How We Went From Tapping Code to Radio Shows

[Robert E. Seastrom]

I've often wondered if the coherer is wholly incapable of demodulating
an AM signal, or simply incapable of demodulating an AM signal that
anyone would actually want to listen to.  It's not hard to imagine a
Fessenden transmission with a coherer-demodulated signal that sounded
raspy and barely intelligible, but obviously not a spark transmission
either.  The wonder would not be what the dog said, but rather the
novelty of a talking dog.

                                        ---rob

"Karl W4KRL" <W4KRL at arrl.net> writes:

> Tom,
>
> I also wondered how the AM signal could be demodulated. According to
> Wikipedia, Fessenden invented the hot wire barretter in 1902 so it is
> possible that some stations were equipped with this demodulator prior to his
> 1906 transmission. Presumably there was at least one other station equipped
> to receive his signal but it strains credulity to claim that stations "up
> and down the coast" heard his transmission.
>
> 73 Karl W4KRL
>
> -----Original Message-----
> From: tacos-bounces+w4krl=arrl.net at amrad.org
> [mailto:tacos-bounces+w4krl=arrl.net at amrad.org] On Behalf Of Tom Azlin,
> N4ZPT
> Sent: Tuesday, January 29, 2008 5:34 PM
> To: W4KRL at arrl.net
> Cc: tacos at amrad.org
> Subject: Re: How We Went From Tapping Code to Radio Shows
>
> Hi Karl,
>
> What kind of receiver did the young United Fruit Company operator use to 
> listen the the 1906 Fessenden broadcast? Would they have had a coherer 
> detector since that was the common detector? Doesn't a coherer require a 
> vibrator to decoherer so that the circuit can be broken.   Wouldn't a 
> standard ship board receiver thus be incapable of receiving AM audio 
> signals?   why would one of those ship board stations have had the type 
> of receiver that that could demodulate Fessenden's signal?  Is there any 
> evidence that the United Fruit Company standard Spark station had a Hot 
> wire barretter detector?
>
> 73, Tom n4zpt
>
> Karl W4KRL wrote:
>> 	
>> 	
>> 
>> Famous Engineers > How We Went From Tapping Code to Radio Shows
>> 
>>  
>> 
>> It’s Christmas Eve, 1906. A Morse code operator on a United Fruit ship in
>> the Atlantic Ocean moves closer to his receiver. Instead of the usual,
>> primitive taps of Morse code, he hears a man speaking over the receiver,
>> followed by music. And so began the world’s first long distance radio
>> transmission.
>> 
>>  
>> 
>> The man’s voice heard up and down the Eastern seaboard that night was
>> Professor Reginald Fessenden. But, that historic night was made possible
> by
>> an alternator developed by a young engineer who had recently emigrated to
>> the U.S. from Sweden.
>>
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