Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Stephan Sandenbergh]

Hi,

I'm using three Motorola GPS Timing 2000 Antennas. They are co-located on
the roof of our building with a clear view of the skies. The view is almost
360deg but a mountain is blocking off a small bit of it to the South-East
side. I'd assume some multipath is possible, but I'd thought that the deep
valleys between the buildings would get rid of most of it, with only the
reflections from the roof top etc remaining.

My latitude is South 33deg.

Yes I'm using one GPS as reference and the others are DUTs. Since, the HP53131A
TICs don't measure negative time (i.e. event on channel2 happens before
event on channel1) I purposely offset the reference GPS by 100ns. Thus, I
could measure negative time by later subtracting the 100ns in
post-processing.

Below is a plot so you could see exactly what I measured. What is peculiar
is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS
receiver decides to offset the time by twice the amount I set it to. Which
is why I initially thought it might be a firmware thing. I suppose
multipath is a good explanation, it is just odd that the time error is
exactly 100ns.

Using a single antenna and splitting it is an idea, but then I still need
to devise something to inject the antenna DC power at the other end of the
splitter etc. And, we are trying to measure the relative offset between the
antenna/receiver pairs for calibration.

Thanks for the suggestions so far.

Regards,

Stephan.


On 19 November 2013 19:31, Graham / KE9H  wrote:

> Stephan:
>
> This sounds like some kind of antenna placement issue.
>
> What is your Latitude?
>
> Can you describe your antenna systems?
>
> Best case: Antennas above all nearby reflecting objects/buildings/trees,
> clear
> view of the sky for 360 degrees,
>
> Worst case: Indoors, patch antenna on the window edge of a North facing
> window, so that
> 100 percent of all signals received are via reflections and multi-path,
> bouncing from
> tall buildings in the area.
>
> When there are signals received via reflection, and the receiver changes
> the
> set of satellites it is using for the solution, you will see a time jump
> equal to
> the apparent change in location of the receiver, for the different
> solution.
>
> With heavy multi-path/reflections, antennas just a few cm apart will be
> looking
> at different solutions, and will jump time/location at different times.
>
> --- Graham / KE9H
>
> ==
>
>
> On 11/19/2013 10:45 AM, Chris Albertson wrote:
>
>> Two antennas near each other?   Could they interact under some conditions?
>>
>> Could you be seeing multi path in some satellite geometries?
>>
>>   Try spacing them apart or BETTER get a splitter and use only one antenna
>> but take the second antenna an far away, I wonder if it is acting like a
>> reflector or if the amplifier is radiating EMI.
>>
>>
>> On Tue, Nov 19, 2013 at 6:01 AM, Azelio Boriani > >wrote:
>>
>>  One M12+ is the reference and the others are DUTs? Three times but in
>>> one direction only for a 300ns total or what? The offset returned to
>>> 0? Please, detail better what happened.
>>>
>>> On Tue, Nov 19, 2013 at 12:17 PM, Stephan Sandenbergh
>>>  wrote:
>>>
 Hi,

 I've recently measured the 1PPS outputs of three Motorola M12+T GPS
 receivers using two HP53131A TICs. Antennas are located next to one

>>> another.
>>>
 Now I notice the one M12+T has changed its time offset by 100ns three

>>> times
>>>
 over the period of 48hrs. The jitter remains the same, only the offset

>>> that
>>>
 changes.

 I'm currently having a re-run of the measurement. But, in meanwhile, has
 anyone seen this kind of behaviour? A firmware issue perhaps?

 Regards,

 Stephan.
 ___


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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Björn]

Hi Stephan,

> Using a single antenna and splitting it is an idea, but then I still need
> to devise something to inject the antenna DC power at the other end of the
> splitter etc. And, we are trying to measure the relative offset between
> the
> antenna/receiver pairs for calibration.

Most generic RF splitters I have worked with have DC connections between
all ports. So you would need to connect one GPS directly to the splitter
and then DC block the other two receivers.

This is taken care of if you buy a splitter designed for GPS use. Look in
the archives. GPS networking, GPS Source, HP/Agilent/Symmetricom/... all
do splitters.

   http://gpsnetworking.com/datasheet%20replacements/LDCBS1X4.pdf

Phase unbalance between the ports of <1 deg, should not contribute to you
error budget significantly.

kind regards,

  Björn



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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Tom Van Baak]

> Below is a plot so you could see exactly what I measured. What is peculiar
> is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS
> receiver decides to offset the time by twice the amount I set it to. Which
> is why I initially thought it might be a firmware thing. I suppose
> multipath is a good explanation, it is just odd that the time error is
> exactly 100ns.

Hi Stephan,

A quick test you could perform is set the offset to 125 ns instead of 100 ns 
and see if the jumps still occur, still occur at 100 ns, or now occur at 125 ns.

Since you have three M12's offset the third one by 150 ns and see if it 
experiences jumps too.

Question -- are you using the external 10 MHz reference input or output for any 
of your 53131A counters?

/tvb

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Re: [time-nuts] Crude Survey Technique

[Robert Atkinson]

I'd also go for a compass if you want magnetic north, but then I have a good 
one, a "medium landing compass". Mine dates from WWII but they are still made 
http://www.sirs.co.uk/ground/landing_compasses/patt2/landing_resource
These are used to align the standbay and remote reading compasses on aircraft. 
Good to half a degree. If you need better ther is the Watts Datum Compass.
 
Robert G8RPI.
 
 From: Chris Albertson 
To: Discussion of precise time and frequency measurement  
Sent: Thursday, 21 November 2013, 23:28
Subject: Re: [time-nuts] Crude Survey Technique
  

On Thu, Nov 21, 2013 at 11:11 AM, Don Latham  wrote:
> Lord no, John. No red wagon is needed. Use a pole and the equation of
> time, and a good watch or clock. At local noon, a shadow will be a n-s
> line.

How accurate do you need to be?   The above requires a very tall pole
to case a 300 foot long shadow.  Then you have to be quick to measure
because the Earth turns at  .25 degrees per minute.

If you need a very tall pole that is 100% vertical then hang a
weighted rope from a tall support.  Then go to the other end and watch
the seconds tick down.

A GOOD magnetic compass can do this job too.  Easier then finding s
1,000 food tall pole.   The better compasses have some kind of optical
aid for sighting a line.

-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Off-Topic Question -- German Composition Resistors

[Erno Peres]

Hi Bruce,

try to use this one 


Resistor Color Code Identification
 


Rgds Ernie.



-Original Message-
From: Brucekareen 
To: time-nuts 
Sent: Thu, Nov 21, 2013 7:17 pm
Subject: [time-nuts] Off-Topic Question -- German Composition Resistors


While tracing out a PC board from an instrument manufactured in Germany, I  
uickly discovered the color code on 1/4-watt composition resistors is not  
he same as that commonly used in the US  For example, I would measure  
bout 10,000-ohms across a presumably good resistor that appeared to be marked  
700-ohms.  Has/does Germany used a different code for such parts?

ruce, KG6OJI 
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Re: [time-nuts] Crude Survey Technique

[Don Latham]

Lord no, John. No red wagon is needed. Use a pole and the equation of
time, and a good watch or clock. At local noon, a shadow will be a n-s
line. If you don't have a decent clock, like your cellphone, put in a
pole at one end of your line. Near local noon, which depends on where
you are in the timezone, start sticking pegs in the end of the shadow of
the pole; the shortest shadow will be the n-s line. Accuracy much better
than 2 deg. I'm sure other ways will come to you :-)
Don

johncr...@aol.com
>  I wish to establish a north south line on my property to an accuracy of
> +/- 2 degrees.
> Could this be done by loading a T-bolt, Antenna, Power source, and
> laptop into my
> little red wagon? The idea being to find two positions several hundred
> ft apart where either LH or T-bolt Mon report the same latitude? Will
> either of these programs report to sufficient accuracy? The base line
> would be 300 ft, though more is possible.I realizes that the T-bolt is
> not a survey device, but I can spend several hours fixing each position
> if required.
>
> All comments appreciated.?? -73 john k6iql
>
>
>
>
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>


-- 
"The power of accurate observation is commonly called cynicism by those
who have not got it."
 -George Bernard Shaw


Dr. Don Latham AJ7LL
Six Mile Systems LLC
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
Skype: buffler2
www.lightningforensics.com
www.sixmilesystems.com


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Re: [time-nuts] Crude Survey Technique

[J. Forster]

For something that crude, I'd consider taking a sight on Polaris. If you
note the time and do the math, you can probably do better than your
bounds.

Also, there is almost certainly an app somewhere to do the math for you. I
think tha reeuction info was in Bowditch or the Nautical Almanac.

FWIW,

-John

===





> In message <8d0b5020292d91e-cc0-4b...@webmail-vm026.sysops.aol.com>,
> johncroos@
> aol.com writes:
>
>> I wish to establish a north south line on my property to an
>>accuracy of +/- 2 degrees.
>
> First of all, at that level of precision you will have to decide what
> you mean by "north south" ?
>
> Magnetic ?  Geodetic ?  (if so: Which Datum ?)  Meridian ?
>
>> The base line would be 300 ft
>
> So your east-west precision needs to be tan(2)*300ft = 10.5 ft.
>
> I don't think you can do that with a single band GPS.
>
> If you can locate suitable landmarks, you may be able to do with
> the arial photograph on maps.google.com (or similar servce) but
> you need to get coordinates figured out (not trivial!)
>
> I would raise a pole or other marker at one end (N or S), calculate
> when a suitable celestial object crosses your designated line and
> that to triangulate the opposite end.
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | 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] Isolation achieved by opamp based isoamp?

[Didier Juges]

One thing to keep in mind is that isolation through shielding usually
results in much greater capacitance to ground (actually to the shield) from
both input and output windings.

Therefore, the actual isolation in practice is totally driven by how good
the ground to the shield is.

At RF, any inductance in series with the shield's connection to ground will
degrade the isolation. Not a problem at 60Hz, but certainly a problem as
the frequency gets higher.

Didier KO4BB




On Thu, Nov 21, 2013 at 8:28 AM, J. Forster  wrote:

> Looking quickly at the prints on the site, the isolation is provided by
> the transformer, not the active circuitry. The transistors/op-amps are
> just buffers for the output.
>
> That means that the isolation is determined, for the most part, by the
> transformer design, so:
>
>  A bifilar wound torroid would have relatively poor isolation,
>  Two windings on opposite ends of a ferrite rod much better.
>
> Some (power line) ultra-isolation transformers have a shield between the
> primary and secondary, and I don't see any reason that could not be done
> at RF. The objective is, of course, to minimize the capacitance between
> the windings. Topaz got 0.001 pF on a 1 kW unit as I remember.
>
> -John
>
> =
>
>
>
>
>
>
> > Hi,
> >
> > I'm curious about the level of isolation that is achieved by an opamp
> > based
> > isoamp. I'm referring to ones described here on Bruce Griffiths' page:
> > http://www.ko4bb.com/~bruce/IsolationAmplifiers.html
> >
> > Anyone has a number for this?
> >
> > I've tried googling it, but the results are mostly filled with the other
> > kind of iso amplifier where isolation refers to galvanic isolation.
> >
> > Regards,
> >
> > Stephan.
> > ___
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Re: [time-nuts] Crude Survey Technique

[Robert Atkinson]

The simplest ones do it by difference in position from one fix to another. no 
need for a map for True North, just trig. For Magnetic North you need a map 
with variation data. More advanced units have magnetic sensors and 
accelerometers. An interesting question that I once spent some hours discussing 
in a pub (bar) about 20 years ago is how does an inertial navigation unit 
determine True North without the aircraft moving? No magnetic sensors, just a 
self contained black box. We know it did it because we had just finished 
installing one and watched it do it. We worked it out after a few pints ;-) 
Hint, it takes longer the closer to the pole you are. For Magnetic headings you 
still need a table of variations. At least one common aircraft inertial nav 
unit has magvar tables that are several years out of date with the OEM (well 
current IP owner, they bought out the real OEM) say it's not possible to update 
them!

Robert G8RPI.





 From: Neville Michie 
To: Discussion of precise time and frequency measurement  
Sent: Thursday, 21 November 2013, 21:46
Subject: Re: [time-nuts] Crude Survey Technique
 

How do the car mounted GPS guidance devices find North?
Is it by deciding which direction you are moving on the map that they have 
stored?
It is amazing how quickly they show the orientation of the map/your direction 
of travel.
Do they have a sensor to register when you turn a corner?
What they do does not seem possible from just a series of position fixes.
cheers,
Neville Michie





On 22/11/2013, at 7:45 AM,  wrote:

> If you want true north, set up a camera that has time or bulb shutter at the 
> south end of your property. Put in a marker stake. take a time exposure at 
> night with the camera facing north. If you expose for about 30 minutes, you 
> will get a landscape with the stars rotating around the north star. You can 
> then mark the north location on your property under the north star.
> 
> A compass siting can give the mag north.
> 
> 
> From: time-nuts-boun...@febo.com  on behalf of 
> Brian Lloyd 
> Sent: Thursday, November 21, 2013 2:04 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Crude Survey Technique
> 
> On Thu, Nov 21, 2013 at 12:52 PM,  wrote:
> 
>> I wish to establish a north south line on my property to an accuracy of
>> +/- 2 degrees.
>> Could this be done by loading a T-bolt, Antenna, Power source, and laptop
>> into my
>> little red wagon? The idea being to find two positions several hundred ft
>> apart where either LH or T-bolt Mon report the same latitude? Will either
>> of these programs report to sufficient accuracy? The base line would be 300
>> ft, though more is possible.I realizes that the T-bolt is not a survey
>> device, but I can spend several hours fixing each position if required.
>> 
> 
> True north or magnetic north? In any case, a good lensatic compass and
> knowing your magnetic variation should easily get you to within 2 degrees
> and is a lot easier than doing a survey with your GPS.
> 
> 
> --
> Brian Lloyd, WB6RQN/J79BPL
> 706 Flightline Drive
> Spring Branch, TX 78070
> br...@lloyd.com
> +1.916.877.5067
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Re: [time-nuts] Off-Topic Question -- German Composition Resistors

[Robert LaJeunesse]

If it had 4 color bands 2701 you are likely reading it backward. 1072 would be 
10.7K

Bob L.



>
> From: "brucekar...@aol.com" 
>To: time-nuts@febo.com 
>Sent: Thursday, November 21, 2013 1:11 PM
>Subject: [time-nuts] Off-Topic Question -- German Composition Resistors
> 
>
>While tracing out a PC board from an instrument manufactured in Germany, I  
>quickly discovered the color code on 1/4-watt composition resistors is not  
>the same as that commonly used in the US  For example, I would measure  
>about 10,000-ohms across a presumably good resistor that appeared to be marked 
> 
>2700-ohms.  Has/does Germany used a different code for such parts?
>
>Bruce, KG6OJI 
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Re: [time-nuts] Off-Topic Question -- German Composition Resistors

[Adrian]

Hi Bruce,
no. Same color code here.
However, certain carbon composition resistors from the 60's/70's are 
notoriously unreliable. The common effect is drift to significantly 
higher values. Besides that, they can get pretty noisy.

Adrian

brucekar...@aol.com schrieb:

While tracing out a PC board from an instrument manufactured in Germany, I
quickly discovered the color code on 1/4-watt composition resistors is not
the same as that commonly used in the US  For example, I would measure
about 10,000-ohms across a presumably good resistor that appeared to be marked
2700-ohms.  Has/does Germany used a different code for such parts?
  
Bruce, KG6OJI

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Re: [time-nuts] Off-Topic Question -- German Composition Resistors

[Robert Atkinson]

May be a bit of drift and reading back to front. Some years ago we bought a 
quantity of moulded carbon compostion resistors from a top US manufacturer. A 
sample check showed that none of them met the 10% tolerance. The maufacturer 
said "bake them for a day two"! The resistors then passed. Why not replace them 
with modert types you ask? Type approved equipment with the original designers 
long gone and the current type certificate holder unwilling or unable to 
approve the change. Welcome to the world of aviation where we are still 
supporting equipment designed 50 or more years ago.

Robert G8RPI.





 From: Adrian 
To: Discussion of precise time and frequency measurement  
Sent: Thursday, 21 November 2013, 20:53
Subject: Re: [time-nuts] Off-Topic Question -- German Composition Resistors
 

Hi Bruce,
no. Same color code here.
However, certain carbon composition resistors from the 60's/70's are 
notoriously unreliable. The common effect is drift to significantly 
higher values. Besides that, they can get pretty noisy.
Adrian

brucekar...@aol.com schrieb:
> While tracing out a PC board from an instrument manufactured in Germany, I
> quickly discovered the color code on 1/4-watt composition resistors is not
> the same as that commonly used in the US  For example, I would measure
> about 10,000-ohms across a presumably good resistor that appeared to be marked
> 2700-ohms.  Has/does Germany used a different code for such parts?
>  
> Bruce, KG6OJI
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>

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Re: [time-nuts] Off-Topic Question -- German Composition Resistors

[Tim Shoppa]

Basic resistor has three color codes - two significant digits and a
multiplier - and then likely silver or (more commonly today) gold band.
Silver is 10%, gold is 5%.

A high -spec resistor can have extra color bands to denote things like
tempco, reliability, etc. and may have a non-silver and non-gold band for a
different tolerance range. You might've been reading the resistor
"backwards" without the gold band to help guide your eye, or confusing
significant digit bands with multiplier bands.

On Thu, Nov 21, 2013 at 1:11 PM,  wrote:

> While tracing out a PC board from an instrument manufactured in Germany, I
> quickly discovered the color code on 1/4-watt composition resistors is not
> the same as that commonly used in the US  For example, I would measure
> about 10,000-ohms across a presumably good resistor that appeared to be
> marked
> 2700-ohms.  Has/does Germany used a different code for such parts?
>
> Bruce, KG6OJI
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Re: [time-nuts] Crude Survey Technique (johncr...@aol.com)

[Brooke Clarke]

Hi John:

I have a web page devoted to Finding North, see:
http://www.prc68.com/I/North.shtml

Have Fun,

Brooke Clarke, N6GCE
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html


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Re: [time-nuts] Crude Survey Technique

[Brooke Clarke]

Hi Neville:

Most low cost hand held and car GPS receivers can only display direction based 
on changes in position.
While on vacation in Japan I was using a hand held Garmin 12-channel GPS, but when standing still the compass did not 
work, I needed to run a block to get a bearing.
My Honda van GPS includes a gyroscope so it know you have turned even in an urban canyon where there may not be enough 
satellites visible to get a fix.


Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

Neville Michie wrote:

How do the car mounted GPS guidance devices find North?
Is it by deciding which direction you are moving on the map that they have 
stored?
It is amazing how quickly they show the orientation of the map/your direction 
of travel.
Do they have a sensor to register when you turn a corner?
What they do does not seem possible from just a series of position fixes.
cheers,
Neville Michie





On 22/11/2013, at 7:45 AM,  wrote:


If you want true north, set up a camera that has time or bulb shutter at the 
south end of your property. Put in a marker stake. take a time exposure at 
night with the camera facing north. If you expose for about 30 minutes, you 
will get a landscape with the stars rotating around the north star. You can 
then mark the north location on your property under the north star.

A compass siting can give the mag north.


From: time-nuts-boun...@febo.com  on behalf of Brian 
Lloyd 
Sent: Thursday, November 21, 2013 2:04 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Crude Survey Technique

On Thu, Nov 21, 2013 at 12:52 PM,  wrote:


I wish to establish a north south line on my property to an accuracy of
+/- 2 degrees.
Could this be done by loading a T-bolt, Antenna, Power source, and laptop
into my
little red wagon? The idea being to find two positions several hundred ft
apart where either LH or T-bolt Mon report the same latitude? Will either
of these programs report to sufficient accuracy? The base line would be 300
ft, though more is possible.I realizes that the T-bolt is not a survey
device, but I can spend several hours fixing each position if required.


True north or magnetic north? In any case, a good lensatic compass and
knowing your magnetic variation should easily get you to within 2 degrees
and is a lot easier than doing a survey with your GPS.


--
Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070
br...@lloyd.com
+1.916.877.5067
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Re: [time-nuts] DIY antenna

[quartz55]

Alain,

Look here. http://lea.hamradio.si/~s53mv/navsats/analog.html It's essentially 2 
loops of different size connected together at the top to give 50 ohm Z.  The 
amp I used is also bandwidth limited.  I should put it next to my PCtel antenna 
with a switch and see which works better.
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Re: [time-nuts] Crude Survey Technique

[J. Forster]

The INS has to be 'aligned' before takeoff.

Remember, the earth is spinning on an axis, and the INS's platform is
stable in Inertial space.  If you know the INS is sitting on the ground
(or even deep in a mine shaft) it's just trig. Nothing external needed,
not even stars.

-John





> The simplest ones do it by difference in position from one fix to another.
> no need for a map for True North, just trig. For Magnetic North you need a
> map with variation data. More advanced units have magnetic sensors and
> accelerometers. An interesting question that I once spent some hours
> discussing in a pub (bar) about 20 years ago is how does an inertial
> navigation unit determine True North without the aircraft moving? No
> magnetic sensors, just a self contained black box. We know it did it
> because we had just finished installing one and watched it do it. We
> worked it out after a few pints ;-) Hint, it takes longer the closer to
> the pole you are. For Magnetic headings you still need a table of
> variations. At least one common aircraft inertial nav unit has magvar
> tables that are several years out of date with the OEM (well current IP
> owner, they bought out the real OEM) say it's not possible to update them!
>
> Robert G8RPI.
>
>
>
>
> 
>  From: Neville Michie 
> To: Discussion of precise time and frequency measurement
> 
> Sent: Thursday, 21 November 2013, 21:46
> Subject: Re: [time-nuts] Crude Survey Technique
>
>
> How do the car mounted GPS guidance devices find North?
> Is it by deciding which direction you are moving on the map that they have
> stored?
> It is amazing how quickly they show the orientation of the map/your
> direction of travel.
> Do they have a sensor to register when you turn a corner?
> What they do does not seem possible from just a series of position fixes.
> cheers,
> Neville Michie
>
>
>
>
>
> On 22/11/2013, at 7:45 AM,  wrote:
>
>> If you want true north, set up a camera that has time or bulb shutter at
>> the south end of your property. Put in a marker stake. take a time
>> exposure at night with the camera facing north. If you expose for about
>> 30 minutes, you will get a landscape with the stars rotating around the
>> north star. You can then mark the north location on your property under
>> the north star.
>>
>> A compass siting can give the mag north.
>>
>> 
>> From: time-nuts-boun...@febo.com  on behalf
>> of Brian Lloyd 
>> Sent: Thursday, November 21, 2013 2:04 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Crude Survey Technique
>>
>> On Thu, Nov 21, 2013 at 12:52 PM,  wrote:
>>
>>> I wish to establish a north south line on my property to an accuracy of
>>> +/- 2 degrees.
>>> Could this be done by loading a T-bolt, Antenna, Power source, and
>>> laptop
>>> into my
>>> little red wagon? The idea being to find two positions several hundred
>>> ft
>>> apart where either LH or T-bolt Mon report the same latitude? Will
>>> either
>>> of these programs report to sufficient accuracy? The base line would be
>>> 300
>>> ft, though more is possible.I realizes that the T-bolt is not a survey
>>> device, but I can spend several hours fixing each position if required.
>>>
>>
>> True north or magnetic north? In any case, a good lensatic compass and
>> knowing your magnetic variation should easily get you to within 2
>> degrees
>> and is a lot easier than doing a survey with your GPS.
>>
>>
>> --
>> Brian Lloyd, WB6RQN/J79BPL
>> 706 Flightline Drive
>> Spring Branch, TX 78070
>> br...@lloyd.com
>> +1.916.877.5067
>> ___
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>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>> 
>> CONFIDENTIALITY NOTICE: The information contained in this electronic
>> message is confidential information intended for the use of the
>> individual or entity named above. If the reader of this message is not
>> the intended recipient, or an employee or agent responsible for
>> delivering this electronic message to the intended recipient, you are
>> hereby notified that any dissemination or copying of this communication
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>> recipient, you are further prohibited under penalty of law from using or
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>> federal Gramm-Leach-Bliley Act. If you have received this electronic
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Re: [time-nuts] Crude Survey Technique (johncr...@aol.com)

[johncroos]

 My thanks to all that contributed ideas, especially Don's sundial approach. 
You all have established that if there is an excessively? complex approach I 
will be sure to think of that first. Let see what else pops up.

-73 john k6iql



 



-Original Message-
From: time-nuts-request 
To: time-nuts 
Sent: Thu, Nov 21, 2013 2:31 pm
Subject: time-nuts Digest, Vol 112, Issue 68

 
 
 
Send time-nuts mailing list submissions to 
time-nuts@febo.com 
 
To subscribe or unsubscribe via the World Wide Web, visit 
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or, via email, send a message with subject or body 'help' to 
time-nuts-requ...@febo.com 
 
You can reach the person managing the list at 
time-nuts-ow...@febo.com 
 
When replying, please edit your Subject line so it is more specific 
than "Re: Contents of time-nuts digest..." 
 
 
Today's Topics: 
 
   1. Re: Off-Topic Question -- German Composition Resistors 
  (Robert LaJeunesse) 
   2. Crude Survey Technique (johncr...@aol.com) 
   3. Re: Crude Survey Technique (Poul-Henning Kamp) 
   4. Re: Crude Survey Technique (Don Latham) 
   5. Re: Crude Survey Technique (Don Latham) 
   6. Re: Crude Survey Technique (J. Forster) 
   7. OT: Putting the Wolfram Language (and Mathematica) on every 
  Raspberry Pi (David J Taylor) 
   8. Re: Crude Survey Technique (Brian Lloyd) 
 
 
-- 
 
Message: 1 
Date: Thu, 21 Nov 2013 10:38:10 -0800 (PST) 
From: Robert LaJeunesse  
To: Discussion of precise time and frequency measurement 
 
Subject: Re: [time-nuts] Off-Topic Question -- German Composition 
Resistors 
Message-ID: 
<1385059090.6740.yahoomail...@web181003.mail.ne1.yahoo.com> 
Content-Type: text/plain; charset=iso-8859-1 
 
If it had 4 color bands 2701 you are likely reading it backward. 1072 would be  
10.7K 
 
Bob L. 
 
 
 
> 
> From: "brucekar...@aol.com"  
>To: time-nuts@febo.com  
>Sent: Thursday, November 21, 2013 1:11 PM 
>Subject: [time-nuts] Off-Topic Question -- German Composition Resistors 
>  
> 
>While tracing out a PC board from an instrument manufactured in Germany, I? 
 
>quickly discovered the color code on 1/4-watt composition resistors is not? 
 
>the same as that commonly used in the US? For example, I would measure?  
>about 10,000-ohms across a presumably good resistor that appeared to be 
marked?  
 
>2700-ohms.? Has/does Germany used a different code for such parts? 
> 
>Bruce, KG6OJI  
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>and follow the instructions there. 
> 
> 
> 
 
-- 
 
Message: 2 
Date: Thu, 21 Nov 2013 13:52:49 -0500 (EST) 
From: johncr...@aol.com 
To: time-nuts@febo.com 
Subject: [time-nuts] Crude Survey Technique 
Message-ID: <8d0b5020292d91e-cc0-4b...@webmail-vm026.sysops.aol.com> 
Content-Type: text/plain; charset="us-ascii" 
 
 I wish to establish a north south line on my property to an accuracy of +/- 2  
degrees. 
Could this be done by loading a T-bolt, Antenna, Power source, and laptop into  
my 
little red wagon? The idea being to find two positions several hundred ft apart 
 
where either LH or T-bolt Mon report the same latitude? Will either of these  
programs report to sufficient accuracy? The base line would be 300 ft, though  
more is possible.I realizes that the T-bolt is not a survey device, but I can  
spend several hours fixing each position if required.  
 
All comments appreciated.?? -73 john k6iql 
 
 
  
 
 
 
-- 
 
Message: 3 
Date: Thu, 21 Nov 2013 19:11:51 + 
From: "Poul-Henning Kamp"  
To: Discussion of precise time and frequency measurement 
, johncr...@aol.com 
Subject: Re: [time-nuts] Crude Survey Technique 
Message-ID: <11440.1385061...@critter.freebsd.dk> 
Content-Type: text/plain; charset=ISO-8859-1 
 
In message <8d0b5020292d91e-cc0-4b...@webmail-vm026.sysops.aol.com>, 
johncroos@ 
aol.com writes: 
 
> I wish to establish a north south line on my property to an 
>accuracy of +/- 2 degrees. 
 
First of all, at that level of precision you will have to decide what 
you mean by "north south" ? 
 
Magnetic ?  Geodetic ?  (if so: Which Datum ?)  Meridian ? 
 
> The base line would be 300 ft 
 
So your east-west precision needs to be tan(2)*300ft = 10.5 ft. 
 
I don't think you can do that with a single band GPS. 
 
If you can locate suitable landmarks, you may be able to do with 
the arial photograph on maps.google.com (or similar servce) but 
you need to get coordinates figured out (not trivial!) 
 
I would raise a pole or other marker at one end (N or S), calc

Re: [time-nuts] Crude Survey Technique

[J. Forster]

FWIW, my Garmin Nuvie 40 (el cheapo) only takes moving maybe 10' to get a
rough compass direction. I doubt it has any gyro or accelerometers.

-John

===


> Hi Neville:
>
> Most low cost hand held and car GPS receivers can only display direction
> based on changes in position.
> While on vacation in Japan I was using a hand held Garmin 12-channel GPS,
> but when standing still the compass did not
> work, I needed to run a block to get a bearing.
> My Honda van GPS includes a gyroscope so it know you have turned even in
> an urban canyon where there may not be enough
> satellites visible to get a fix.
>
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
>
> Neville Michie wrote:
>> How do the car mounted GPS guidance devices find North?
>> Is it by deciding which direction you are moving on the map that they
>> have stored?
>> It is amazing how quickly they show the orientation of the map/your
>> direction of travel.
>> Do they have a sensor to register when you turn a corner?
>> What they do does not seem possible from just a series of position
>> fixes.
>> cheers,
>> Neville Michie
>>
>>
>>
>>
>>
>> On 22/11/2013, at 7:45 AM,  wrote:
>>
>>> If you want true north, set up a camera that has time or bulb shutter
>>> at the south end of your property. Put in a marker stake. take a time
>>> exposure at night with the camera facing north. If you expose for about
>>> 30 minutes, you will get a landscape with the stars rotating around the
>>> north star. You can then mark the north location on your property under
>>> the north star.
>>>
>>> A compass siting can give the mag north.
>>>
>>> 
>>> From: time-nuts-boun...@febo.com  on behalf
>>> of Brian Lloyd 
>>> Sent: Thursday, November 21, 2013 2:04 PM
>>> To: Discussion of precise time and frequency measurement
>>> Subject: Re: [time-nuts] Crude Survey Technique
>>>
>>> On Thu, Nov 21, 2013 at 12:52 PM,  wrote:
>>>
 I wish to establish a north south line on my property to an accuracy
 of
 +/- 2 degrees.
 Could this be done by loading a T-bolt, Antenna, Power source, and
 laptop
 into my
 little red wagon? The idea being to find two positions several hundred
 ft
 apart where either LH or T-bolt Mon report the same latitude? Will
 either
 of these programs report to sufficient accuracy? The base line would
 be 300
 ft, though more is possible.I realizes that the T-bolt is not a survey
 device, but I can spend several hours fixing each position if
 required.

>>> True north or magnetic north? In any case, a good lensatic compass and
>>> knowing your magnetic variation should easily get you to within 2
>>> degrees
>>> and is a lot easier than doing a survey with your GPS.
>>>
>>>
>>> --
>>> Brian Lloyd, WB6RQN/J79BPL
>>> 706 Flightline Drive
>>> Spring Branch, TX 78070
>>> br...@lloyd.com
>>> +1.916.877.5067
>>> ___
>>> 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.
>>>
>>> 
>>> CONFIDENTIALITY NOTICE: The information contained in this electronic
>>> message is confidential information intended for the use of the
>>> individual or entity named above. If the reader of this message is not
>>> the intended recipient, or an employee or agent responsible for
>>> delivering this electronic message to the intended recipient, you are
>>> hereby notified that any dissemination or copying of this communication
>>> is strictly prohibited. If this message contains non-public personal
>>> information about any consumer or customer of the sender or intended
>>> recipient, you are further prohibited under penalty of law from using
>>> or disclosing the information to any third party by provisions of the
>>> federal Gramm-Leach-Bliley Act. If you have received this electronic
>>> message in error, please immediately notify us by telephone and return
>>> or destroy the original message to assure that it is not read, copied,
>>> or distributed by others.
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>
>
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Re: [time-nuts] Crude Survey Technique

[Chris Albertson]

On Thu, Nov 21, 2013 at 11:11 AM, Don Latham  wrote:
> Lord no, John. No red wagon is needed. Use a pole and the equation of
> time, and a good watch or clock. At local noon, a shadow will be a n-s
> line.

How accurate do you need to be?   The above requires a very tall pole
to case a 300 foot long shadow.  Then you have to be quick to measure
because the Earth turns at  .25 degrees per minute.

If you need a very tall pole that is 100% vertical then hang a
weighted rope from a tall support.  Then go to the other end and watch
the seconds tick down.

A GOOD magnetic compass can do this job too.  Easier then finding s
1,000 food tall pole.   The better compasses have some kind of optical
aid for sighting a line.

-- 

Chris Albertson
Redondo Beach, California
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[time-nuts] Isolation achieved by opamp based isoamp?

[cdelect]

Try looking here.

http://www.cliftonlaboratories.com/z1_buffer_amp.htm

This opamp buffer has 80-90db isolation.

Corby

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Re: [time-nuts] Crude Survey Technique

[Chris Albertson]

On Thu, Nov 21, 2013 at 12:45 PM,   wrote:
> If you want true north, set up a camera that has time or bulb shutter at the 
> south end of your property. Put in a marker stake. take a time exposure at 
> night with the camera facing north. If you expose for about 30 minutes, you 
> will get a landscape with the stars rotating around the north star. You can 
> then mark the north location on your property under the north star.

I vote this suggestion as the winner.  The north ster is offset a
little from the pole but if will make an arc like the others and you
can find it's center.  This method could get you to better than a
degree..
-- 

Chris Albertson
Redondo Beach, California
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[time-nuts] Isolation achieved by opamp based isoamp?

[Stephan Sandenbergh]

Hi,

I'm curious about the level of isolation that is achieved by an opamp based
isoamp. I'm referring to ones described here on Bruce Griffiths' page:
http://www.ko4bb.com/~bruce/IsolationAmplifiers.html

Anyone has a number for this?

I've tried googling it, but the results are mostly filled with the other
kind of iso amplifier where isolation refers to galvanic isolation.

Regards,

Stephan.
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Re: [time-nuts] Crude Survey Technique

[J. Forster]

As I said before, the RA and Dec of Polaris is well known.

Spherical trig and the Siderial Time will give you the offset from the
true pole in Az and El.

With corrections for refraction, this is good to better than an arc-second.

-John

==




> On Thu, Nov 21, 2013 at 12:45 PM,   wrote:
>> If you want true north, set up a camera that has time or bulb shutter at
>> the south end of your property. Put in a marker stake. take a time
>> exposure at night with the camera facing north. If you expose for about
>> 30 minutes, you will get a landscape with the stars rotating around the
>> north star. You can then mark the north location on your property under
>> the north star.
>
> I vote this suggestion as the winner.  The north ster is offset a
> little from the pole but if will make an arc like the others and you
> can find it's center.  This method could get you to better than a
> degree..
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Bob Camp]

Hi

The counter and offset generator both should be quite accurate at a 1 us 
offset. That’s large enough that you are outside the range of most GPS jumps. 
If you are going to move things around, you might as well move out to that 
vicinity.

Bob

On Nov 21, 2013, at 6:20 AM, Tom Van Baak  wrote:

>> Below is a plot so you could see exactly what I measured. What is peculiar
>> is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS
>> receiver decides to offset the time by twice the amount I set it to. Which
>> is why I initially thought it might be a firmware thing. I suppose
>> multipath is a good explanation, it is just odd that the time error is
>> exactly 100ns.
> 
> Hi Stephan,
> 
> A quick test you could perform is set the offset to 125 ns instead of 100 ns 
> and see if the jumps still occur, still occur at 100 ns, or now occur at 125 
> ns.
> 
> Since you have three M12's offset the third one by 150 ns and see if it 
> experiences jumps too.
> 
> Question -- are you using the external 10 MHz reference input or output for 
> any of your 53131A counters?
> 
> /tvb
> 
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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Azelio Boriani]

Yes, do not use tiny offsets, go to 1us: I use microseconds offsets to
take PPSes measurements .

On Thu, Nov 21, 2013 at 1:34 PM, Bob Camp  wrote:
> Hi
>
> The counter and offset generator both should be quite accurate at a 1 us 
> offset. That’s large enough that you are outside the range of most GPS jumps. 
> If you are going to move things around, you might as well move out to that 
> vicinity.
>
> Bob
>
> On Nov 21, 2013, at 6:20 AM, Tom Van Baak  wrote:
>
>>> Below is a plot so you could see exactly what I measured. What is peculiar
>>> is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS
>>> receiver decides to offset the time by twice the amount I set it to. Which
>>> is why I initially thought it might be a firmware thing. I suppose
>>> multipath is a good explanation, it is just odd that the time error is
>>> exactly 100ns.
>>
>> Hi Stephan,
>>
>> A quick test you could perform is set the offset to 125 ns instead of 100 ns 
>> and see if the jumps still occur, still occur at 100 ns, or now occur at 125 
>> ns.
>>
>> Since you have three M12's offset the third one by 150 ns and see if it 
>> experiences jumps too.
>>
>> Question -- are you using the external 10 MHz reference input or output for 
>> any of your 53131A counters?
>>
>> /tvb
>>
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>
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[time-nuts] Upcoming Loran shutdown

[Rich and Marcia Putz]

Loran followers;

This test period is scheduled to end sometime on the 22nd, so don't panic when 
it disappears!  Also on the X secondary a message is being sent on the 9th 
pulse for those with a scope attached. 

Regards;

Rich
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Re: [time-nuts] Isolation achieved by opamp based isoamp?

[J. Forster]

A good transformer has very high CMRR. The purpose of the interwinding
shield is to prevent CM on the input swide, coupling through to the buffer
input, and yes, it should be well grounded. However, even if the shield is
not perfectly grounded, it greatly reduces the interwinding coupling
capacitance. Model it as a C-L reactive voltage divider.

-John

=



> One thing to keep in mind is that isolation through shielding usually
> results in much greater capacitance to ground (actually to the shield)
> from
> both input and output windings.
>
> Therefore, the actual isolation in practice is totally driven by how good
> the ground to the shield is.
>
> At RF, any inductance in series with the shield's connection to ground
> will
> degrade the isolation. Not a problem at 60Hz, but certainly a problem as
> the frequency gets higher.
>
> Didier KO4BB
>
>
>
>
> On Thu, Nov 21, 2013 at 8:28 AM, J. Forster  wrote:
>
>> Looking quickly at the prints on the site, the isolation is provided by
>> the transformer, not the active circuitry. The transistors/op-amps are
>> just buffers for the output.
>>
>> That means that the isolation is determined, for the most part, by the
>> transformer design, so:
>>
>>  A bifilar wound torroid would have relatively poor isolation,
>>  Two windings on opposite ends of a ferrite rod much better.
>>
>> Some (power line) ultra-isolation transformers have a shield between the
>> primary and secondary, and I don't see any reason that could not be done
>> at RF. The objective is, of course, to minimize the capacitance between
>> the windings. Topaz got 0.001 pF on a 1 kW unit as I remember.
>>
>> -John
>>
>> =
>>
>>
>>
>>
>>
>>
>> > Hi,
>> >
>> > I'm curious about the level of isolation that is achieved by an opamp
>> > based
>> > isoamp. I'm referring to ones described here on Bruce Griffiths' page:
>> > http://www.ko4bb.com/~bruce/IsolationAmplifiers.html
>> >
>> > Anyone has a number for this?
>> >
>> > I've tried googling it, but the results are mostly filled with the
>> other
>> > kind of iso amplifier where isolation refers to galvanic isolation.
>> >
>> > Regards,
>> >
>> > Stephan.
>> > ___
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>> > To unsubscribe, go to
>> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> > and follow the instructions there.
>> >
>> >
>>
>>
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>>
>


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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Tom Van Baak]

> The 100ns is exactly one cycle at 10 MHz.  GPS receivers use this, or 
> something very close, as an internal clock.

Joe,

The vintage Oncore VP used a 9.54 MHz clock (which is why its sawtooth is about 
+/- 52 ns).

Stephan is using the newer M12+T (~40 MHz clock, which is why its sawtooth is 
about +/- 13 ns).

A 100.0 ns offset is more likely something to do with 10.00 MHz, which is why I 
suspect connections and settings of the 53131A counter.

/tvb


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Re: [time-nuts] Crude Survey Technique

[quartz55]

I've done this and your best option is to go out at night with a home made 
tripod, plumb bob and sight from one place to another with polaris and the 
plumb bob string.  The farther the better, then keep your reference points with 
a couple of iron posts. You will be well  under 1/2 deg and probably within 
10ths.  Mind you, it won't line up with the survey markers on your property 
survey.  I have 3 different maps of mine and all the county wants is closure on 
the property lines, they don't care if you use magnetic north or true north or 
your own system.  My house is lined up this way, I have clerestory windows and 
I've set up the overhang to let the sun come in on the vernal equinox and leave 
on the autumnal equinox.  I did it with drawings and it worked out to the day.

Dave
N3DT
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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Joseph Gwinn]

On Thu, 21 Nov 2013 03:55:57 -0500, time-nuts-requ...@febo.com wrote:
time-nuts Digest, Vol 112, Issue 64
> 
> Message: 6
> Date: Thu, 21 Nov 2013 10:49:43 +0200
> From: Stephan Sandenbergh 
> To: Discussion of precise time and frequency measurement
>   
> Subject: Re: [time-nuts] Strange 100ns jumps on Motorola M12+T
> Message-ID:
>   
> Content-Type: text/plain; charset="utf-8"
> 
> Hi,
> 
> I'm using three Motorola GPS Timing 2000 Antennas. They are co-located on
> the roof of our building with a clear view of the skies. The view is almost
> 360deg but a mountain is blocking off a small bit of it to the South-East
> side. I'd assume some multipath is possible, but I'd thought that the deep
> valleys between the buildings would get rid of most of it, with only the
> reflections from the roof top etc remaining.
> 
> My latitude is South 33deg.
> 
> Yes I'm using one GPS as reference and the others are DUTs. Since, 
> the HP53131A
> TICs don't measure negative time (i.e. event on channel2 happens before
> event on channel1) I purposely offset the reference GPS by 100ns. Thus, I
> could measure negative time by later subtracting the 100ns in
> post-processing.
> 
> Below is a plot so you could see exactly what I measured. What is peculiar
> is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS
> receiver decides to offset the time by twice the amount I set it to. Which
> is why I initially thought it might be a firmware thing. I suppose
> multipath is a good explanation, it is just odd that the time error is
> exactly 100ns.
> 
>  URL: 
<http://www.febo.com/pipermail/time-nuts/attachments/20131121/218b90fa/attachment.png>
>
> Using a single antenna and splitting it is an idea, but then I still need
> to devise something to inject the antenna DC power at the other end of the
> splitter etc. And, we are trying to measure the relative offset between the
> antenna/receiver pairs for calibration.
> 
> Thanks for the suggestions so far.

The 100ns is exactly one cycle at 10 MHz.  GPS receivers use this, or 
something very close, as an internal clock.

I bet that the receiver is going in and out of lock, or is hovering 
right on the edge.

What kind of signal strength and number of satellites tracked are you 
seeing?  Plotting this along with the offset plot may be instructive.  
By the way, it may be that a reference receiver is jumping, not the 
receiver under test.

Joe Gwinn
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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Bob Camp]

Hi

To be clear - the idea of going to a non-100 ns multiple is a good one. You 
probably should avoid multiples of 1/10.24 MHz as well.

Bob

On Nov 21, 2013, at 8:00 AM, Azelio Boriani  wrote:

> Yes, do not use tiny offsets, go to 1us: I use microseconds offsets to
> take PPSes measurements .
> 
> On Thu, Nov 21, 2013 at 1:34 PM, Bob Camp  wrote:
>> Hi
>> 
>> The counter and offset generator both should be quite accurate at a 1 us 
>> offset. That’s large enough that you are outside the range of most GPS 
>> jumps. If you are going to move things around, you might as well move out to 
>> that vicinity.
>> 
>> Bob
>> 
>> On Nov 21, 2013, at 6:20 AM, Tom Van Baak  wrote:
>> 
 Below is a plot so you could see exactly what I measured. What is peculiar
 is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS
 receiver decides to offset the time by twice the amount I set it to. Which
 is why I initially thought it might be a firmware thing. I suppose
 multipath is a good explanation, it is just odd that the time error is
 exactly 100ns.
>>> 
>>> Hi Stephan,
>>> 
>>> A quick test you could perform is set the offset to 125 ns instead of 100 
>>> ns and see if the jumps still occur, still occur at 100 ns, or now occur at 
>>> 125 ns.
>>> 
>>> Since you have three M12's offset the third one by 150 ns and see if it 
>>> experiences jumps too.
>>> 
>>> Question -- are you using the external 10 MHz reference input or output for 
>>> any of your 53131A counters?
>>> 
>>> /tvb
>>> 
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>> 
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Re: [time-nuts] Isolation achieved by opamp based isoamp?

[Charles Steinmetz]

Corby wrote:


This opamp buffer has 80-90db isolation.


That is typical at 5 to 10 MHz *if* (i) all of the splitting is done 
on the input side (i.e., each output has its own op amp), and (ii) 
the splitter and all of the construction (grounds, shielding, etc.) 
is done correctly.


If any splitting is done on the output side of the op amp(s), by 
using one op amp to drive more than one output through separate back 
terminating resistors, the outputs that share an op amp will only be 
isolated by 30 to maybe 40 dB (again, assuming that the op amp has 
been well chosen and all of the construction is done correctly).


Best regards,

Charles



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[time-nuts] Off-Topic Question -- German Composition Resistors

[Brucekareen]

While tracing out a PC board from an instrument manufactured in Germany, I  
quickly discovered the color code on 1/4-watt composition resistors is not  
the same as that commonly used in the US  For example, I would measure  
about 10,000-ohms across a presumably good resistor that appeared to be marked  
2700-ohms.  Has/does Germany used a different code for such parts?
 
Bruce, KG6OJI 
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Re: [time-nuts] Crude Survey Technique

[Bill Beam]

On Thu, 21 Nov 2013 15:28:32 -0800, Chris Albertson wrote:

>If you need a very tall pole that is 100% vertical then hang a
>weighted rope from a tall support.  Then go to the other end and watch
>the seconds tick down.


Be carefull!...  A plumb bob does not hang vertically (point to center of 
Earth).
Since the suspension point is undergoing accelerated motion the bob will be
deflected toword the equator.  This problem also applies to bubble levels, etc.
And there are other perturbations due to Sun, Moon, Jupiter, etc. which are not 
constant.
Which leads to the question:  How to make the pole vertical?

Newtons laws are NOT valid in a noninertial frame.  (That's why the Coriolis 
force
was invented.)

Thus the term "rocket science".


Bill Beam
NL7F



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Re: [time-nuts] Crude Survey Technique

[Dale J. Robertson]

An interesting technique for improving the accuracy of single band gps is 
embodied in an open source program/project called rtklib.
Essentially it uses one GPS receiver in a fixed location that has been very 
carefully surveyed (gps reported location averaged over a long period) as a 
phase reference.
The roving receiver then uses the raw phase data from the base to subtract 
errors in the location of the rover.
10 cm accuracy is achievable in real time using consumer grade GPS 
receivers, though only a relative few provide the raw phase data required by 
the system. It is also possible to use one of the public internet feeds of 
gps phase data. The accuracy when using this approach depends on how close 
the reporting station is.
Of course in order to use this system in real time you need to establish 
connectivity between the base and rover. Simple WiFi should suffice for a 
couple hundred feet. 1200 baud packet would work for longer distances. A 
pair of u-blox lea-4t based gps receivers could be procured for under a 
hundred bucks.
I realize that this is gross overkill for the task at hand as there are 
tried and true (some might even pre-date christianity!) methods

available that would fit your needs.
Building this system is one of my 'time available' projects for the 
surveying of my property which covers 15 acres and has 16 corners.

Dale
NV8U

-Original Message- 
From: johncr...@aol.com

Sent: Thursday, November 21, 2013 1:52 PM
To: time-nuts@febo.com
Subject: [time-nuts] Crude Survey Technique

I wish to establish a north south line on my property to an accuracy of +/- 
2 degrees.
Could this be done by loading a T-bolt, Antenna, Power source, and laptop 
into my
little red wagon? The idea being to find two positions several hundred ft 
apart where either LH or T-bolt Mon report the same latitude? Will either of 
these programs report to sufficient accuracy? The base line would be 300 ft, 
though more is possible.I realizes that the T-bolt is not a survey device, 
but I can spend several hours fixing each position if required.


All comments appreciated.?? -73 john k6iql




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Re: [time-nuts] Crude Survey Technique

[Don Latham]

Coriolis ain't a force :-)
A real tall pole isn't required, just another person

Bill Beam
> On Thu, 21 Nov 2013 15:28:32 -0800, Chris Albertson wrote:
>
>>If you need a very tall pole that is 100% vertical then hang a
>>weighted rope from a tall support.  Then go to the other end and watch
>>the seconds tick down.
>
>
> Be carefull!...  A plumb bob does not hang vertically (point to center
> of Earth).
> Since the suspension point is undergoing accelerated motion the bob will
> be
> deflected toword the equator.  This problem also applies to bubble
> levels, etc.
> And there are other perturbations due to Sun, Moon, Jupiter, etc. which
> are not constant.
> Which leads to the question:  How to make the pole vertical?
>
> Newtons laws are NOT valid in a noninertial frame.  (That's why the
> Coriolis force
> was invented.)
>
> Thus the term "rocket science".
>
>
> Bill Beam
> NL7F
>
>
>
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> 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.
>
>


-- 
"The power of accurate observation is commonly called cynicism by those
who have not got it."
 -George Bernard Shaw


Dr. Don Latham AJ7LL
Six Mile Systems LLC
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
Skype: buffler2
www.lightningforensics.com
www.sixmilesystems.com


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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Chris Albertson]

On Thu, Nov 21, 2013 at 12:49 AM, Stephan Sandenbergh
 wrote:
...
> Using a single antenna and splitting it is an idea, but then I still need
> to devise something to inject the antenna DC power at the other end of the
> splitter etc. And, we are trying to measure the relative offset between the
> antenna/receiver pairs for calibration.

Many splitters have a DC passthrough.  Even some cheap under $10
satellite TV splitters have this.
>From memory, I think you can disable the antenna supply on the Oncore,
you don't want all three GPSes trying to supply DC power.

I looked at the graph.  It is such a clean jump that I doubt this is
noise at the antenna.  Also it looks like 50nS of noise.  Seems to
much for an MT12-T.   Are they running in position hold mode?   Did
you do a long enough site survey?
-- 

Chris Albertson
Redondo Beach, California
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[time-nuts] Crude Survey Technique

[johncroos]

 I wish to establish a north south line on my property to an accuracy of +/- 2 
degrees.
Could this be done by loading a T-bolt, Antenna, Power source, and laptop into 
my
little red wagon? The idea being to find two positions several hundred ft apart 
where either LH or T-bolt Mon report the same latitude? Will either of these 
programs report to sufficient accuracy? The base line would be 300 ft, though 
more is possible.I realizes that the T-bolt is not a survey device, but I can 
spend several hours fixing each position if required. 

All comments appreciated.?? -73 john k6iql


 

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Re: [time-nuts] Crude Survey Technique

[Bill Beam]

That's my point.  'Coriolis force' was invented to make it appear that Newtons 
laws
were valid in an Earth based frame.


On Thu, 21 Nov 2013 18:06:54 -0700, Don Latham wrote:

>Coriolis ain't a force :-)

>>
>> Newtons laws are NOT valid in a noninertial frame.  (That's why the
>> Coriolis force
>> was invented.)
>>


Bill Beam
NL7F



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Re: [time-nuts] Crude Survey Technique

[Jim Lux]

On 11/21/13 3:28 PM, Chris Albertson wrote:

On Thu, Nov 21, 2013 at 11:11 AM, Don Latham  wrote:

Lord no, John. No red wagon is needed. Use a pole and the equation of
time, and a good watch or clock. At local noon, a shadow will be a n-s
line.


How accurate do you need to be?   The above requires a very tall pole
to case a 300 foot long shadow.  Then you have to be quick to measure
because the Earth turns at  .25 degrees per minute.


The original request was for "accurate to a degree or two", so he has 
4-8 minutes to make the measurement.


The sun is 1/2 degree wide, which is actually the practical challenge in 
measuring using shadows, because the shadow is not sharp edged.


I don't know why you need a 300 foot long shadow.

Let's assume I have a 1 meter tall rod that is 1cm in diameter.
The sun isn't that high in the sky at noon these days (in the Northern 
Hemisphere).. let's say it's about 45 degrees, so the 1 meter long stick 
casts a shadow that is 1 meter long.  If the sun were a point source, 
the shadow would be 1 cm wide, or 1 part in 1/100 which is about half a 
degree.  That's comparable to the width of the sun, so you might want to 
choose a "bigger stick".  maybe a 2" piece of pipe?  estimate the center 
of the shadow, which could easily be done within 1/2".


You now have your north direction.

Solar noon is trivial to find out.  The USNO Astronomical Applications 
page will give you a solar ephemeris for a specified lat/lon.  or 
knowing your longitude and applying the equation of time, you can 
calculate when solar noon is.


Or, whip out your current copy of the Nautical Almanac






If you need a very tall pole that is 100% vertical then hang a
weighted rope from a tall support.  Then go to the other end and watch
the seconds tick down.

A GOOD magnetic compass can do this job too.  Easier then finding s
1,000 food tall pole.   The better compasses have some kind of optical
aid for sighting a line.




Getting 1 degree accuracy with a magnetic compass is challenging. 
Finding out the *current* magnetic variation is only part of the 
challenge, because it varies (about 1 degree in 10 years in Southern 
California, last I checked).

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Re: [time-nuts] DIY antenna

[Alain2_4GBC]

Hi Dave,
your antenna is somehow surprising to me.
If you do not want to have a large band of frequencies, you can adapt the 
two loops of this QFH (in the band of doppler effect naturally), at the same 
GPS frequency; if think this will improve the gain.
I do not see how do you realised the isolation of the hot point of the 
loops. All seems to me made of copper...

Alain
F4GBC
i apologies for my bad english.


-Message d'origine- 
From: quartz55

Sent: Wednesday, November 20, 2013 11:34 PM
To: time-nuts@febo.com
Subject: [time-nuts] DIY antenna

Haven't seen this posted in the past, but I haven't seen everything. 
Anyhow, it appears to work as good signal strength wise as the PCTEL antenna 
I got with this Nortel unit.  Of course it needs to be installed in some PVC 
or similar.  The chip was only about $3 from mouser (MAALSS0042-38878), I've 
got maybe 5 more and I made the board by trimming a single sided board with 
exacto knife.  I'm going to try another and get the elements more precise, 
these are somewhat not round and of not equal lengths, plus I'm going to run 
some coax through a piece of brass tubing as an infinite balun, but I'm not 
expecting to see any or much improvement.  This one is made from semi rigid 
line, thanks Jim.  It was easy enough to do, just very detailed soldering 
and my soldering tools are really not small enough to work on these surface 
mount devices.  So far I've only used it sitting on the deck railing which 
is not a great location, but then I don't have any great locations for GPS 
antennas.


This is after I re-worked it, originally it didn't work very good, I think 
some of my solder joints weren't good, it's so hard to see.  I have to use 
one of those headband things with all the mag to see the details and it's 
impossible to solder on it with the headband mag.  I use a large magnifier 
with the round fluorescent tube around it.


http://i251.photobucket.com/albums/gg287/DogTi/time/diyant_zps7849aa73.jpg

Dave
N3DT
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Re: [time-nuts] Crude Survey Technique

[Brian Lloyd]

On Thu, Nov 21, 2013 at 12:52 PM,  wrote:

>  I wish to establish a north south line on my property to an accuracy of
> +/- 2 degrees.
> Could this be done by loading a T-bolt, Antenna, Power source, and laptop
> into my
> little red wagon? The idea being to find two positions several hundred ft
> apart where either LH or T-bolt Mon report the same latitude? Will either
> of these programs report to sufficient accuracy? The base line would be 300
> ft, though more is possible.I realizes that the T-bolt is not a survey
> device, but I can spend several hours fixing each position if required.
>

True north or magnetic north? In any case, a good lensatic compass and
knowing your magnetic variation should easily get you to within 2 degrees
and is a lot easier than doing a survey with your GPS.


-- 
Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070
br...@lloyd.com
+1.916.877.5067
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Re: [time-nuts] Isolation achieved by opamp based isoamp?

[J. Forster]

Looking quickly at the prints on the site, the isolation is provided by
the transformer, not the active circuitry. The transistors/op-amps are
just buffers for the output.

That means that the isolation is determined, for the most part, by the
transformer design, so:

 A bifilar wound torroid would have relatively poor isolation,
 Two windings on opposite ends of a ferrite rod much better.

Some (power line) ultra-isolation transformers have a shield between the
primary and secondary, and I don't see any reason that could not be done
at RF. The objective is, of course, to minimize the capacitance between
the windings. Topaz got 0.001 pF on a 1 kW unit as I remember.

-John

=






> Hi,
>
> I'm curious about the level of isolation that is achieved by an opamp
> based
> isoamp. I'm referring to ones described here on Bruce Griffiths' page:
> http://www.ko4bb.com/~bruce/IsolationAmplifiers.html
>
> Anyone has a number for this?
>
> I've tried googling it, but the results are mostly filled with the other
> kind of iso amplifier where isolation refers to galvanic isolation.
>
> Regards,
>
> Stephan.
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>


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Re: [time-nuts] Strange 100ns jumps on Motorola M12+T

[Stephan Sandenbergh]

Hi,

Bjorn, it is good to know such splitter devices exist. This is really neat.

I'm using the built-in offset function of the M12+, and not an offset
generator. I'm currently redoing the measurement to see if it has similar
issues. And yes, I was also interested to see what would happen at other
offsets. And, if all of them would do it. I'll post when I get the results.

At the moment, I don't have something stable to serve as reference for the
53131As so I use the 10MHz output of the one as reference for the other. At
least they are locked together.




On 21 November 2013 14:34, Bob Camp  wrote:

> Hi
>
> The counter and offset generator both should be quite accurate at a 1 us
> offset. That’s large enough that you are outside the range of most GPS
> jumps. If you are going to move things around, you might as well move out
> to that vicinity.
>
> Bob
>
> On Nov 21, 2013, at 6:20 AM, Tom Van Baak  wrote:
>
> >> Below is a plot so you could see exactly what I measured. What is
> peculiar
> >> is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS
> >> receiver decides to offset the time by twice the amount I set it to.
> Which
> >> is why I initially thought it might be a firmware thing. I suppose
> >> multipath is a good explanation, it is just odd that the time error is
> >> exactly 100ns.
> >
> > Hi Stephan,
> >
> > A quick test you could perform is set the offset to 125 ns instead of
> 100 ns and see if the jumps still occur, still occur at 100 ns, or now
> occur at 125 ns.
> >
> > Since you have three M12's offset the third one by 150 ns and see if it
> experiences jumps too.
> >
> > Question -- are you using the external 10 MHz reference input or output
> for any of your 53131A counters?
> >
> > /tvb
> >
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[time-nuts] Crude Survey Technique

[Arthur Dent]

Brooke Clarke wrote: "Most low cost hand held and car GPS receivers can only 
display direction 
based on changes in position." 

True, but the Garmin 62s handheld that I use for geocaching and hiking 
($200-$400) has a 
3-axis, tilt-compensated electronic compass that shows your heading even when 
you're 
standing still and holding the unit upright or at an angle. Accuracy is +/-2° 
except 
near the poles where it is +/-5° . My Casio watch on the other hand is +/-11°, 
if you 
hold it level.

-Arthur
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[time-nuts] Off-Topic Question -- German Composition Resistors

[Brucekareen]

My sincere thanks to those who responded to my request for help.  
 
The link to a chart provided by Ernie allowed me to recognize I was  
looking at five-stripe resistors with three significant figure stripes  
followed 
by a multiplier stripe and spaced a little further away a red stripe  
indicating two-percent tolerance.  Otherwise, they looked like conventional  
1/4-watt composition resistors. 
 
I have never encountered five stripe resistors before!
 
Bruce
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Re: [time-nuts] Crude Survey Technique

[Neville Michie]

How do the car mounted GPS guidance devices find North?
Is it by deciding which direction you are moving on the map that they have 
stored?
It is amazing how quickly they show the orientation of the map/your direction 
of travel.
Do they have a sensor to register when you turn a corner?
What they do does not seem possible from just a series of position fixes.
cheers,
Neville Michie





On 22/11/2013, at 7:45 AM,  wrote:

> If you want true north, set up a camera that has time or bulb shutter at the 
> south end of your property. Put in a marker stake. take a time exposure at 
> night with the camera facing north. If you expose for about 30 minutes, you 
> will get a landscape with the stars rotating around the north star. You can 
> then mark the north location on your property under the north star.
> 
> A compass siting can give the mag north.
> 
> 
> From: time-nuts-boun...@febo.com  on behalf of 
> Brian Lloyd 
> Sent: Thursday, November 21, 2013 2:04 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Crude Survey Technique
> 
> On Thu, Nov 21, 2013 at 12:52 PM,  wrote:
> 
>> I wish to establish a north south line on my property to an accuracy of
>> +/- 2 degrees.
>> Could this be done by loading a T-bolt, Antenna, Power source, and laptop
>> into my
>> little red wagon? The idea being to find two positions several hundred ft
>> apart where either LH or T-bolt Mon report the same latitude? Will either
>> of these programs report to sufficient accuracy? The base line would be 300
>> ft, though more is possible.I realizes that the T-bolt is not a survey
>> device, but I can spend several hours fixing each position if required.
>> 
> 
> True north or magnetic north? In any case, a good lensatic compass and
> knowing your magnetic variation should easily get you to within 2 degrees
> and is a lot easier than doing a survey with your GPS.
> 
> 
> --
> Brian Lloyd, WB6RQN/J79BPL
> 706 Flightline Drive
> Spring Branch, TX 78070
> br...@lloyd.com
> +1.916.877.5067
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> CONFIDENTIALITY NOTICE: The information contained in this electronic message 
> is confidential information intended for the use of the individual or entity 
> named above. If the reader of this message is not the intended recipient, or 
> an employee or agent responsible for delivering this electronic message to 
> the intended recipient, you are hereby notified that any dissemination or 
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> contains non-public personal information about any consumer or customer of 
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Re: [time-nuts] Crude Survey Technique

[TMiller]

If you want true north, set up a camera that has time or bulb shutter at the 
south end of your property. Put in a marker stake. take a time exposure at 
night with the camera facing north. If you expose for about 30 minutes, you 
will get a landscape with the stars rotating around the north star. You can 
then mark the north location on your property under the north star.

A compass siting can give the mag north.


From: time-nuts-boun...@febo.com  on behalf of 
Brian Lloyd 
Sent: Thursday, November 21, 2013 2:04 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Crude Survey Technique

On Thu, Nov 21, 2013 at 12:52 PM,  wrote:

>  I wish to establish a north south line on my property to an accuracy of
> +/- 2 degrees.
> Could this be done by loading a T-bolt, Antenna, Power source, and laptop
> into my
> little red wagon? The idea being to find two positions several hundred ft
> apart where either LH or T-bolt Mon report the same latitude? Will either
> of these programs report to sufficient accuracy? The base line would be 300
> ft, though more is possible.I realizes that the T-bolt is not a survey
> device, but I can spend several hours fixing each position if required.
>

True north or magnetic north? In any case, a good lensatic compass and
knowing your magnetic variation should easily get you to within 2 degrees
and is a lot easier than doing a survey with your GPS.


--
Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070
br...@lloyd.com
+1.916.877.5067
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CONFIDENTIALITY NOTICE: The information contained in this electronic message is 
confidential information intended for the use of the individual or entity named 
above. If the reader of this message is not the intended recipient, or an 
employee or agent responsible for delivering this electronic message to the 
intended recipient, you are hereby notified that any dissemination or copying 
of this communication is strictly prohibited. If this message contains 
non-public personal information about any consumer or customer of the sender or 
intended recipient, you are further prohibited under penalty of law from using 
or disclosing the information to any third party by provisions of the federal 
Gramm-Leach-Bliley Act. If you have received this electronic message in error, 
please immediately notify us by telephone and return or destroy the original 
message to assure that it is not read, copied, or distributed by others.
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Re: [time-nuts] Crude Survey Technique

[Don Latham]

John: for local noon:
http://education.illinois.edu/noon-project/noontime.html

Don
johncr...@aol.com
>  I wish to establish a north south line on my property to an accuracy of
> +/- 2 degrees.
> Could this be done by loading a T-bolt, Antenna, Power source, and
> laptop into my
> little red wagon? The idea being to find two positions several hundred
> ft apart where either LH or T-bolt Mon report the same latitude? Will
> either of these programs report to sufficient accuracy? The base line
> would be 300 ft, though more is possible.I realizes that the T-bolt is
> not a survey device, but I can spend several hours fixing each position
> if required.
>
> All comments appreciated.?? -73 john k6iql
>
>
>
>
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> and follow the instructions there.
>
>


-- 
"The power of accurate observation is commonly called cynicism by those
who have not got it."
 -George Bernard Shaw


Dr. Don Latham AJ7LL
Six Mile Systems LLC
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
Skype: buffler2
www.lightningforensics.com
www.sixmilesystems.com


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[time-nuts] OT: Putting the Wolfram Language (and Mathematica) on every Raspberry Pi

[David J Taylor]

Putting the Wolfram Language (and Mathematica) on every Raspberry Pi

 
http://blog.wolfram.com/2013/11/21/putting-the-wolfram-language-and-mathematica-on-every-raspberry-pi/

and it's free.

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 


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Re: [time-nuts] Off-Topic Question -- German Composition Resistors

[Erno Peres]

Hi Bruce,

sorry but the server removed the embedded pics.


here is a link

http://www.diyaudioandvideo.com/Electronics/Color/


Rgds Ernie.





-Original Message-
From: Brucekareen 
To: time-nuts 
Sent: Thu, Nov 21, 2013 7:17 pm
Subject: [time-nuts] Off-Topic Question -- German Composition Resistors


While tracing out a PC board from an instrument manufactured in Germany, I  
uickly discovered the color code on 1/4-watt composition resistors is not  
he same as that commonly used in the US  For example, I would measure  
bout 10,000-ohms across a presumably good resistor that appeared to be marked  
700-ohms.  Has/does Germany used a different code for such parts?

ruce, KG6OJI 
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Re: [time-nuts] Crude Survey Technique

[Poul-Henning Kamp]

In message <8d0b5020292d91e-cc0-4b...@webmail-vm026.sysops.aol.com>, johncroos@
aol.com writes:

> I wish to establish a north south line on my property to an
>accuracy of +/- 2 degrees.

First of all, at that level of precision you will have to decide what
you mean by "north south" ?

Magnetic ?  Geodetic ?  (if so: Which Datum ?)  Meridian ?

> The base line would be 300 ft

So your east-west precision needs to be tan(2)*300ft = 10.5 ft.

I don't think you can do that with a single band GPS.

If you can locate suitable landmarks, you may be able to do with
the arial photograph on maps.google.com (or similar servce) but
you need to get coordinates figured out (not trivial!)

I would raise a pole or other marker at one end (N or S), calculate
when a suitable celestial object crosses your designated line and
that to triangulate the opposite end.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | 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] Crude Survey Technique

[Chris Howard]

Southward (toward equator) deflection would actually improve
the geometry.  All non-north vectors would
be lengthened in proportion.




On 11/21/2013 6:37 PM, Bill Beam wrote:
> On Thu, 21 Nov 2013 15:28:32 -0800, Chris Albertson wrote:
> 
>> If you need a very tall pole that is 100% vertical then hang a
>> weighted rope from a tall support.  Then go to the other end and watch
>> the seconds tick down.
> 
> 
> Be carefull!...  A plumb bob does not hang vertically (point to center of 
> Earth).
> Since the suspension point is undergoing accelerated motion the bob will be
> deflected toword the equator.  This problem also applies to bubble levels, 
> etc.
> And there are other perturbations due to Sun, Moon, Jupiter, etc. which are 
> not constant.
> Which leads to the question:  How to make the pole vertical?
> 
> Newtons laws are NOT valid in a noninertial frame.  (That's why the Coriolis 
> force
> was invented.)
> 
> Thus the term "rocket science".
> 
> 
> Bill Beam
> NL7F
> 
> 
> 
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Re: [time-nuts] Upcoming Loran shutdown

[paul swed]

Rich as they say its been great while it lasted. Yes still on tonight and I
have checked my local references against it so I am good for another 6
months.
Good job on catching it in the first place.
How are you finding information like the test period will start or stop??
Regards
Paul
WB8TSL


On Thu, Nov 21, 2013 at 6:57 PM, Rich and Marcia Putz wrote:

> Loran followers;
>
> This test period is scheduled to end sometime on the 22nd, so don't panic
> when it disappears!  Also on the X secondary a message is being sent on the
> 9th pulse for those with a scope attached.
>
> Regards;
>
> Rich
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