On Thu, 24 Jul 2003 10:47:21 -0500, Bob Miller belch-spoke these words:

On Wed, 23 Jul 2003 18:26:21 -0000, (Dave Platt)
wrote:

FM receivers are designed to not respond to amplitude variations. CW is
about as pure an example of "information conveyed by variations in
amplitude" as one is likely to find. To cut to the chase, what you
propose won't work.

Sure it will! Open the squelch up all the way. You'll hear the
background noise from the band and/or the front-end electronics when
there's no carrier being sent. When the OM at the other end keys up,
the FM receiver will lock onto the carrier, and happily demodulate the
(nonexistant) sidebands - it'll go silent. No CW filter needed... in
fact it'd make the noise/silence difference harder to hear.

Admittedly, trying to copy "negative noise" CW is likely to be a real
hassle at first, but I imagine that one can train oneself to do it
(just as one can train oneself to read a book held upside-down).

Hey, it'd be easier to just pick up the mike on an FM rig and say, dah
di dah dit, dah dah di dahhh.


I've heard it done. Or hell, try whistling without having the airstream go into the mic.

John

On Thu, 24 Jul 2003 10:47:21 -0500, Bob Miller belch-spoke these words:

On Wed, 23 Jul 2003 18:26:21 -0000, (Dave Platt)
wrote:

FM receivers are designed to not respond to amplitude variations. CW is
about as pure an example of "information conveyed by variations in
amplitude" as one is likely to find. To cut to the chase, what you
propose won't work.

Sure it will! Open the squelch up all the way. You'll hear the
background noise from the band and/or the front-end electronics when
there's no carrier being sent. When the OM at the other end keys up,
the FM receiver will lock onto the carrier, and happily demodulate the
(nonexistant) sidebands - it'll go silent. No CW filter needed... in
fact it'd make the noise/silence difference harder to hear.

Admittedly, trying to copy "negative noise" CW is likely to be a real
hassle at first, but I imagine that one can train oneself to do it
(just as one can train oneself to read a book held upside-down).

Hey, it'd be easier to just pick up the mike on an FM rig and say, dah
di dah dit, dah dah di dahhh.


I've heard it done. Or hell, try whistling without having the airstream go into the mic.

John

On Wed, 23 Jul 2003 18:26:21 -0000, (Dave Platt)
wrote:

FM receivers are designed to not respond to amplitude variations. CW is
about as pure an example of "information conveyed by variations in
amplitude" as one is likely to find. To cut to the chase, what you
propose won't work.

Sure it will! Open the squelch up all the way. You'll hear the
background noise from the band and/or the front-end electronics when
there's no carrier being sent. When the OM at the other end keys up,
the FM receiver will lock onto the carrier, and happily demodulate the
(nonexistant) sidebands - it'll go silent. No CW filter needed... in
fact it'd make the noise/silence difference harder to hear.

Admittedly, trying to copy "negative noise" CW is likely to be a real
hassle at first, but I imagine that one can train oneself to do it
(just as one can train oneself to read a book held upside-down).

Hey, it'd be easier to just pick up the mike on an FM rig and say, dah
di dah dit, dah dah di dahhh.

Bob
k5qwg



For _conventional_ CW reception, you need something rather different.

;-)

FM receivers are designed to not respond to amplitude variations. CW is
about as pure an example of "information conveyed by variations in
amplitude" as one is likely to find. To cut to the chase, what you
propose won't work.

Sure it will! Open the squelch up all the way. You'll hear the
background noise from the band and/or the front-end electronics when
there's no carrier being sent. When the OM at the other end keys up,
the FM receiver will lock onto the carrier, and happily demodulate the
(nonexistant) sidebands - it'll go silent. No CW filter needed... in
fact it'd make the noise/silence difference harder to hear.

Admittedly, trying to copy "negative noise" CW is likely to be a real
hassle at first, but I imagine that one can train oneself to do it
(just as one can train oneself to read a book held upside-down).

For _conventional_ CW reception, you need something rather different.

;-)

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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Matthew and Wendy Plante wrote:
Is CW just FM without an audio signal? So, If I have a FM receiver, can I
install a CW audio filter and pick up CW. Such as... an IC 207H or BC 780xlt
and a Vectronics CW Audio Filter. Thanks

FM receivers are designed to not respond to amplitude variations. CW is
about as pure an example of "information conveyed by variations in
amplitude" as one is likely to find. To cut to the chase, what you
propose won't work.

That being said, one can send Morse in a format receivable on an FM
receiver, but it'll be MCW rather than CW. Feeding a keyed audio
oscillator into an FM transmitter will produce MCW. The caveat here is
it is legal here in the states only from 50.1 to 54 MHz and above 144.1
MHz.

HTH

de kg7yy
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