Space modulation
 

I was going through some FAA course material on Instument Landing Systems
and the term SPACE MODULATION was mentioned several times. What the heck is
this. From what I gather signals modulate each other out in space without
benifit of any nonlinear device. I personally beleave this cannot happen but
here is a reference to an FAA document.I assume they know what they are
talking about.

Abstract : The report describes an investigation into the cause of
incompatibility between ground and airborne measurements of VOR space
modulation when using the latest flight inspection receiver, FA-4165:3A. The
effort included a survey of the existing procedures and equipment used
throughout the FAA, an evaluation of the ground measurement technique, and
an evaluation of the airborne measurement technique. The result of the
investigation identified problem areas with both the ground and airborne
techniques.

I suspect that space modulation is more of a concept used to more easily
understand/teach the operation of ILS systems and that actual modulation
takes place in the receiver.

Jimmie

Space modulation
 

Jimmie D wrote:
I was going through some FAA course material on Instument Landing Systems
and the term SPACE MODULATION was mentioned several times. What the heck is
this. From what I gather signals modulate each other out in space without
benifit of any nonlinear device. I personally beleave this cannot happen but
here is a reference to an FAA document.I assume they know what they are
talking about.

Abstract : The report describes an investigation into the cause of
incompatibility between ground and airborne measurements of VOR space
modulation when using the latest flight inspection receiver, FA-4165:3A. The
effort included a survey of the existing procedures and equipment used
throughout the FAA, an evaluation of the ground measurement technique, and
an evaluation of the airborne measurement technique. The result of the
investigation identified problem areas with both the ground and airborne
techniques.

I suspect that space modulation is more of a concept used to more easily
understand/teach the operation of ILS systems and that actual modulation
takes place in the receiver.

Jimmie



Sounds like it would need my set of "imaginary numbers" to define ...

Regards,
JS

Space modulation
 

It is possible to get nonlinear interactions among electromagnetic
waves in plasmas, but you generally need very large amplitudes to get
nonlinearities to kick in.

I'm guessing that "space modulation" has something to do with multipath
reflections or something; the VOR signal that rotates is going to be
modulated by the buildings, mountains, and so forth around the
transmitter, generally, the "space"

Just a guess; I don't really know anything about VOR.

Dan

Space modulation
 

The only context that I have seen 'Space Modulation' refered to is where
information is conveyed by a 'lack of signal'. ie the length of silence
conveys information.

Reagrds
Jeff

Space modulation
 

Jeff wrote:
The only context that I have seen 'Space Modulation' refered to is where
information is conveyed by a 'lack of signal'. ie the length of silence
conveys information.

Reagrds
Jeff



Jeff:

Darn little info in the silence. Just means the aliens got tired
chatting, or else there is a coffee break going on. straight face

Regards,
JS

Space modulation
 

wrote in message
ups.com...
It is possible to get nonlinear interactions among electromagnetic
waves in plasmas, but you generally need very large amplitudes to get
nonlinearities to kick in.

I'm guessing that "space modulation" has something to do with multipath
reflections or something; the VOR signal that rotates is going to be
modulated by the buildings, mountains, and so forth around the
transmitter, generally, the "space"

Just a guess; I don't really know anything about VOR.

Dan


No, I know it has nothing to do with things like that,it is as described in
the FAA lit a normal process of forming the ILS radiation patterns and
applies to VOR, Glide slopes and localizers. Google doesnt help much on the
subject.and I ve gone thru the indexs of about 20 radio and antenna books
without finding anything on it.

Space modulation
 

wrote in message
ups.com...
It is possible to get nonlinear interactions among electromagnetic
waves in plasmas, but you generally need very large amplitudes to get
nonlinearities to kick in.

I'm guessing that "space modulation" has something to do with multipath
reflections or something; the VOR signal that rotates is going to be
modulated by the buildings, mountains, and so forth around the
transmitter, generally, the "space"

Just a guess; I don't really know anything about VOR.

Dan

Space modulation, in the case of VOR, is produced by a dipole
rotating at 1800 rpm. The rotating dipole pattern produces a
30 Hz amplitude modulation of the VOR omni-directional
pattern. This rotating pattern provides bearing information
to the receiver. The reference 30 Hz is provided by
FM modulation of the omni-directional pattern.

73,

Frank (VE6CB)

Space modulation
 

Jimmie D wrote:

No, I know it has nothing to do with things like that, ...

Jimmie:

Just having a bit of fun. I am only familiar with "space modulation"
when it comes to modems, as much data is contained in the key off mode,
and the length of time key off occurs, as in the key on condition and
its length of time (at least in one method of data transfer I am
familiar with.)

Whether there is any relationship of one to the other is a mystery to
me--like I said, just poking a bit of fun.

Regards,
JS

Space modulation
 

Jimmie D wrote:
I was going through some FAA course material on Instument Landing Systems
and the term SPACE MODULATION was mentioned several times. What the heck is
this.

I believe this was fully explained in a documentary I saw as a kid.
Something about the Q-36 Explosive Space Modulator.

Tim.

Space modulation