Speed of waves
 

"This finding had practical applications for telegraph communications. For
example, Heaviside actually solved one of the biggest problems affecting
long distance telegraph and telephone communication in 1887 -distortion. It
was known that different frequencies travel with different speeds on a long
cable. For example, the low bass frequencies in a voice signal travel faster
than the high treble frequencies. When the cable is long enough, the
frequencies smear, and both voice and telegraph signals become garbled
noise. Heaviside used his equations to show that if inductances (i.e., a
small coil of wire) were added along the length of the cable, the distortion
could be reduced." From:
http://www.ieeeghn.org/wiki/index.php/Oliver_Heaviside

" It was known that different frequencies travel with different speeds on a
long cable".

Is the same in air and space?
S*

Speed of waves
 

On Thu, 24 Mar 2011 10:53:09 +0100, Szczepan Bialek rearranged some
electrons to say:


" It was known that different frequencies travel with different speeds
on a long cable".

Is the same in air and space?
S*

No, how many people have to tell you that?

Speed of waves
 

On 24 mar, 10:53, "Szczepan Bialek" wrote:
"This finding had practical applications for telegraph communications. For
example, Heaviside actually solved one of the biggest problems affecting
long distance telegraph and telephone communication in 1887 -distortion. It
was known that different frequencies travel with different speeds on a long
cable. For example, the low bass frequencies in a voice signal travel faster
than the high treble frequencies. When the cable is long enough, the
frequencies smear, and both voice and telegraph signals become garbled
noise. Heaviside used his equations to show that if inductances (i.e., a
small coil of wire) were added along the length of the cable, the distortion
could be reduced." From:http://www.ieeeghn.org/wiki/index.php/Oliver_Heaviside

" It was known that different frequencies travel with different speeds on a
long cable".

Is the same in air and space?
S*

Hello Szczepan,

Search for the effective permittivity of media with free electrons
(plasma). You will see that the effective permittivity changes with
frequency, hence the phase velocity. Don't look strange to find
apparent permittivities below the value for vacuum.

Just ignore DC magnetic field as this complicates that math
significantly.


Wim
PA3DJS
www.tetech.nl
without abc, PM will reach me.

Speed of waves
 

"Wimpie" napisal w wiadomosci
...
On 24 mar, 10:53, "Szczepan Bialek" wrote:
"This finding had practical applications for telegraph communications.
For
example, Heaviside actually solved one of the biggest problems affecting
long distance telegraph and telephone communication in 1887 -distortion.
It
was known that different frequencies travel with different speeds on a
long
cable. For example, the low bass frequencies in a voice signal travel
faster
than the high treble frequencies. When the cable is long enough, the
frequencies smear, and both voice and telegraph signals become garbled
noise. Heaviside used his equations to show that if inductances (i.e., a
small coil of wire) were added along the length of the cable, the
distortion
could be reduced."
From:http://www.ieeeghn.org/wiki/index.php/Oliver_Heaviside

" It was known that different frequencies travel with different speeds on
a
long cable".

Is the same in air and space?
S*

Hello Szczepan,

Search for the effective permittivity of media with free electrons
(plasma). You will see that the effective permittivity changes with
frequency, hence the phase velocity. Don't look strange to find
apparent permittivities below the value for vacuum.

Just ignore DC magnetic field as this complicates that math
significantly.

Hello Wim,

So you confirm that in plasma is the same as in metal.

But what with the space. The AM should be better than FM to communicate with
the Mars.
Is/were FM used for long distances?

Were done the proper experiments in the early years of radio?
S*

Speed of waves
 

"david" napisa³ w wiadomo¶ci
...
On Thu, 24 Mar 2011 10:53:09 +0100, Szczepan Bialek rearranged some
electrons to say:


" It was known that different frequencies travel with different speeds
on a long cable".

Is the same in air and space?
S*

No, how many people have to tell you that?

And what they tell:
"Because of the low signal-to-noise ratio, as with amateur-radio practice,
EME signals can generally only be detected using narrow-band receiving
systems. This means that the only aspect of the TV signal that could be
detected is the field scan modulation (AM vision carrier). FM broadcast
signals also feature wide frequency modulation, hence EME reception is
generally not possible. There are no published records of VHF/UHF EME
amateur radio contacts using FM." From:
http://en.wikipedia.org/wiki/TV_and_FM_DX

Could you explain it?

S*

Speed of waves
 

On 24 mar, 18:42, "Szczepan Bialek" wrote:
*"Wimpie" napisal w ...



On 24 mar, 10:53, "Szczepan Bialek" wrote:
"This finding had practical applications for telegraph communications.
For
example, Heaviside actually solved one of the biggest problems affecting
long distance telegraph and telephone communication in 1887 -distortion.

Speed of waves
 

Szczepan Bialek wrote:

"david" napisa? w wiadomo?ci
...
On Thu, 24 Mar 2011 10:53:09 +0100, Szczepan Bialek rearranged some
electrons to say:


" It was known that different frequencies travel with different speeds
on a long cable".

Is the same in air and space?
S*

No, how many people have to tell you that?

And what they tell:
"Because of the low signal-to-noise ratio, as with amateur-radio practice,
EME signals can generally only be detected using narrow-band receiving
systems. This means that the only aspect of the TV signal that could be
detected is the field scan modulation (AM vision carrier). FM broadcast
signals also feature wide frequency modulation, hence EME reception is
generally not possible. There are no published records of VHF/UHF EME
amateur radio contacts using FM." From:
http://en.wikipedia.org/wiki/TV_and_FM_DX

Could you explain it?

Explain what?

You quote has absolutely nothing to do with the speed of propagation, you
babbling moron.


--
Jim Pennino

Remove .spam.sux to reply.

Speed of waves
 

On 3/24/2011 1:06 PM, Wimpie wrote:
On 24 mar, 18:42, "Szczepan wrote:
napisal w ...

But what with the space. The AM should be better than FM to communicate with
the Mars.
Is/were FM used for long distances?

As power is limiting factor, a modulation scheme with coherent
detection and digital decoding will give best performance (best Eb/N0
ratio for certain BER) I think. So it is not just a question of AM or
FM/PM, but more how it is processed at the receiver. Processing power
changed over time, so theoretically the best method may not be used
because of technical limitations.

Were done the proper experiments in the early years of radio?
S*

Best regards,

Wim
PA3DJS
www.tetech.nl


There's a non-zero chance you went beyond his knowledge base. :) (no ;
needed)

tom
K0TAR

Speed of waves
 

Uzytkownik "Wimpie" napisal w wiadomosci
...
On 24 mar, 18:42, "Szczepan Bialek" wrote:
"Wimpie" napisal w
...



On 24 mar, 10:53, "Szczepan Bialek" wrote:
"This finding had practical applications for telegraph communications.
For
example, Heaviside actually solved one of the biggest problems
affecting
long distance telegraph and telephone communication in
1887 -distortion.
It
was known that different frequencies travel with different speeds on a
long
cable. For example, the low bass frequencies in a voice signal travel
faster
than the high treble frequencies. When the cable is long enough, the
frequencies smear, and both voice and telegraph signals become garbled
noise. Heaviside used his equations to show that if inductances (i.e.,
a
small coil of wire) were added along the length of the cable, the
distortion
could be reduced."
From:http://www.ieeeghn.org/wiki/index.php/Oliver_Heaviside

" It was known that different frequencies travel with different speeds
on
a
long cable".

Is the same in air and space?
S*

Hello Szczepan,

Search for the effective permittivity of media with free electrons
(plasma). You will see that the effective permittivity changes with
frequency, hence the phase velocity. Don't look strange to find
apparent permittivities below the value for vacuum.

Just ignore DC magnetic field as this complicates that math
significantly.

Hello Wim,

So you confirm that in plasma is the same as in metal.

No


But what with the space. The AM should be better than FM to communicate
with
the Mars.
Is/were FM used for long distances?

As power is limiting factor, a modulation scheme with coherent
detection and digital decoding will give best performance (best Eb/N0
ratio for certain BER) I think. So it is not just a question of AM or
FM/PM, but more how it is processed at the receiver. Processing power
changed over time, so theoretically the best method may not be used
because of technical limitations.

Were done the proper experiments in the early years of radio?
S*

Best regards,

Wim

I am simple asking if radio people have trouble with the fact that the speed
of waves are frequeny dependent.
I am interesting with the real radio waves in the real media. Here is an
example Pulsars are spinning neutron stars that emit pulses at very regular
intervals ranging from milliseconds to seconds. Astronomers believe that the
pulses are emitted simultaneously over a wide range of frequencies. However,
as observed on Earth, the components of each pulse emitted at higher radio
frequencies arrive before those emitted at lower frequencies. This
dispersion occurs because of the ionised component of the interstellar
medium, which makes the group velocity frequency dependent

S

Speed of waves
 

On 25 mar, 10:17, "Szczepan Bialek" wrote:
Uzytkownik "Wimpie" napisal w ...
On 24 mar, 18:42, "Szczepan Bialek" wrote:



"Wimpie" napisal w
...

On 24 mar, 10:53, "Szczepan Bialek" wrote:
"This finding had practical applications for telegraph communications.
For
example, Heaviside actually solved one of the biggest problems
affecting
long distance telegraph and telephone communication in
1887 -distortion.
It
was known that different frequencies travel with different speeds on a
long
cable. For example, the low bass frequencies in a voice signal travel
faster
than the high treble frequencies. When the cable is long enough, the
frequencies smear, and both voice and telegraph signals become garbled
noise. Heaviside used his equations to show that if inductances (i.e..,
a
small coil of wire) were added along the length of the cable, the
distortion
could be reduced."
From:http://www.ieeeghn.org/wiki/index.php/Oliver_Heaviside

" It was known that different frequencies travel with different speeds
on
a
long cable".

Is the same in air and space?
S*

Hello Szczepan,

Search for the effective permittivity of media with free electrons
(plasma). You will see that the effective permittivity changes with
frequency, hence the phase velocity. Don't look strange to find
apparent permittivities below the value for vacuum.

Just ignore DC magnetic field as this complicates that math
significantly.

Hello Wim,

So you confirm that in plasma is the same as in metal.

No



But what with the space. The AM should be better than FM to communicate
with
the Mars.
Is/were FM used for long distances?

As power is limiting factor, a modulation scheme with coherent
detection and digital decoding will give best performance (best Eb/N0
ratio for certain BER) I think. So it is not just a question of AM or
FM/PM, but more how it is processed at the receiver. *Processing power
changed over time, so theoretically the best method may not be used
because of technical limitations.



Were done the proper experiments in the early years of radio?
S*

Best regards,

Wim

I am simple asking if radio people have trouble with the fact that the speed
of waves are frequeny dependent.
I am interesting with the real radio waves in the real media. Here is an
example Pulsars are spinning neutron stars that emit pulses at very regular
intervals ranging from milliseconds to seconds. Astronomers believe that the
pulses are emitted simultaneously over a wide range of frequencies. However,
as observed on Earth, the components of each pulse emitted at higher radio
frequencies arrive before those emitted at lower frequencies. This
dispersion occurs because of the ionised component of the interstellar
medium, which makes the group velocity frequency dependent

S

Try to find document "Descanso4--Voyager_new.pdf" (very likely the
first result in google). This describes the Voyager communication
system. It is now more the 10 light hours from us (as far as I
know).

As far as I know, they don't equalize to correct for in band
dispersion (due to wave propagation). Maybe other people have better
info on this.

Best regards,

Wim
PA3DJS
www.tetech.nl