The other party to air traffic communication are aircraft. Those happen
to roam about quite a bit :-)

Seriously, disregarding the airstrip that's almost next to the office
here we are also roughly in the flight path for Mather Field. Altitude
above our building maybe 1500ft, give or take. If Fedex, DHL and other
pilots would report some weird shhhhht noise everytime they pass a
certain spot, guess what would happen?

Don Bowey wrote:
On 4/18/08 8:16 AM, in article fuae44$6tg$1@dns3.cae.ca, "Claude"
claudec@cae.com> wrote:

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:cJMNj.6968$GE1.6102@nlpi061.nbdc.sbc.com...
Michael Black wrote:
On Wed, 16 Apr 2008, Bob Eld wrote:

"Archimedes" <shelton.dcruz@gmail.com> wrote in message
news:b3b30960-27bc-4d59-924f-4312caffe7c2@x41g2000hsb.googlegroups.com...
Hi all

If I change the tank circuit components (reduce the capacitance and
inductance) and change the transistors to appropriate VHF ones, will I
be able to pick up ATC (Air Traffic Conversations) using this
circuit ?

http://www.electronics-lab.com/projects/rf/006/index.html

Thanks
Shelton.
Not likely. I doubt you'd ever get that circuit to work at VHF
frequencies
no matter what you did with the resonant circuit portion. There are many
problems including wrong impedances for the various parasitic
capacitances.

Secondly air traffic stuff is FM I believe.

Military may use FM, I don't know, but airplane related communication is
unique in that it does use actual AM.

A project that saw publication a number of times in the old days took
advantage of that, a "crystal radio" that tuned VHF. It was nothing
more than a tuned circuit and a diode detector feeding an earphone, not
sensitive but useful near airports and since it didn't radiate anything,
even useable (though maybe not legally) on an actual airplane.

The description of the circuit says it's a regen receiver, and those
were never popular at VHF, I'm assuming instability came into play.
You did see superregen receivers there. Either type will radiate, and
that's not a good thing in the aircraft band.

Yes, and then you'd quickly have visitors coming with vehicles bearing
government license plates. A regen-receiver is most definitely not a good
idea in the aircraft band.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Quite correct, it is most likely jail time where you will have hours and
hours of fun designing electronics such as movement alarms
that will detect the proximity of "fellow inmates" . Just swearing on an ATC
frequency will net you a $2,500 fine in Canada, I can't even imagine what
they would do to you if you jammed one of their frequencies.

Claude
Montreal



One of you naysayers should estimate the amount of radiated energy from a
typical regen receiver.

Also, what is the distance from the intended regen location to the airport,
and what would you imagine the comparative strengths would be of the regen
signal and air traffic signals at air traffic receivers?

The regen receiver radiated signal would be lost in the noise.


The other party to air traffic communication are aircraft. Those happen
to roam about quite a bit :-)

Seriously, disregarding the airstrip that's almost next to the office
here we are also roughly in the flight path for Mather Field. Altitude
above our building maybe 1500ft, give or take. If Fedex, DHL and other
pilots would report some weird shhhhht noise everytime they pass a
certain spot, guess what would happen?

Don Bowey wrote:
One of you naysayers should estimate the amount of radiated energy from a
typical regen receiver.

Also, what is the distance from the intended regen location to the
airport,
and what would you imagine the comparative strengths would be of the
regen
signal and air traffic signals at air traffic receivers?

The regen receiver radiated signal would be lost in the noise.


The other party to air traffic communication are aircraft. Those happen to
roam about quite a bit :-)

Seriously, disregarding the airstrip that's almost next to the office here
we are also roughly in the flight path for Mather Field. Altitude above
our building maybe 1500ft, give or take. If Fedex, DHL and other pilots
would report some weird shhhhht noise everytime they pass a certain spot,
guess what would happen?

One of the nice things about AM, and the reason they use it for aviation,
is that power wins. If two signals are colliding, the more powerful one
will always be heard.

"Bob Monsen"


One of the nice things about AM, and the reason they use it for aviation,
is that power wins. If two signals are colliding, the more powerful one
will always be heard.


** That is how FM behaves - ie the "capture effect".

AM does no such thing - " colliding " signals simply combine in the
receiver and are heard together.

Weak signals are heard in the background of strong ones.



...... Phil

"Phil Allison"

One of the nice things about AM, and the reason they use it for
aviation, is that power wins. If two signals are colliding, the more
powerful one will always be heard.


** That is how FM behaves - ie the "capture effect".

AM does no such thing - " colliding " signals simply combine in the
receiver and are heard together.

Weak signals are heard in the background of strong ones.


Thanks for the clarification. However, I'm curious about this.

An FM signal is really just a frequency shift on the carrier. As I
understand it, the transmitted signal is the carrier frequency shifted in
proportion to the amplitude of the sound that will get transmitted (for
mono).

So, given two transmitters on the same frequency, you end up with two
varying carriers. If your receiver is just receiving both signals, mixing
them down to a lower frequency, detecting the shift, and converting that
into an amplitude, the detector must be doing this locking on. Do you know
how it works? How does it lock on rather than just outputting a mess?

On 4/18/08 11:25 AM, in article lI5Oj.4682$iK6.2220@nlpi069.nbdc.sbc.com,
"Joerg" <notthisjoergsch@removethispacbell.net> wrote:

Don Bowey wrote:
On 4/18/08 8:16 AM, in article fuae44$6tg$1@dns3.cae.ca, "Claude"
claudec@cae.com> wrote:

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:cJMNj.6968$GE1.6102@nlpi061.nbdc.sbc.com...
Michael Black wrote:
On Wed, 16 Apr 2008, Bob Eld wrote:

"Archimedes" <shelton.dcruz@gmail.com> wrote in message
news:b3b30960-27bc-4d59-924f-4312caffe7c2@x41g2000hsb.googlegroups.com...
Hi all

If I change the tank circuit components (reduce the capacitance and
inductance) and change the transistors to appropriate VHF ones,
will I
be able to pick up ATC (Air Traffic Conversations) using this
circuit ?

http://www.electronics-lab.com/projects/rf/006/index.html

Thanks
Shelton.
Not likely. I doubt you'd ever get that circuit to work at VHF
frequencies
no matter what you did with the resonant circuit portion. There are
many
problems including wrong impedances for the various parasitic
capacitances.

Secondly air traffic stuff is FM I believe.

Military may use FM, I don't know, but airplane related communication
is
unique in that it does use actual AM.

A project that saw publication a number of times in the old days took
advantage of that, a "crystal radio" that tuned VHF. It was nothing
more than a tuned circuit and a diode detector feeding an earphone,
not
sensitive but useful near airports and since it didn't radiate
anything,
even useable (though maybe not legally) on an actual airplane.

The description of the circuit says it's a regen receiver, and those
were never popular at VHF, I'm assuming instability came into play.
You did see superregen receivers there. Either type will radiate,
and
that's not a good thing in the aircraft band.

Yes, and then you'd quickly have visitors coming with vehicles bearing
government license plates. A regen-receiver is most definitely not a
good
idea in the aircraft band.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Quite correct, it is most likely jail time where you will have hours
and
hours of fun designing electronics such as movement alarms
that will detect the proximity of "fellow inmates" . Just swearing on
an ATC
frequency will net you a $2,500 fine in Canada, I can't even imagine
what
they would do to you if you jammed one of their frequencies.

Claude
Montreal



One of you naysayers should estimate the amount of radiated energy from
a
typical regen receiver.

Also, what is the distance from the intended regen location to the
airport,
and what would you imagine the comparative strengths would be of the
regen
signal and air traffic signals at air traffic receivers?

The regen receiver radiated signal would be lost in the noise.


The other party to air traffic communication are aircraft. Those happen
to roam about quite a bit :-)

Seriously, disregarding the airstrip that's almost next to the office
here we are also roughly in the flight path for Mather Field. Altitude
above our building maybe 1500ft, give or take. If Fedex, DHL and other
pilots would report some weird shhhhht noise everytime they pass a
certain spot, guess what would happen?

I doubt that at 1500 feet the signal from a regen receiver would break the
squelch.

On 4/18/08 11:25 AM, in article lI5Oj.4682$iK6.2220@nlpi069.nbdc.sbc.com,
"Joerg" <notthisjoergsch@removethispacbell.net> wrote:

Don Bowey wrote:
On 4/18/08 8:16 AM, in article fuae44$6tg$1@dns3.cae.ca, "Claude"
claudec@cae.com> wrote:

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:cJMNj.6968$GE1.6102@nlpi061.nbdc.sbc.com...
Michael Black wrote:
On Wed, 16 Apr 2008, Bob Eld wrote:

"Archimedes" <shelton.dcruz@gmail.com> wrote in message
news:b3b30960-27bc-4d59-924f-4312caffe7c2@x41g2000hsb.googlegroups.com...
Hi all

If I change the tank circuit components (reduce the capacitance and
inductance) and change the transistors to appropriate VHF ones, will I
be able to pick up ATC (Air Traffic Conversations) using this
circuit ?

http://www.electronics-lab.com/projects/rf/006/index.html

Thanks
Shelton.
Not likely. I doubt you'd ever get that circuit to work at VHF
frequencies
no matter what you did with the resonant circuit portion. There are many
problems including wrong impedances for the various parasitic
capacitances.

Secondly air traffic stuff is FM I believe.

Military may use FM, I don't know, but airplane related communication is
unique in that it does use actual AM.

A project that saw publication a number of times in the old days took
advantage of that, a "crystal radio" that tuned VHF. It was nothing
more than a tuned circuit and a diode detector feeding an earphone, not
sensitive but useful near airports and since it didn't radiate anything,
even useable (though maybe not legally) on an actual airplane.

The description of the circuit says it's a regen receiver, and those
were never popular at VHF, I'm assuming instability came into play.
You did see superregen receivers there. Either type will radiate, and
that's not a good thing in the aircraft band.

Yes, and then you'd quickly have visitors coming with vehicles bearing
government license plates. A regen-receiver is most definitely not a good
idea in the aircraft band.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Quite correct, it is most likely jail time where you will have hours and
hours of fun designing electronics such as movement alarms
that will detect the proximity of "fellow inmates" . Just swearing on an ATC
frequency will net you a $2,500 fine in Canada, I can't even imagine what
they would do to you if you jammed one of their frequencies.

Claude
Montreal


One of you naysayers should estimate the amount of radiated energy from a
typical regen receiver.

Also, what is the distance from the intended regen location to the airport,
and what would you imagine the comparative strengths would be of the regen
signal and air traffic signals at air traffic receivers?

The regen receiver radiated signal would be lost in the noise.

The other party to air traffic communication are aircraft. Those happen
to roam about quite a bit :-)

Seriously, disregarding the airstrip that's almost next to the office
here we are also roughly in the flight path for Mather Field. Altitude
above our building maybe 1500ft, give or take. If Fedex, DHL and other
pilots would report some weird shhhhht noise everytime they pass a
certain spot, guess what would happen?

I doubt that at 1500 feet the signal from a regen receiver would break the
squelch.

** Capture effect is almost entirly due to the " limiting " that occurs
in the IF amplifier stages.


...... Phil

Don Bowey wrote:
On 4/18/08 11:25 AM, in article lI5Oj.4682$iK6.2220@nlpi069.nbdc.sbc.com,
"Joerg" <notthisjoergsch@removethispacbell.net> wrote:

Don Bowey wrote:
On 4/18/08 8:16 AM, in article fuae44$6tg$1@dns3.cae.ca, "Claude"
claudec@cae.com> wrote:

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:cJMNj.6968$GE1.6102@nlpi061.nbdc.sbc.com...
Michael Black wrote:
On Wed, 16 Apr 2008, Bob Eld wrote:

"Archimedes" <shelton.dcruz@gmail.com> wrote in message
news:b3b30960-27bc-4d59-924f-4312caffe7c2@x41g2000hsb.googlegroups.com.
..
Hi all

If I change the tank circuit components (reduce the capacitance and
inductance) and change the transistors to appropriate VHF ones, will I
be able to pick up ATC (Air Traffic Conversations) using this
circuit ?

http://www.electronics-lab.com/projects/rf/006/index.html

Thanks
Shelton.
Not likely. I doubt you'd ever get that circuit to work at VHF
frequencies
no matter what you did with the resonant circuit portion. There are
many
problems including wrong impedances for the various parasitic
capacitances.

Secondly air traffic stuff is FM I believe.

Military may use FM, I don't know, but airplane related communication is
unique in that it does use actual AM.

A project that saw publication a number of times in the old days took
advantage of that, a "crystal radio" that tuned VHF. It was nothing
more than a tuned circuit and a diode detector feeding an earphone, not
sensitive but useful near airports and since it didn't radiate anything,
even useable (though maybe not legally) on an actual airplane.

The description of the circuit says it's a regen receiver, and those
were never popular at VHF, I'm assuming instability came into play.
You did see superregen receivers there. Either type will radiate, and
that's not a good thing in the aircraft band.

Yes, and then you'd quickly have visitors coming with vehicles bearing
government license plates. A regen-receiver is most definitely not a good
idea in the aircraft band.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Quite correct, it is most likely jail time where you will have hours and
hours of fun designing electronics such as movement alarms
that will detect the proximity of "fellow inmates" . Just swearing on an
ATC
frequency will net you a $2,500 fine in Canada, I can't even imagine what
they would do to you if you jammed one of their frequencies.

Claude
Montreal


One of you naysayers should estimate the amount of radiated energy from a
typical regen receiver.

Also, what is the distance from the intended regen location to the airport,
and what would you imagine the comparative strengths would be of the regen
signal and air traffic signals at air traffic receivers?

The regen receiver radiated signal would be lost in the noise.

The other party to air traffic communication are aircraft. Those happen
to roam about quite a bit :-)

Seriously, disregarding the airstrip that's almost next to the office
here we are also roughly in the flight path for Mather Field. Altitude
above our building maybe 1500ft, give or take. If Fedex, DHL and other
pilots would report some weird shhhhht noise everytime they pass a
certain spot, guess what would happen?

I doubt that at 1500 feet the signal from a regen receiver would break the
squelch.


From a regen that misbehaves it certainly can.

"Bob Monsen"



One of the nice things about AM, and the reason they use it for aviation,
is that power wins. If two signals are colliding, the more powerful one
will always be heard.

** That is how FM behaves  -  ie  the  "capture effect".

AM does no such thing  -  " colliding " signals simply combine in the
receiver and are heard together.

On Apr 19, 2:05 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:
"Bob Monsen"



One of the nice things about AM, and the reason they use it for aviation,
is that power wins. If two signals are colliding, the more powerful one
will always be heard.

** That is how FM behaves  -  ie  the  "capture effect".

AM does no such thing  -  " colliding " signals simply combine in the
receiver and are heard together.



Don't know abou that. When two stations broadcast over each other its
generally just distorted garbage. I speak as a pilot, not from theory.

Don't know abou that. When two stations broadcast over each other its
generally just distorted garbage. I speak as a pilot, not from theory.

From a regen that misbehaves it certainly can.

Hi all

If I change the tank circuit components (reduce the capacitance and
inductance) and change the transistors to appropriate VHF ones, will I
be able to pick up ATC (Air Traffic Conversations) using this
circuit ?

http://www.electronics-lab.com/projects/rf/006/index.html

Thanks
Shelto,