In message <9ae0e07a-568c-43d1-8cb6-0d0e21ee6...@rtty.us>, Bob Camp writes:
>The thing that makes the CFL's nasty for lab use are the cheap
>little switchers built into them. Conventional LED lights also have
>cheap little switchers in them. Doing them with a 30% efficient
>linear regulator gets y
If you dim the halogens, you will be operating them outside of the
temperature required for the Halogen Cycle to operate.
http://en.wikipedia.org/wiki/Halogen_lamp
Shorter filament life and bulb darkening.
That being said, I have a couple of halogen lights on dimmers and love them
-- I like the
12 volt Halogen from a big transformer run from a Variac if you want dimming.
As long as the Variac brushes aren't arcing that setup will create zero noise.
On 9/16/2012 9:55 PM, Mike S wrote:
On 9/16/2012 8:09 PM, Tom Knox wrote:
In this green era here in the USA there is a big push toward
On 9/16/2012 8:09 PM, Tom Knox wrote:
In this green era here in the USA there is a big push toward CFL
lighting. Problem is I can see my CFL lighting on my PN measurements
and other equipment. I am finding it is very noisy
Run 12 VDC lighting, or hydrocarbon (NG/propane/naptha, which is noisy
HI
Most of my little desktop cheap halogens got turned into LED's a while back.
Forgot about them….
Bob
On Sep 16, 2012, at 9:06 PM, Peter Gottlieb wrote:
> I've seen lots of halogen power supplies which use cheap switchers too!
>
> On 9/16/2012 8:55 PM, Bob Camp wrote:
>> Hi
>>
>> The thi
The Z3805A has two serial ports:
* An
I/O Port (Port 1) 25-pin female DB series connector which provides a serial
interface under RS-232 control.
* A
second Output Port (Port 2) which provides a continuous (broadcast) time and
date serial output once every two seconds (even sec
I've seen lots of halogen power supplies which use cheap switchers too!
On 9/16/2012 8:55 PM, Bob Camp wrote:
Hi
The thing that makes the CFL's nasty for lab use are the cheap little switchers
built into them. Conventional LED lights also have cheap little switchers in
them. Doing them with a
Another good source of low-noise lighting is marine hardware stores.
I owned a sailboat for a while. Sailboats are floating radio
stations. I had Marine HF and VHF and Radar all running off banks of
lead acid batteries. You have the same noise issues on the water as
in ham radio stations.So
Hi
The thing that makes the CFL's nasty for lab use are the cheap little switchers
built into them. Conventional LED lights also have cheap little switchers in
them. Doing them with a 30% efficient linear regulator gets you back to halogen
type lumens per watt...
Bob
On Sep 16, 2012, at 8:09
In this green era here in the USA there is a big push toward CFL lighting.
Problem is I can see my CFL lighting on my PN measurements and other equipment.
I am finding it is very noisy so I have started researching cost effective LED
lighting and was amazed at what is available. On eBay there a
On 09/16/2012 11:51 PM, Poul-Henning Kamp wrote:
In message, Dennis Ferguson wr
ites:
If you
are using a PLL in both cases, however, then the problems are
essentially the same.
Well, not quite: Depending on the stiffness of your PLL, you can
minimize phase error at the cost of frequency erro
On 09/16/2012 11:47 PM, Poul-Henning Kamp wrote:
In message<505642f5.1000...@rubidium.dyndns.org>, Magnus Danielson writes:
On 09/16/2012 10:30 PM, Poul-Henning Kamp wrote:
A good PI-based PLL actually combines the FLL and PLL domains [...]
But it is the phase correction that doubles the (a
HI
In some cases, the difference can be your definition of "time accuracy". If
short term GPS time is what you are worried about, then indeed that's a
different beast than a 30 day plot against your direct line to USNO.
Bob
On Sep 16, 2012, at 4:12 PM, Dennis Ferguson
wrote:
>
> On 16 Sep,
Sorry I should have said pulse per even second. I recall the pulses are
aligned with the UTC even second.
--- On Sun, 9/16/12, Mark Spencer wrote:
> From: Mark Spencer
> Subject: Re: Even pulse per second signals
> To: time-nuts@febo.com
> Received: Sunday, September 16, 2012, 3:07 PM
> Whil
While I don't have first hand knowledge of CDMA base stations, I recall seeing
a symmetricom data sheet that stated that even pulse per second signals were
(or are ?) used for timing in CDMA base stations. Sorry I have no idea why the
even pulse per second signal is preferable in that applcatio
In message , Dennis Ferguson wr
ites:
>If you
>are using a PLL in both cases, however, then the problems are
>essentially the same.
Well, not quite: Depending on the stiffness of your PLL, you can
minimize phase error at the cost of frequency error or frequency
error at the cost of phase error,
On 16 Sep, 2012, at 16:30 , Poul-Henning Kamp wrote:
> In message <34d5c3ce-6b3d-4944-996a-7637373b2...@gmail.com>, Dennis Ferguson
> wr
> ites:
>
>> I'm not sure there could be a difference between the goals of
>> frequency accuracy and time accuracy that would effect that time
>> constant.
N
In message <505642f5.1000...@rubidium.dyndns.org>, Magnus Danielson writes:
>On 09/16/2012 10:30 PM, Poul-Henning Kamp wrote:
>A good PI-based PLL actually combines the FLL and PLL domains [...]
But it is the phase correction that doubles the (absolute) magnitude
of the frequency noise, by "overc
Per the 58503B brochure:
"An even-second (1 PP2S) output is available as an option to the 58503B.
The even-second output option provides one pulse every other second,
synchronized to the even seconds in GPS time. This is the reference time
used in CDMA base stations."
> Some GPSDO have both a 1P
On 16 Sep, 2012, at 17:11 , Tom Van Baak wrote:
> Some GPSDO have both a 1PPS and a PP2S (pulse per 2 second) output. I have
> two questions for one of you telecom experts: 1) What is the history, and the
> purpose of that PP2S signal? 2) What is the official spec for which second
> the PP2S la
On 09/16/2012 10:30 PM, Poul-Henning Kamp wrote:
In message<34d5c3ce-6b3d-4944-996a-7637373b2...@gmail.com>, Dennis Ferguson wr
ites:
I'm not sure there could be a difference between the goals of
frequency accuracy and time accuracy that would effect that time
constant.
It does.
A PLL more o
On 09/16/2012 10:28 PM, Jim Lux wrote:
On 9/16/12 10:20 AM, Magnus Danielson wrote:
On 09/16/2012 05:47 PM, Poul-Henning Kamp wrote:
Dave Mills coined the term "allan intercept" as the cross over of
the two sources allan variances and it's a good google search for
his relevant papers.
I'm no
Some GPSDO have both a 1PPS and a PP2S (pulse per 2 second) output. I have two
questions for one of you telecom experts: 1) What is the history, and the
purpose of that PP2S signal? 2) What is the official spec for which second the
PP2S lands on? Is it odd seconds or even seconds? Is it GPS time
In message <34d5c3ce-6b3d-4944-996a-7637373b2...@gmail.com>, Dennis Ferguson wr
ites:
>I'm not sure there could be a difference between the goals of
>frequency accuracy and time accuracy that would effect that time
>constant.
It does.
A PLL more or less corresponds to an "PI" regulation, where
On 9/16/12 10:20 AM, Magnus Danielson wrote:
On 09/16/2012 05:47 PM, Poul-Henning Kamp wrote:
Dave Mills coined the term "allan intercept" as the cross over of
the two sources allan variances and it's a good google search for
his relevant papers.
I'm not entirely sure his rule of thumb for re
On 16 Sep, 2012, at 00:40 , Tom Van Baak wrote:
> I worry in your example about the long cross-over time. This may be ideal for
> frequency stability, but probably is not good for time accuracy. If one is
> using the GPSDO as a timing reference, I would think a shorter time constant
> will keep
Hi
…but endless testing for minimal return is what being a Time Nut is all about ….
Bob
On Sep 16, 2012, at 3:39 PM, "Poul-Henning Kamp" wrote:
> In message <2dea9396-95eb-4092-a443-a72350cc1...@rtty.us>, Bob Camp writes:
>
>> The basic assumption is that this is a lab gizmo and that there
>>
On 9/16/2012 12:03 PM, Gerhard Hoffmann wrote:
Am 20.07.2012 00:57, schrieb Richard (Rick) Karlquist:
A fast comparator seems like a good idea, and it
is simple, however it is actually the last thing
you want to use. High thermal sensitivity and high jitter.
Rick
On 7/19/2012 1:35 PM, Dan K
In message <2dea9396-95eb-4092-a443-a72350cc1...@rtty.us>, Bob Camp writes:
>The basic assumption is that this is a lab gizmo and that there
>is indeed a static adev (or very low frequency phase noise) plot
>for the OCXO (or Rb).
Bob,
I think this is where the premier-league differs from the
ama
In message , Tom Knox writes:
>Great dialog, One thing I have seen is the Allan intercept almost
>always has a "knee". If you wanted the best possible GPS quartz
>reference developing a variable Allan intercept would allow this
>knee to be moved and then mathematically removed during a gated
>meas
Hi
The "knee" is a basic artifact of the cross over in the noise of one (say the
OCXO) to the noise of the other (say the GPS). It's one of those things you can
reduce, but never eliminate completely. The noise of the combined pair will
always be slightly worse than the best of the two when th
Hi
The basic assumption is that this is a lab gizmo and that there is indeed a
static adev (or very low frequency phase noise) plot for the OCXO (or Rb). The
other assumption is that this plot is quite good (say decreasing or flat to
>10,000 seconds).
IF that's all true, then the "running co
Am 20.07.2012 00:57, schrieb Richard (Rick) Karlquist:
A fast comparator seems like a good idea, and it
is simple, however it is actually the last thing
you want to use. High thermal sensitivity and high jitter.
Rick
On 7/19/2012 1:35 PM, Dan Kemppainen wrote:
Or use a fast comparator such as
Great dialog, One thing I have seen is the Allan intercept almost always has a
"knee". If you wanted the best possible GPS quartz reference developing a
variable Allan intercept would allow this knee to be moved and then
mathematically removed during a gated measurement.
Allowing to effectivel
In message <3a001267-52de-4ee9-b6ee-6638fb270...@rtty.us>, Bob Camp writes:
>Hi
>
>By far the most common approach to optimizing these is the "measure
>it and see" approach.
>
>1) measure the noise out of the GPS ( must be done no matter what)
>2) measurer the noise of the specific OCXO (again must
In message , Bob Camp writes:
>The purpose of my examples was to keep things simple and look at
>the "running condition" of the loop rather than it's performance
>while it settles down.
But what is "running condition" ?
I see my PLL adjust to thermal conditions during summer (A/C) and
winter (he
Hi
By far the most common approach to optimizing these is the "measure it and see"
approach.
1) measure the noise out of the GPS ( must be done no matter what)
2) measurer the noise of the specific OCXO (again must be done)
3) *guess* at a cross over
4) try it and measure the result.
5) step an
In message <50560a58.5010...@rubidium.dyndns.org>, Magnus Danielson writes:
>> What I did instead was to (badly) reinvent Shewarts ideas for testing
>> if the phase residual is under "statistical process control":
>>
>> I increase the timeconstant if the phase residual has too frequent
>> zero-cro
Hi
The time constant can indeed be changed dynamically, that's what is often done.
The purpose of my examples was to keep things simple and look at the "running
condition" of the loop rather than it's performance while it settles down.
Bob
On Sep 16, 2012, at 9:49 AM, Poul-Henning Kamp wrote:
On 09/16/2012 05:47 PM, Poul-Henning Kamp wrote:
In message<5C52FBDBA5084AD4A36300FBA73BEF5E@pc52>, "Tom Van Baak" writes:
Yes, timing accuracy has been my main focus and in general I have been
using integration times on the low side of 1 seconds for that,
but it depends a lot on the OCXO/Rb
On Sat, Sep 15, 2012 at 7:04 PM, paul swed wrote:
> As Bob mentions there may be more to it then just nailing that particular
> command.
> But worth taking a look after I deal with the wwvb psk issue. As far as the
> 5 to 3 V I would just use a 3 term reg like the cherry semi chip. But there
> are
Le 16/09/2012 15:38, Hui Zhang a écrit :
I just bought a second-hand Z3801A, it also had a error message when self test
- GPS Rcv error, and I saw a red LED on main board on. I want test it alone but
I don't know GPS board's pin define, can someone tell me? Thanks.
--
Les chiens aboient, et
In message <5C52FBDBA5084AD4A36300FBA73BEF5E@pc52>, "Tom Van Baak" writes:
>> Yes, timing accuracy has been my main focus and in general I have been
>> using integration times on the low side of 1 seconds for that,
>> but it depends a lot on the OCXO/Rb and environment.
>>
>> The PLL in NTPns
I've been unable to ship this summer but I am back now and have PC boards for
the PICTIC II and DMDT projects for 8 USD each plus shipping. If you are
interested please reply direct to me and not the list. If you have questions
please check links below. Will also help with parts that are not ava
I just acquired one of fluke.l's "Samsung" labeled z3805a units (the one
with double-oven 10811A, 2 10 MHz, 2 PPS, and 2 comm ports. Bob tells
me that the comm ports are configured for RS-232, but I haven't powered
the thing up yet (still working on power supply) so haven't inspected
what the
In message , Bob Camp writes:
Bob,
There's one thing makes me scratch my head here: Why do you keep
arguing like the timeconstant cannot be changed dynamically ?
I use a very aggresive timeconstants initially, to quickly get the
phase offset under control, and then I ramp up the timeconstant in
HI
This is a pretty good start:
http://www.febo.com/pages/hardware/VPCommands.pdf
http://gpsd.berlios.de/vendor-docs/motorola/toc.pdf
There are lots of other references out there.
Bob
On Sep 16, 2012, at 9:38 AM, "Hui Zhang" wrote:
> I just bought a second-hand Z3801A, it also had a error m
Hi
It's probably easier to just make up an emulator for the UT rather than doing
it on a string by string basis. Only one of the strings needs to synch up with
the PPS. The rest can all be generated as needed. I'm not saying it would be
easy, only easier.
Maybe put something like an LEA-6T an
I just bought a second-hand Z3801A, it also had a error message when self test
- GPS Rcv error, and I saw a red LED on main board on. I want test it alone but
I don't know GPS board's pin define, can someone tell me? Thanks.
Hui
At 2012-09-16 21:20:26,"Azelio Boriani" wrote:
>Anyway, are you
Anyway, are you sure that the GPS unit is faulty? Can you test it alone?
The unit is responsive on the serial port? Is the Z3801A sending commands?
Can you verify with a 'scope on the serial line if there is any signal?
On Sun, Sep 16, 2012 at 2:54 PM, Mike S wrote:
> On 9/15/2012 2:11 PM, paul
On 9/15/2012 2:11 PM, paul swed wrote:
Then respond back with whatever the response might be and then simply pass
through in both direction whatever comes next.
Could an updated rcvr be used.
Is this init command really the only gotcha?
It's more than just the init command. The z3801a also send
Hi
If your definition of timing accuracy is "within 100 ns of GPS time ten minutes
after lock" then a faster crossover is a better idea. A faster loop will track
GPS better. If your GPS noise is on the order of 10 ns, your time error will
be pretty low. An example: 100s loop and 10 ns GPS, =>
> Yes, timing accuracy has been my main focus and in general I have been
> using integration times on the low side of 1 seconds for that,
> but it depends a lot on the OCXO/Rb and environment.
>
> The PLL in NTPns is a (by now) old attempt to make a self-tuning PLL
> for optimal time stability
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