an inadvertent key down during a special event is a pretty run of the mill
it happens more often when you bring out the reserves and equip them with
the dregs from the storage room.
could be anything from a sticky mic switch to someone sitting on the mic.
|> | I have a wave file from a radio reception made four decades ago.
|> | ftp://
|> | The sound is familiar to me and wonder how others would characterize
|> | this signal?
|> Here's one I found. See if you can tell what the sound is from, as
|> opposed to what the sound is.
| A kazoo?
Nope. Hint: the device is electrically powered.
i beleive this statement, without further qualification, is innaccurate.
"Since keying on of a second transmitter decreases the received audio of the
first, this renders attack characteristics of AGC as inconclusive evidence,
especially when magnitudes of the decreases are unreported."
the statement should address the relative signal strengths of the 2 (or
this sentance makes no sense to me
"In a FM system as used by the DPD, cross talk modulates the frequency of
transmitters are modulated by audio, not cross-talk.
the next sentance is poorly worded and thus difficult to make sense of.
When another station transmits concurrently and creates a heterodyne, its
frequencies shift in accordance with changes in loudness of the cross talk
at the transmitter
what frequencies shift? audio? RF? the phrase "cross talk at the
transmitter" has no apparent meaning... please define it.
the phrase "by-radio nature" has no commonly accepted meaning in radio
"Although the Committee on Ballistic Acoustics should have tested
heterodynes for frequency modulation as conclusive evidence of the by-radio
nature of the cross talk, they pursued fallacious arguments"
you cannot test an unmodulated carrier for frequency modulation. perhaps
you can gaive a probabal determiantion the the recorded audio was
de-moduladed by a FM receiver section.
Hubert, i know my writing style is a little curt, but im not intending to
"flame". im just pointing to what seem to me to be errors.
The strengths of the radio signals at the receiver are unknown.
See my next response.
Cross-talk arises when a transmitter operates within an earshot of a
blaring receiver on another channel. Now the cross-talk at the
transmitter modulates the frequency of the RF. When another station
transmits the frequency of the heterodyne would not be constant.
Instead the interaction of the two carriers produce a frequency
"By-radio nature" is a vague and inaccurate term to describe nonlinear
processes that produce an interaction between signals. Corresponding
they use the term "by-audio nature" to describe linear operations that
produce no interaction between the signals.
The brief burst of noise at the end of a solo transmission shows
squelch action. This is evidence of reception by a FM receiver.
A simultaneous transmission of unmodulated carriers of nearly the same
strength produces a heterodyne with prominent second harmonic. This
harmonic provides strong evidence of reception by a FM receiver. A
frequency modulated heterodyne arising from a simultaneous transmission
of at least one modulated carrier is the strongest evidence of
reception by a FM receiver.
| email@example.com writes:
|>Here's one I found. See if you can tell what the sound is from, as
|>opposed to what the sound is.
| Is that one of those things where they program an old computer to make
| music by running a program and listening to the interference produced
| in an AM radio near it?
Not quit. In this case it is an IBM model 1403 line printer printing an
output with a pattern of characters designed to control the impact timing
on each of the 132 print hammers as the character chain runs around in
the univac I used a program for diagnostics, it was called 'blue tango'.
it was a bunch of algorithms that played the tune through an audio amplifier
attached to the junction of the arithmetics.
it sounded very mechanical but it was a big help to know that thwe system
also, at GE computer, we used a diagnostic program and an AM radio to
listen to the generated noise. we would rap on the PC board backs
and, if the machine stopped, we knew where there was a loose connection
on that card.
this was when discrete components were used. ICs still hadn't happened.