EM pulse detection

EM pulse detection

Is it possible to measure with great precision the time
at which a very short EM pulse reaches a receiver situated
at some distance from the emitter?
The time should be recorded on the emitter's clock and
also on the receiver's clock.

Thank you very much,

Marcel Luttgens

 

On Sep 15, 3:17 pm, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com> wrote:

mluttg...@wanadoo.fr> wrote in message

news:04746a31-2c53-4614-9562-f520585d6cea@59g2000hsb.googlegroups.com...

EM pulse detection

Is it possible to measure with great precision the time
at which a very short EM pulse reaches a receiver situated
at some distance from the emitter?
The time should be recorded on the emitter's clock and
also on the receiver's clock.

If you have ideal measuring devices you can! The error is going be in
generating the pulse and recieving it(assuming any dispersion is
irrelevant).

It think you need to give more information about such things as in general
the lower the frequency the less well defined a "pulse" is. (i.e., a square
wave pulese has infinite frequency and is "exact" but a sinewave has one
frequency and is inexact)

You might combine different methods of testing and such but you need to
determine what "great precision" is and how you can calibrate your system to
check your "great precision".

I think your question is just to general to get any specific answer.

Thank you for your remarks
The aim is to measure the speed of light. I don't know
if there are devices having the required precision.

Marcel Luttgens

 

[extremesoundandlight@yaho]

On Sep 15, 5:54 am, mluttg...@wanadoo.fr wrote:

EM pulse detection

Is it possible to measure with great precision the time
at which a very short EM pulse reaches a receiver situated
at some distance from the emitter?
The time should be recorded on the emitter's clock and
also on the receiver's clock.

Thank you very much,

Marcel Luttgens

is the receiver situated
at some distance from the emitter with a rough terrain or or smooth
you can use this formula if you modulate two separate frequecies of
coherent light with an Em frequency
over any terrain at any distance
∇′2ψ(x′, z′, ω) + k2(ω)n2ψ(x′, z′, ω) = 0 (1)
where ψ represents the field for either the vertically or horizontally
polarized wave. For
vertically polarized wave, ψ is the magnetic field, which has
component only along the
y direction. For horizontally polarized wave, ψ represents the
electric field, which is
pointed along the y direction. In addition, ∇′2 = ∂2/∂x′2 + ∂2/∂z′2,
k2(ω) = ω2µ0ǫ0,
and n is the index of refraction of the propagating medium. It can be
shown that
many important radio wave propagation phenomena can be reduced to this
twodimensional
problem [3]. In two dimensions, the irregular terrain is described by
the function z′ = f(x′). In this paper the terrain surface profile
f(x) is assumed to
be a stochastic process. The problem we are concerned with is that of
radio wave
propagation over irregular terrain, in which a transmitter located at
the horizontal
position x′ = x0 and at a height of h above ground radiates a
transient pulse. The
pulse then propagates in the positive x′ direction until it reaches a
receiver located
at the horizontal position x′ = x, and a height of z above ground.. The
geometry of
the problem under consideration is shown in figure 1, where the
horizontal distance
between the transmitter and receiver is R.
We further assume that the terrain material can be approximated by
perfect
electric conductors (PEC). Therefore, for vertically polarized wave,
equation (1)
satisfies the Neumann boundary condition,
∂ψ
∂z′ z′=f(x′)
= 0. (2)
While for horizontally polarized wave, the boundary condition is given
by the Dirichlet
boundary condition,
ψ|z′=f(x′) = 0. (3)
We make the assumption that the terrain elevation varies on a scale
length large
compare to the wavelength of the radio wave and also that the wave
propagates at small
grazing angle relative to the x axis. Then, using the forward
scattering approximation,

 

On Sep 15, 5:36 pm, "extremesoundandli...@yahoo.com"
<extremesoundandli...@yahoo.com> wrote:

On Sep 15, 5:54 am, mluttg...@wanadoo.fr wrote:

EM pulse detection

Is it possible to measure with great precision the time
at which a very short EM pulse reaches a receiver situated
at some distance from the emitter?
The time should be recorded on the emitter's clock and
also on the receiver's clock.

Thank you very much,

Marcel Luttgens

is the  receiver situated
 at some distance from the emitter with a rough terrain or or smooth
you can use this formula if you modulate two separate frequecies of
coherent light with an Em frequency
over any terrain at any distance
∇′2ψ(x′, z′, ω) + k2(ω)n2ψ(x′, z′, ω) = 0 (1)
where ψ represents the field for either the vertically or horizontally
polarized wave. For
vertically polarized wave, ψ is the magnetic field, which has
component only along the
y direction. For horizontally polarized wave, ψ represents the
electric field, which is
pointed along the y direction. In addition, ∇′2 = ∂2/∂x′2 + ∂2/∂z′2,
k2(ω) = ω2µ0ǫ0,
and n is the index of refraction of the propagating medium. It can be
shown that
many important radio wave propagation phenomena can be reduced to this
twodimensional
problem [3]. In two dimensions, the irregular terrain is described by
the function z′ = f(x′). In this paper the terrain surface profile
f(x) is assumed to
be a stochastic process. The problem we are concerned with is that of
radio wave
propagation over irregular terrain, in which a transmitter located at
the horizontal
position x′ = x0 and at a height of h above ground radiates a
transient pulse. The
pulse then propagates in the positive x′ direction until it reaches a
receiver located
at the horizontal position x′ = x, and a height of z above ground. The
geometry of
the problem under consideration is shown in figure 1, where the
horizontal distance
between the transmitter and receiver is R.
We further assume that the terrain material can be approximated by
perfect
electric conductors (PEC). Therefore, for vertically polarized wave,
equation (1)
satisfies the Neumann boundary condition,
∂ψ
∂z′     z′=f(x′)
= 0. (2)
While for horizontally polarized wave, the boundary condition is given
by the Dirichlet
boundary condition,
ψ|z′=f(x′) = 0. (3)
We make the assumption that the terrain elevation varies on a scale
length large
compare to the wavelength of the radio wave and also that the wave
propagates at small
grazing angle relative to the x axis. Then, using the forward
scattering approximation,

Thank you!

Do you think that it would be possible, with a commercial
emitter situated on the ground and a commercial receiver carried
on a plane moving at a velocity v, for instance 1000 km/h, and
situated at some distance from the emitter, to determine if
the speed of light is c or c-v ?

Marcel Luttgens

 

[Jasen Betts]

On 2008-09-15, mluttgens@wanadoo.fr <mluttgens@wanadoo.fr> wrote:

Do you think that it would be possible, with a commercial
emitter situated on the ground and a commercial receiver carried
on a plane moving at a velocity v, for instance 1000 km/h, and
situated at some distance from the emitter, to determine if
the speed of light is c or c-v ?

Is this a trick question?

c is the speed of light in a vacuum, aircraft don't work too well without air.


Anyway if you could solve that you'd still need more than 12 significant digits
to detect relativistic effects and tell the difference.

Bye.
Jasen

 

On Sep 16, 12:26 pm, Jasen Betts <ja...@xnet.co.nz> wrote:

On 2008-09-15, mluttg...@wanadoo.fr <mluttg...@wanadoo.fr> wrote:

Do you think that it would be possible, with a commercial
emitter situated on the ground and a commercial receiver carried
on a plane moving at a velocity v, for instance 1000 km/h, and
situated at some distance from the emitter, to determine if
the speed of light is c or c-v ?

Is this a trick question?

c is the speed of light in a vacuum, aircraft don't work too well without air.

Anyway if you could solve that you'd still need more than 12 significant digits
to detect relativistic effects and tell the difference.

Bye.
   Jasen

Thank you, Jasen, but the aim of the experiment is not to
detect relativistic effects, it is to measure the so-called
one-way speed of light.
One could try to determine if there is a statistically
significative difference between the time taken by
an EM pulse (in air, of course) to travel some distance d
to a receiver situated on Earth and to a receiver situated
at the same distance, but on a plane moving at some velocity,
for instance 1000 km/h.
But existing devices are perhaps not precise enough.

Marcel Luttgens

 

[Dan Coby]

mluttgens@wanadoo.fr wrote:

EM pulse detection

Is it possible to measure with great precision the time
at which a very short EM pulse reaches a receiver situated
at some distance from the emitter?
The time should be recorded on the emitter's clock and
also on the receiver's clock.

One way that this sort of experiment is done is use a mirror.
The light pulse is sent from the source and then reflected off
of the mirror back to the source location. The time delay
between sending the pulse to receiving the reflection is measured.

The experiment, as you described it, would require two separate
and very accurate clocks to record the sending and receiving
times. It is much simpler to measure the time delay when both
the sender and receiver are near to each other.