Empathy List Archives

RH

Rick Harold

Mon, Nov 24, 2008 2:34 AM

All,

I'm planning doing some experiments in distance measurement. They don't
deal with atomic time directly but with extreme short periods of time.

I need to determine the position of a instrument with a 1mm accuracy or
less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of a
11"x11" square.

I thought of using 1 RF transmitters (not sure of freq) on bottom of the
device near the surface.
The surface would have RF receivers on 3 or 4 edges/corners to receive the
signal.

If each of the receivers positions are known and they then send a signal to
a central circuit (again known positions) how can I differentiate the time
of arrival
at the central location? Does anybody know of a circuit/chip or system
which would determine the time 'difference'.
Obviously this is used to triangulate the position of the instrument.
Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
would have to have that or better resolution.
It could also use some proportional method to extrapolate the position since
the surface has a fixed size.

Any ideas/thoughts?

Thanks in advance.

Rick Harold

All, I'm planning doing some experiments in distance measurement. They don't deal with atomic time directly but with extreme short periods of time. I need to determine the position of a instrument with a 1mm accuracy or less. The instrument is not connected to a mechanical device but is separate & independent. The surface which the instrument is positioned on is close to the size of a 11"x11" square. I thought of using 1 RF transmitters (not sure of freq) on bottom of the device near the surface. The surface would have RF receivers on 3 or 4 edges/corners to receive the signal. If each of the receivers positions are known and they then send a signal to a central circuit (again known positions) how can I differentiate the time of arrival at the central location? Does anybody know of a circuit/chip or system which would determine the time 'difference'. Obviously this is used to triangulate the position of the instrument. Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator would have to have that or better resolution. It could also use some proportional method to extrapolate the position since the surface has a fixed size. Any ideas/thoughts? Thanks in advance. Rick Harold

BG

Bruce Griffiths

Mon, Nov 24, 2008 2:52 AM

Rick Harold wrote:

All,

I'm planning doing some experiments in distance measurement. They don't
deal with atomic time directly but with extreme short periods of time.

I need to determine the position of a instrument with a 1mm accuracy or
less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of a
11"x11" square.

I thought of using 1 RF transmitters (not sure of freq) on bottom of the
device near the surface.
The surface would have RF receivers on 3 or 4 edges/corners to receive the
signal.

If each of the receivers positions are known and they then send a signal to
a central circuit (again known positions) how can I differentiate the time
of arrival
at the central location? Does anybody know of a circuit/chip or system
which would determine the time 'difference'.
Obviously this is used to triangulate the position of the instrument.
Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
would have to have that or better resolution.
It could also use some proportional method to extrapolate the position since
the surface has a fixed size.

Any ideas/thoughts?

Thanks in advance.

Rick Harold

Rick

The techniques used in early geodimeters spring to mind.
Just modulate the RF transmissions with various carriers and make a
sequence of modulation phase shift measurements.

Of course one could also use the same techniques employed in the GPS system.

Are you sure that you cant just use optical techniques with corner cube
reflectors?

Can you not triangulate using 3 or more cameras?

Bruce

Rick Harold wrote: > All, > > I'm planning doing some experiments in distance measurement. They don't > deal with atomic time directly but with extreme short periods of time. > > I need to determine the position of a instrument with a 1mm accuracy or > less. > The instrument is not connected to a mechanical device but is separate & > independent. > The surface which the instrument is positioned on is close to the size of a > 11"x11" square. > > I thought of using 1 RF transmitters (not sure of freq) on bottom of the > device near the surface. > The surface would have RF receivers on 3 or 4 edges/corners to receive the > signal. > > If each of the receivers positions are known and they then send a signal to > a central circuit (again known positions) how can I differentiate the time > of arrival > at the central location? Does anybody know of a circuit/chip or system > which would determine the time 'difference'. > Obviously this is used to triangulate the position of the instrument. > Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator > would have to have that or better resolution. > It could also use some proportional method to extrapolate the position since > the surface has a fixed size. > > Any ideas/thoughts? > > Thanks in advance. > > Rick Harold > Rick The techniques used in early geodimeters spring to mind. Just modulate the RF transmissions with various carriers and make a sequence of modulation phase shift measurements. Of course one could also use the same techniques employed in the GPS system. Are you sure that you cant just use optical techniques with corner cube reflectors? Can you not triangulate using 3 or more cameras? Bruce

P

phil

Mon, Nov 24, 2008 2:58 AM

----- Original Message -----
From: "Rick Harold" rickharold@gmail.com
To: time-nuts@febo.com
Sent: Sunday, November 23, 2008 9:34 PM
Subject: [time-nuts] position determination over short distance

All,

I'm planning doing some experiments in distance measurement. They don't
deal with atomic time directly but with extreme short periods of time.

I need to determine the position of a instrument with a 1mm accuracy or
less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of
a
11"x11" square.

I thought of using 1 RF transmitters (not sure of freq) on bottom of the
device near the surface.
The surface would have RF receivers on 3 or 4 edges/corners to receive the
signal.

If each of the receivers positions are known and they then send a signal
to
a central circuit (again known positions) how can I differentiate the time
of arrival
at the central location? Does anybody know of a circuit/chip or system
which would determine the time 'difference'.
Obviously this is used to triangulate the position of the instrument.
Light travels 1 mm in ~3.3 picoseconds so I would suspect the
differentiator
would have to have that or better resolution.
It could also use some proportional method to extrapolate the position
since
the surface has a fixed size.

Any ideas/thoughts?

Thanks in advance.

Rick Harold

Rather vague as to what you are doing.
Have you considered ultrasonics or even laser rather than RF?

----- Original Message ----- From: "Rick Harold" <rickharold@gmail.com> To: <time-nuts@febo.com> Sent: Sunday, November 23, 2008 9:34 PM Subject: [time-nuts] position determination over short distance > All, > > I'm planning doing some experiments in distance measurement. They don't > deal with atomic time directly but with extreme short periods of time. > > I need to determine the position of a instrument with a 1mm accuracy or > less. > The instrument is not connected to a mechanical device but is separate & > independent. > The surface which the instrument is positioned on is close to the size of > a > 11"x11" square. > > I thought of using 1 RF transmitters (not sure of freq) on bottom of the > device near the surface. > The surface would have RF receivers on 3 or 4 edges/corners to receive the > signal. > > If each of the receivers positions are known and they then send a signal > to > a central circuit (again known positions) how can I differentiate the time > of arrival > at the central location? Does anybody know of a circuit/chip or system > which would determine the time 'difference'. > Obviously this is used to triangulate the position of the instrument. > Light travels 1 mm in ~3.3 picoseconds so I would suspect the > differentiator > would have to have that or better resolution. > It could also use some proportional method to extrapolate the position > since > the surface has a fixed size. > > Any ideas/thoughts? > > Thanks in advance. > > Rick Harold Rather vague as to what you are doing. Have you considered ultrasonics or even laser rather than RF?

E

EB4APL

Mon, Nov 24, 2008 3:24 AM

Rick Harold wrote:

All,

I'm planning doing some experiments in distance measurement. They don't
deal with atomic time directly but with extreme short periods of time.

I need to determine the position of a instrument with a 1mm accuracy or
less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of a
11"x11" square.

I thought of using 1 RF transmitters (not sure of freq) on bottom of the
device near the surface.
The surface would have RF receivers on 3 or 4 edges/corners to receive the
signal.

If each of the receivers positions are known and they then send a signal to
a central circuit (again known positions) how can I differentiate the time
of arrival
at the central location? Does anybody know of a circuit/chip or system
which would determine the time 'difference'.
Obviously this is used to triangulate the position of the instrument.
Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
would have to have that or better resolution.
It could also use some proportional method to extrapolate the position since
the surface has a fixed size.

Any ideas/thoughts?

Thanks in advance.

Rick Harold

Use a laser distance meter (or homebuild one)
Regards,
Ignacio, EB4APL

Rick Harold wrote: > All, > > I'm planning doing some experiments in distance measurement. They don't > deal with atomic time directly but with extreme short periods of time. > > I need to determine the position of a instrument with a 1mm accuracy or > less. > The instrument is not connected to a mechanical device but is separate & > independent. > The surface which the instrument is positioned on is close to the size of a > 11"x11" square. > > I thought of using 1 RF transmitters (not sure of freq) on bottom of the > device near the surface. > The surface would have RF receivers on 3 or 4 edges/corners to receive the > signal. > > If each of the receivers positions are known and they then send a signal to > a central circuit (again known positions) how can I differentiate the time > of arrival > at the central location? Does anybody know of a circuit/chip or system > which would determine the time 'difference'. > Obviously this is used to triangulate the position of the instrument. > Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator > would have to have that or better resolution. > It could also use some proportional method to extrapolate the position since > the surface has a fixed size. > > Any ideas/thoughts? > > Thanks in advance. > > Rick Harold > > Use a laser distance meter (or homebuild one) Regards, Ignacio, EB4APL

TV

Tom Van Baak

Mon, Nov 24, 2008 3:41 AM

I need to determine the position of a instrument with a 1mm accuracy or less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of a
11"x11" square.

1 mm or better accuracy on a 300x300 mm surface can be
obtained with a cheap webcam mounted above the surface
and a little bit a creative software.

Obviously this is used to triangulate the position of the instrument.
Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
would have to have that or better resolution.

Sound travels about a million times slower than light. 343 m/s
is 1 mm in 2.9 microseconds. Perhaps this is the way to go?

I remind visitors here that a WWV tick takes the same time to
travel from Ft Collins to Seattle as it does to travel from the SW
radio speaker to your ear.

/tvb

> I need to determine the position of a instrument with a 1mm accuracy or less. > The instrument is not connected to a mechanical device but is separate & > independent. > The surface which the instrument is positioned on is close to the size of a > 11"x11" square. 1 mm or better accuracy on a 300x300 mm surface can be obtained with a cheap webcam mounted above the surface and a little bit a creative software. > Obviously this is used to triangulate the position of the instrument. > Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator > would have to have that or better resolution. Sound travels about a million times slower than light. 343 m/s is 1 mm in 2.9 microseconds. Perhaps this is the way to go? I remind visitors here that a WWV tick takes the same time to travel from Ft Collins to Seattle as it does to travel from the SW radio speaker to your ear. /tvb

BG

Bruce Griffiths

Mon, Nov 24, 2008 3:52 AM

Tom Van Baak wrote:

I need to determine the position of a instrument with a 1mm accuracy or less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of a
11"x11" square.

1 mm or better accuracy on a 300x300 mm surface can be
obtained with a cheap webcam mounted above the surface
and a little bit a creative software.

Obviously this is used to triangulate the position of the instrument.
Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
would have to have that or better resolution.

Sound travels about a million times slower than light. 343 m/s
is 1 mm in 2.9 microseconds. Perhaps this is the way to go?

I remind visitors here that a WWV tick takes the same time to
travel from Ft Collins to Seattle as it does to travel from the SW
radio speaker to your ear.

/tvb

If you use sound then compensation for the temperature, pressure and
humidity dependence of the speed of sound may be required.
If your accuracy requirements are higher then compensating for
variations in the C02 content will also be required.
One of the simpler ways is to use the same techniques to measure a fixed
reference path difference.

Bruce

Tom Van Baak wrote: >> I need to determine the position of a instrument with a 1mm accuracy or less. >> The instrument is not connected to a mechanical device but is separate & >> independent. >> The surface which the instrument is positioned on is close to the size of a >> 11"x11" square. >> > > 1 mm or better accuracy on a 300x300 mm surface can be > obtained with a cheap webcam mounted above the surface > and a little bit a creative software. > > >> Obviously this is used to triangulate the position of the instrument. >> Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator >> would have to have that or better resolution. >> > > Sound travels about a million times slower than light. 343 m/s > is 1 mm in 2.9 microseconds. Perhaps this is the way to go? > > I remind visitors here that a WWV tick takes the same time to > travel from Ft Collins to Seattle as it does to travel from the SW > radio speaker to your ear. > > /tvb > > If you use sound then compensation for the temperature, pressure and humidity dependence of the speed of sound may be required. If your accuracy requirements are higher then compensating for variations in the C02 content will also be required. One of the simpler ways is to use the same techniques to measure a fixed reference path difference. Bruce

BG

Bruce Griffiths

Mon, Nov 24, 2008 3:56 AM

Tom Van Baak wrote:

I need to determine the position of a instrument with a 1mm accuracy or less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of a
11"x11" square.

1 mm or better accuracy on a 300x300 mm surface can be
obtained with a cheap webcam mounted above the surface
and a little bit a creative software.

/tvb

Dont forget to calibrate the camera distortion and ensure that this
doesnt over over time.

i.e. lock the focus and ensure the camera position, tilt etc with
respect to the reference surface do not vary.

Bruce

Tom Van Baak wrote: >> I need to determine the position of a instrument with a 1mm accuracy or less. >> The instrument is not connected to a mechanical device but is separate & >> independent. >> The surface which the instrument is positioned on is close to the size of a >> 11"x11" square. >> > > 1 mm or better accuracy on a 300x300 mm surface can be > obtained with a cheap webcam mounted above the surface > and a little bit a creative software. > > /tvb > Dont forget to calibrate the camera distortion and ensure that this doesnt over over time. i.e. lock the focus and ensure the camera position, tilt etc with respect to the reference surface do not vary. Bruce

LJ

Lux, James P

Mon, Nov 24, 2008 4:26 AM

There's a fair amount of F/OSS software from JPL available to do this sort of calibration. It's used to calibrate cameras used on Mars rovers, among other things. The target pattern for calibration is a bunch of big circular dots on a background.

On 11/23/08 7:56 PM, "Bruce Griffiths" bruce.griffiths@xtra.co.nz wrote:

Tom Van Baak wrote:

I need to determine the position of a instrument with a 1mm accuracy or less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of a
11"x11" square.

1 mm or better accuracy on a 300x300 mm surface can be
obtained with a cheap webcam mounted above the surface
and a little bit a creative software.

/tvb

Dont forget to calibrate the camera distortion and ensure that this
doesnt over over time.

i.e. lock the focus and ensure the camera position, tilt etc with
respect to the reference surface do not vary.

Bruce

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.

There's a fair amount of F/OSS software from JPL available to do this sort of calibration. It's used to calibrate cameras used on Mars rovers, among other things. The target pattern for calibration is a bunch of big circular dots on a background. On 11/23/08 7:56 PM, "Bruce Griffiths" <bruce.griffiths@xtra.co.nz> wrote: Tom Van Baak wrote: >> I need to determine the position of a instrument with a 1mm accuracy or less. >> The instrument is not connected to a mechanical device but is separate & >> independent. >> The surface which the instrument is positioned on is close to the size of a >> 11"x11" square. >> > > 1 mm or better accuracy on a 300x300 mm surface can be > obtained with a cheap webcam mounted above the surface > and a little bit a creative software. > > /tvb > Dont forget to calibrate the camera distortion and ensure that this doesnt over over time. i.e. lock the focus and ensure the camera position, tilt etc with respect to the reference surface do not vary. Bruce _______________________________________________ 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.

JO

Jean-Louis Oneto

Mon, Nov 24, 2008 11:22 AM

Hi,
A graphic tablet (11" square is a common size) should give you about 120
positions/mm for something like a hundred bucks.
That's not very different from the "mouse" solution, but give you absolute
position rather than relative.
Regards,
Jean-Louis Oneto

----- Original Message -----
From: "Rick Harold" rickharold@gmail.com
To: time-nuts@febo.com
Sent: Monday, November 24, 2008 2:34 AM
Subject: [time-nuts] position determination over short distance

All,

I'm planning doing some experiments in distance measurement. They don't
deal with atomic time directly but with extreme short periods of time.

I need to determine the position of a instrument with a 1mm accuracy or
less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of
a
11"x11" square.

I thought of using 1 RF transmitters (not sure of freq) on bottom of the
device near the surface.
The surface would have RF receivers on 3 or 4 edges/corners to receive the
signal.

If each of the receivers positions are known and they then send a signal
to
a central circuit (again known positions) how can I differentiate the time
of arrival
at the central location? Does anybody know of a circuit/chip or system
which would determine the time 'difference'.
Obviously this is used to triangulate the position of the instrument.
Light travels 1 mm in ~3.3 picoseconds so I would suspect the
differentiator
would have to have that or better resolution.
It could also use some proportional method to extrapolate the position
since
the surface has a fixed size.

Any ideas/thoughts?

Thanks in advance.

Rick Harold

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.

Hi, A graphic tablet (11" square is a common size) should give you about 120 positions/mm for something like a hundred bucks. That's not very different from the "mouse" solution, but give you absolute position rather than relative. Regards, Jean-Louis Oneto ----- Original Message ----- From: "Rick Harold" <rickharold@gmail.com> To: <time-nuts@febo.com> Sent: Monday, November 24, 2008 2:34 AM Subject: [time-nuts] position determination over short distance > All, > > I'm planning doing some experiments in distance measurement. They don't > deal with atomic time directly but with extreme short periods of time. > > I need to determine the position of a instrument with a 1mm accuracy or > less. > The instrument is not connected to a mechanical device but is separate & > independent. > The surface which the instrument is positioned on is close to the size of > a > 11"x11" square. > > I thought of using 1 RF transmitters (not sure of freq) on bottom of the > device near the surface. > The surface would have RF receivers on 3 or 4 edges/corners to receive the > signal. > > If each of the receivers positions are known and they then send a signal > to > a central circuit (again known positions) how can I differentiate the time > of arrival > at the central location? Does anybody know of a circuit/chip or system > which would determine the time 'difference'. > Obviously this is used to triangulate the position of the instrument. > Light travels 1 mm in ~3.3 picoseconds so I would suspect the > differentiator > would have to have that or better resolution. > It could also use some proportional method to extrapolate the position > since > the surface has a fixed size. > > Any ideas/thoughts? > > Thanks in advance. > > Rick Harold > _______________________________________________ > 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.

E

EB4APL

Mon, Nov 24, 2008 2:20 PM

Of course you can use any of the standard photogrammetric tecniques and
programs. Even you can do it automatically using image correlation to
find the paralax and hence the distance.

But I have a simpler and cheaper (and also accurate) solution:

Put a transmiting coil in the object to be measured, about 1-2 cm
diameter, 0.5 cm high (I don´t remember the frequency now, it is quite
low but it doesn't matter).
Lay a receiving antenna grid of vertical and horizontal wires, spaced
about 1 cm, in a surface below the object.
Scan the antennas noting the amplitudes an phases on the 4 or 6
horizontal and vertical wires surrounding the Tx coil in each moment .
Calculate the position in real time (you obtain a precision of about 0.1
mm if the antenna surface is calibrated)
Sound complicated? buy a digitizing tablet (used ones are really
cheap). This is how these things works.
Regards,
Ignacio Cembreros

Lux, James P wrote:

There's a fair amount of F/OSS software from JPL available to do this sort of calibration. It's used to calibrate cameras used on Mars rovers, among other things. The target pattern for calibration is a bunch of big circular dots on a background.

On 11/23/08 7:56 PM, "Bruce Griffiths" bruce.griffiths@xtra.co.nz wrote:

Tom Van Baak wrote:

I need to determine the position of a instrument with a 1mm accuracy or less.
The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size of a
11"x11" square.

1 mm or better accuracy on a 300x300 mm surface can be
obtained with a cheap webcam mounted above the surface
and a little bit a creative software.

/tvb

Dont forget to calibrate the camera distortion and ensure that this
doesnt over over time.

i.e. lock the focus and ensure the camera position, tilt etc with
respect to the reference surface do not vary.

Bruce

Of course you can use any of the standard photogrammetric tecniques and programs. Even you can do it automatically using image correlation to find the paralax and hence the distance. But I have a simpler and cheaper (and also accurate) solution: Put a transmiting coil in the object to be measured, about 1-2 cm diameter, 0.5 cm high (I don´t remember the frequency now, it is quite low but it doesn't matter). Lay a receiving antenna grid of vertical and horizontal wires, spaced about 1 cm, in a surface below the object. Scan the antennas noting the amplitudes an phases on the 4 or 6 horizontal and vertical wires surrounding the Tx coil in each moment . Calculate the position in real time (you obtain a precision of about 0.1 mm if the antenna surface is calibrated) Sound complicated? buy a digitizing tablet (used ones are really cheap). This is how these things works. Regards, Ignacio Cembreros Lux, James P wrote: > There's a fair amount of F/OSS software from JPL available to do this sort of calibration. It's used to calibrate cameras used on Mars rovers, among other things. The target pattern for calibration is a bunch of big circular dots on a background. > > > On 11/23/08 7:56 PM, "Bruce Griffiths" <bruce.griffiths@xtra.co.nz> wrote: > > Tom Van Baak wrote: > >>> I need to determine the position of a instrument with a 1mm accuracy or less. >>> The instrument is not connected to a mechanical device but is separate & >>> independent. >>> The surface which the instrument is positioned on is close to the size of a >>> 11"x11" square. >>> >>> >> 1 mm or better accuracy on a 300x300 mm surface can be >> obtained with a cheap webcam mounted above the surface >> and a little bit a creative software. >> >> /tvb >> >> > Dont forget to calibrate the camera distortion and ensure that this > doesnt over over time. > > i.e. lock the focus and ensure the camera position, tilt etc with > respect to the reference surface do not vary. > > Bruce >

MI

Marco IK1ODO -2

Mon, Nov 24, 2008 3:31 PM

Hi all,

I have to carry a 10 MHz standard frequency signal inside an EMC
screened room via fiber optic cable.

Not willing to re-invent the wheel, do something like an optical
standard frequency link exist on the market?
I think it is possible to use standard 100MB LAN transceivers, and
POF. Phase noise requirements
are not very stringent, and the distance is in the order of some tens
of meters.

Marco IK1ODO / AI4YF

Hi all, I have to carry a 10 MHz standard frequency signal inside an EMC screened room via fiber optic cable. Not willing to re-invent the wheel, do something like an optical standard frequency link exist on the market? I think it is possible to use standard 100MB LAN transceivers, and POF. Phase noise requirements are not very stringent, and the distance is in the order of some tens of meters. Marco IK1ODO / AI4YF

DC

David C. Partridge

Mon, Nov 24, 2008 3:41 PM

Why fibre optic? You'll only need to convert back to copper when you get it
in there (unless the kit that needs the 10Mhz reference has optical 10MHz
in), and if you do that you may as well just take it in there using high
quality coax (say RG-400U) and a bulkhead connector in the wall of the room.

Dave
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Marco IK1ODO -2
Sent: 24 November 2008 15:31
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] 10 MHz over optical fiber?

Hi all,

I have to carry a 10 MHz standard frequency signal inside an EMC screened
room via fiber optic cable.

Why fibre optic? You'll only need to convert back to copper when you get it in there (unless the kit that needs the 10Mhz reference has optical 10MHz in), and if you do that you may as well just take it in there using high quality coax (say RG-400U) and a bulkhead connector in the wall of the room. Dave -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Marco IK1ODO -2 Sent: 24 November 2008 15:31 To: Discussion of precise time and frequency measurement Subject: [time-nuts] 10 MHz over optical fiber? Hi all, I have to carry a 10 MHz standard frequency signal inside an EMC screened room via fiber optic cable.

MI

Marco IK1ODO -2

Mon, Nov 24, 2008 3:48 PM

At 16.41 24/11/2008, you wrote:

Why fibre optic? You'll only need to convert back to copper when you get it
in there (unless the kit that needs the 10Mhz reference has optical 10MHz
in), and if you do that you may as well just take it in there using high
quality coax (say RG-400U) and a bulkhead connector in the wall of the room.

Dave

Dave,

the customer wants no bulkheads and asks specifically for an optical
connection.
The signal will be, of course, be converted back to electrical inside the room.

Marco

At 16.41 24/11/2008, you wrote: >Why fibre optic? You'll only need to convert back to copper when you get it >in there (unless the kit that needs the 10Mhz reference has optical 10MHz >in), and if you do that you may as well just take it in there using high >quality coax (say RG-400U) and a bulkhead connector in the wall of the room. > >Dave Dave, the customer wants no bulkheads and asks specifically for an optical connection. The signal will be, of course, be converted back to electrical inside the room. Marco

PK

Poul-Henning Kamp

Mon, Nov 24, 2008 3:56 PM

In message 20081124152247.DCDB0E91529@mail.ebirds.it, Marco IK1ODO -2 writes:

Hi all,

I have to carry a 10 MHz standard frequency signal inside an EMC
screened room via fiber optic cable.

Not willing to re-invent the wheel, do something like an optical
standard frequency link exist on the market?
I think it is possible to use standard 100MB LAN transceivers, and
POF. Phase noise requirements
are not very stringent, and the distance is in the order of some tens
of meters.

HP used to have kits consisting of transmitter + receiver + plastic
fiber in various lengths.

HParchive.org has a service note that explains how to use that for
reference frequency distribution.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@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.

In message <20081124152247.DCDB0E91529@mail.ebirds.it>, Marco IK1ODO -2 writes: >Hi all, > >I have to carry a 10 MHz standard frequency signal inside an EMC >screened room via fiber optic cable. > >Not willing to re-invent the wheel, do something like an optical >standard frequency link exist on the market? >I think it is possible to use standard 100MB LAN transceivers, and >POF. Phase noise requirements >are not very stringent, and the distance is in the order of some tens >of meters. HP used to have kits consisting of transmitter + receiver + plastic fiber in various lengths. HParchive.org has a service note that explains how to use that for reference frequency distribution. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@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.

BM

Bob Martinson

Mon, Nov 24, 2008 4:03 PM

Her's another approach, see:

http://www.youtube.com/watch?v=FBy_e4yvqhQ

Regards,
Bob Martinson, N1VQR

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of EB4APL
Sent: Monday, November 24, 2008 9:20 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] position determination over short distance

Of course you can use any of the standard photogrammetric tecniques and
programs. Even you can do it automatically using image correlation to
find the paralax and hence the distance.

But I have a simpler and cheaper (and also accurate) solution:

Put a transmiting coil in the object to be measured, about 1-2 cm
diameter, 0.5 cm high (I don´t remember the frequency now, it is quite
low but it doesn't matter).
Lay a receiving antenna grid of vertical and horizontal wires, spaced
about 1 cm, in a surface below the object.
Scan the antennas noting the amplitudes an phases on the 4 or 6
horizontal and vertical wires surrounding the Tx coil in each moment .
Calculate the position in real time (you obtain a precision of about 0.1
mm if the antenna surface is calibrated)
Sound complicated? buy a digitizing tablet (used ones are really
cheap). This is how these things works.
Regards,
Ignacio Cembreros

Lux, James P wrote:

There's a fair amount of F/OSS software from JPL available to do this sort

of calibration. It's used to calibrate cameras used on Mars rovers, among
other things. The target pattern for calibration is a bunch of big circular
dots on a background.

On 11/23/08 7:56 PM, "Bruce Griffiths" bruce.griffiths@xtra.co.nz wrote:

Tom Van Baak wrote:

I need to determine the position of a instrument with a 1mm accuracy or

less.

The instrument is not connected to a mechanical device but is separate &
independent.
The surface which the instrument is positioned on is close to the size

of a

11"x11" square.

1 mm or better accuracy on a 300x300 mm surface can be
obtained with a cheap webcam mounted above the surface
and a little bit a creative software.

/tvb

Dont forget to calibrate the camera distortion and ensure that this
doesnt over over time.

i.e. lock the focus and ensure the camera position, tilt etc with
respect to the reference surface do not vary.

Bruce

time-nuts mailing list -- time-nuts@febo.com
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Her's another approach, see: http://www.youtube.com/watch?v=FBy_e4yvqhQ Regards, Bob Martinson, N1VQR -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On Behalf Of EB4APL Sent: Monday, November 24, 2008 9:20 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] position determination over short distance Of course you can use any of the standard photogrammetric tecniques and programs. Even you can do it automatically using image correlation to find the paralax and hence the distance. But I have a simpler and cheaper (and also accurate) solution: Put a transmiting coil in the object to be measured, about 1-2 cm diameter, 0.5 cm high (I don´t remember the frequency now, it is quite low but it doesn't matter). Lay a receiving antenna grid of vertical and horizontal wires, spaced about 1 cm, in a surface below the object. Scan the antennas noting the amplitudes an phases on the 4 or 6 horizontal and vertical wires surrounding the Tx coil in each moment . Calculate the position in real time (you obtain a precision of about 0.1 mm if the antenna surface is calibrated) Sound complicated? buy a digitizing tablet (used ones are really cheap). This is how these things works. Regards, Ignacio Cembreros Lux, James P wrote: > There's a fair amount of F/OSS software from JPL available to do this sort of calibration. It's used to calibrate cameras used on Mars rovers, among other things. The target pattern for calibration is a bunch of big circular dots on a background. > > > On 11/23/08 7:56 PM, "Bruce Griffiths" <bruce.griffiths@xtra.co.nz> wrote: > > Tom Van Baak wrote: > >>> I need to determine the position of a instrument with a 1mm accuracy or less. >>> The instrument is not connected to a mechanical device but is separate & >>> independent. >>> The surface which the instrument is positioned on is close to the size of a >>> 11"x11" square. >>> >>> >> 1 mm or better accuracy on a 300x300 mm surface can be >> obtained with a cheap webcam mounted above the surface >> and a little bit a creative software. >> >> /tvb >> >> > Dont forget to calibrate the camera distortion and ensure that this > doesnt over over time. > > i.e. lock the focus and ensure the camera position, tilt etc with > respect to the reference surface do not vary. > > Bruce > _______________________________________________ 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.

SM

Scott Mace

Mon, Nov 24, 2008 4:36 PM

I'm looking for the same thing, but between buildings over singlemode
fiber. I have not evaluated any of these but I've been looking at:

http://www.terahertztechnologies.com
http://www.highlandtechnology.com/
http://www.luxlink.com/

Scott

Marco IK1ODO -2 wrote:

Hi all,

I have to carry a 10 MHz standard frequency signal inside an EMC
screened room via fiber optic cable.

Not willing to re-invent the wheel, do something like an optical
standard frequency link exist on the market?
I think it is possible to use standard 100MB LAN transceivers, and
POF. Phase noise requirements
are not very stringent, and the distance is in the order of some tens
of meters.

Marco IK1ODO / AI4YF

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.

I'm looking for the same thing, but between buildings over singlemode fiber. I have not evaluated any of these but I've been looking at: http://www.terahertztechnologies.com http://www.highlandtechnology.com/ http://www.luxlink.com/ Scott Marco IK1ODO -2 wrote: > Hi all, > > I have to carry a 10 MHz standard frequency signal inside an EMC > screened room via fiber optic cable. > > Not willing to re-invent the wheel, do something like an optical > standard frequency link exist on the market? > I think it is possible to use standard 100MB LAN transceivers, and > POF. Phase noise requirements > are not very stringent, and the distance is in the order of some tens > of meters. > > Marco IK1ODO / AI4YF > > > _______________________________________________ > 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. > >

LJ

Lux, James P

Mon, Nov 24, 2008 4:55 PM

We do lots of this sort of thing at JPL. But the high precision does come at a cost..
Here's a paper from Bob Tjoelker and colleagues..
http://ipnpr.jpl.nasa.gov/progress_report/42-167/167C.pdf

There are various off the shelf products too, (you could buy a receiver and transmitter module from Ortel, for instance)

James Lux, P.E.
Task Manager, SOMD Software Defined Radios
Flight Communications Systems Section
Jet Propulsion Laboratory
4800 Oak Grove Drive, Mail Stop 161-213
Pasadena, CA, 91109
+1(818)354-2075 phone
+1(818)393-6875 fax

-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of Scott Mace
Sent: Monday, November 24, 2008 8:37 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10 MHz over optical fiber?

I'm looking for the same thing, but between buildings over
singlemode fiber. I have not evaluated any of these but I've
been looking at:

http://www.terahertztechnologies.com
http://www.highlandtechnology.com/
http://www.luxlink.com/

     Scott

Marco IK1ODO -2 wrote:

We do lots of this sort of thing at JPL. But the high precision does come at a cost.. Here's a paper from Bob Tjoelker and colleagues.. http://ipnpr.jpl.nasa.gov/progress_report/42-167/167C.pdf There are various off the shelf products too, (you could buy a receiver and transmitter module from Ortel, for instance) James Lux, P.E. Task Manager, SOMD Software Defined Radios Flight Communications Systems Section Jet Propulsion Laboratory 4800 Oak Grove Drive, Mail Stop 161-213 Pasadena, CA, 91109 +1(818)354-2075 phone +1(818)393-6875 fax > -----Original Message----- > From: time-nuts-bounces@febo.com > [mailto:time-nuts-bounces@febo.com] On Behalf Of Scott Mace > Sent: Monday, November 24, 2008 8:37 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] 10 MHz over optical fiber? > > I'm looking for the same thing, but between buildings over > singlemode fiber. I have not evaluated any of these but I've > been looking at: > > http://www.terahertztechnologies.com > http://www.highlandtechnology.com/ > http://www.luxlink.com/ > > Scott > > Marco IK1ODO -2 wrote:

SM

Scott Mace

Mon, Nov 24, 2008 5:13 PM

I've used the ortel/emcore 5100 series for L-band IF links in places where the
distances and costs of running coax were too high. Some of the products
launch hot as they were designed for passive/splitter based distribution
so you have to pad the optical rx.

Scott

Lux, James P wrote:

We do lots of this sort of thing at JPL. But the high precision does come at a cost..
Here's a paper from Bob Tjoelker and colleagues..
http://ipnpr.jpl.nasa.gov/progress_report/42-167/167C.pdf

There are various off the shelf products too, (you could buy a receiver and transmitter module from Ortel, for instance)

James Lux, P.E.
Task Manager, SOMD Software Defined Radios
Flight Communications Systems Section
Jet Propulsion Laboratory
4800 Oak Grove Drive, Mail Stop 161-213
Pasadena, CA, 91109
+1(818)354-2075 phone
+1(818)393-6875 fax

-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of Scott Mace
Sent: Monday, November 24, 2008 8:37 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10 MHz over optical fiber?

I'm looking for the same thing, but between buildings over
singlemode fiber. I have not evaluated any of these but I've
been looking at:

http://www.terahertztechnologies.com
http://www.highlandtechnology.com/
http://www.luxlink.com/

     Scott

Marco IK1ODO -2 wrote:

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.

I've used the ortel/emcore 5100 series for L-band IF links in places where the distances and costs of running coax were too high. Some of the products launch hot as they were designed for passive/splitter based distribution so you have to pad the optical rx. Scott Lux, James P wrote: > We do lots of this sort of thing at JPL. But the high precision does come at a cost.. > Here's a paper from Bob Tjoelker and colleagues.. > http://ipnpr.jpl.nasa.gov/progress_report/42-167/167C.pdf > > There are various off the shelf products too, (you could buy a receiver and transmitter module from Ortel, for instance) > > James Lux, P.E. > Task Manager, SOMD Software Defined Radios > Flight Communications Systems Section > Jet Propulsion Laboratory > 4800 Oak Grove Drive, Mail Stop 161-213 > Pasadena, CA, 91109 > +1(818)354-2075 phone > +1(818)393-6875 fax > >> -----Original Message----- >> From: time-nuts-bounces@febo.com >> [mailto:time-nuts-bounces@febo.com] On Behalf Of Scott Mace >> Sent: Monday, November 24, 2008 8:37 AM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] 10 MHz over optical fiber? >> >> I'm looking for the same thing, but between buildings over >> singlemode fiber. I have not evaluated any of these but I've >> been looking at: >> >> http://www.terahertztechnologies.com >> http://www.highlandtechnology.com/ >> http://www.luxlink.com/ >> >> Scott >> >> Marco IK1ODO -2 wrote: > > _______________________________________________ > 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. > >

MI

Marco IK1ODO -2

Mon, Nov 24, 2008 5:58 PM

Thanks to all for the quick answers and all the info. As usual,
time-nuts is a great resource :-)

Marco IK1ODO

Thanks to all for the quick answers and all the info. As usual, time-nuts is a great resource :-) Marco IK1ODO

BK

Brian Kirby

Mon, Nov 24, 2008 6:12 PM

You might look at video fiber optic transmitter/receiver. I used one
once to carry a certain telemetry signal for the same reasons your are
looking for. The fiber optics were analog in this case and rated from
30 hz to 10 Mhz at 1 volt P-P. We had to attenuate the signal going
into the transmitter and we had to amplify the receiver. Our run was
around 400 feet. The signal to noise ratio was somewhere around 55 db.

You might look at video fiber optic transmitter/receiver. I used one once to carry a certain telemetry signal for the same reasons your are looking for. The fiber optics were analog in this case and rated from 30 hz to 10 Mhz at 1 volt P-P. We had to attenuate the signal going into the transmitter and we had to amplify the receiver. Our run was around 400 feet. The signal to noise ratio was somewhere around 55 db.

time-nuts@lists.febo.com

position determination over short distance