Re: [time-nuts] Antennas in apartments

[Hal Murray]

> 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?

You said " I cannot  hang any antenna over the railing or on it".  Does that 
mean you can put things out there as long as they are not visible from the 
outside?  Try it just inside/below the railing.


Talk to your building superintendent.  Offer to provide NTP service to the 
whole complex if he will help you setup a GPS antenna.

What do people who want satellite TV do?

I like the hide-it-in-a-bird-feeder suggestion.  Are plants and bird feeders 
prohibited?



-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] time-nuts Digest, Vol 41, Issue 56

[James Maynard]

-- Original Message --
>Received: Sat, 15 Dec 2007 05:53:00 PM PST
>From: "Ronald Held" <[EMAIL PROTECTED]>
>To: time-nuts@febo.com
>Subject: Re: [time-nuts] time-nuts Digest, Vol 41, Issue 56
>
>My apartment is in a reinforced concrete building, not near the roof.
>Many years ago I tried a Garmin handheld and could not get a lock.
>Recently, I tried a GPS watch near the window, and could not get e
>lock, even though it did lock up outside(cold) after a few minutes.
>that is why i do not think I can use a GPS disciplining option.
>  Since my unit already gets no worse than 1 millisecond when locked
>up, i would want no worse than 1 microsecond in phase over long
>periods of time. What non GPS options are there with the electronic
>building skills I do not have?
>
Does a cell phone work in your apartment? If so, you might consider
an oscillator that gets its frequency discipline indirectly:
GPS receiver disciplines oscillator at cell phone tower,
then CDMA cell phone network disciplines oscillator in your
apartment.

See 
for an example.

James Maynard, K7KK
Salem, Oregon, USA





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Re: [time-nuts] re low noise regulators

[Magnus Danielson]

From: Bruce Griffiths <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] re low noise regulators
Date: Mon, 17 Dec 2007 11:19:05 +1300
Message-ID: <[EMAIL PROTECTED]>

> [EMAIL PROTECTED] wrote:
> > Hi Bruce,
> >  
> > The capacitors' microphonic sensitivity may actuallyy be more of a factor  
> > here.
> >   
> Are electrolytics microphonic?
> Ferroelectric (X7R, Z5U,Y5V, X5R, etc but not NP0/C0G) ceramic caps are
> microphonic

All caps is more or less microphonic. Even a pair of plates with vacuum between
them are microphonic. However, the higher capacitivity of the dielectrum, the
higher microphonic sensitivity can you expect. You can as always reduce the
microphonic aspect through mechanical design, including wise use of symmetry,
but the effect will always be there. The point being, the effect is always
there, but the coupling degree may be stronger or weaker.

Traditionally electrolytics have not been the main concern thought. But they
are not always the best choice for many other reasons, as you are fully aware.

Cheers,
Magnus

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Re: [time-nuts] re low noise regulators

[Bruce Griffiths]

[EMAIL PROTECTED] wrote:
> Hi Bruce,
>  
> The capacitors' microphonic sensitivity may actuallyy be more of a factor  
> here.
>   
Are electrolytics microphonic?
Ferroelectric (X7R, Z5U,Y5V, X5R, etc but not NP0/C0G) ceramic caps are
microphonic
>  
>   
>> It still helps to have as low a noise as possible before using  such
>> brute force filtering to get that extra few dB of noise  reduction.
>> 
>
> It's not just a few dB, it's -3dB at 17Hz already, and that drops  at ~-20dB 
> per decade. At 170Hz it could theoretically give -23dB already,  or in other 
> words if the noise floor was entirely due to the supply voltage  noise, then 
> the difference would be between say -140dBc/Hz and about  -160dBc/Hz at 170Hz 
> - 
> this could be a very significant improvement.
>  
> You are absolutely right, it is very difficult to get low noise  <10Hz.
>  
> bye,
> Said
>   
Bruce

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Re: [time-nuts] re low noise regulators

[Bruce Griffiths]

[EMAIL PROTECTED] wrote:
> Hi Bruce,
>  
> the tempco effect of the series resistor may not be a factor at all for  
> typical OCXO's.
>  
> If we take a standard 1% resistor such as the Panasonic ERO-S2PHF2R00  
> (available on Digikey) with 100ppm/C tempco (that's a fairly bad tempco),  
> then we 
> get:
>  
>0.32V * 100ppm = 32 microvolts per Degree C change (actually  it's 
> +/-50ppm, so this example is worse than what we would see in real  life).
>  
> If we now take the Supply-Voltage-versus-Frequency characteristic of  a 
> typical standard single oven OCXO  of 1E-08, at +/-5% variation for  a 12V 
> part we 
> get:
>  
>1E-08 for 1.2V change, then we get: 8.33E-09/V * 32E-06V =  2.66E-013 
> change per degree C.
>  
> For this particular OCXO with a stability of 1E-09 per degree C, the  change 
> in frequency due to the change in the 2 Ohm resistor value is about 3700x  
> less than the temperature stability of the OCXO itself.
>  
> In other words the effect of the resistor is  inconsequential.
>  
> For a good double-oven OCXO this is even less of a factor, for  exampe the 
> MTI double oven we use only has 8.3E-11 per volt change -  two orders of 
> magnitude less sensitivity than the example above.
>  
> The capacitors' microphonic sensitivity may actuallyy be more of a factor  
> here.
>  
>   
>> It still helps to have as low a noise as possible before using  such
>> brute force filtering to get that extra few dB of noise  reduction.
>> 
>
> It's not just a few dB, it's -3dB at 17Hz already, and that drops  at ~-20dB 
> per decade. At 170Hz it could theoretically give -23dB already,  or in other 
> words if the noise floor was entirely due to the supply voltage  noise, then 
> the difference would be between say -140dBc/Hz and about  -160dBc/Hz at 170Hz 
> - 
> this could be a very significant improvement.
>  
>   
I usually regard anything less than about 20dB as a few dB.
> You are absolutely right, it is very difficult to get low noise  <10Hz.
>  
> bye,
> Said
>
>   
Said

I should have been more explicit:
If the OCXO has a single supply shared by both the OCXO and the oven
then since the oven current varies with ambient temperature the voltage
drop across the resistor will also vary which in turn will affect the
OCXO frequency.
If the Oven and oscillator/buffer supplies are separate the tempco of
voltage drop across the filter isnt a problem.
However some care is still required as the leakage current of an
electrolytic can be quite noisy.

Bruce

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Re: [time-nuts] re low noise regulators

[Didier Juges]

I think the issue with the series resistor is that the oven current is
temperature dependant, so the drop through the 2 ohm resistor is temperature
dependant too, regardless of the tolerance or stability of the resistor
itself.

As long as the current/temperature curve of the oven is predictable, that
could be compensated, assuming the loop response of the oven has no
overshoot. I think it requires making too many assumptions for that scheme
to work though.

Didier KO4BB 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
> Sent: Sunday, December 16, 2007 2:27 PM
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] re low noise regulators
> 
> In a message dated 12/14/2007 15:00:00 Pacific Standard Time, 
> [EMAIL PROTECTED] writes:
> 
> >>  A simple RC filter of say 2 Ohms into 4700uF has a -3dB cut-off at
> around  
> >> 17Hz (4700uF caps are getting quite small these  days). That would 
> >> take
> care  of 
> >> most of the 100Hz to 10KHz  noise.
> > 
> >It still helps to have as low a noise as possible  before using such 
> >brute force filtering to get that extra few dB of  noise reduction.
> >> Using a typical current of 0.16A at 12V for a  Euro-can 
> OCXO we would 
> >> only
>  
> >> have 0.32V voltage drop across  the resistor.
> >>   
> >However the resultant drop will  depend on the ambient temperature.
> >In principle the regulator output  could be given a suitable 
> >temperature drift characteristic to  compensate.
> >However doing this without degrading the noise at the  filter output 
> >may be challenging.
> Hi Bruce,
>  
> the tempco effect of the series resistor may not be a factor 
> at all for typical OCXO's.
>  
> If we take a standard 1% resistor such as the Panasonic 
> ERO-S2PHF2R00 (available on Digikey) with 100ppm/C tempco 
> (that's a fairly bad tempco),  then we
> get:
>  
>0.32V * 100ppm = 32 microvolts per Degree C change (actually  it's 
> +/-50ppm, so this example is worse than what we would see in 
> real  life).
>  
> If we now take the Supply-Voltage-versus-Frequency 
> characteristic of  a typical standard single oven OCXO  of 
> 1E-08, at +/-5% variation for  a 12V part we
> get:
>  
>1E-08 for 1.2V change, then we get: 8.33E-09/V * 32E-06V = 
>  2.66E-013 change per degree C.
>  
> For this particular OCXO with a stability of 1E-09 per degree 
> C, the  change in frequency due to the change in the 2 Ohm 
> resistor value is about 3700x less than the temperature 
> stability of the OCXO itself.
>  
> In other words the effect of the resistor is  inconsequential.
>  
> For a good double-oven OCXO this is even less of a factor, 
> for  exampe the MTI double oven we use only has 8.3E-11 per 
> volt change -  two orders of magnitude less sensitivity than 
> the example above.
>  
> The capacitors' microphonic sensitivity may actuallyy be more 
> of a factor here.
>  
> >It still helps to have as low a noise as possible before using  such 
> >brute force filtering to get that extra few dB of noise  reduction.
> 
> It's not just a few dB, it's -3dB at 17Hz already, and that 
> drops  at ~-20dB per decade. At 170Hz it could theoretically 
> give -23dB already,  or in other words if the noise floor was 
> entirely due to the supply voltage  noise, then the 
> difference would be between say -140dBc/Hz and about  
> -160dBc/Hz at 170Hz - this could be a very significant improvement.
>  
> You are absolutely right, it is very difficult to get low 
> noise  <10Hz.
>  
> bye,
> Said
> 
> 
> 
> 
> 
> **See AOL's top rated recipes
> (http://food.aol.com/top-rated-recipes?NCID=aoltop000304)
> ___
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Re: [time-nuts] Upgrading possibilities for more accurate, precise stable time system

[Brooke Clarke]

Hi Ronald:

Have a look at the different time transfer methods at:
http://www.prc68.com/I/timefreq.shtml#TT

Since these involve receiving a signal from a transmitter you need to have a 
way to know which signals you can get in your building.

For example LORAN-C and WWVB are low frequency signals.  CDMA cell phone is 
microwave.  VLF military stations are used to send subs encrypted messages and 
have well controlled carriers.


Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Ronald Held wrote:
> 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" <[EMAIL PROTECTED]>
>>Subject: Re: [time-nuts] Upgrading possibilities for more accurate,
>>   precise  stable mark ii
>>To: "'Discussion of precise time and frequency measurement'"
>>   
>>Message-ID: <[EMAIL PROTECTED]>
>>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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> 

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Re: [time-nuts] Time Transfer

[Brooke Clarke]

Hi Dave:

The HP 114 is a 1 PPS trigger generator with offset and was made for use with 
WWV, see: http://www.prc68.com/I/TF_rack.html
The audio from an HF receiver is fed to the V input on the scope and you can 
adjust the sweep speed as fast as propagation will allow.  The 114 time offset 
moves the trace left or right.  Then watching how long it takes to drift a 
division you can see what your house standard is doing.

An interesting way to use HF for time transfer would be to use a chirp based 
system.  Most chirp transmitters now use GPS control of their timing.  Chirp is 
used to determine what the propagation is between a given transmitter and 
receiver.  Since the chirp receiver knows exactly what the propagation is it 
should make for a more acccurate HF timing receiver.
http://www.prc68.com/I/RCS-5A.shtml

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Dave Brown wrote:
> - Original Message - 
> From: "Tim Shoppa" <[EMAIL PROTECTED]>
> To: 
> Sent: Monday, December 17, 2007 8:37 AM
> Subject: Re: [time-nuts] Time Transfer
> 
> 
> snip--
> 
> 
>>>Yes, it's interesting to look at the WWV signal wander on the HP 
>>>3586,
>>>compared to it's OCXO, and while listening to it on the speaker or 
>>>on a
>>>receiver. I need to plot it over a 24 hour period or so.
>>
>>It depends on where you are and how long you average over, but
>>by eye I see WWV on 10 and 15 MHz going up and down by tenths of a 
>>Hz
>>in the several minute timespan from here on the East Coast.
> 
> 
> Its also instructive to use a scope triggered off a local PPS and 
> watch the timing of the 1 second pips on WWV bounce around.
> 
> DaveB, NZ 
> 
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Re: [time-nuts] re low noise regulators

[SAIDJACK]

In a message dated 12/14/2007 15:00:00 Pacific Standard Time,  
[EMAIL PROTECTED] writes:

>>  A simple RC filter of say 2 Ohms into 4700uF has a -3dB cut-off at  
around  
>> 17Hz (4700uF caps are getting quite small these  days). That would take 
care  of 
>> most of the 100Hz to 10KHz  noise.
> 
>It still helps to have as low a noise as possible  before using such
>brute force filtering to get that extra few dB of  noise reduction.
>> Using a typical current of 0.16A at 12V for a  Euro-can OCXO we would only 
 
>> have 0.32V voltage drop across  the resistor.
>>   
>However the resultant drop will  depend on the ambient temperature.
>In principle the regulator output  could be given a suitable temperature
>drift characteristic to  compensate.
>However doing this without degrading the noise at the  filter output may
>be challenging.
Hi Bruce,
 
the tempco effect of the series resistor may not be a factor at all for  
typical OCXO's.
 
If we take a standard 1% resistor such as the Panasonic ERO-S2PHF2R00  
(available on Digikey) with 100ppm/C tempco (that's a fairly bad tempco),  then 
we 
get:
 
   0.32V * 100ppm = 32 microvolts per Degree C change (actually  it's 
+/-50ppm, so this example is worse than what we would see in real  life).
 
If we now take the Supply-Voltage-versus-Frequency characteristic of  a 
typical standard single oven OCXO  of 1E-08, at +/-5% variation for  a 12V part 
we 
get:
 
   1E-08 for 1.2V change, then we get: 8.33E-09/V * 32E-06V =  2.66E-013 
change per degree C.
 
For this particular OCXO with a stability of 1E-09 per degree C, the  change 
in frequency due to the change in the 2 Ohm resistor value is about 3700x  
less than the temperature stability of the OCXO itself.
 
In other words the effect of the resistor is  inconsequential.
 
For a good double-oven OCXO this is even less of a factor, for  exampe the 
MTI double oven we use only has 8.3E-11 per volt change -  two orders of 
magnitude less sensitivity than the example above.
 
The capacitors' microphonic sensitivity may actuallyy be more of a factor  
here.
 
>It still helps to have as low a noise as possible before using  such
>brute force filtering to get that extra few dB of noise  reduction.

It's not just a few dB, it's -3dB at 17Hz already, and that drops  at ~-20dB 
per decade. At 170Hz it could theoretically give -23dB already,  or in other 
words if the noise floor was entirely due to the supply voltage  noise, then 
the difference would be between say -140dBc/Hz and about  -160dBc/Hz at 170Hz - 
this could be a very significant improvement.
 
You are absolutely right, it is very difficult to get low noise  <10Hz.
 
bye,
Said





**See AOL's top rated recipes 
(http://food.aol.com/top-rated-recipes?NCID=aoltop000304)
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Re: [time-nuts] time-nuts Digest, Vol 41, Issue 57

[Daun Yeagley]

Sounds like you need to move!

Daun 

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Ronald Held
Sent: Sunday, December 16, 2007 1:17 PM
To: time-nuts@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" <[EMAIL PROTECTED]>
> Subject: Re: [time-nuts] Upgrading possibilities for more accurate,
>precise  stable mark ii
> To: "'Discussion of precise time and frequency measurement'"
>
> Message-ID: <[EMAIL PROTECTED]>
> 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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Re: [time-nuts] time-nuts Digest, Vol 41, Issue 57

[michael taylor]

On Dec 16, 2007 1:16 PM, Ronald Held <[EMAIL PROTECTED]> wrote:
> 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

The tiny mag mount antennas with small diameter coax commonly sold for
as an accessory for automotive GPS units should work fine with a
modern GPS module (perhaps a cheap SiRF III based unit if it includes
PPS out), and I believe you can find the mag mount antennas for about
$20-30 online.

It would be small enough that if you secured the cable (tie wraps or
tape) that it would be undetectable.



-Michael

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Re: [time-nuts] Time Transfer

[Dave Brown]

- Original Message - 
From: "Tim Shoppa" <[EMAIL PROTECTED]>
To: 
Sent: Monday, December 17, 2007 8:37 AM
Subject: Re: [time-nuts] Time Transfer


snip--

>> Yes, it's interesting to look at the WWV signal wander on the HP 
>> 3586,
>> compared to it's OCXO, and while listening to it on the speaker or 
>> on a
>> receiver. I need to plot it over a 24 hour period or so.
>
> It depends on where you are and how long you average over, but
> by eye I see WWV on 10 and 15 MHz going up and down by tenths of a 
> Hz
> in the several minute timespan from here on the East Coast.

Its also instructive to use a scope triggered off a local PPS and 
watch the timing of the 1 second pips on WWV bounce around.

DaveB, NZ 

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Re: [time-nuts] re low noise regulators

[michael taylor]

On Dec 16, 2007 6:09 AM, Ulrich Bangert <[EMAIL PROTECTED]> wrote:
> Gentlemen,
>
> over the last years I have been confronted with numerous nonsense and
> rubbish technical ideas as part of my job. Over the years I came to the
> conclusion that just for the sake of clarity it MUST be allowed to call
> them "nonsense" and "rubbish" without applying any political or other


I certainly agree, as long as such criticisms are clearly directed to
the mistaken or false claims, and not an attack on the person who made
the claim.

-Michael

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Re: [time-nuts] time-nuts Digest, Vol 41, Issue 57

[Peter Vince]

On Sun Dec 16 17:43 , 'Poul-Henning Kamp' sent:

>Find a bird-feed where the top-lid is plastic.
>Mount the GPS-antenna inside the bird-feeder lid.

But take some precautions to prevent those pesky squirrels chewing on the cable!

   Peter Vince



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Re: [time-nuts] time-nuts Digest, Vol 41, Issue 57

[Poul-Henning Kamp]

In message <[EMAIL PROTECTED]>, [EMAIL PROTECTED] writes:

>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?

Find a bird-feed where the top-lid is plastic.

Mount the GPS-antenna inside the bird-feeder lid.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] Time Transfer

[Tim Shoppa]

"Didier Juges" <[EMAIL PROTECTED]> wrote:
> That's what I meant I suppose. The interesting part is that the timing GPS
> receivers don't continualy try to select the best satellites from all those
> it can see, so other than eliminating outliers, there may still be some that
> are not far out enough to be eliminated, but will negatively affect the
> average. What is the criterion to determine an SV is an outlier? How far off
> should it be?
>
> An algorithm could select the best 3 at all times for instance, even if 5
> are visible and unmasked. I am not sure that would be better, but it's a
> possibility. On the other hand, I suppose that's what the mask if for. Maybe
> we need a dynamic mask so that we could force the receiver to never look at
> more than the best 3 or 4? 

Didier -
  I think this is what many are doing when they set their timing
receiver to only use satellites above a given elevation.

> > > If so,
> > > what's the point of a self survey?
> > 
> > ??? If you're wrong by 1000 feet about where you are, then 
> > that could be hundreds of nanoseconds in time error. And that 
> > hundreds of nanoseconds would jump around like the dickens as 
> > you chose different satllites or the chosen satellite pans 
> > across the sky.
> > 
>
> I agree, but to do a self-survey, you need to look at more than one
> satelite, which was my point.

Oh, all the timing receivers I know of refuse to self-survey without
at least 6 satellites in view. By definition it's impossible to do
without at least 4. Presumably those who advocate very picky elevation
angles dial the angle up only after getting a decent survey. I think
the Motorola timing receivers specifically disable any custom elevation
angle mask before doing a self-survey; at least that's the way the one
in my Z3801A works (although to be honest it might be the firmware
in the Z3801A and not on the GPS board).

> > > I talk about WWV because most ham operators have a receiver that 
> > > receives WWV, so it is an inexpensive and convenient way to get an 
> > > absolute reference, even though it is not as good as GPS.
> > 
> > WWV is great. But again, you gotta know where you are to have 
> > the right time. Fluctuations in propogation will change path 
> > length and if you don't know the path length, it is NOT an 
> > absolute reference in the nanosecond or even microsecond 
> > range. For typical conditions the propogation delay for WWV 
> > cannot be estimated much better than the tens of 
> > microseconds; combining WWV with a better "absolute"
> > clock in fact lets you study propogation by studying the 
> > shifting of the various ionospheric layers. (There have been 
> > ham operators who do this, including me!)
> > 
> > Tim. (N3QE)
> > 
>
> OK, once again I confused "frequency standard" and "time standard". I
> promise that's the last time :-)
>
> Yes, it's interesting to look at the WWV signal wander on the HP 3586,
> compared to it's OCXO, and while listening to it on the speaker or on a
> receiver. I need to plot it over a 24 hour period or so.

It depends on where you are and how long you average over, but
by eye I see WWV on 10 and 15 MHz going up and down by tenths of a Hz
in the several minute timespan from here on the East Coast.

Dave Mills has done a lot of DSP-type work on extracting the
leading edge of the second and minute pulse tones from WWV in
autocorrelator fashion.

I think that overall, you and I need to better quantify needs before
deciding on a solution as suitable :-). It's easy to overkill in
time and frequency, and I think the point of this list is to
do even more overkill! 

Personally I am so delighted with the abilities of any but the
cruddiest GPS timing receivers that I see no need to tweak elevation
angles. (I think I already said that I think that several consumer
non-timing GPS receivers common out there are not worth crap
for timing applications. Remember the SV6, it's PPS will go in and
out by six milliseconds as satellites go in and out of view!! Most
new stuff is better...)

Tim.

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Re: [time-nuts] Unit of Fame

[Poul-Henning Kamp]

In message <[EMAIL PROTECTED]
>, Doug Millar writes:
>   
>How about calling the unit the "Borat"?
>   Doug Millar

That would be a hard unit to use, because you would have to calibrate
out any talent, of which your chosen reference has a non-zero amount.

A much better unit would be the "Hilton".

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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[time-nuts] Unit of Fame

[Doug Millar]

How about calling the unit the "Borat"? 
Doug Millar


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Re: [time-nuts] time-nuts Digest, Vol 41, Issue 57

[GandalfG8]

 
In a message dated 16/12/2007 18:17:18 GMT Standard Time,  
[EMAIL PROTECTED] writes:

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?



---
I can't quite picture the overhang arrangement, but when you consider that  a 
variety of manufacturers supply GPS antennas that are approx 1 1/2 inches  
square by 1/2 inch deep I'd be very surprised if you couldn't attach  one of 
these somewhere outside without it noticing.
They may not have the filtering etc of a "proper" timing antenna but they'd  
do the job and certainly be a lot less obtrusive.
 
Alternatively, I've used one of these quite succesfully on an internal  
window sill and am running an Odetics timing antenna just propped up on the 
same  
window sill right now.
That's feeding an Oncore UT+ timing module in a test jig and  tracking 6 of 
the 8 satellites it can see.
Oncore modules, sometimes complete with a small antenna, are regulalrly on  
Ebay quite cheaply so why not invest a small amount and run some tests?
You might find the results are better than expected but even if not  you'd at 
least have some definite answers. 
 
regards
 
Nigel
GM8PZR
 



   
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[time-nuts] newbie questions

[kf6pqt]

Hi,

My name's Jason, and I must admit to being drawn in by the fascinating
article on Wired. ( if that makes me a dork, so be it!)

As a kid I thought it was neat to try and set my watches and clocks to
WWV from the cheap, crummy 1960's JC-penny all-band receiver , but was
always annoyed that the net result was "The time on the clock in the
front of the classroom IS the correct time, and the only clock that
matters, PERIOD.  ;)

In terms of "Knowing thy enemy," I find this study of time very
intriguing.  I've also built the AVR oscilloscope clock kit, (board
which drives a regular scope) which has the option of being driven by
an external source. I've also scrounged some battered gear with Nixie
displays, a Nixie clock is definitely  on my list of things to do.

So I've read through the links on
http://www.leapsecond.com/time-nuts.htm... some of this stuff I
understand, some I clearly don't!  Any other links to newbie-type
documentation would be greatly appreciated.

I guess my interest at this point would be as such: Obtaining an
accurate time signal, from GPS, etc, possibly accurising it further,
and then using it to likely BOTH drive a homebrew clock, AND setting
the time on one of my computers that would become my "master time
server."

My first two targeted questions are:

1)  I have a Handar 541 WWV receiver. I've searched high and low for a
manual for the the thing (so I can power it up without frying it) with
no luck, even the company that acquired Handar couldn't put their
hands on a copy. Would anybody on this list have this info?

2)  What exactly IS, and what is contained within the Lucent RFG XO? I
did a bit of googling, and didn't come up with any documentation for
this device. Is the "manual" out there?  Being a Ham who enjoys older
tube-based gear, I gather that at its simplest, its not unlike a "xtal
calibrator" reference oscillator.

Thanks,
Jason kf6pqt

-- 
--... ...-- -.. . -.- ..-. - .--. --.- -
AMI #1625 SKCC #3768
http://kf6pqt.net

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Re: [time-nuts] time-nuts Digest, Vol 41, Issue 57

[Ronald Held]

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" <[EMAIL PROTECTED]>
> Subject: Re: [time-nuts] Upgrading possibilities for more accurate,
>precise  stable mark ii
> To: "'Discussion of precise time and frequency measurement'"
>
> Message-ID: <[EMAIL PROTECTED]>
> 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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Re: [time-nuts] Time Transfer

[Didier Juges]

Tim,

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Tim Shoppa
> Sent: Sunday, December 16, 2007 7:29 AM
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Time Transfer
> 
> "Didier Juges" <[EMAIL PROTECTED]> wrote:
> > I would have thought the GPS receiver averages the readings when it 
> > locks on multiple satellites. Are you saying it only uses 
> one at a time?
> 
> Average is perhaps too simple of a word.
> 
> The good GPS receivers (here I'm assuming we aren't talking 
> about Trimble SV6!) look at all the satellites in view and 
> in mask, throw out obvious outliers, and average among the 
> remaining.
> 

That's what I meant I suppose. The interesting part is that the timing GPS
receivers don't continualy try to select the best satellites from all those
it can see, so other than eliminating outliers, there may still be some that
are not far out enough to be eliminated, but will negatively affect the
average. What is the criterion to determine an SV is an outlier? How far off
should it be?

An algorithm could select the best 3 at all times for instance, even if 5
are visible and unmasked. I am not sure that would be better, but it's a
possibility. On the other hand, I suppose that's what the mask if for. Maybe
we need a dynamic mask so that we could force the receiver to never look at
more than the best 3 or 4? 

> > If so,
> > what's the point of a self survey?
> 
> ??? If you're wrong by 1000 feet about where you are, then 
> that could be hundreds of nanoseconds in time error. And that 
> hundreds of nanoseconds would jump around like the dickens as 
> you chose different satllites or the chosen satellite pans 
> across the sky.
> 

I agree, but to do a self-survey, you need to look at more than one
satelite, which was my point.

> > I talk about WWV because most ham operators have a receiver that 
> > receives WWV, so it is an inexpensive and convenient way to get an 
> > absolute reference, even though it is not as good as GPS.
> 
> WWV is great. But again, you gotta know where you are to have 
> the right time. Fluctuations in propogation will change path 
> length and if you don't know the path length, it is NOT an 
> absolute reference in the nanosecond or even microsecond 
> range. For typical conditions the propogation delay for WWV 
> cannot be estimated much better than the tens of 
> microseconds; combining WWV with a better "absolute"
> clock in fact lets you study propogation by studying the 
> shifting of the various ionospheric layers. (There have been 
> ham operators who do this, including me!)
> 
> Tim. (N3QE)
> 

OK, once again I confused "frequency standard" and "time standard". I
promise that's the last time :-)

Yes, it's interesting to look at the WWV signal wander on the HP 3586,
compared to it's OCXO, and while listening to it on the speaker or on a
receiver. I need to plot it over a 24 hour period or so.

Didier KO4BB


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Re: [time-nuts] Time Transfer

[Tim Shoppa]

"Didier Juges" <[EMAIL PROTECTED]> wrote:
> I would have thought the GPS receiver averages the readings when it locks on
> multiple satellites. Are you saying it only uses one at a time?

Average is perhaps too simple of a word.

The good GPS receivers (here I'm assuming we aren't talking about Trimble
SV6!) look at all the satellites in view and in mask, throw out obvious
outliers, and average among the remaining.

> If so,
> what's the point of a self survey?

??? If you're wrong by 1000 feet about where you are, then that could
be hundreds of nanoseconds in time error. And that hundreds of nanoseconds
would jump around like the dickens as you chose different satllites
or the chosen satellite pans across the sky.

> I talk about WWV because most ham operators have a receiver that receives
> WWV, so it is an inexpensive and convenient way to get an absolute
> reference, even though it is not as good as GPS.

WWV is great. But again, you gotta know where you are to have the
right time. Fluctuations in propogation will change path length
and if you don't know the path length, it is NOT an absolute reference
in the nanosecond or even microsecond range. For typical conditions
the propogation delay for WWV cannot be estimated much better than
the tens of microseconds; combining WWV with a better "absolute"
clock in fact lets you study propogation by studying the shifting
of the various ionospheric layers. (There have been ham operators
who do this, including me!)

Tim. (N3QE)

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Re: [time-nuts] re low noise regulators

[Ulrich Bangert]

Gentlemen,

over the last years I have been confronted with numerous nonsense and
rubbish technical ideas as part of my job. Over the years I came to the
conclusion that just for the sake of clarity it MUST be allowed to call
them "nonsense" and "rubbish" without applying any political or other
correctness. I stand for that claim even if it caused some "Kiss my
back" reactions from my boss form time to time.  

Best regards
Ulrich Bangert

> -Ursprungliche Nachricht-
> Von: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] Im Auftrag von Bruce Griffiths
> Gesendet: Freitag, 14. Dezember 2007 22:11
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] re low noise regulators
> 
> 
> Rob Kimberley wrote:
> > "Nonsense", rubbish"??
> >
> > Not the words I want to hear from a fellow Time Nut.
> >
> > Bruce, next time how about giving constructive criticism without 
> > belittling other peoples efforts?
> >
> > Remember that this group contains everyone from professionals to 
> > complete newcomers. We want to encourage and grow the group by 
> > collective help and encouragement, not by insulting them.
> >
> > Season of goodwill to all men?
> >
> > Cheers
> >
> > Rob Kimberley
> >   
> No insults or belittling intended, they were merely robust 
> comments about the statements made. If you ever think that 
> anything I say is nonsense (or rubbish) please don't hesitate 
> to say so, I will not be offended in any way.
> 
> Bruce
> 
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> 


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