[time-nuts] accurate portable time source (Ronald Held)
Ronald Held
ronaldheld at gmail.com
Fri Dec 28 22:05:42 UTC 2007
to Hal:
I meant a device which was independent. I suppose a phone in constant
contact with a CDMA tower/transmitter could be quite accurate, but
that is not what I wanted. The cell phone was just an estimate for
size and weight since people do not generally complain,nowadays about
the weight and volume.
To Jeff:
the most accurate watch by spec is the Citizen chronomaster(movement
A660) It is spec ed to +/- 5 seconds/year, but some have had better
success(not me) The are also watches with Thermoline movements, spec
ed to +/-10 seconds/year. However with knowledge from the maintenance
manual you can adjust the rate. With a lot of timing and patience, you
can get to a few seconds/year with regular wearing habits
To Tom:
I will look at those products. Isn't there a problem if the
crystals are not preaged, for the accuracies I am looking for? Since
I am circuit impaired, besides the power supply, what other inputs are
needed and what is the output(1 PPS, a Frequency)?
Ronald
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Date: Dec 28, 2007 4:41 PM
Subject: time-nuts Digest, Vol 41, Issue 87
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Today's Topics:
1.
2. Re: accurate portable time source (Hal Murray)
3. Re: accurate portable time source (Jeff Mock)
4. Re: NLTL comb generators going away... (Richard (Rick) Karlquist)
5. Re: NLTL comb generators going away... (John Miles)
6. Re: Upgrading possibilities for more accurate, precise stable
mark ii (Jack Hudler)
7. Re: NLTL comb generators going away... (John Miles)
8. Re: accurate portable time source (Tom Van Baak)
----------------------------------------------------------------------
Message: 1
Date: Fri, 28 Dec 2007 12:35:40 -0500
From: "Ronald Held" <ronaldheld at gmail.com>
Subject: [time-nuts] accurate portable time source
To: time-nuts at febo.com
Message-ID:
<9a86fb0e0712280935x7457c250j76a47fff1aa8b84d at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
This request is different than the last one.
The most accurate TCXO watch is about 1 seconds/year, with regular
wear and lots of adjustment. For at least 1 order of magnitude in
accuracy, what can be made/bought given these initial requirements: it
has to run of its own power supply for ~18 hours a day, and recharge
fully at night. the device must be intrinsically accurate without be
disciplined by an external signal, although that could be done at
night. The size and wei8ght need to be pocketable such a a large cell
phone.I am open to all suggestions and more/altered requirements.
Ronald.
------------------------------
Message: 2
Date: Fri, 28 Dec 2007 09:55:34 -0800
From: Hal Murray <hmurray at megapathdsl.net>
Subject: Re: [time-nuts] accurate portable time source
To: Discussion of precise time and frequency measurement
<time-nuts at febo.com>
Message-ID: <20071228175535.DFF68BE33 at ip-64-139-1-69.sjc.megapath.net>
Content-Type: text/plain; charset=us-ascii
> it has to run of its own power supply for ~18 hours a day, and
> recharge fully at night. the device must be intrinsically accurate
> without be disciplined by an external signal, although that could be
> done at night. The size and wei8ght need to be pocketable such a a
> large cell phone.I
Is an actual cell phone an interesting answer?
Has anybody checked how good the time displays on various cell phones are?
It's software. All sorts of dumb things are possible. I think I've heard
stories of one being off by several/many seconds. The basic time-of-day info
must be included in the basic timing transmission or places like EndRun
wouldn't be able to provide it.
--
These are my opinions, not necessarily my employer's. I hate spam.
------------------------------
Message: 3
Date: Fri, 28 Dec 2007 10:03:33 -0800
From: Jeff Mock <jeff at mock.com>
Subject: Re: [time-nuts] accurate portable time source
To: Discussion of precise time and frequency measurement
<time-nuts at febo.com>
Message-ID: <47753A75.7030704 at mock.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Ronald Held wrote:
> This request is different than the last one.
> The most accurate TCXO watch is about 1 seconds/year, with regular
> wear and lots of adjustment. [...]
Really? What watch is good to 1s per year? Can you point me at one?
That's amazing for a watch.
jeff
------------------------------
Message: 4
Date: Fri, 28 Dec 2007 10:07:57 -0800
From: "Richard (Rick) Karlquist" <richard at karlquist.com>
Subject: Re: [time-nuts] NLTL comb generators going away...
To: Discussion of precise time and frequency measurement
<time-nuts at febo.com>
Message-ID: <47753B7D.2070809 at karlquist.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
The SRD (step recovery diode) definitely degrades the phase
noise beyond 20 LOG N, according to Agilent engineers I have
talked to. They mentioned a number like -150 dBc/Hz or something.
Having said that, you also have to be very careful to design
the driver (especially with NLTL) or it will become the limiting
factor.
Rick Karlquist N6RK
Mike Feher wrote:
> John -
>
> I have a nice 3585B, 11729C (with all filters) and a nice working 8662A. I
> assume the PN of the 640 output of the 8662A is still more than adequate.
> You are suggesting replacing the multiplier within the 11729C with the NLTL
> comb generator instead of the currently used SRD. I do not see how the SRD
> itself would significantly degrade the source's PN beyond the 20 log N
> factor. I will be definitely very interested in your results. 73 - Mike
>
>
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of John Miles
> Sent: Friday, December 28, 2007 2:42 AM
> To: time-nuts at febo.com
> Subject: [time-nuts] NLTL comb generators going away...
>
> FYI, I don't know how many others on the list are interested in microwave PN
> measurement with gear like the HP 11729B/C or 70420/E5500 series, but I'm in
> the (slow) process of upgrading my own 11729C setup to lower its measurement
> floor and thought I'd mention something I learned the other day in case it's
> helpful to anyone else.
>
> Briefly, the HP noise test sets all seem to use low-noise comb generator
> modules fed by 600 or 640 MHz from a quiet OCXO-based multiplier chain, with
> filters to select the desired comb harmonic to downconvert the signal under
> test. Since I'm replacing my 11729C's 10811A-derived 640-MHz source with a
> much-quieter ULN OCXO-derived source, I also wanted to upgrade its
> step-recovery diode-based comb generator with one of the nonlinear
> transmission-line parts produced by Picosecond Pulse Labs. I've been
> plotting this upgrade for awhile, but there was no incentive to do it until
> upgrading the OCXO.
>
> NLTL comb geneators are awesome. They have 15-20 dB better residual phase
> noise specs than the SRD multipliers that HP was using in the 80s and 90s,
> much faster output edges, *and* their inputs are much more broadband in
> nature than SRD-multiplier inputs usually are. They work well with input
> frequencies over the better part of an octave, whereas the 11729C's
> multiplier is very peaky around 640 MHz. All of these attributes make them
> ideal for use in high-performance PN downconverters. If you were building a
> high-end phase noise test set today, I don't know what else you'd specify.
>
> Unfortunately, when I called Picosecond Pulse Labs to order my first choice
> (the 7103 model), they told me they'd shut down their fab in Oregon and were
> no longer producing NLTL multipliers. They have a few left in stock and are
> selling them for $975 each regardless of the part number. The connectorized
> 7103s were gone when I called, so I bought their last connectorized 7123,
> which is one of the higher-spec parts (input=+29 dBm at 800 MHz-1.5 GHz,
> output=0 dBm at 50 GHz). It works fine with inputs down to 640 MHz, so
> it'll be OK in the 11729C, although it has a 2.4-mm output connector rather
> than SMA.
>
> So this really sucks... hopefully somebody will buy that fab and continue
> production, but it sounds like they just didn't sell enough of the comb
> generators to be worthwhile. I haven't been able to find any other
> off-the-shelf multipliers with additive jitter specs anywhere close. If
> this sort of thing is your sort of thing, get 'em while you can.
>
> Specs:
> http://www.picosecond.com/product/category.asp?pd_id=22
>
> Residual PN measurement notes:
> http://www.picosecond.com/objects/RPN-Measurement.pdf
>
> -- john, KE5FX
>
>
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------------------------------
Message: 5
Date: Fri, 28 Dec 2007 10:26:45 -0800
From: "John Miles" <jmiles at pop.net>
Subject: Re: [time-nuts] NLTL comb generators going away...
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Message-ID: <PKEGJHPHLLBACEOICCBJMEIMDGAB.jmiles at pop.net>
Content-Type: text/plain; charset="us-ascii"
> I have a nice 3585B, 11729C (with all filters) and a nice working 8662A. I
> assume the PN of the 640 output of the 8662A is still more than adequate.
Right; it doesn't make sense to swap out the 11729's SRD multiplier unless
you are also upgrading the 640-MHz drive source at the same time.
There is some room for improvement in that 640-MHz multiplier chain, though,
and the SRD multiplier appears to be the next weak link after the 640-MHz
chain is cleaned up.
> You are suggesting replacing the multiplier within the 11729C
> with the NLTL
> comb generator instead of the currently used SRD. I do not see how the SRD
> itself would significantly degrade the source's PN beyond the 20 log N
> factor. I will be definitely very interested in your results. 73
The 8662A's 640 MHz output comes from multiplying a 10811A-class oscillator
by 64 (with a 36-dB noise penalty) and shaving off the noise sidebands with
a couple of monolithic crystal filters. At 1 kHz from the carrier, the PN
spec from the 640-MHz output is -121 dBc/Hz; at 10 kHz it's -145 dBc/Hz.
So, say you're measuring a 10 GHz carrier with your 11729C. You use the
15th harmonic of 640 MHz for that (24 dB penalty). Your measurement floor
at 9600 MHz is -97 dBc/Hz (1 kHz) to -121 dBc/Hz (10 kHz). These levels are
comfortably above the 11729C's residual noise spec at 10 GHz (-132 dBc/Hz
quoted on page 42 of AN 11729B-1).
However, the target specs for my upgraded 8662A reference chain's 640 MHz
output are circa -142 dBc/Hz (1 kHz) to 158 dBc/Hz (10 kHz). At 9600 MHz
this would be -118 dBc/Hz to -134 dBc/Hz. My thinking is that the NLTL
multiplier adds some headroom insurance at that point. According to
Picosecond, the NLTL floor is at or below the thermal limit of their test
setup (-140 dBc/Hz or better). Their marketing spiel is centered around the
idea that their multiplier will not degrade the PN of the quietest crystal
oscillators available. That's not true of SRDs, in my understanding.
An exercise in lily-gilding, certainly, but that seems to be the point
around here. :)
-- john, KE5FX
------------------------------
Message: 6
Date: Fri, 28 Dec 2007 14:40:12 -0600
From: "Jack Hudler" <jack at hudler.org>
Subject: Re: [time-nuts] Upgrading possibilities for more accurate,
precise stable mark ii
To: "'Discussion of precise time and frequency measurement'"
<time-nuts at febo.com>
Message-ID: <017401c84991$d9365000$8ba2f000$@org>
Content-Type: text/plain; charset="US-ASCII"
Sorry for the late reply. didn't see this until now.
Seeing only one part of the sky is not an issue for time keeping at the
accuracy you wanted.
I would worry about animals harming my DirecTV or 58532A GPS antenna, when
they were the size of a condor or had teeth like a beaver. Were such animals
around, you'd have other problems to worry about.
I never hung the antenna on or over any part of the apartment. A 5 gallon
bucket and filled with a couple of bags concrete, drive in and level a
galvanized pole, and let it set. Weighs about 160 lbs when all done, and
goes with me or the dumpster when I move. If they don't like that, start
quoting them FCC regulations.
Jack
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Ronald Held
Sent: Sunday, December 16, 2007 12:17 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] time-nuts Digest, Vol 41, Issue 57
i thought of tha balcony option. The balcony as an overhang which
effectively blots out the other half of ths sky not covered by the
building. I cannot hang any antenna over the railing or on it(in my
lease and enofrce;I asked), plus there are birds and squirrels which
would get into it.
Any other suggestions?
> Date: Sat, 15 Dec 2007 21:25:14 -0600
> From: "Jack Hudler" <jack at hudler.org>
> Subject: Re: [time-nuts] Upgrading possibilities for more accurate,
> precise stable mark ii
> To: "'Discussion of precise time and frequency measurement'"
> <time-nuts at febo.com>
> Message-ID: <020301c83f93$462f0c50$d28d24f0$@org>
> Content-Type: text/plain; charset="us-ascii"
>
> If you have a porch or balcony, just drilled a 1/4 inch hole through the
> edge of the sliding door frame to handle an external antenna. Hide the
wire
> in the carpet edge or behind the baseboard.
> When you leave just caulk up the holes and no one's the wiser. Most of the
> time (well the ones I lived in) apartments have touch up paint kits (or
the
> paint codes at the local big box) so you can fill nail holes and such for
> move out.
>
> I did this at four different apartments and no one ever found it, or if
they
> did, didn't care. Most of the time I drilled three holes for coaxial
cables
> to DirecTV and 58532A GPS antenna mounted on the back of the DirecTV
antenna
> (Note: I never used the thin flat strip to run coax through the door there
> was too much static build up. That being said; it is still a viable option
> for GPS or DirecTV).
>
>
>
>
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------------------------------
Message: 7
Date: Fri, 28 Dec 2007 12:46:57 -0800
From: "John Miles" <jmiles at pop.net>
Subject: Re: [time-nuts] NLTL comb generators going away...
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Message-ID: <PKEGJHPHLLBACEOICCBJMEJDDGAB.jmiles at pop.net>
Content-Type: text/plain; charset="us-ascii"
It's hard to read the tea leaves on that. Dieter Scherer has one note
(Generation of Low PN Microwave Signals) that shows the 33004A multiplier's
output noise at -140 dBc/Hz to -148 dBc/Hz from 1 to 10 kHz, at 5.5 GHz
(N=11). If that is the case with the 11729's multiplier, then the NLTL part
is not really necessary even with an upgraded 640 MHz reference chain. But
then, something else must be responsible for the 11729's residual PN spec,
and I don't see what that would be.
Of course, I'd assume that PSPL's measurements were taken with the crappiest
SRD part they could find. :)
It appears that the 11729's 640-MHz PA can drive the 7123 adequately,
although the 12.16 GHz comb line is somewhat close to the spec limit of -20
dBm. The 7113-110 is a better replacement for the 33004A in the 11729C,
since it would actually be operating in spec. They have several of those in
stock (I just ordered 2 of the 8 they had left).
-- john, KE5FX
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Richard (Rick) Karlquist
> Sent: Friday, December 28, 2007 10:08 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] NLTL comb generators going away...
>
>
> The SRD (step recovery diode) definitely degrades the phase
> noise beyond 20 LOG N, according to Agilent engineers I have
> talked to. They mentioned a number like -150 dBc/Hz or something.
> Having said that, you also have to be very careful to design
> the driver (especially with NLTL) or it will become the limiting
> factor.
>
> Rick Karlquist N6RK
>
------------------------------
Message: 8
Date: Fri, 28 Dec 2007 13:39:32 -0800
From: "Tom Van Baak" <tvb at LeapSecond.com>
Subject: Re: [time-nuts] accurate portable time source
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Message-ID: <001201c8499a$22a5edb0$0800a8c0 at pc52>
Content-Type: text/plain; format=flowed; charset="Windows-1252";
reply-type=original
> This request is different than the last one.
> The most accurate TCXO watch is about 1 seconds/year, with regular
> wear and lots of adjustment. For at least 1 order of magnitude in
> accuracy, what can be made/bought given these initial requirements: it
> has to run of its own power supply for ~18 hours a day, and recharge
> fully at night. the device must be intrinsically accurate without be
> disciplined by an external signal, although that could be done at
> night. The size and wei8ght need to be pocketable such a a large cell
> phone.I am open to all suggestions and more/altered requirements.
> Ronald.
Ronald,
Since a TCXO doesn't cut it, you could always try a miniature
OCXO. Take a look at Morion ( for
their tiny, low power, high stability, low drift quartz oscillators.
Do the math and see what the time error would be per month or
per year. Use lithium batteries; my guess is your 18 hour use
with 6 hour recharge requirement is easily met.
I don't quite get the "intrinsically accurate" requirement, though.
Time used to be something that you could have in isolation or
use in isolation but all the trends now are the other way.
No one predicted ten or twenty years ago that a billion people
today would have sub-second time (effectively, atomic clocks)
in their pockets or on their wrists. But that is exactly what radio
controlled watches, cell phones, internet enabled PDA's, and
personal navigation devices have done.
Send us a picture of your OCXO watch prototype when it's
ready! Combine that with one of these for extra credit:
Nixie Watch (David Forbes)
http://www.cathodecorner.com/nixiewatch/
The Nixie Tube Digital Wristwatch (Jeff Thomas)
http://www.amug.org/~jthomas/watch.html
/tvb
http://www.LeapSecond.com
------------------------------
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