Bls: time-nuts Digest, Vol 130, Issue 38
Dear All
This is the first time I posted in this forum so please forgive me if its already discuss before
I like to ask You who has more experience about my plan for "USD75 GPSDO" before I explain my plan let me tell You some "real world" limitation
- The parts I choose must be available in local store (custom bussiness cost a lot of time)
- I do not aim for something special a magnitude better than my MTI milliren OCXO is welcome.
Now What in my mind
I will use Ublox 7m GPS board that can program from 0,25Mhz to 10Mhz
(https://sites.google.com/site/g4zfqradio/u-blox_neo-6-7)
But the problem are I found someone (http://www.ra3apw.ru/proekty/ublox-neo-7m/) already do the spectrum analysis for this board and the result is like this :
and the last picture is far better, correct ? so what I need to do I have 2 plan :
- use the board 10Mhz output than use very narrow (100Hz bandwith) Crystal filter
- Use the 4Mhz output than again filter it use Crystal filter to clean it than use it as reference for PLL for controling 10Mhz OCXO
Which one you think a better way.
last I also like to know because MTI only spec the OCXO model 240 harmonics to down to -30dB (http://www.mti-milliren.com/pdfs/240.pdf) is there any benefit to use a crystal filter in the output to clearer it more.
any opinion is very welcome
Thank You
Anton
Pada Selasa, 26 Mei 2015 23:00, "time-nuts-request@febo.com" <time-nuts-request@febo.com> menulis:
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Today's Topics:
1. Re: Terrestrial Tides and Land Movement (Bob Camp)
2. Re: Terrestrial Tides and Land Movement (Bob Stewart)
3. pp2s? No, 1pps from a Nortel GPSTM! (Nathaniel Bezanson)
4. Re: FTS 8400 (Gregory Beat)
5. Re: 3048A software question (davidh)
6. Re: LTC6957 internal architecture (David C. Partridge)
7. Re: pp2s? No, 1pps from a Nortel GPSTM! (Tom Van Baak)
8. Re: 3048A software question (Chuck Harris)
9. Re: Terrestrial Tides and Land Movement (Chuck Harris)
10. Re: TymServe 2100 1995 Issue - A Kludgy Fix (Esa Heikkinen)
Message: 1
Date: Mon, 25 May 2015 19:01:02 -0400
From: Bob Camp kb8tq@n1k.org
To: Bob Stewart bob@evoria.net, Discussion of precise time and
frequency measurement time-nuts@febo.com
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Message-ID: C83D4DA8-3E3D-462F-ABFF-3DAE1F645A69@n1k.org
Content-Type: text/plain; charset=utf-8
Hi
Let’s step back a bit:
Your module is accurate to maybe 2 ns over a short period of time and something in the 10 to 20 ns range
over 24 hours. The 2 ns comes from a variety of issues. The 20 ns comes mainly from the ionosphere.
One example of a part of the 2 ns - the satellite positions in orbit are only known to some level of accuracy. The
data your module gets is a broadcast data set that represents a “best guess” made yesterday to fit the fight
path today.
A GPS that does an on the fly position solution to 3M is not that exceptional these days. You certainly see
claims of performance at the 1M or even 0.5M level. Yes people do fudge the numbers. Yes they do use WAAS
and the like to improve things.
A 3M error is at most a 10 ns timing error. It’s more likely to be a 3-4 ns timing error. That’s not all that big compared to the numbers above.
Am I fudging the numbers a bit? Of course I am. There is an implicit assumption that the mobile platform has
a good view of the sky. Dropping below 4 sats would not happen in this case. I’d also upgrade the LEA-6T to
an LEA-8T (or similar). More sats is going to give you a better position solution.
The bottom line is that an L1 GPSDO that wanders 10 to 20 ns per 24 hours compared to a Cesium or maser is
doing pretty well. Taking that to 8 to 18 ns vs 12 to 22 is a worthy thing to do. Proving that a specific implementation better … maybe not so easy. I’ve seen a lot of plots of well respected eBay GPSDO’s that wander
30 ns or more (peak to peak) per day one day and 20 ns p-p the next….
Bob
On May 25, 2015, at 5:28 PM, Bob Stewart bob@evoria.net wrote:
Hi Tom,
I'm not sure what you mean by this 0D vs 3D. I'm using an LEA-6T. There are three time transfer modes 0=disabled, 1=survey-in, 2=fixed mode. Are you suggesting that I set it to disabled to run a test? I've never tried that. I know that if I monitor the output while doing a survey, the phase is all over the place.
I'm in the middle of a therm correction test at the moment, but the plots at the link below are essentially where I am in development. The PRS-45A is driving the reference and start inputs of the 5370A. I'm using a somewhat modified PID system.
http://evoria.net/AE6RV/Status/
Development is essentially over, at this point except for details, like adding code for the M12+ receiver. I can post a link to the schematic, if there's interest, but I've decided that the code will remain proprietary. This has turned into something a lot bigger than a $25 GPSDO engine.
Bob
From: Tom Van Baak tvb@LeapSecond.com
To: Discussion of Precise Time and Frequency Measurement time-nuts@febo.com
Sent: Monday, May 25, 2015 3:09 PM
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Hi Bob,
You only need a survey if your timing receiver is running in zero-D mode. If you move the antenna more than some practical threshold you should adjust the fixed position or maybe just do another survey.
If you plan to move a lot, or if your application is mobile, or are on a slippery slope, or you just don't want to bother with a time-consuming survey, then run the timing receiver in 3D mode. As I said it will perform "almost as well". If you normally get, say 9 SV, I predict the timing accuracy difference is maybe only 10 or 20%.
You're still building a homebrew GPSDO, right? Collect a day of performance data in 0-D and then a day in 3-D and see what difference there is in RMS timing residuals (or in ADEV). I wonder if your GPSDO can even measure the difference.
/tvb
----- Original Message -----
From: "Bob Stewart" bob@evoria.net
To: "Discussion of Precise Time and Frequency Measurement" time-nuts@febo.com
Sent: Monday, May 25, 2015 11:09 AM
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Tom said: "The nice thing about GPS, unlike other time transfer methods, is that can handle the case of a moving antenna. As the antenna moves so does the time. This is why GPS timing receivers work (almost as well) on top of your car as on top of your house."
I don't get that. What's the purpose of doing a survey when you move your antenna if this the case?
Bob
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Message: 2
Date: Tue, 26 May 2015 00:40:20 +0000 (UTC)
From: Bob Stewart bob@evoria.net
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Message-ID:
1737488028.1532538.1432600820263.JavaMail.yahoo@mail.yahoo.com
Content-Type: text/plain; charset=UTF-8
Hi Bob,
Thanks for taking the time to explain the 4ns and 20ns wanders. I have just been calling them "constellation errors" without being able to explain it better than that. I've also wondered how much of the 20ns, if any, is attributable to the PRS-45A.
I still don't have the antenna located in a position suitable for precision timing. The power of the HOA is not to be trifled with. That, and the sky is full of power lines and other junk around here.
Bob
From: Bob Camp kb8tq@n1k.org
To: Bob Stewart bob@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Monday, May 25, 2015 6:01 PM
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Hi
Let’s step back a bit:
Your module is accurate to maybe 2 ns over a short period of time and something in the 10 to 20 ns range
over 24 hours. The 2 ns comes from a variety of issues. The 20 ns comes mainly from the ionosphere.
One example of a part of the 2 ns - the satellite positions in orbit are only known to some level of accuracy. The
data your module gets is a broadcast data set that represents a “best guess” made yesterday to fit the fight
path today.
A GPS that does an on the fly position solution to 3M is not that exceptional these days. You certainly see
claims of performance at the 1M or even 0.5M level. Yes people do fudge the numbers. Yes they do use WAAS
and the like to improve things.
A 3M error is at most a 10 ns timing error. It’s more likely to be a 3-4 ns timing error. That’s not all that big compared to the numbers above.
Am I fudging the numbers a bit? Of course I am. There is an implicit assumption that the mobile platform has
a good view of the sky. Dropping below 4 sats would not happen in this case. I’d also upgrade the LEA-6T to
an LEA-8T (or similar). More sats is going to give you a better position solution.
The bottom line is that an L1 GPSDO that wanders 10 to 20 ns per 24 hours compared to a Cesium or maser is
doing pretty well. Taking that to 8 to 18 ns vs 12 to 22 is a worthy thing to do. Proving that a specific implementation better … maybe not so easy. I’ve seen a lot of plots of well respected eBay GPSDO’s that wander
30 ns or more (peak to peak) per day one day and 20 ns p-p the next….
Bob
Message: 3
Date: Mon, 25 May 2015 22:08:21 -0400
From: Nathaniel Bezanson myself@telcodata.us
To: time-nuts@febo.com
Subject: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
Message-ID: 1432606101373908991@telcodata.us
Content-Type: text/plain
As anyone with a Nortel GPSTM knows, it's a close cousin to the Thunderbolt but not exactly identical. Notably, coming from a CDMA environment, the unit has an "even second" output, aka PP2S, aka 0.5pps, aka 0.5Hz, etc. (Hoping to make this searchable...) There are software commands to configure this on the Thunderbolt too, but the GPSTM appears to have this function hard-coded into the PAL, and it can't be set back to PPS in software.
However, there exists a PPS signal on the PCB, at TP13 between the Trimble chip and the PAL, discovered by some folks at the hackerspace here, during some noodling-around with an oscilloscope this afternoon. It's all documented here:
https://www.i3detroit.org/wiki/Nortel_GPSTM
This is for a NTBW50AA-11 module (single long board), other parts may have the signal in different places but I bet it's in there.
Enjoy!-Nate B-
Message: 4
Date: Mon, 25 May 2015 20:31:03 -0500
From: Gregory Beat w9gb@icloud.com
To: "time-nuts@febo.com" time-nuts@febo.com
Subject: Re: [time-nuts] FTS 8400
Message-ID: 06B6BAB6-8866-4FCA-BBE7-AD68AA9E0458@icloud.com
Content-Type: text/plain; charset=us-ascii
Ole -
These became obsolete in 1999. Actually led to development of TAC-2 board (TAPR) in 1996.
Tom Clark, K3IO could tell you about the FTS 8400 usage with the
VLBI large dish array in 1980s and 1990s.
Scroll down the TAC32Plus software notes for discussion on Trimble FTS 8400.
https://www.cnssys.com/cnsclock/Tac32PlusSoftware.php
Greg
w9gb
Message: 5
Date: Tue, 26 May 2015 12:19:06 +1000
From: davidh dhooke@gmail.com
To: Discussion of precise time and frequency measurement
public-time-nuts-JSkTLETqlTM@plane.gmane.org
Subject: Re: [time-nuts] 3048A software question
Message-ID: 5563D81A.6040604@gmail.com
Content-Type: text/plain; charset=windows-1252; format=flowed
Folks,
I'm also working on getting the MSDOS version running. What is the most
recent version of DOS that people have found to work with the A 01.01
version.
Also, can anyone advise where the command drivers for the 82335 can be
found?
Cheers,
david
Hi Adrian,
Got the spec lines working now, thanks!
Yes, the DOS version. I was hoping for an updated user manual for that version as the manual describes the other software version, and maybe a slightly later sw version. Oh well.
Thanks for you help!
Said
On Feb 17, 2012, at 5:06, Adrian rfnuts-KvP5wT2u2U0@public.gmane.org wrote:
Said,
are you using the Opt. 311 (MS-DOS) software?
I don't know of any more recent versions.
To answer your initial question:
You can not change anything on the diagram after the measurement, not even the title.
The spec lines will be visible only when you have defined them prior to starting the measurement.
Regards,
Adrian
Hello team,
I am trying to get an HP 3048A system up and running, and I am having
problems with enabling spec limit lines on the graph.
I can enter the spec line data under the "manipulate results" then "spec
lines" menu, but the lines I entered are not visible. There are the standard
spec lines visible when I do the internal noise floor test, so I know this
should work.
Does anyone know how to enable these properly? The user manual doesn't talk
about this, and it is written for an older version of the software
anyway's.
Also, I have software version A 01.01 from 1994, does anyone have any more
recent software version?
Thanks in advance,
Said
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Message: 6
Date: Tue, 26 May 2015 09:51:26 +0100
From: "David C. Partridge" david.partridge@perdrix.co.uk
To: "'Discussion of precise time and frequency measurement'"
time-nuts@febo.com
Subject: Re: [time-nuts] LTC6957 internal architecture
Message-ID: 81474EBE905B4522A24C6B8FFE76BB7D@APOLLO
Content-Type: text/plain; charset="utf-8"
With all this talk of the LT6957 I'm wondering if there's interest in a re-spin of my frequency divider with one of these at the front end instead.
Regards,
David Partridge
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Bruce Griffiths
Sent: 26 May 2015 00:40
To: time-nuts@febo.com
Subject: [time-nuts] LTC6957 internal architecture
The following patent hints that the LTC6957 front end probably consists of several cascaded long tailed pair differential amplifier stages each with a selectable bandwidth set by capacitors shunting the collector load resistors. : US8319551 The input limiter is in effect a Collins style limiter with selectable bandwidth for each stage to reduce the noise with respect to a comparator which typically has several high gain wide bandwidth cascaded differential amplifier stages.
Bruce
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Message: 7
Date: Tue, 26 May 2015 05:09:05 -0700
From: "Tom Van Baak" tvb@LeapSecond.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Subject: Re: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
Message-ID: 75D41F5911C04B70A87A2FB2EE8F993B@pc52
Content-Type: text/plain; charset="utf-8"
Hi Nate,
Nice page. Thanks for sharing your work.
The Nortel units are a reasonable and slightly cheaper alternative to a TBolt, if you don't mind the much larger size, mass, and non-standard connector issues.
The performance depends somewhat on which vendor's oscillator was used. I tested a bunch here:
http://www.leapsecond.com/pages/nortel/
For NTP none of these plots matter (most GPSDO are a thousand to a million times more stable than NTP or a PC can handle).
/tvb
----- Original Message -----
From: "Nathaniel Bezanson" myself@telcodata.us
To: time-nuts@febo.com
Sent: Monday, May 25, 2015 7:08 PM
Subject: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
As anyone with a Nortel GPSTM knows, it's a close cousin to the Thunderbolt but not exactly identical. Notably, coming from a CDMA environment, the unit has an "even second" output, aka PP2S, aka 0.5pps, aka 0.5Hz, etc. (Hoping to make this searchable...) There are software commands to configure this on the Thunderbolt too, but the GPSTM appears to have this function hard-coded into the PAL, and it can't be set back to PPS in software.
However, there exists a PPS signal on the PCB, at TP13 between the Trimble chip and the PAL, discovered by some folks at the hackerspace here, during some noodling-around with an oscilloscope this afternoon. It's all documented here:
https://www.i3detroit.org/wiki/Nortel_GPSTM
This is for a NTBW50AA-11 module (single long board), other parts may have the signal in different places but I bet it's in there.
Enjoy!-Nate B-
Message: 8
Date: Tue, 26 May 2015 08:41:52 -0400
From: Chuck Harris cfharris@erols.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] 3048A software question
Message-ID: 55646A10.6020200@erols.com
Content-Type: text/plain; charset=UTF-8; format=flowed
The easiest way of getting a new well supported version of
DOS, is to download FreeDOS. Anything that worked on any
version of MSDOS will run under FreeDOS... and so much more!
-Chuck Harris
davidh wrote:
Folks,
I'm also working on getting the MSDOS version running. What is the most recent
version of DOS that people have found to work with the A 01.01 version.
Also, can anyone advise where the command drivers for the 82335 can be found?
Cheers,
david
Message: 9
Date: Tue, 26 May 2015 08:39:44 -0400
From: Chuck Harris cfharris@erols.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Message-ID: 55646990.3050502@erols.com
Content-Type: text/plain; charset=UTF-8; format=flowed
Hi Bob S,
An HOA can be a daunting problem, but not one that cannot be
solved with a little guile.
Every house I have ever seen that has modern plumbing has a few
vent stacks on the roof. Would the HOA even notice if yours
sprouted another one dark weekend evening?
All the kit you need to add one to your roof is available at
your local big box store.
The usual bullet style antenna, sitting on top of a PVC vent
pipe would be invisible on most houses, particularly if it were
to be placed in the same vicinity as the rest.
Also, GPS bullet antennas are pretty well sealed, save for the
connector on the bottom. If you do a good job of sealing the
connector (eg. lots of wraps of electrical tape, followed by
a few of friction tape) there in no intrinsic reason you couldn't
safely mount yours on top of the main plumbing vent stack. Drill
a hole in the side at some convenient spot inside of the house,
and snake the coax up through the vent stack, mount the antenna
over the top, leaving adequate vent space. (OBTW, it isn't a
vent stack until it is above the highest fixture in the house.)
Although I don't have an HOA on my farm, I have my antenna mounted
that way on my radon mitigation pipe. I bent up a couple of
pieces of aluminum to make an open plug and put the antenna up
without ever setting foot on my roof. I simply snaked the cable
up and out the top of the radon pipe, and when I could reach it
from a window, installed the GPS antenna, and aluminum "plug",
and then pulled the antenna cable back through the pipe, causing
the plug and antenna to pop into the pipe mounting the antenna.
-Chuck Harris
Bob Stewart wrote:
Hi Bob, Thanks for taking the time to explain the 4ns and 20ns wanders. I have
just been calling them "constellation errors" without being able to explain it
better than that. I've also wondered how much of the 20ns, if any, is
attributable to the PRS-45A.
I still don't have the antenna located in a position suitable for precision
timing. The power of the HOA is not to be trifled with. That, and the sky is
full of power lines and other junk around here.
Bob
Message: 10
Date: Tue, 26 May 2015 17:18:47 +0300
From: Esa Heikkinen tn1ajb@nic.fi
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] TymServe 2100 1995 Issue - A Kludgy Fix
Message-ID: 556480C7.2090106@nic.fi
Content-Type: text/plain; charset=UTF-8; format=flowed
descoubes kirjoitti:
I am very pleased to inform you that the 1995 year bug on the TS2100 has
been solved. You will have to replace the existing Trimble ACE III
GPS receiver by our N024 with special firmware.
Does this also correct the 1 sec offset caused by upcoming leap second?
To remind, TS2100 GPS mode failed already in February, having 1 sec
offset right after the information about upcoming leap second was added.
How can we know that it doesn't fail again when actual GPS week rollover
will happen? Now it seems to be week 1846 and 2047 will come less than
four years. Did you test this with GPS simulator?
Best regards,
--
73s!
Esa
OH4KJU
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End of time-nuts Digest, Vol 130, Issue 38
Hi
What is your goal?
Do you want something that works as well as a $125 eBay GPSDO?
What is your end application?
Do you have a cheap source of 100 Hz wide 10 MHz crystal filters?
========
The main problem with a simple approach like the one you propose is that the filter is probably to wide at 100 Hz and at
the same time to narrow to source cheaply.
Your PLL loop filter will need to be in the 1/100 to 1/1000 Hz range to work “as well as” the eBay part. The as received
GPS signal has a lot of noise on it. How do you plan to implement this filter? Normally digital filtering is used. Once you
go digital, a 1 pps lock frequency is a easy thing to do.
Lots of choices.
Bob
On May 26, 2015, at 12:58 PM, Anton Moehammad via time-nuts time-nuts@febo.com wrote:
Dear All
This is the first time I posted in this forum so please forgive me if its already discuss before
I like to ask You who has more experience about my plan for "USD75 GPSDO" before I explain my plan let me tell You some "real world" limitation
- The parts I choose must be available in local store (custom bussiness cost a lot of time)
- I do not aim for something special a magnitude better than my MTI milliren OCXO is welcome.
Now What in my mind
I will use Ublox 7m GPS board that can program from 0,25Mhz to 10Mhz
(https://sites.google.com/site/g4zfqradio/u-blox_neo-6-7)
But the problem are I found someone (http://www.ra3apw.ru/proekty/ublox-neo-7m/) already do the spectrum analysis for this board and the result is like this :
and the last picture is far better, correct ? so what I need to do I have 2 plan :
- use the board 10Mhz output than use very narrow (100Hz bandwith) Crystal filter
- Use the 4Mhz output than again filter it use Crystal filter to clean it than use it as reference for PLL for controling 10Mhz OCXO
Which one you think a better way.
last I also like to know because MTI only spec the OCXO model 240 harmonics to down to -30dB (http://www.mti-milliren.com/pdfs/240.pdf) is there any benefit to use a crystal filter in the output to clearer it more.
any opinion is very welcome
Thank You
Anton
Pada Selasa, 26 Mei 2015 23:00, "time-nuts-request@febo.com" <time-nuts-request@febo.com> menulis:
Send time-nuts mailing list submissions to
time-nuts@febo.com
To subscribe or unsubscribe via the World Wide Web, visit
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
or, via email, send a message with subject or body 'help' to
time-nuts-request@febo.com
You can reach the person managing the list at
time-nuts-owner@febo.com
When replying, please edit your Subject line so it is more specific
than "Re: Contents of time-nuts digest..."
Today's Topics:
- Re: Terrestrial Tides and Land Movement (Bob Camp)
- Re: Terrestrial Tides and Land Movement (Bob Stewart)
- pp2s? No, 1pps from a Nortel GPSTM! (Nathaniel Bezanson)
- Re: FTS 8400 (Gregory Beat)
- Re: 3048A software question (davidh)
- Re: LTC6957 internal architecture (David C. Partridge)
- Re: pp2s? No, 1pps from a Nortel GPSTM! (Tom Van Baak)
- Re: 3048A software question (Chuck Harris)
- Re: Terrestrial Tides and Land Movement (Chuck Harris)
- Re: TymServe 2100 1995 Issue - A Kludgy Fix (Esa Heikkinen)
Message: 1
Date: Mon, 25 May 2015 19:01:02 -0400
From: Bob Camp kb8tq@n1k.org
To: Bob Stewart bob@evoria.net, Discussion of precise time and
frequency measurement time-nuts@febo.com
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Message-ID: C83D4DA8-3E3D-462F-ABFF-3DAE1F645A69@n1k.org
Content-Type: text/plain; charset=utf-8
Hi
Let’s step back a bit:
Your module is accurate to maybe 2 ns over a short period of time and something in the 10 to 20 ns range
over 24 hours. The 2 ns comes from a variety of issues. The 20 ns comes mainly from the ionosphere.
One example of a part of the 2 ns - the satellite positions in orbit are only known to some level of accuracy. The
data your module gets is a broadcast data set that represents a “best guess” made yesterday to fit the fight
path today.
A GPS that does an on the fly position solution to 3M is not that exceptional these days. You certainly see
claims of performance at the 1M or even 0.5M level. Yes people do fudge the numbers. Yes they do use WAAS
and the like to improve things.
A 3M error is at most a 10 ns timing error. It’s more likely to be a 3-4 ns timing error. That’s not all that big compared to the numbers above.
Am I fudging the numbers a bit? Of course I am. There is an implicit assumption that the mobile platform has
a good view of the sky. Dropping below 4 sats would not happen in this case. I’d also upgrade the LEA-6T to
an LEA-8T (or similar). More sats is going to give you a better position solution.
The bottom line is that an L1 GPSDO that wanders 10 to 20 ns per 24 hours compared to a Cesium or maser is
doing pretty well. Taking that to 8 to 18 ns vs 12 to 22 is a worthy thing to do. Proving that a specific implementation better … maybe not so easy. I’ve seen a lot of plots of well respected eBay GPSDO’s that wander
30 ns or more (peak to peak) per day one day and 20 ns p-p the next….
Bob
On May 25, 2015, at 5:28 PM, Bob Stewart bob@evoria.net wrote:
Hi Tom,
I'm not sure what you mean by this 0D vs 3D. I'm using an LEA-6T. There are three time transfer modes 0=disabled, 1=survey-in, 2=fixed mode. Are you suggesting that I set it to disabled to run a test? I've never tried that. I know that if I monitor the output while doing a survey, the phase is all over the place.
I'm in the middle of a therm correction test at the moment, but the plots at the link below are essentially where I am in development. The PRS-45A is driving the reference and start inputs of the 5370A. I'm using a somewhat modified PID system.
http://evoria.net/AE6RV/Status/
Development is essentially over, at this point except for details, like adding code for the M12+ receiver. I can post a link to the schematic, if there's interest, but I've decided that the code will remain proprietary. This has turned into something a lot bigger than a $25 GPSDO engine.
Bob
From: Tom Van Baak tvb@LeapSecond.com
To: Discussion of Precise Time and Frequency Measurement time-nuts@febo.com
Sent: Monday, May 25, 2015 3:09 PM
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Hi Bob,
You only need a survey if your timing receiver is running in zero-D mode. If you move the antenna more than some practical threshold you should adjust the fixed position or maybe just do another survey.
If you plan to move a lot, or if your application is mobile, or are on a slippery slope, or you just don't want to bother with a time-consuming survey, then run the timing receiver in 3D mode. As I said it will perform "almost as well". If you normally get, say 9 SV, I predict the timing accuracy difference is maybe only 10 or 20%.
You're still building a homebrew GPSDO, right? Collect a day of performance data in 0-D and then a day in 3-D and see what difference there is in RMS timing residuals (or in ADEV). I wonder if your GPSDO can even measure the difference.
/tvb
----- Original Message -----
From: "Bob Stewart" bob@evoria.net
To: "Discussion of Precise Time and Frequency Measurement" time-nuts@febo.com
Sent: Monday, May 25, 2015 11:09 AM
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Tom said: "The nice thing about GPS, unlike other time transfer methods, is that can handle the case of a moving antenna. As the antenna moves so does the time. This is why GPS timing receivers work (almost as well) on top of your car as on top of your house."
I don't get that. What's the purpose of doing a survey when you move your antenna if this the case?
Bob
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Message: 2
Date: Tue, 26 May 2015 00:40:20 +0000 (UTC)
From: Bob Stewart bob@evoria.net
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Message-ID:
1737488028.1532538.1432600820263.JavaMail.yahoo@mail.yahoo.com
Content-Type: text/plain; charset=UTF-8
Hi Bob,
Thanks for taking the time to explain the 4ns and 20ns wanders. I have just been calling them "constellation errors" without being able to explain it better than that. I've also wondered how much of the 20ns, if any, is attributable to the PRS-45A.
I still don't have the antenna located in a position suitable for precision timing. The power of the HOA is not to be trifled with. That, and the sky is full of power lines and other junk around here.
Bob
From: Bob Camp <kb8tq@n1k.org>
To: Bob Stewart bob@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Monday, May 25, 2015 6:01 PM
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Hi
Let’s step back a bit:
Your module is accurate to maybe 2 ns over a short period of time and something in the 10 to 20 ns range
over 24 hours. The 2 ns comes from a variety of issues. The 20 ns comes mainly from the ionosphere.
One example of a part of the 2 ns - the satellite positions in orbit are only known to some level of accuracy. The
data your module gets is a broadcast data set that represents a “best guess” made yesterday to fit the fight
path today.
A GPS that does an on the fly position solution to 3M is not that exceptional these days. You certainly see
claims of performance at the 1M or even 0.5M level. Yes people do fudge the numbers. Yes they do use WAAS
and the like to improve things.
A 3M error is at most a 10 ns timing error. It’s more likely to be a 3-4 ns timing error. That’s not all that big compared to the numbers above.
Am I fudging the numbers a bit? Of course I am. There is an implicit assumption that the mobile platform has
a good view of the sky. Dropping below 4 sats would not happen in this case. I’d also upgrade the LEA-6T to
an LEA-8T (or similar). More sats is going to give you a better position solution.
The bottom line is that an L1 GPSDO that wanders 10 to 20 ns per 24 hours compared to a Cesium or maser is
doing pretty well. Taking that to 8 to 18 ns vs 12 to 22 is a worthy thing to do. Proving that a specific implementation better … maybe not so easy. I’ve seen a lot of plots of well respected eBay GPSDO’s that wander
30 ns or more (peak to peak) per day one day and 20 ns p-p the next….
Bob
Message: 3
Date: Mon, 25 May 2015 22:08:21 -0400
From: Nathaniel Bezanson myself@telcodata.us
To: time-nuts@febo.com
Subject: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
Message-ID: 1432606101373908991@telcodata.us
Content-Type: text/plain
As anyone with a Nortel GPSTM knows, it's a close cousin to the Thunderbolt but not exactly identical. Notably, coming from a CDMA environment, the unit has an "even second" output, aka PP2S, aka 0.5pps, aka 0.5Hz, etc. (Hoping to make this searchable...) There are software commands to configure this on the Thunderbolt too, but the GPSTM appears to have this function hard-coded into the PAL, and it can't be set back to PPS in software.
However, there exists a PPS signal on the PCB, at TP13 between the Trimble chip and the PAL, discovered by some folks at the hackerspace here, during some noodling-around with an oscilloscope this afternoon. It's all documented here:
https://www.i3detroit.org/wiki/Nortel_GPSTM
This is for a NTBW50AA-11 module (single long board), other parts may have the signal in different places but I bet it's in there.
Enjoy!-Nate B-
Message: 4
Date: Mon, 25 May 2015 20:31:03 -0500
From: Gregory Beat w9gb@icloud.com
To: "time-nuts@febo.com" time-nuts@febo.com
Subject: Re: [time-nuts] FTS 8400
Message-ID: 06B6BAB6-8866-4FCA-BBE7-AD68AA9E0458@icloud.com
Content-Type: text/plain; charset=us-ascii
Ole -
These became obsolete in 1999. Actually led to development of TAC-2 board (TAPR) in 1996.
Tom Clark, K3IO could tell you about the FTS 8400 usage with the
VLBI large dish array in 1980s and 1990s.
Scroll down the TAC32Plus software notes for discussion on Trimble FTS 8400.
https://www.cnssys.com/cnsclock/Tac32PlusSoftware.php
Greg
w9gb
Message: 5
Date: Tue, 26 May 2015 12:19:06 +1000
From: davidh dhooke@gmail.com
To: Discussion of precise time and frequency measurement
public-time-nuts-JSkTLETqlTM@plane.gmane.org
Subject: Re: [time-nuts] 3048A software question
Message-ID: 5563D81A.6040604@gmail.com
Content-Type: text/plain; charset=windows-1252; format=flowed
Folks,
I'm also working on getting the MSDOS version running. What is the most
recent version of DOS that people have found to work with the A 01.01
version.
Also, can anyone advise where the command drivers for the 82335 can be
found?
Cheers,
david
Hi Adrian,
Got the spec lines working now, thanks!
Yes, the DOS version. I was hoping for an updated user manual for that version as the manual describes the other software version, and maybe a slightly later sw version. Oh well.
Thanks for you help!
Said
On Feb 17, 2012, at 5:06, Adrian rfnuts-KvP5wT2u2U0@public.gmane.org wrote:
Said,
are you using the Opt. 311 (MS-DOS) software?
I don't know of any more recent versions.
To answer your initial question:
You can not change anything on the diagram after the measurement, not even the title.
The spec lines will be visible only when you have defined them prior to starting the measurement.
Regards,
Adrian
Hello team,
I am trying to get an HP 3048A system up and running, and I am having
problems with enabling spec limit lines on the graph.
I can enter the spec line data under the "manipulate results" then "spec
lines" menu, but the lines I entered are not visible. There are the standard
spec lines visible when I do the internal noise floor test, so I know this
should work.
Does anyone know how to enable these properly? The user manual doesn't talk
about this, and it is written for an older version of the software
anyway's.
Also, I have software version A 01.01 from 1994, does anyone have any more
recent software version?
Thanks in advance,
Said
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Message: 6
Date: Tue, 26 May 2015 09:51:26 +0100
From: "David C. Partridge" david.partridge@perdrix.co.uk
To: "'Discussion of precise time and frequency measurement'"
time-nuts@febo.com
Subject: Re: [time-nuts] LTC6957 internal architecture
Message-ID: 81474EBE905B4522A24C6B8FFE76BB7D@APOLLO
Content-Type: text/plain; charset="utf-8"
With all this talk of the LT6957 I'm wondering if there's interest in a re-spin of my frequency divider with one of these at the front end instead.
Regards,
David Partridge
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Bruce Griffiths
Sent: 26 May 2015 00:40
To: time-nuts@febo.com
Subject: [time-nuts] LTC6957 internal architecture
The following patent hints that the LTC6957 front end probably consists of several cascaded long tailed pair differential amplifier stages each with a selectable bandwidth set by capacitors shunting the collector load resistors. : US8319551 The input limiter is in effect a Collins style limiter with selectable bandwidth for each stage to reduce the noise with respect to a comparator which typically has several high gain wide bandwidth cascaded differential amplifier stages.
Bruce
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Message: 7
Date: Tue, 26 May 2015 05:09:05 -0700
From: "Tom Van Baak" tvb@LeapSecond.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Subject: Re: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
Message-ID: 75D41F5911C04B70A87A2FB2EE8F993B@pc52
Content-Type: text/plain; charset="utf-8"
Hi Nate,
Nice page. Thanks for sharing your work.
The Nortel units are a reasonable and slightly cheaper alternative to a TBolt, if you don't mind the much larger size, mass, and non-standard connector issues.
The performance depends somewhat on which vendor's oscillator was used. I tested a bunch here:
http://www.leapsecond.com/pages/nortel/
For NTP none of these plots matter (most GPSDO are a thousand to a million times more stable than NTP or a PC can handle).
/tvb
----- Original Message -----
From: "Nathaniel Bezanson" myself@telcodata.us
To: time-nuts@febo.com
Sent: Monday, May 25, 2015 7:08 PM
Subject: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
As anyone with a Nortel GPSTM knows, it's a close cousin to the Thunderbolt but not exactly identical. Notably, coming from a CDMA environment, the unit has an "even second" output, aka PP2S, aka 0.5pps, aka 0.5Hz, etc. (Hoping to make this searchable...) There are software commands to configure this on the Thunderbolt too, but the GPSTM appears to have this function hard-coded into the PAL, and it can't be set back to PPS in software.
However, there exists a PPS signal on the PCB, at TP13 between the Trimble chip and the PAL, discovered by some folks at the hackerspace here, during some noodling-around with an oscilloscope this afternoon. It's all documented here:
https://www.i3detroit.org/wiki/Nortel_GPSTM
This is for a NTBW50AA-11 module (single long board), other parts may have the signal in different places but I bet it's in there.
Enjoy!-Nate B-
Message: 8
Date: Tue, 26 May 2015 08:41:52 -0400
From: Chuck Harris cfharris@erols.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] 3048A software question
Message-ID: 55646A10.6020200@erols.com
Content-Type: text/plain; charset=UTF-8; format=flowed
The easiest way of getting a new well supported version of
DOS, is to download FreeDOS. Anything that worked on any
version of MSDOS will run under FreeDOS... and so much more!
-Chuck Harris
davidh wrote:
Folks,
I'm also working on getting the MSDOS version running. What is the most recent
version of DOS that people have found to work with the A 01.01 version.
Also, can anyone advise where the command drivers for the 82335 can be found?
Cheers,
david
Message: 9
Date: Tue, 26 May 2015 08:39:44 -0400
From: Chuck Harris cfharris@erols.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Terrestrial Tides and Land Movement
Message-ID: 55646990.3050502@erols.com
Content-Type: text/plain; charset=UTF-8; format=flowed
Hi Bob S,
An HOA can be a daunting problem, but not one that cannot be
solved with a little guile.
Every house I have ever seen that has modern plumbing has a few
vent stacks on the roof. Would the HOA even notice if yours
sprouted another one dark weekend evening?
All the kit you need to add one to your roof is available at
your local big box store.
The usual bullet style antenna, sitting on top of a PVC vent
pipe would be invisible on most houses, particularly if it were
to be placed in the same vicinity as the rest.
Also, GPS bullet antennas are pretty well sealed, save for the
connector on the bottom. If you do a good job of sealing the
connector (eg. lots of wraps of electrical tape, followed by
a few of friction tape) there in no intrinsic reason you couldn't
safely mount yours on top of the main plumbing vent stack. Drill
a hole in the side at some convenient spot inside of the house,
and snake the coax up through the vent stack, mount the antenna
over the top, leaving adequate vent space. (OBTW, it isn't a
vent stack until it is above the highest fixture in the house.)
Although I don't have an HOA on my farm, I have my antenna mounted
that way on my radon mitigation pipe. I bent up a couple of
pieces of aluminum to make an open plug and put the antenna up
without ever setting foot on my roof. I simply snaked the cable
up and out the top of the radon pipe, and when I could reach it
from a window, installed the GPS antenna, and aluminum "plug",
and then pulled the antenna cable back through the pipe, causing
the plug and antenna to pop into the pipe mounting the antenna.
-Chuck Harris
Bob Stewart wrote:
Hi Bob, Thanks for taking the time to explain the 4ns and 20ns wanders. I have
just been calling them "constellation errors" without being able to explain it
better than that. I've also wondered how much of the 20ns, if any, is
attributable to the PRS-45A.
I still don't have the antenna located in a position suitable for precision
timing. The power of the HOA is not to be trifled with. That, and the sky is
full of power lines and other junk around here.
Bob
Message: 10
Date: Tue, 26 May 2015 17:18:47 +0300
From: Esa Heikkinen tn1ajb@nic.fi
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] TymServe 2100 1995 Issue - A Kludgy Fix
Message-ID: 556480C7.2090106@nic.fi
Content-Type: text/plain; charset=UTF-8; format=flowed
descoubes kirjoitti:
I am very pleased to inform you that the 1995 year bug on the TS2100 has
been solved. You will have to replace the existing Trimble ACE III
GPS receiver by our N024 with special firmware.
Does this also correct the 1 sec offset caused by upcoming leap second?
To remind, TS2100 GPS mode failed already in February, having 1 sec
offset right after the information about upcoming leap second was added.
How can we know that it doesn't fail again when actual GPS week rollover
will happen? Now it seems to be week 1846 and 2047 will come less than
four years. Did you test this with GPS simulator?
Best regards,
--
73s!
Esa
OH4KJU
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On Tue, 26 May 2015 16:58:00 +0000 (UTC)
Anton Moehammad via time-nuts time-nuts@febo.com wrote:
Could you specify a bit more clearly what kind of problem
you are trying to solve? Do you want to build a GPSDO
to stabilize your OCXO? If so, what is the main measure
you want to improve? Is it ADEV at a certain tau? Or
is it frequency accuracy?
What is the level you want to reach? Or if you do not know
this, what do you want to use the GPSDO+OCXO for?
Now What in my mind
I will use Ublox 7m GPS board that can program from 0,25Mhz to 10Mhz
(https://sites.google.com/site/g4zfqradio/u-blox_neo-6-7)
But the problem are I found someone (http://www.ra3apw.ru/proekty/ublox-
neo-7m/) already do the spectrum analysis for this board and the result is
like this :
and the last picture is far better, correct ? so what I need to do I have 2
plan :
Uhmm.. I don't know any russian. And i don't think many of the people here
do. Could you shortly summarize what the graphs show and to what conclusion
you came?
What I think I see there, are the spurs in the Timepulse output if
frequencies are used that are not an even divisor of the internal clock.
The internal clock runs at 48MHz, if they didnt change the general design
of the LEA modules since the LEA-6 family. Ie, a 8MHz output produces lower
spurs than a 10MHz output, because 48/8=6 while 48/10=4.8
Also keep in mind that there are two modi for the timepulse: fixed
frequency and fixed phase. Depending on which application you are
targeting, the one or the other might be the better choice.
- use the board 10Mhz output than use very narrow (100Hz bandwith) Crystal
filter
Narrow filters induce large (for time-nuts values of large) phase shifts in
the ouput if the center frequency of the filter moves around due to
temperature changes. Hence this might not be what you want.
- Use the 4Mhz output than again filter it use Crystal filter to clean it
than use it as reference for PLL for controling 10Mhz OCXO
The use of a PLL is definitly the better way. If you make the loop filter
of the PLL narrow enough, then the jitter/spurs of the reference signal
will be filtered out by the PLL and the OCXO will dominate the noise for
offset frequencies larger than the loop filter bandwidth. Ie, you can
get rid of the output filter of the LEA module.
I don't know the MTI 240, but from the datasheet it looks quite decent.
So i would guess that you want to go for an as small loop filter
bandwidth as possible, probably just a couple of Hz wide, even.
How far down you can go with the bandwidth will be limited by the stability
of the PLL circuit.
Which one you think a better way.
last I also like to know because MTI only spec the OCXO model 240 harmonics
to down to -30dB (http://www.mti-milliren.com/pdfs/240.pdf) is there any
benefit to use a crystal filter in the output to clearer it more.
You can use filters on OCXOs to improve their output. But my understanding
is, that it is more likely to decrease the purity and stability of the
output instead. But i have to admit that this is definitly not my field
of expertise, so i leave it to others to answer.
Attila Kinali
--
< av500> phd is easy
< av500> getting dsl is hard
Hello,
Recently, I acquired video distribution amplifier (model Altinex
DA1804NT). It says it could handle 350Mhz. I am planing to use it to
split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction site.
It has Oscilloquarz model 8663-SX plus some components which give me 4
outputs - 2 sines and two squares. After few days of "warm up" I did
measurement of ADV from one of the sine outputs and then measurement of
the same sine signal from OCXO, but this time through the Altinex DA.
Each test took 8 hours. Attached is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO. So,
its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am
interesting, what will be the quick method to measure the phase noise
for that DA ?
--
WBW,
V.P.
Hi Vlad,
Before we get to your phase noise question...
Your plots ALTINEX-DA-F.png ALTINEX-DA-T.png look odd and the plot ALTINEX-DA.png shows massive amount of glitches. You must make sure that the frequency and the phase plots look "nice" before doing an ADEV plot. In this case there's probably something wrong with your setup. You should NOT be seeing all those jumps, spikes, wiggles, and noise in a frequency plot. Hundreds of outlier data points are destroying the validity of the ADEV calculations. Something is very wrong.
Check wires, connectors, power supplies, groundings, vibration, air flow, mains voltage, etc. Try a 3rd oscillator in case it's a problem with one of your two oscillators. But you have to get rid of those spikes in the ALTINEX-DA-F.png plot. The way we usually test a distribution amp is to use a single oscillator and a splitter; one leg goes through the DA and the other does not. The phase difference plot then reveals the stability of the DA.
But regardless of how you measure a DA, the frequency plot should not have so many erratic glitches. The kind of plot you should expect is the smooth portion between the 8700 second and 11600 second grid lines.
/tvb
----- Original Message -----
From: "Vlad" time@patoka.org
To: "Discussion of precise time and frequency measurement" time-nuts@febo.com
Sent: Wednesday, May 27, 2015 7:04 PM
Subject: [time-nuts] Distributiuon Amlifier Altinex DA1804NT
Hello,
Recently, I acquired video distribution amplifier (model Altinex
DA1804NT). It says it could handle 350Mhz. I am planing to use it to
split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction site.
It has Oscilloquarz model 8663-SX plus some components which give me 4
outputs - 2 sines and two squares. After few days of "warm up" I did
measurement of ADV from one of the sine outputs and then measurement of
the same sine signal from OCXO, but this time through the Altinex DA.
Each test took 8 hours. Attached is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO. So,
its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am
interesting, what will be the quick method to measure the phase noise
for that DA ?
--
WBW,
V.P.
Tom,
I agree that spikes looks weird. Looking for the raw data, I see its
fluctuate from 9.999999958E+6 to 1.0000000049E+7
And here how its spread:
#occurr. / FREQ
1 +9.999999958E+6
1 +9.999999980E+6
1 +9.999999981E+6
1 +9.999999988E+6
1 +9.999999989E+6
1 +9.999999990E+6
1 +9.999999992E+6
1 +9.999999996E+6
1 +9.999999999E+6
2 +1.0000000001E+7
1 +1.0000000004E+7
1 +1.0000000005E+7
3 +1.0000000006E+7
2 +1.0000000007E+7
4 +1.0000000008E+7
4 +1.0000000010E+7
4 +1.0000000011E+7
7 +1.0000000012E+7
1 +1.0000000013E+7
17 +1.0000000014E+7
12 +1.0000000015E+7
37 +1.0000000016E+7
394 +1.0000000017E+7
1772 +1.0000000018E+7
1362 +1.0000000019E+7
550 +1.0000000020E+7
120 +1.0000000021E+7
73 +1.0000000022E+7
34 +1.0000000023E+7
12 +1.0000000024E+7
8 +1.0000000025E+7
6 +1.0000000026E+7
5 +1.0000000027E+7
1 +1.0000000028E+7
3 +1.0000000030E+7
2 +1.0000000031E+7
2 +1.0000000032E+7
1 +1.0000000033E+7
1 +1.0000000049E+7
I am not sure what to blame. ;-) The setup is pretty simple (on my
taste). Its Trimble TB, connected to linear power supply. The GPS
antenna connected via HP GPS Distribution amplifier and mounted
permanently. The 10 Mhz output from that Trimble TB, connected by coax.
cable to Ref input of HP 5386A.
The OCXO connected to the input A of counter by very short coax. cable.
I was using diffrent PSU for all OCXO. Its switching PSU from IBM
LapTop, its HP laboratory PSU (Linear, 0-24V) and its XL125 switching
Power Supply. I tried following OCXO: MV89A, its Oscilloquarz 8663-SX
and its DATUM OCXO (not remember its model. It looks exactly the same as
one in use inside of Trimble TB). And all of them shows spikes. Today,
I'll try to use one of those OCXO as Ref signal for counter and try to
measure another OCXO using that ref. That will give me some clue if
Trimble TB has an issue.
Regards,
Vlad
On 2015-05-28 03:32, Tom Van Baak wrote:
Hi Vlad,
Before we get to your phase noise question...
Your plots ALTINEX-DA-F.png ALTINEX-DA-T.png look odd and the plot
ALTINEX-DA.png shows massive amount of glitches. You must make sure
that the frequency and the phase plots look "nice" before doing an
ADEV plot. In this case there's probably something wrong with your
setup. You should NOT be seeing all those jumps, spikes, wiggles, and
noise in a frequency plot. Hundreds of outlier data points are
destroying the validity of the ADEV calculations. Something is very
wrong.
Check wires, connectors, power supplies, groundings, vibration, air
flow, mains voltage, etc. Try a 3rd oscillator in case it's a problem
with one of your two oscillators. But you have to get rid of those
spikes in the ALTINEX-DA-F.png plot. The way we usually test a
distribution amp is to use a single oscillator and a splitter; one leg
goes through the DA and the other does not. The phase difference plot
then reveals the stability of the DA.
But regardless of how you measure a DA, the frequency plot should not
have so many erratic glitches. The kind of plot you should expect is
the smooth portion between the 8700 second and 11600 second grid
lines.
/tvb
----- Original Message -----
From: "Vlad" time@patoka.org
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Wednesday, May 27, 2015 7:04 PM
Subject: [time-nuts] Distributiuon Amlifier Altinex DA1804NT
Hello,
Recently, I acquired video distribution amplifier (model Altinex
DA1804NT). It says it could handle 350Mhz. I am planing to use it to
split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction
site.
It has Oscilloquarz model 8663-SX plus some components which give me 4
outputs - 2 sines and two squares. After few days of "warm up" I did
measurement of ADV from one of the sine outputs and then measurement
of
the same sine signal from OCXO, but this time through the Altinex DA.
Each test took 8 hours. Attached is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO.
So,
its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am
interesting, what will be the quick method to measure the phase noise
for that DA ?
--
WBW,
V.P.
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WBW,
V.P.
On Thu, 28 May 2015 14:09:36 -0400, Vlad wrote:
I am not sure what to blame. ;-)
I'm using a TB on a 350Mhz video amplifier 6xRGB , and discovered that
the Video DistAmp was clipping the 10Mhz from the TB.
I used a 10dB attenuator on the TB signal (6dB would have been better) ,
but i had a 10dB in the drawer.
Watch out for putting a too high signal into a 1V-PP Video Dist Amp.
CFO
Denmark
I know some manufacturers use pot core transformers on the output signal.
HP does it for sure. Any vibration or shock transforms right into the
phase error of the signal. IMO, those distribution amps should be avoided
as any level of shock or vibration will contribute to jitter.
On Thu, May 28, 2015 at 3:28 PM, cfo xnews5@luna.dyndns.dk wrote:
On Thu, 28 May 2015 14:09:36 -0400, Vlad wrote:
I am not sure what to blame. ;-)
I'm using a TB on a 350Mhz video amplifier 6xRGB , and discovered that
the Video DistAmp was clipping the 10Mhz from the TB.
I used a 10dB attenuator on the TB signal (6dB would have been better) ,
but i had a 10dB in the drawer.
Watch out for putting a too high signal into a 1V-PP Video Dist Amp.
CFO
Denmark
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Hi
IF I’m understanding you correctly, you are measuring this data with an HP 5386.
That’s only a 4 ns counter. I agree with Tom that there is something weird in your setup, but that
still does not help the basic limit of the counter’s resolution. You will need to be out around 1,000
seconds or more to get to the noise on the OCXO. At any time shorter than that you are either
measuring the counter’s noise or noise in your setup.
If you have one, a 5335 would be a better counter to use than the 5386.
Bob
On May 27, 2015, at 10:04 PM, Vlad time@patoka.org wrote:
Hello,
Recently, I acquired video distribution amplifier (model Altinex DA1804NT). It says it could handle 350Mhz. I am planing to use it to split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction site. It has Oscilloquarz model 8663-SX plus some components which give me 4 outputs - 2 sines and two squares. After few days of "warm up" I did measurement of ADV from one of the sine outputs and then measurement of the same sine signal from OCXO, but this time through the Altinex DA. Each test took 8 hours. Attached is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO. So, its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am interesting, what will be the quick method to measure the phase noise for that DA ?
--
WBW,
V.P.<ALTINEX-DA.png><ALTINEX-DA-F.png><ALTINEX-DA-T.png><OCXO2.png>_______________________________________________
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Bob,
You are correct. I am using HP 5386A. And its only HP counter I have. I
set Gate time equal to 10sec. May be this gate time is an issue ? The
other settings is .1s, and 1s.
Meantime, I did switch ref signal source from Trimble TB to Oscilloquarz
8663-SX OCXO and connected MV89A to counter input. 8 hours later, I'll
see what will be on chart.
Regards,
Vlad
On 2015-05-28 21:50, Bob Camp wrote:
Hi
IF I’m understanding you correctly, you are measuring this data
with an HP 5386.
That’s only a 4 ns counter. I agree with Tom that there is something
weird in your setup, but that
still does not help the basic limit of the counter’s resolution. You
will need to be out around 1,000
seconds or more to get to the noise on the OCXO. At any time shorter
than that you are either
measuring the counter’s noise or noise in your setup.
If you have one, a 5335 would be a better counter to use than the 5386.
Bob
On May 27, 2015, at 10:04 PM, Vlad time@patoka.org wrote:
Hello,
Recently, I acquired video distribution amplifier (model Altinex
DA1804NT). It says it could handle 350Mhz. I am planing to use it to
split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction
site. It has Oscilloquarz model 8663-SX plus some components which
give me 4 outputs - 2 sines and two squares. After few days of "warm
up" I did measurement of ADV from one of the sine outputs and then
measurement of the same sine signal from OCXO, but this time through
the Altinex DA. Each test took 8 hours. Attached is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO.
So, its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am
interesting, what will be the quick method to measure the phase noise
for that DA ?
--
WBW,
V.P.<ALTINEX-DA.png><ALTINEX-DA-F.png><ALTINEX-DA-T.png><OCXO2.png>_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
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--
WBW,
V.P.
On Thu, 28 May 2015 23:21:31 -0400
Vlad time@patoka.org wrote:
You are correct. I am using HP 5386A. And its only HP counter I have. I
set Gate time equal to 10sec. May be this gate time is an issue ? The
other settings is .1s, and 1s.
Meantime, I did switch ref signal source from Trimble TB to Oscilloquarz
8663-SX OCXO and connected MV89A to counter input. 8 hours later, I'll
see what will be on chart.
You might want to have a look the discussion
Subject: is there a cheap and simple way to measure OCXOs?
Date: Wed, 30 May 2012 15:11:03 +0200
Where i asked how to measure the phase noise of (coincidentaly)
some 8663's.
One technique to measure the phase noise would be to use your
PC's sound card (or rather a low noise external sound card).
You can find details how to do that at
http://attila.kinali.ch/phase_noise_measurement/
(Again, thanks to Azelio Boriani for the translation)
There have been many discussions on phase noise on this mailinglist,
you should be able to find plenty of input how to improve your setup
in the archvies.
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
Hello,
I've finished the test. Here is the links to charts:
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A-AD.png
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A-PD.png
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A.png
It looks different, but its not better, I think.
Regards,
Vlad
On 2015-05-28 23:21, Vlad wrote:
Bob,
You are correct. I am using HP 5386A. And its only HP counter I have.
I set Gate time equal to 10sec. May be this gate time is an issue ?
The other settings is .1s, and 1s.
Meantime, I did switch ref signal source from Trimble TB to
Oscilloquarz 8663-SX OCXO and connected MV89A to counter input. 8
hours later, I'll see what will be on chart.
Regards,
Vlad
On 2015-05-28 21:50, Bob Camp wrote:
Hi
IF I’m understanding you correctly, you are measuring this data
with an HP 5386.
That’s only a 4 ns counter. I agree with Tom that there is something
weird in your setup, but that
still does not help the basic limit of the counter’s resolution. You
will need to be out around 1,000
seconds or more to get to the noise on the OCXO. At any time shorter
than that you are either
measuring the counter’s noise or noise in your setup.
If you have one, a 5335 would be a better counter to use than the
5386.
Bob
On May 27, 2015, at 10:04 PM, Vlad time@patoka.org wrote:
Hello,
Recently, I acquired video distribution amplifier (model Altinex
DA1804NT). It says it could handle 350Mhz. I am planing to use it to
split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction
site. It has Oscilloquarz model 8663-SX plus some components which
give me 4 outputs - 2 sines and two squares. After few days of "warm
up" I did measurement of ADV from one of the sine outputs and then
measurement of the same sine signal from OCXO, but this time through
the Altinex DA. Each test took 8 hours. Attached is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO.
So, its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am
interesting, what will be the quick method to measure the phase noise
for that DA ?
--
WBW,
V.P.<ALTINEX-DA.png><ALTINEX-DA-F.png><ALTINEX-DA-T.png><OCXO2.png>_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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--
WBW,
V.P.
Hi
I think that looks about as good as your counter can do. The slope down at
the start is the resolution of the counter. The slope up on the right is the actual stability of
the oscillator.
Bob
On May 29, 2015, at 9:52 AM, Vlad time@patoka.org wrote:
Hello,
I've finished the test. Here is the links to charts:
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A-AD.png
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A-PD.png
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A.png
It looks different, but its not better, I think.
Regards,
Vlad
On 2015-05-28 23:21, Vlad wrote:
Bob,
You are correct. I am using HP 5386A. And its only HP counter I have.
I set Gate time equal to 10sec. May be this gate time is an issue ?
The other settings is .1s, and 1s.
Meantime, I did switch ref signal source from Trimble TB to
Oscilloquarz 8663-SX OCXO and connected MV89A to counter input. 8
hours later, I'll see what will be on chart.
Regards,
Vlad
On 2015-05-28 21:50, Bob Camp wrote:
Hi
IF I’m understanding you correctly, you are measuring this data
with an HP 5386.
That’s only a 4 ns counter. I agree with Tom that there is something
weird in your setup, but that
still does not help the basic limit of the counter’s resolution. You
will need to be out around 1,000
seconds or more to get to the noise on the OCXO. At any time shorter
than that you are either
measuring the counter’s noise or noise in your setup.
If you have one, a 5335 would be a better counter to use than the 5386.
Bob
On May 27, 2015, at 10:04 PM, Vlad time@patoka.org wrote:
Hello,
Recently, I acquired video distribution amplifier (model Altinex DA1804NT). It says it could handle 350Mhz. I am planing to use it to split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction site. It has Oscilloquarz model 8663-SX plus some components which give me 4 outputs - 2 sines and two squares. After few days of "warm up" I did measurement of ADV from one of the sine outputs and then measurement of the same sine signal from OCXO, but this time through the Altinex DA. Each test took 8 hours. Attached is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO. So, its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am interesting, what will be the quick method to measure the phase noise for that DA ?
WBW,
V.P.<ALTINEX-DA.png><ALTINEX-DA-F.png><ALTINEX-DA-T.png><OCXO2.png>_______________________________________________
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.
--
WBW,
V.P.
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I did couple of other measurements, using MV89A as a ref source for
5386A
DATUM OCXO is DUT:
http://www.patoka.ca/OCXO/OCXO-MV89Aref-DATUM-AD.png
http://www.patoka.ca/OCXO/OCXO-MV89Aref-DATUM-TM.png
http://www.patoka.ca/OCXO/OCXO-MV89Aref-DATUM-FD.png
Drift(Hz/sec): -2.20E-7
Trimble TB is DUT:
http://www.patoka.ca/OCXO/OCXO-MV89Aref-TB-AD.png
http://www.patoka.ca/OCXO/OCXO-MV89Aref-TB-TM.png
http://www.patoka.ca/OCXO/OCXO-MV89Aref-TB-FD.png
Drift(Hz/sec): -5.17E-8
Looking to the drift values, the case with T-Bolt has better value, I
think. But it has bigger spikes.
On 2015-05-29 18:59, Bob Camp wrote:
Hi
I think that looks about as good as your counter can do. The slope down
at
the start is the resolution of the counter. The slope up on the right
is the actual stability of
the oscillator.
Bob
On May 29, 2015, at 9:52 AM, Vlad time@patoka.org wrote:
Hello,
I've finished the test. Here is the links to charts:
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A-AD.png
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A-PD.png
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A.png
It looks different, but its not better, I think.
Regards,
Vlad
On 2015-05-28 23:21, Vlad wrote:
Bob,
You are correct. I am using HP 5386A. And its only HP counter I have.
I set Gate time equal to 10sec. May be this gate time is an issue ?
The other settings is .1s, and 1s.
Meantime, I did switch ref signal source from Trimble TB to
Oscilloquarz 8663-SX OCXO and connected MV89A to counter input. 8
hours later, I'll see what will be on chart.
Regards,
Vlad
On 2015-05-28 21:50, Bob Camp wrote:
Hi
IF I’m understanding you correctly, you are measuring this data
with an HP 5386.
That’s only a 4 ns counter. I agree with Tom that there is
something
weird in your setup, but that
still does not help the basic limit of the counter’s resolution.
You
will need to be out around 1,000
seconds or more to get to the noise on the OCXO. At any time shorter
than that you are either
measuring the counter’s noise or noise in your setup.
If you have one, a 5335 would be a better counter to use than the
5386.
Bob
On May 27, 2015, at 10:04 PM, Vlad time@patoka.org wrote:
Hello,
Recently, I acquired video distribution amplifier (model Altinex
DA1804NT). It says it could handle 350Mhz. I am planing to use it
to split 10Mhz Ref signal from my OCXO. This OCXO I bought on
auction site. It has Oscilloquarz model 8663-SX plus some
components which give me 4 outputs - 2 sines and two squares. After
few days of "warm up" I did measurement of ADV from one of the sine
outputs and then measurement of the same sine signal from OCXO, but
this time through the Altinex DA. Each test took 8 hours. Attached
is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO.
So, its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am
interesting, what will be the quick method to measure the phase
noise for that DA ?
WBW,
V.P.<ALTINEX-DA.png><ALTINEX-DA-F.png><ALTINEX-DA-T.png><OCXO2.png>_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
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--
WBW,
V.P.
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On Sat, 30 May 2015 23:11:41 -0400
Vlad time@patoka.org wrote:
Looking to the drift values, the case with T-Bolt has better value, I
think. But it has bigger spikes.
That is not 100% clear. If you look at the MV89 vs DATUM frequency difference,
you see that (at least) one of the OCXO is still settling in the first hour.
Looking at the ADEV values, then you can say that the DATUM is more
stable than the T-Bolt up to 1000s. You cannot say much over 1000s
as you have measured only for 8h.
The spikes in the frequency diffrence you have in the T-Bolt case,
might be due to bad antenna position. You are measuring at a precision
level, where i wouldn't trust a GPS based system to stay on frequency
short term (below couple 100s to 1000s)
I am not 100% sure what you want to measure, if it's just the noise
and ADEV performance of your distribution amplifier, then the canonical
way to do this, would be to use one low noise XO and a power splitter,
feed one signal trough the amplifier, and one directly into something
with which you can measure phase.
One way would be the sound card based system i mentioned earlier.
Another would be to build a DMTD like [1] and use a TDC like [2].
Attila Kinali
[1] "A Small Dual Mixer Time Difference (DMTD) Clock Measuring System",
by W.J. Riley, 2010
http://www.wriley.com/A%20Small%20DMTD%20System.pdf
[2] http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
--
< av500> phd is easy
< av500> getting dsl is hard
Hi
The OCXO vs OCXO stuff looks about as good as you will get until
they both warm up for a few weeks. The output of the TBolt has
some sort of problem that can be troubleshot. The key data there
is the phase plot rather than either of the other two. You know what
a “good” phase plot looks like from the OCXO vs OCXO stuff.
The objective in your troubleshooting is to figure out what’s wrong with
the TBolt. Monitoring logs with Lady Heather (that software is one of the
best things about the TBolt) would be the first thing to do. See when
you get the spikes and see what’s going on with the unit.
Another approach would be to toss a second or third GPSDO into the mix
or an Rb. They would not tell you a lot in the troubleshooting. They
would give you some different curves to look at. Since the data only
starts to appear at 1,000 seconds, things take a while. You should have
a hundred or so samples at the “start” (in this case 1K sec). That gets you
out to a minimum run of a day and a “two decades” run of many days.
Back in the old days we spent the $50 to build a single mixer setup in
these cases. None of us had the patience for one day runs ….
The most interesting way to do it is one that Bruce suggested several years
back. I don’t think anybody has tried it and reported back (yet). Rather than
take the double balanced mixer output and limit it, you lowpass filter it and
feed it into an ADC. DSP-ish software extracts the frequency data from the
estimated zero crossings of the beat note. Doing it with a normal sound
card isn’t very easy since the have issues (noise etc) below 20 Hz or so.
Bob
On May 30, 2015, at 11:11 PM, Vlad time@patoka.org wrote:
I did couple of other measurements, using MV89A as a ref source for 5386A
DATUM OCXO is DUT:
http://www.patoka.ca/OCXO/OCXO-MV89Aref-DATUM-AD.png
http://www.patoka.ca/OCXO/OCXO-MV89Aref-DATUM-TM.png
http://www.patoka.ca/OCXO/OCXO-MV89Aref-DATUM-FD.png
Drift(Hz/sec): -2.20E-7
Trimble TB is DUT:
http://www.patoka.ca/OCXO/OCXO-MV89Aref-TB-AD.png
http://www.patoka.ca/OCXO/OCXO-MV89Aref-TB-TM.png
http://www.patoka.ca/OCXO/OCXO-MV89Aref-TB-FD.png
Drift(Hz/sec): -5.17E-8
Looking to the drift values, the case with T-Bolt has better value, I think. But it has bigger spikes.
On 2015-05-29 18:59, Bob Camp wrote:
Hi
I think that looks about as good as your counter can do. The slope down at
the start is the resolution of the counter. The slope up on the right
is the actual stability of
the oscillator.
Bob
On May 29, 2015, at 9:52 AM, Vlad time@patoka.org wrote:
Hello,
I've finished the test. Here is the links to charts:
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A-AD.png
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A-PD.png
http://www.patoka.ca/OCXO/OCXO-8663ref-MV89A.png
It looks different, but its not better, I think.
Regards,
Vlad
On 2015-05-28 23:21, Vlad wrote:
Bob,
You are correct. I am using HP 5386A. And its only HP counter I have.
I set Gate time equal to 10sec. May be this gate time is an issue ?
The other settings is .1s, and 1s.
Meantime, I did switch ref signal source from Trimble TB to
Oscilloquarz 8663-SX OCXO and connected MV89A to counter input. 8
hours later, I'll see what will be on chart.
Regards,
Vlad
On 2015-05-28 21:50, Bob Camp wrote:
Hi
IF I’m understanding you correctly, you are measuring this data
with an HP 5386.
That’s only a 4 ns counter. I agree with Tom that there is something
weird in your setup, but that
still does not help the basic limit of the counter’s resolution. You
will need to be out around 1,000
seconds or more to get to the noise on the OCXO. At any time shorter
than that you are either
measuring the counter’s noise or noise in your setup.
If you have one, a 5335 would be a better counter to use than the 5386.
Bob
On May 27, 2015, at 10:04 PM, Vlad time@patoka.org wrote:
Hello,
Recently, I acquired video distribution amplifier (model Altinex DA1804NT). It says it could handle 350Mhz. I am planing to use it to split 10Mhz Ref signal from my OCXO. This OCXO I bought on auction site. It has Oscilloquarz model 8663-SX plus some components which give me 4 outputs - 2 sines and two squares. After few days of "warm up" I did measurement of ADV from one of the sine outputs and then measurement of the same sine signal from OCXO, but this time through the Altinex DA. Each test took 8 hours. Attached is the results.
NOTE: on the ALTINEX* charts I forgot to change the label for OCXO. So, its not DATUM. It is Oscilloquarz 8663-SX
I was using Trimble TB as a ref signal for HP 5386
Since I have no instruments which measuring phase noise, I am interesting, what will be the quick method to measure the phase noise for that DA ?
WBW,
V.P.<ALTINEX-DA.png><ALTINEX-DA-F.png><ALTINEX-DA-T.png><OCXO2.png>_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
--
WBW,
V.P.
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