RadioBanter - View Single Post

November 29th 03, 07:12 PM

(N2EY) wrote in
:

In article , Alun
writes:

Fessenden demonstrated voice modulated spark operation as early as
1900. His methods have been verified by actual tests using replica
transmitters and dummy loads.

Fessenden transmitted voice over one mile during December 1900,
possibly on the 12th, on Cobb Island, Maryland.

Yep. You can even listen to re-creations of what it may have sounded
like on-line. I posted the urls here some time back.

By 1903, he had reached 50 miles.

Of course in a way *almost all* spark transmitters use alternators,
because except for simple spark coils, they *all* use AC generated by
alternators...

Fessenden's innovation was to use AC above the voice frequency range.

Brilliant guy. Over 500 patents, in a variety of fields.

Fessenden had a two-way transatlantic radiotelephone setup in
operation by November of 1906 using alternator RF sources.

The demo of Christmas Eve 1906 was repeated a week later (New Year's
Eve).

These events are well documented.

As is DeForrest's later voice coverage of the New York yacht race,
using a spark transmitter of the earlier type (no alternator) but using
a regenerative detector with a triode tube. I can't remember when that
took place, although it is in several books, but the triode (audion)
patent discloses the regenerative detector and was issued in 1907, so
the yacht race must have taken place around that period.

Practical regenerative detection is generally credited to Armstrong in
1915.

'Empire of the Air' (both the TV show and the book) claimed that Armstrong
came up with regeneration in 1911. De Forrest's patent pre-dated that by
another four years, and he won the court case. How could it ever have been
in doubt, when Armstrong's 'eureka' moment was four years after DeForrest
had the patent in his hand?

Armstrong seemed to rely on the argument that DeForrest didn't understand
what he had done, which is a lame argument to say the least. Maybe he
didn't understand what he had done, but he still did it first.

However, DeForest's use of voice communication at such an early
date is another
historic fact.

Seems to me that Fessenden's transatlantic 2 way radiotelephone
operation is the most significant of these early developments. Less
than 5 years after Marconi claimed one-time one-way reception of a
single coded letter, Fessenden had practical, repeatable, two-way voice
transatlantic radio communications over a longer path, using much less
power.

73 de Jim, N2EY

Undoubtedly. Do you know what types of transmitter and receiver were used
in 1906?

73 de Alun, N3KIP