[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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[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] Crude Survey Technique

[Dan Kemppainen]

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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] 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
>
>
>
>
> ___
> 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] 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] 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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> 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 
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> message in error, please immediately notify us by telephone and return or 
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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] 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
>> ___
>> 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

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

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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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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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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>


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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] 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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>


-- 
"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

[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] 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] 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 
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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 
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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
>
>
>
>
> ___
> 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] 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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> 
> 

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Re: [time-nuts] Crude Survey Technique

[Stephan Sandenbergh]

John,

We had a similar problem when we're trying to setup various antennas at
various locations pointing at different true North bearings. It turned out
quite hard to find true North.

We found single carrier GPS surveyed points to be inaccurate to produce
good bearings across such a short base line. Also, you'll end up with two
points with some bearing w.r.t. North. Now the problem is that of finding a
third point to give you your N-S base line.

In the end we used a tripod, calibrated gun sight and a turn table with
degrees markings (those that the photonics people use). If you'd like to
use this method, you survey a single point on your property (preferably on
the base line your interested in). Also survey a land mark, like a radio
mast a few km's away. The further away (the longer the base line) the less
accurate your surveyed points need to be. Now calculate the North
bearing of this base line using these two points. Now back at your property
at the surveyed point, point your cross hair at the radio mast and set the
number of degrees on the turn table to that you have calculated. Fix the
turn table. 0 degrees should now be true North, and you could now use the
cross hair to survey the other point.

The tripod should be levelled very carefully, since errors here will put
you in a different plane and you will end up calculating vector components
in that plane.



On 21 November 2013 20:52,  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.
>
> All comments appreciated.?? -73 john k6iql
>
>
>
>
> ___
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Re: [time-nuts] Crude Survey Technique

[Jim Lux]

On 11/21/13 11:32 PM, Robert Atkinson wrote:

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.


That compass is *precise* to 1/2 degree, but not *accurate* to 1/2 
degree. It comes with a calibration card, and is presumably used in a 
place with a uniform field (e.g. for calibrating an aircraft compass, 
which is done in an open area with no known magnetic anomalies).  If 
you're in a different environment, the card values may be incorrect.


It is essentially as "comparison standard".  You put it next to the 
aircraft and move both in a systematic pattern and you use it to 
"calibrate out" the variations in the plane's internal compass.


However you're going to be subject to the local magnetic field anomalies 
(and they're surprisingly large).


http://minerals.usgs.gov/news/newsletter/v1n2/3aeromag.html

On the 1km scale maps in the USGS reports, you can see magnetic 
anomalies of 500 nT.  Earth's field is about 30-60 microTesla, so these 
anomalies are in the "one part in 100" kind of range.  It is true that 
the gradient is fairly small: It is unlikely you have an anomaly of 500 
nT and your neighbor has -200 nT. But it's obvious that the magnetic 
variation (angle between true and indicated magnetic north) isn't the 
nice smooth surface implied by the map of variation you get with the 
compass.


http://dspace.sunyconnect.suny.edu/bitstream/handle/1951/47859/Winslow_MS.pdf;jsessionid=7D7A116045A54816C9DCF963AF3D2580?sequence=1

is a short paper that talks about gradients in a small scale anomaly of 
0.22 nT/meter  (and I get the impression that that is big).


There's also other locally produced magnetic fields you'd have to worry 
about.


I gave an E&M class a problem to figure out if you could tell whether 
you could use a hand compass to tell if the Pacific Intertie 1MV HVDC 
link (3000 A) was operating bipolar or unipolar. (at 50 meters, the 
field from one wire is about 6 microTesla, so yes, you can detect it)



http://msi.nga.mil/MSISiteContent/StaticFiles/HoMCA.pdf
is all about calibrating a ship's compass
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Re: [time-nuts] Crude Survey Technique

[johncroos]

 Stephen -


 [time-nuts] Crude Survey Technique

 

 Thanks for describing your method. I am learning a lot. here is agovt web site 
that will give the compass correction for any long and lat. Here in KS the 
magnetic pole is about 2.3 degrees to the east.

Once all the ideas are in, I will put together a summary.

I have a number of the required tools, compass, several T-bolts, surveyor's 
transit, tall poles, laser level, and bulls-eye levels.
So with all of these good ideas I am sure I will get it right. It will be 
interesting to cross check the various methods.

It also occurred to me that I could buy a 3 ft length of hardened steel 
shafting, wrap a couple of dozen turns of # 6 around it and then connect it to 
a big lead acid battery via a 200 Amp fuse. Should result in a 3 ft long 
compass needle. You only get to use the fuse once though!

Thanks to all  -john

 

-Original Message-
From: time-nuts-request 
To: time-nuts 
Sent: Fri, Nov 22, 2013 6:29 am
Subject: time-nuts Digest, Vol 112, Issue 75


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   1. Re: Motorola M12+ (Azelio Boriani)
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   3. Re: DMTD: Mixer DC offset will result in time offset at
  zero-crossing detector out? (Bruce Griffiths)
   4. Re: Crude Survey Technique (Stephan Sandenbergh)
   5. Re: Strange 100ns jumps on Motorola M12+T (Bob Camp)
   6. Re: DMTD: Mixer DC offset will result in time offset at
  zero-crossing detector out? (Stephan Sandenbergh)


--

Message: 1
Date: Fri, 22 Nov 2013 11:45:17 +0100
From: Azelio Boriani 
To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Motorola M12+
Message-ID:

Content-Type: text/plain; charset=ISO-8859-1

Strange item... it has an M12+ and a supporting board full of
components. Protocol translation from 12-channel to 8-channel? The
link to the PDF file returns a 404.

On Fri, Nov 22, 2013 at 9:32 AM, Pascual Arbona Lopez
 wrote:
> I am wondering if this is a sustitute of  the original oncore VP receiver for 
the Z3801 -Z3805. (E-pay 281161070304 )
> ___
> 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.


--

Message: 2
Date: Sat, 23 Nov 2013 00:18:50 +1300
From: Bruce Griffiths 
To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Isolation achieved by opamp based isoamp?
Message-ID: <528f3d9a.5090...@xtra.co.nz>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Stephan Sandenbergh wrote:
> Something that would be interesting to know is if certain opamps are better
> suited toward S12 isolation than others. I guess at the expense of noise
> floor and 1/f corner one could cascade two opamps to improve the S12
> isolation further.
>
>
The flicker noise corner of an opamp may be lower than you think.
Current feedback opamps may have higher flicker noise corners than volt 
feedback opamps
> As soon as you are looking at frequencies of 100MHz you are probably left
> with the discrete options in any way.
>
There are 1GHz and 10GHz opamps available.

Bruce
>
> On 22 November 2013 11:45, Stephan Sandenberghwrote:
>
>
>> Thanks for the spec. I suspected that it would be in that ball park.
>>
>> The discrete transistor type amplifiers achieve around 120dB or more at
>> 10MHz. But, they are a lot more effort to implement than the opamp designs.
>>
>> I believe the transformer in this case is for ground loop isolation rather
>> than S12 isolation.
>>
>>
>> On 21 November 2013 20:20, Charles Steinmetzwrote:
>>
>>  
>>> 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 d

Re: [time-nuts] Crude Survey Technique

[J. Forster]

If the telescope on your transit can go to your lattitude, sight Polaris
and you're done after a simple calculation.

-John



>
>  Stephen -
>
>
>  [time-nuts] Crude Survey Technique
>
>
>
>  Thanks for describing your method. I am learning a lot. here is agovt web
> site that will give the compass correction for any long and lat. Here in
> KS the magnetic pole is about 2.3 degrees to the east.
>
> Once all the ideas are in, I will put together a summary.
>
> I have a number of the required tools, compass, several T-bolts,
> surveyor's transit, tall poles, laser level, and bulls-eye levels.
> So with all of these good ideas I am sure I will get it right. It will be
> interesting to cross check the various methods.
>
> It also occurred to me that I could buy a 3 ft length of hardened steel
> shafting, wrap a couple of dozen turns of # 6 around it and then connect
> it to a big lead acid battery via a 200 Amp fuse. Should result in a 3 ft
> long compass needle. You only get to use the fuse once though!
>
> Thanks to all  -john
>
>
>
> -Original Message-
> From: time-nuts-request 
> To: time-nuts 
> Sent: Fri, Nov 22, 2013 6:29 am
> Subject: time-nuts Digest, Vol 112, Issue 75
>
>
> Send time-nuts mailing list submissions to
>   time-nuts@febo.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
>   https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> or, via email, send a message with subject or body 'help' to
>   time-nuts-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: Motorola M12+ (Azelio Boriani)
>2. Re: Isolation achieved by opamp based isoamp? (Bruce Griffiths)
>3. Re: DMTD: Mixer DC offset will result in time offset at
>   zero-crossing detector out? (Bruce Griffiths)
>4. Re: Crude Survey Technique (Stephan Sandenbergh)
>5. Re: Strange 100ns jumps on Motorola M12+T (Bob Camp)
>6. Re: DMTD: Mixer DC offset will result in time offset at
>   zero-crossing detector out? (Stephan Sandenbergh)
>
>
> --
>
> Message: 1
> Date: Fri, 22 Nov 2013 11:45:17 +0100
> From: Azelio Boriani 
> To: Discussion of precise time and frequency measurement
>   
> Subject: Re: [time-nuts] Motorola M12+
> Message-ID:
>   
> Content-Type: text/plain; charset=ISO-8859-1
>
> Strange item... it has an M12+ and a supporting board full of
> components. Protocol translation from 12-channel to 8-channel? The
> link to the PDF file returns a 404.
>
> On Fri, Nov 22, 2013 at 9:32 AM, Pascual Arbona Lopez
>  wrote:
>> I am wondering if this is a sustitute of  the original oncore VP
>> receiver for
> the Z3801 -Z3805. (E-pay 281161070304 )
>> ___
>> 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.
>
>
> --
>
> Message: 2
> Date: Sat, 23 Nov 2013 00:18:50 +1300
> From: Bruce Griffiths 
> To: Discussion of precise time and frequency measurement
>   
> Subject: Re: [time-nuts] Isolation achieved by opamp based isoamp?
> Message-ID: <528f3d9a.5090...@xtra.co.nz>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Stephan Sandenbergh wrote:
>> Something that would be interesting to know is if certain opamps are
>> better
>> suited toward S12 isolation than others. I guess at the expense of noise
>> floor and 1/f corner one could cascade two opamps to improve the S12
>> isolation further.
>>
>>
> The flicker noise corner of an opamp may be lower than you think.
> Current feedback opamps may have higher flicker noise corners than volt
> feedback opamps
>> As soon as you are looking at frequencies of 100MHz you are probably
>> left
>> with the discrete options in any way.
>>
> There are 1GHz and 10GHz opamps available.
>
> Bruce
>>
>> On 22 November 2013 11:45, Stephan
>> Sandenberghwrote:
>>
>>
>>> Thanks for the spec. I suspected that it would be in that ball park.
>>>
>>> The discrete transistor type amplifiers achieve around 120dB or more at
>>> 10MHz. But, they are a lot more effort to implement than the opamp
>>> designs.
>>>
>>> I believe

Re: [time-nuts] Crude Survey Technique

[Robert Atkinson]

Hi Jim,
I disagree, the Medium Landing Compass IS accurate to better than 30 minutes 
(0.5deg). This is also the smallest graduation so it can be read to better than 
15 minutes. The calibration chart is given to 10 minutes every 15 degrees. It 
does of course indicate the orientation of the local magnetic field. To ensure 
there is no local distortions you need to do a site survey. This can be 
acheived by comparing bearings to a distant object along a baseline or taking 
reciprical bearings. CAA CAP562 part 8 leaflet 1 
http://www.helitavia.com/docs/CAP562_2007_08.pdf  
has lots of good info.

(full version here http://www.caa.co.uk/docs/33/CAP562RFS.pdf  large file over 
10MB)

Robert G8RPI (CEng, licenced aircraft engineer for 30 years, I've done many 
aircraft swings)  




 From: Jim Lux 
To: time-nuts@febo.com 
Sent: Friday, 22 November 2013, 14:25
Subject: Re: [time-nuts] Crude Survey Technique
 

On 11/21/13 11:32 PM, Robert Atkinson wrote:
> 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.

That compass is *precise* to 1/2 degree, but not *accurate* to 1/2 
degree. It comes with a calibration card, and is presumably used in a 
place with a uniform field (e.g. for calibrating an aircraft compass, 
which is done in an open area with no known magnetic anomalies).  If 
you're in a different environment, the card values may be incorrect.

It is essentially as "comparison standard".  You put it next to the 
aircraft and move both in a systematic pattern and you use it to 
"calibrate out" the variations in the plane's internal compass.

However you're going to be subject to the local magnetic field anomalies 
(and they're surprisingly large).

http://minerals.usgs.gov/news/newsletter/v1n2/3aeromag.html

On the 1km scale maps in the USGS reports, you can see magnetic 
anomalies of 500 nT.  Earth's field is about 30-60 microTesla, so these 
anomalies are in the "one part in 100" kind of range.  It is true that 
the gradient is fairly small: It is unlikely you have an anomaly of 500 
nT and your neighbor has -200 nT. But it's obvious that the magnetic 
variation (angle between true and indicated magnetic north) isn't the 
nice smooth surface implied by the map of variation you get with the 
compass.

http://dspace.sunyconnect.suny.edu/bitstream/handle/1951/47859/Winslow_MS.pdf;jsessionid=7D7A116045A54816C9DCF963AF3D2580?sequence=1

is a short paper that talks about gradients in a small scale anomaly of 
0.22 nT/meter  (and I get the impression that that is big).

There's also other locally produced magnetic fields you'd have to worry 
about.

I gave an E&M class a problem to figure out if you could tell whether 
you could use a hand compass to tell if the Pacific Intertie 1MV HVDC 
link (3000 A) was operating bipolar or unipolar. (at 50 meters, the 
field from one wire is about 6 microTesla, so yes, you can detect it)


http://msi.nga.mil/MSISiteContent/StaticFiles/HoMCA.pdf
is all about calibrating a ship's compass
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Re: [time-nuts] Crude Survey Technique

[Brian Lloyd]

On Friday, November 22, 2013, J. Forster wrote:

> If the telescope on your transit can go to your lattitude, sight Polaris
> and you're done after a simple calculation.


This is the simplest high-accuracy solution. Celestial navigation is your
friend.

A magnetic compass is the simplest solution. Magnetic variation is found on
all VFR aviation navigation charts.

2 degrees is an interesting number. It seems either too accurate or not
accurate enough for most applications I can think of.





-- 
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] Crude Survey Technique

[johncroos]

 Hello and thanks to all for the great ideas.


Re: [time-nuts] Crude Survey Technique

 

 Some interim comments:

*agree with regard to using pole star. However it is below freezing here and so 
I won't be out in the dark with my camera. A good verification technique that 
must await warmer weather!!

*thanks for the suggestion re. the transit. Unfortunately the elevation 
measurement only goes to 30 degrees and I am at 38.7 degrees latitude. I should 
have bought the one with more elevation range and a built in precision compass. 
Still might do that.

*I have a Stocker and Yale Army compass - nice thing but 2 degrees is probabily 
beyond its capability except as a sanity check 

*Forced my T-bolt to find itself 9 times in the last 24 hours:
Average Longitude : -94.70983
Extreme Spread :90 degrees
Standard Devation : 2.58 e-5 degrees

At my latitude 1 degree is 285,402.9 Ft
So the error at 1 standard deviation is 7.4 ft.
Who ever guessed 10 ft has achieved GURU status.

So doing the ATAN at various ranges we get

200 ft  2.12 degrees
400 ft  1.06 degrees
600ft  0.71 degrees.

400 ft is easy and 600 is possible. However the sun shadow method seems an 
equally good approach.

Question - If I use 3 T-bolts on the same antenna, feedline, splitter etc. and 
run 3 instances of T-bolt mon - can the results be improved???

Thanks for all the help   - john k6iql





 

-Original Message-
From: time-nuts-request 
To: time-nuts 
Sent: Fri, Nov 22, 2013 1:35 pm
Subject: time-nuts Digest, Vol 112, Issue 77


Send time-nuts mailing list submissions to
time-nuts@febo.com

To subscribe or unsubscribe via the World Wide Web, visit
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
or, via email, send a message with subject or body 'help' to
time-nuts-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: Crude Survey Technique (Robert Atkinson)
   2. Re: DMTD: Mixer DC offset will result in time offset at
  zero-crossing detector out? (Bruce Griffiths)
   3. Re: Isolation achieved by opamp based isoamp? (Charles Steinmetz)
   4. Re: Off-Topic Question -- German Composition Resistors
  (Didier Juges)
   5. Re: Thunderbolt Simulator (paul swed)
   6. Re: Crude Survey Technique (Brian Lloyd)


--

Message: 1
Date: Fri, 22 Nov 2013 17:06:51 + (GMT)
From: Robert Atkinson 
To: Discussion of precise time and frequency measurement
    
Subject: Re: [time-nuts] Crude Survey Technique
Message-ID:
<1385140011.91089.yahoomail...@web171902.mail.ir2.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Hi Jim,
I disagree, the Medium Landing Compass IS accurate to better than 30 minutes 
(0.5deg). This is also the smallest graduation so it can be read to better than 
15 minutes. The calibration chart is given to 10 minutes every 15 degrees. It 
does of course indicate the orientation of the local magnetic field. To ensure 
there is no local distortions you need to do a site survey. This can be 
acheived 
by comparing bearings to a distant object along a baseline or taking reciprical 
bearings. CAA CAP562 part 8 leaflet 1 
http://www.helitavia.com/docs/CAP562_2007_08.pdf? 

has lots of good info.

(full version here http://www.caa.co.uk/docs/33/CAP562RFS.pdf? large file over 
10MB)

Robert G8RPI (CEng, licenced aircraft engineer for 30 years, I've done many 
aircraft swings)? 




 From: Jim Lux 
To: time-nuts@febo.com 
Sent: Friday, 22 November 2013, 14:25
Subject: Re: [time-nuts] Crude Survey Technique
 

On 11/21/13 11:32 PM, Robert Atkinson wrote:
> 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.

That compass is *precise* to 1/2 degree, but not *accurate* to 1/2 
degree. It comes with a calibration card, and is presumably used in a 
place with a uniform field (e.g. for calibrating an aircraft compass, 
which is done in an open area with no known magnetic anomalies).? If 
you're in a different environment, the card values may be incorrect.

It is essentially as "comparison standard".? You put it next to the 
aircraft and move both in a systematic pattern and you use it to 
"calibrate out" the variations in the plane's internal compass.

However you're going to be subject to the local magnetic field anomalies 
(and they're 

Re: [time-nuts] Crude Survey Technique

[J. Forster]

On the transite, I thought that might be an issue. You really need a
Theodolite. You can probably pick up a used Wild T-2 or Kern DKM-2 for not
a lot on eBay. A T-3 is o0verkill.

Asian Total Stations have pretty much killed the commercial marked for
manual survey instruments. The ones w/ inverting telescopes tend to be
cheaper.

-John

===




>
>  Hello and thanks to all for the great ideas.
>
>
> Re: [time-nuts] Crude Survey Technique
>
>
>
>  Some interim comments:
>
> *agree with regard to using pole star. However it is below freezing here
> and so I won't be out in the dark with my camera. A good verification
> technique that must await warmer weather!!
>
> *thanks for the suggestion re. the transit. Unfortunately the elevation
> measurement only goes to 30 degrees and I am at 38.7 degrees latitude. I
> should have bought the one with more elevation range and a built in
> precision compass. Still might do that.
>
> *I have a Stocker and Yale Army compass - nice thing but 2 degrees is
> probabily beyond its capability except as a sanity check
>
> *Forced my T-bolt to find itself 9 times in the last 24 hours:
> Average Longitude : -94.70983
> Extreme Spread :90 degrees
> Standard Devation : 2.58 e-5 degrees
>
> At my latitude 1 degree is 285,402.9 Ft
> So the error at 1 standard deviation is 7.4 ft.
> Who ever guessed 10 ft has achieved GURU status.
>
> So doing the ATAN at various ranges we get
>
> 200 ft  2.12 degrees
> 400 ft  1.06 degrees
> 600ft  0.71 degrees.
>
> 400 ft is easy and 600 is possible. However the sun shadow method seems an
> equally good approach.
>
> Question - If I use 3 T-bolts on the same antenna, feedline, splitter etc.
> and run 3 instances of T-bolt mon - can the results be improved???
>
> Thanks for all the help   - john k6iql
>
>
>
>
>
>
>
> -Original Message-
> From: time-nuts-request 
> To: time-nuts 
> Sent: Fri, Nov 22, 2013 1:35 pm
> Subject: time-nuts Digest, Vol 112, Issue 77
>
>
> Send time-nuts mailing list submissions to
>   time-nuts@febo.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
>   https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> or, via email, send a message with subject or body 'help' to
>   time-nuts-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: Crude Survey Technique (Robert Atkinson)
>2. Re: DMTD: Mixer DC offset will result in time offset at
>   zero-crossing detector out? (Bruce Griffiths)
>3. Re: Isolation achieved by opamp based isoamp? (Charles Steinmetz)
>4. Re: Off-Topic Question -- German Composition Resistors
>   (Didier Juges)
>5. Re: Thunderbolt Simulator (paul swed)
>6. Re: Crude Survey Technique (Brian Lloyd)
>
>
> --
>
> Message: 1
> Date: Fri, 22 Nov 2013 17:06:51 + (GMT)
> From: Robert Atkinson 
> To: Discussion of precise time and frequency measurement
>   
> Subject: Re: [time-nuts] Crude Survey Technique
> Message-ID:
>   <1385140011.91089.yahoomail...@web171902.mail.ir2.yahoo.com>
> Content-Type: text/plain; charset=iso-8859-1
>
> Hi Jim,
> I disagree, the Medium Landing Compass IS accurate to better than 30
> minutes
> (0.5deg). This is also the smallest graduation so it can be read to better
> than
> 15 minutes. The calibration chart is given to 10 minutes every 15 degrees.
> It
> does of course indicate the orientation of the local magnetic field. To
> ensure
> there is no local distortions you need to do a site survey. This can be
> acheived
> by comparing bearings to a distant object along a baseline or taking
> reciprical
> bearings. CAA CAP562 part 8 leaflet 1
> http://www.helitavia.com/docs/CAP562_2007_08.pdf?
>
> has lots of good info.
>
> (full version here http://www.caa.co.uk/docs/33/CAP562RFS.pdf? large file
> over
> 10MB)
>
> Robert G8RPI (CEng, licenced aircraft engineer for 30 years, I've done
> many
> aircraft swings)?
>
>
>
> 
>  From: Jim Lux 
> To: time-nuts@febo.com
> Sent: Friday, 22 November 2013, 14:25
> Subject: Re: [time-nuts] Crude Survey Technique
>
>
> On 11/21/13 11:32 PM, Robert Atkinson wrote:
>> 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 f

Re: [time-nuts] Crude Survey Technique

[WarrenS]

John

In answer to your original questions,

No problem if you have a good setup including a good sky view, antenna, and 
TBolt setup.
It is important to do each run at the different locations at the same time 
of the day and average the results for as long as you can.

Best is to do a 24 Hr survey at each location.
see the attached LH plot for the effect of time on location reading error.

Multiple Tbolts on the same antenna don't help, unless they are on different 
antennas.


ws

***
- Original Message - 
From: 

To: 
Sent: Thursday, November 21, 2013 10:52 AM
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


Question - >If I use 3 T-bolts on the same antenna, feedline, splitter etc. 
and run 3 instances of T-bolt mon - can the results be improved???





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Re: [time-nuts] Crude Survey Technique

[David J Taylor]

I hope no-one believes all the decimal digits shown in that screen-shot!  It 
seems to me that it would be better if more realistic values were presented!


37.808842 °C - really!

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] Crude Survey Technique

[Didier Juges]

The Thunderbolt uses single precision floating point and digital filtering for 
temperature so yes, you are going to see values like this. This is not unusual 
(precision clearly out of step with accuracy), like the HP network analyzers 
returning gain in dB with 4 decimals at microwave frequencies.
Not sure what your point is?
Should Lady Heather pretend to know better and muck with what's sent by the 
receiver?
I prefer not but it's a matter of opinion.

Didier KO4BB


David J Taylor  wrote:
>I hope no-one believes all the decimal digits shown in that
>screen-shot!  It 
>seems to me that it would be better if more realistic values were
>presented!
>
>37.808842 °C - really!
>
>David
>-- 
>SatSignal Software - Quality software written to your requirements
>Web: http://www.satsignal.eu
>Email: david-tay...@blueyonder.co.uk 
>
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-- 
Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other 
things.
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Re: [time-nuts] Crude Survey Technique

[David J Taylor]

The Thunderbolt uses single precision floating point and digital filtering 
for temperature so yes, you are going to see values like this. This is not 
unusual (precision clearly out of step with accuracy), like the HP network 
analyzers returning gain in dB with 4 decimals at microwave frequencies.

Not sure what your point is?
Should Lady Heather pretend to know better and muck with what's sent by the 
receiver?

I prefer not but it's a matter of opinion.

Didier KO4BB
===

Oh, if that's what the Thunderbolt sends, then that's what should be 
reported.  I hadn't appreciated that.  Makes you wonder why the designers 
did that, though.


More modern equipment I've seen uses (for example) integers to report dB x 
10, so tenths of a dB resolution.  I do see computer temperature sensors 
reporting in millidegrees, with an accuracy of +/-  2°C!


73,
David GM8ARV
--
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] Crude Survey Technique

[Jim Lux]

On 11/24/13 4:23 AM, Didier Juges wrote:

The Thunderbolt uses single precision floating point and digital filtering for 
temperature so yes, you are going to see values like this. This is not unusual 
(precision clearly out of step with accuracy), like the HP network analyzers 
returning gain in dB with 4 decimals at microwave frequencies.
Not sure what your point is?
Should Lady Heather pretend to know better and muck with what's sent by the 
receiver?
I prefer not but it's a matter of opinion.

Didier KO4BB


David J Taylor  wrote:

I hope no-one believes all the decimal digits shown in that
screen-shot!  It
seems to me that it would be better if more realistic values were
presented!

37.808842 °C - really!




Often it's useful to report all the digits used in the calculation, so 
you can reverse it back to the original, no doubt, limited precision 
fixed point number.







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Re: [time-nuts] Crude Survey Technique

[Brian Lloyd]

On Sun, Nov 24, 2013 at 7:13 AM, David J Taylor <
david-tay...@blueyonder.co.uk> wrote:

> The Thunderbolt uses single precision floating point and digital filtering
> for temperature so yes, you are going to see values like this. This is not
> unusual (precision clearly out of step with accuracy), like the HP network
> analyzers returning gain in dB with 4 decimals at microwave frequencies.
> Not sure what your point is?
> Should Lady Heather pretend to know better and muck with what's sent by
> the receiver?
> I prefer not but it's a matter of opinion.
>
> Didier KO4BB
> ===
>
> Oh, if that's what the Thunderbolt sends, then that's what should be
> reported.  I hadn't appreciated that.  Makes you wonder why the designers
> did that, though.
>

Oh, the answer to that question is easy. They knew that they had to produce
a function to convert 32-bit floating point numbers to decimal
representation in ascii for transmission over the serial port. But it would
require additional code to round off the numbers to desired precision. And
then they would have to decide what the proper resolution should be for
each value. So I would have done the same thing they did.

>
> More modern equipment I've seen uses (for example) integers to report dB x
> 10, so tenths of a dB resolution.  I do see computer temperature sensors
> reporting in millidegrees, with an accuracy of +/-  2°C!
>

Sure the accuracy may be off but if the repeatability is good the high
precision with reduced accuracy is still useful for calculations in a
control loop.

-- 
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] Crude Survey Technique

[Attila Kinali]

On Thu, 21 Nov 2013 19:47:03 -0500
"Dale J. Robertson"  wrote:

> 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,

If you go non-realtime you can acheive sub-cm accuracy.
A project i was involved with at the side lines uses LEA6-T modules and
records the phase data. Processing over 4-6h data gives then something
in the range of 4mm accuracy.

Attila Kinali

-- 
1.) Write everything down.
2.) Reduce to the essential.
3.) Stop and question.
-- The Habits of Highly Boring People, Chris Sauve
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Re: [time-nuts] Crude Survey Technique

[johncroos]

When I asked about "Crude Survey Techniques" I never expected results much 
better than the 10 ft accuracy someone volunteered from the first. In a former 
life I ran an engineering department that worked on the old FAA SCAT-1 DGPS 
landing project, where I did learn a bit about GPS and its limitations for L1 
positioning. Thus the title "Crude   "

I realize that any number to the right of the 5th decimal point reported by 
T-Bolt mon is likely bogus. The data I reported earlier pretty much supports 
that. Now I am running tests with 3 units set for 10K, 20K, and 40K fixes to 
see how long each takes and to compare results obtained. In any case using a 
400 to 600 ft base line between fixes should establish my north- south line. 
The I will check it with compass(crude) and the sun shadow method.

All comments and contributions most appreciated   - john k6iql


 
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Re: [time-nuts] Crude Survey Technique

[Poul-Henning Kamp]

In message <8d0b752c7051aaf-1670-69...@webmail-d157.sysops.aol.com>, johncroos@
aol.com writes:

>I realize that any number to the right of the 5th decimal point
>reported by T-Bolt mon is likely bogus. The data I reported earlier
>pretty much supports that. Now I am running tests with 3 units set
>for 10K, 20K, and 40K fixes to see how long each takes and to compare
>results obtained. 

Been there, done that, your result will depend on the time of day.

No, seriously.

Back when I had 10 GPS receives sitting on my roof:

http://phk.freebsd.dk/raga/

I collected positions from all 10 for over a month, and tried all
sorts of ways to see what you could do with post-processing.

The primary result is that you need to average over N*12 hours,
since that is the major periodicity of the GPS orbits.

Once you do that, your result will have reasonably reproducibility,
as long as you start at the same time of day, not too many days
from each other.

The problem here is that the local reflection environment repeats
on the orbital 12 period, and it introduces biases into your
position.

The next experiment I tried, was more successful:  I adjusted the
averaged position, based on the position hold mode residuals:

http://phk.freebsd.dk/raga/sneak/

This was an incredibly slow process, but after some months it
did in fact converge.

Because these are "remote" GPS receivers, where the downcable
signal is RS-422, temperature effects totally negated any
beneficial effect on the PPS signal, and I dropped it from
the project.

If somebody wants a interesting little project, try taking
that up again, and see if the 12h wiggles in the PPS signal
can be reduced that way.

-- 
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

[Tom Van Baak (lab)]

Try averaging for about 86160 seconds instead of 86400 seconds.
See: http://spot.colorado.edu/~kristine/gpsrep.pdf

/tvb

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Re: [time-nuts] Crude Survey Technique

[Hal Murray]

david-tay...@blueyonder.co.uk said:
> I do see computer temperature sensors reporting in millidegrees, with an
> accuracy of +/-  2°C!

That's perfectly reasonable if the sensor is locally linear so the deltas 
between nearby readings are meaningful.

It's the same thing as measuring the frequency of a crystal to 1 ppm when the 
rating on the data sheet is 100 ppm.

It's stability vs accuracy.



-- 
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Re: [time-nuts] Crude Survey Technique (WarrenS)

[johncroos]

 Warren,

Understood. I have a couple more questions. Once the thunderbolt has completed 
a survey, does it continue to update its position or are the final numbers at 
the end of the survey frozen until a new survey has started.

If it continues to update the logging feature in the thunderbolt monitor 
outputs the data in a convenient format.I will also give Lady Heather a try.

it has several operational modes such as; stationary, land and a couple of 
others. Which mode would be most useful to determine a fixed position.

I have three of the little beasties chugging away and doing an initial survey. 
Later on this evening I'll see what they come up with.

Thanks for your help – John




Re: Crude Survey Technique (WarrenS)


 

 

 

-Original Message-
From: time-nuts-request 
To: time-nuts 
Sent: Sat, Nov 23, 2013 1:07 pm
Subject: time-nuts Digest, Vol 112, Issue 80


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Today's Topics:

   1. Re: Crude Survey Technique (WarrenS)


--

Message: 1
Date: Sat, 23 Nov 2013 11:03:54 -0800
From: "WarrenS" 
To: "Discussion of precise time and frequency measurement"
    
Subject: Re: [time-nuts] Crude Survey Technique
Message-ID: 
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"


John

In answer to your original questions,

No problem if you have a good setup including a good sky view, antenna, and 
TBolt setup.
It is important to do each run at the different locations at the same time 
of the day and average the results for as long as you can.
Best is to do a 24 Hr survey at each location.
see the attached LH plot for the effect of time on location reading error.

Multiple Tbolts on the same antenna don't help, unless they are on different 
antennas.

ws

***
- Original Message ----- 
From: 
To: 
Sent: Thursday, November 21, 2013 10:52 AM
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

>Question - >If I use 3 T-bolts on the same antenna, feedline, splitter etc. 
>and run 3 instances of T-bolt mon - can the results be improved???




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Re: [time-nuts] Crude Survey Technique (WarrenS)

[Hal Murray]

johncr...@aol.com said:
> Understood. I have a couple more questions. Once the thunderbolt has
> completed a survey, does it continue to update its position or are the final
> numbers at the end of the survey frozen until a new survey has started. 

The position is frozen.  That's the whole point of the survey.  After the 
survey, it switches to a different mode, different math.  It assumes it knows 
the position and uses that to get a more accurate time.  It also works with 
fewer satellites.


-- 
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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 (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 <time-nuts-requ...@febo.com>
To: time-nuts <time-nuts@febo.com>
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 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts 
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 <rlajeune...@sbcglobal.net> 
To: Discussion of precise time and frequency measurement 
<time-nuts@febo.com> 
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" <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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> 
> 
> 
 
---------- 
 
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" <p...@phk.freebsd.dk> 
To: Discussion of precise time and frequency measurement 
<time-nuts@febo.com>, 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 land