[Premium-Rx] Spread Spectrum (Was: real basic question on stability etc.)

[Edward Knobloch]

Hi,

Frequency hopping  "spread spectrum"  was invented by the late actress 
Hedy Lamarr.
She proposed using  player-piano rolls to control the  frequencies on 
both ends
of the communications circuit.  The patent was issued to her 
then-married name,
Hedy Kiessler Markey.  (She was born Hedwig Kiesler in Vienna).
Her co-inventer was American composer George Antheil, who's most famous work
was "Ballet Mechanique," a 1924 composition which included 16 synchronized
player pianos.

Regards,
Ed Knobloch


Ahmet Gundes wrote:

> Hi Eugene,
>
> I don't know what was going thru my mind when i wrote this. but i 
> think a lot of the FM receivers had this AFC back in those days. I 
> remember when I was little, around mid 70s - 80s most of the FM home 
> receivers and even TVs had AFC buttons that you can switch in if you 
> would want it. Perhaps it is the nature of Frequency Modulation 
> coupled with less reliable tuning curcuitry in those equipment lead to 
> the use of AFC.  I remember a lot of the TVs actually had this and 
> when you presses the button, it would pick up the weak signal nearby 
> and center it.  Maybe this was used with Varactor tuning circuitry 
> which easily changed voltage to find the maximum strength of signal.
>
> But the idea of "Jurrasic Frequency Hopping System" just sounded 
> better to me at that time.  If I am not mistaken, Frequency Hopping 
> was invented by a Hollywood actress whose husband was a German 
> scientist. I don't know how she came up with the idea ( or am I 
> thinking of something else ) !...
>
> In modern Frequency Hopping Transmitter and Receivers, there are 
> algorithms used in order to eliminate errors of signals appearing in 
> the hopping range but not actually belonging to the intended 
> transmission.  So my proposed freq hop would be an unreliable one, 
> simply relying on signal strength / signal in the Bandwidth, making it 
> Jurrasic for sure ( unless there is an audio decoding in the receiver 
> )!...
>
> It would be interesting to know the +/- frequency range swing.  Please 
> let us know. 
>
> Ahmet
>