[GreenKeys] Tone frequency history?

[Harold Hallikainen]

On Thu, October 7, 2021 8:01 pm, ad7i wrote:
> Excellent question.  I've wondered about this as well.
>
> I don't know that this is relevant to the reason for choosing 2125 & 2975
> Hz, but I note that
>
> 2125 = 17 x 5 x 5 x5
>
> 2975 = 17 x 5 x5 x 7
>
> Paul, ad7i


Thanks! I'm seeing that before Bell 103, there was Bell 101. But I'm
finding very little information about that. Some of the information gave
me the idea it used amplitude shift keying instead of frequency, but I may
have misread that.

Harold

-- 
http://w6iwi.org