest among time nuts for a discipline
controller
for the FE5680 to make it available? Looking at the postings over the
last
two years I am not so sure.
The construction and preliminary testing of a Brooks Shera style GPS
discipline controller for the later version (6.81e-13 resolution) of
the
FE5680
has been completed. We are trying to determine the number of people
that
would be interested in obtaining an FE5680 discipline controller (if
there
is
sufficient interest about $45 a kit shipping included, $75 for an
assembled and tested board, international orders for an additional $5)
when
it is
released.
We are also looking for three Beta testers that would be willing to
purchase, assemble, and test our Beta release controller kit with their
own
FE5680A and GPS receiver or Tbolt and provide feedback. Please send an
email to
[email protected]_ (mailto:[email protected]) Subject Time-Nuts FE
5680A,
if you would be interested in being one of the three Beta testers. A
key
requirement is the willingness to get to it right away, the board
assembly
takes about 30 minutes. Instrumentation to measure results is also a
requirement. We obtained impressive results using a cheap ublox 6M
receiver.
The FE5680 GPS discipline controller is a small (2? x 2?) board using 8
DIP?s and 1 SOT23-5 package powered by +5v with 0.1? headers for all
inputs
and outputs. Our plan is to have the kit supplier solder in the only
SMD
device on the board. A GPS receiver 1PPS and 10 MHz sine from the
FE5680
feed the board with two 9600 baud serial ports sending TTL level tuning
commands to the FE5680 and receiving commands from and sending status
data
to a
PC for data logging and system control via a simple terminal program.
In the chip count are two opto couplers that allow the use of isolated
TTL
to USB conversion. These USB adapters are readily available and furnish
the 5 V necessary for the secondary of the opto circuit. An option is
to
not
use the opto couplers and send the PIC TTL level RX and TX into a TTL
to
RS232 adapter. Another option is to use a TTL to RS232 converter after
the
opto couplers but then an external 5 V source would have to be supplied
for
the opto couplers.
As I mentioned before to get best performance from the FE5680
temperature
control is a must and after much fan and metal work I realized that a
Lap
Top heat pipe is the easiest lowest cost solution. Comments
appreciated.
As
an alternative the temperature correction needs to be disabled.
Otherwise
two control loops fight each other. If you look close on page 7 of
the
brochure temperature stability from ?10 to +60 C looks good but a closer
look
and you see 4 E-11 changes over small temperature changes in the -10 to
60
C range. Extensive analysis has been done on the FE 5680 A and maybe
some
one can tackle that problem. Please look at what N5TNL did. It is
attached
and click on his link. The FE 5680A does have a 4 channel MAX 1246 ADC
and
most likely it is used to monitor temperature.
Also mentioned before the FE 5680 output is not the cleanest, I did
observe it and some one posted the attached. I apologize but my records
do
not
show who did, so if you posted the data please come forward. For
serious
applications where you are using it as your main reference a clean up
like
the
Morion MV89 or HP 10811 should be considered.
This addition is not required for beta tests but temperature control
will
help.
I am also enclosing the express PCB layout, be free to use it but it
would
be more economical to do a group buy if there is enough interest and
some
one steps up to kit.
Bert Kehren
To not exceed the attachment limit the plot will be a separate posting
----------------------------------------------------------------------------
----
> _______________________________________________
> time-nuts mailing list -- [email protected]
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
------------------------------
Message: 5
Date: Thu, 19 Jun 2014 15:36:29 -0400
From: Charles Steinmetz <[email protected]>
To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] TBolt signal levels
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Tom wrote:
I'm testing several Trimble Thunderbolts here with several different
antenna setups: indoor/outdoor, low-gain/high-gain, patch/helix,
plain/choke-ring.
Has anyone done a comparative analysis of antenna make/model/type
against signal levels for this receiver?
Or is there a rule of thumb for what is consider "good" vs. "bad"
reception?
Be careful when you say "signal levels" in connection with a
Thunderbolt. The figure reported by the Thunderbolt is NOT the RF
signal level, it is the carrier to noise ratio. The c/n is mostly a
function of the antenna location, and only a weak function of the
antenna and LNA. So mostly you switch antennas and things don't seem
to change much unless the new antenna is in a different
location. Unless you are looking at the antenna output with a
spectrum analyzer or frequency-selective voltmeter/power meter, you
will not know the relative signal levels from the different
antennas. But c/n is what is important, so that's all good.
Lots of Lady Heather screen shots have been posted on the list
showing accumulated signal strengths (commands SAS or SAD). To be
"good," you want to have large swaths of the plot in cool colors
(blues and greens) (c/n over 40 dBc), and preferably mostly greens
(c/n over 45 dBc). Look at Warren's screen shots -- his antenna
location is pretty good. Contrast with Dave's screen shots -- his
antenna location is adequate but not really very good.
Finally, note that not all similar c/n plots represent equally good
reception. Multipath can look like "carrier" to the Thunderbolt
rather than "noise," so an antenna location with substantial
multipath can look just as "good" as a location that is free from
multipath. Depending on the direction from which the reflections
arrive, an antenna with good multipath rejection (e.g., a choke-ring
design) may give superior results without looking any better on the c/n
plot.
Best regards,
Charles
------------------------------
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End of time-nuts Digest, Vol 119, Issue 33
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